CHAPTER 18

Cyclovertical Deviations

he diagnosis and management of cyclovertical they may present insurmountable obstacles to a Tdeviations are special challenges to the oph- functional cure. thalmologist. There are several disorders that on The prevalence of cyclovertical deviations in first glance appear similar clinically but differ association with horizontal deviations or as iso- widely in etiology and management. As in no lated anomalies is high. White and Brown128 ob- other aspect of strabismology, correct diagnosis is served that in patients with motility disorders, of utmost importance, since an operation per- approximately half had isolated vertical anomalies formed on the basis of an erroneous interpretation and another third had combined horizontal and of the underlying problem may cause disastrous vertical muscle problems. Scobee103 found a verti- and permanent consequences with respect to the cal component in 43% of 457 patients with esotro- patient’s binocular function. Once the correct diag- pia. nosis has been made, medical and surgical man- Bielschowsky7 classified cyclovertical devia- agement of such deviations does not present any tions into five groups: (1) purely comitant vertical special problems, and the therapeutic results can deviations, (2) vertical deviations of paretic origin, be the most gratifying in the field of strabismus. (3) deviations with unilateral overaction of the Cyclovertical deviations differ from horizontal inferior oblique muscles, (4) dissociated vertical deviations in several aspects. Sensorial adaptations deviations, and (5) vertical deviations combined in the form of amblyopia or anomalous retinal with features of several of the other groups. This correspondence are noted far less frequently with classification is still of some usefulness today even this type of deviation than with horizontal strabis- though we have learned since Bielschowsky that mus. Comitance is rare, and the deviation is gener- elevation in adduction is not exclusively caused ally smaller in magnitude, yet the size of a cyclo- by an overacting inferior oblique muscle. vertical deviation is not an indication of the extent In this chapter nonparalytic and nonmechanical of the problem caused for the patient. Although cyclodeviations are described. Paralytic deviations some patients with well-developed binocular func- are discussed in Chapter 20, and hyperdeviations tions often are able, by motor fusion, to overcome caused by mechanical factors (endocrine myopa- surprisingly large vertical deviations, the low fu- thy, congenital fibrosis, and orbital floor fractures) sional reserve in the vertical directions in most are described in Chapter 21. others precludes this compensatory mechanism. Consequently, a hyperdeviation of only 1⌬ or 2⌬ Comitant Hyperdeviations can cause diplopia or blurring of vision, especially during reading. Such small residual hyperdevi- Etiology and Clinical Characteristics ations following surgical alignment of horizontal Truly comitant hyperdeviations occur infrequently. strabismus are of special clinical significance, for To find a patient with a significant vertical devia- 377 378 Clinical Characteristics of Neuromuscular Anomalies of the Eye tion of the same magnitude in all positions of gaze Terminology with either eye fixating and with the head tilted to either shoulder is indeed unusual. Anderson,2, p.12 The lack of precise etiologic information about in a survey of 600 patients with cyclovertical DVD is reflected by the plethora of terms in anomalies, was unable to find a single truly comi- use at one time or another: anatopia, alternating tant deviation. Repeated measurements in the di- hyperphoria or hypertropia, double hypertropia, agnostic positions of gaze in the majority of pa- occlusion hypertropia, alternating sursumduction, tients may reveal a paretic component or an dissociated double hypertropia, dissociated alter- apparently primary overaction of one or several nating hyperphoria, and dissociated vertical diver- cyclovertical muscles. The etiology of truly comi- gence. To speak in this context of alternating, tant deviations of a magnitude rarely exceeding a dissociated, double,orocclusion hyperphoria or few prism diopters is not clear. At one point, some hypertropia, as many authors (including Biel- 6 of the patients may have had a paretic deviation schowsky ) have, is incorrect, because DVD is that became comitant with the passage of time different from ordinary hyperdeviations. For in- (see Chapter 20). In others, an anomalous position stance, in a patient with right hypertropia, either of rest caused by anatomical or mechanical factors the right eye is elevated when the left eye is or abnormal innervation may be a causative mech- fixating or the left eye is depressed when the right anism. eye is fixating. On the other hand, in DVD, either eye elevates when the fellow eye is fixating. Alter- nating sursumduction, a term introduced by Lan- Therapy caster65 and Swan121 emphasizes the monocular nature of the movement (a duction and not a The very nature of comitant cyclovertical devia- version or vergence), and its use has become tions means that prisms are ideally suited for relief rather widespread. Nevertheless, this description of the patient. They should be distributed evenly is not completely accurate because the movements before the two eyes (base-down before the hyper- are not limited exclusively to sursumduction but tropic eye), and the prescription should be based contain substantial elements of excycloduction on the minimal prismatic power that provides and sometimes abduction. Moreover, the deviation comfortable single binocular vision. When per- does not always alternate but may be restricted to forming surgery to correct a coexisting horizontal one eye. For these reasons, we prefer the generic deviation, comitant hyperdeviations can be elimi- term dissociated vertical deviation, which carries nated by lowering the horizontal muscle insertions no implications with regard to the etiology of the of the hypertropic eye or raising the insertions of condition and for which the abbreviation DVD the hypotropic eye (see Chapter 26). has become widely accepted. Although no great friends of medical abbreviations, we will use DVD during the remainder of this discussion. Dissociated Vertical Deviations Clinical Characteristics Dissociated vertical deviation (DVD) is among DVD is characterized by the spontaneous drifting the most intriguing and least understood of all of either eye upward when the patient is fatigued forms of strabismus. Even though the unique clini- or daydreaming or when fusion is artificially inter- cal features of this anomaly clearly distinguish it rupted by covering one eye (Fig. 18–1). When the from other forms of vertical motor disturbance, elevated eye is covered, it may perform pendular, the diagnosis may be difficult when associated vertical movements. When the cover is removed, with other forms of strabismus, especially with the elevated eye will move slowly downward and cylcovertical deviations. Although Bielschow- settle in the primary position. sky8, p.34 credited Schweigger (1894),102 Stevens The amount of elevation when the eye is cov- (1895), and Duane (1896) for the first reports ered is variable, tending to increase after pro- of this entity, it was he who provided the first longed occlusion, and often differing between the comprehensive description and minute clinical two eyes. According to Bielschowsky6 several analysis of DVD.6 other features are present in most patients with Cyclovertical Deviations 379

while it manifests itself as an isolated excycloduc- tion in the other. Anderson2 and Lyle and Bridgeman69 drew at- tention to the association of a head tilt with DVD. The prevalence of anomalous head posture in this condition has been reported to range between 23%19 and 35%.5 Most authors reported the head to be tilted away from the eye with the larger vertical deviation19, 101 but the opposite has also been observed.5, 23 Passive tilting of the head to- ward the opposite of the side of the habitual pos- ture increases the vertical deviation, which has led FIGURE 18–1. Dissociated vertical deviation. A, Left eye to the conclusion that the anomalous head posture fixating. B, Right eye fixating. decreases the magnitude and thus improves the motor control of the type of alternatinng hyper- phoria investigated by these authors. De Decker DVD. These include excycloduction of the ele- and Dannheim de-Decker23 reported chin depres- vated eye and incycloduction of the fixating eye. sion in patients with bilateral dissociated devia- As the elevated eye returns to the primary position tions. Surgical correction of DVD improves the it incycloducts. This torsional movement of the head posture.23, 101 globe is often easily detected without magnifica- DVD occurs in patients with and without over- tion by the observer. Latent nystagmus, which action of the inferior oblique muscles and may often but not always has a cyclovertical compo- also be associated with overaction of the superior nent, may be associated with DVD.6 oblique muscles and an A-pattern exodeviation in These additional symptoms justify consider- downward gaze45, 71 (Fig. 18–2). The vertical angle ation of DVDs as a syndrome. Observation of the of dissociated deviations is usually somewhat less iris pattern and the conjunctival vessels will nearly in abduction than in adduction; however, it may always reveal incycloduction as the elevated eye also be larger in abduction.46 Latent nystagmus returns to the midline, indicating that it was ex- occurs in approximately half the patients with cycloducted while in the dissociated position. The DVD and, in fact, is seldom encountered in the excycloduction of the elevating eye may be ac- absence of this anomaly (see Anderson2, p.16). companied by a synchronous incycloduction of If a photometric neutral filter wedge is placed the fixating eye (cycloversion).54 Occasionally, ex- before the fixating eye while the other eye is cycloduction of each eye under cover or spontane- occluded and elevated, the eye behind the cover ously and latent nystagmus may be the only mani- will make a gradual downward movement, and festation of a dissociated deviation. In such cases may even move below the primary position as the we speak of a dissociated torsional deviation visual input to the fixating eye is progressively (DTD). In other cases, the full syndrome with its decreased by the filter wedge. When the wedge is vertical component may involve one eye only moved from positions of greater to lesser filter

FIGURE 18–2. Dissociated vertical deviation with overaction of both superior oblique muscles. A, Left hypertropia with the right eye fixating and right hypertropia with the left eye fixating. B, Underaction of both inferior oblique and overaction of both superior oblique muscles. 380 Clinical Characteristics of Neuromuscular Anomalies of the Eye density, the eye behind the cover will elevate. CASE 18–1 This intriguing observation was first reported by Bielschowsky6 and has become known as the This 26-year-old man has had crossed eyes since Bielschowsky phenomenon. Bielschowsky ex- infancy. Surgery was performed on the eye muscles plained the phenomenon that bears his name in when he was 3 years of age. For the past 13 years he has experienced intermittent double vision. Ex- the following manner: When the visual input to amination showed corrected visual acuity of 6/4.5 the fixating, say, the right eye is decreased by OD and 6/6 OS. He wore prescription glasses to holding filters of increasing density before it, the correct a mild compound myopic astigmatism. The effort to maintain fixation triggers an abnormal patient had fairly pronounced latent nystagmus and an esotropia of 14⌬ at near and distance fixation. In innervation to the elevators. The effort to maintain addition he had 18⌬ right hypertropia with the OS fixation with the right eye against this innervation fixating and 10⌬ left hypertropia with the OD fixating. elicits a compensatory innervation to the de- He exhibited characteristic incycloduction as each pressors. The left eye follows this innervation elevated eye took up fixation in primary position. A under cover and returns to the primary position or V pattern was absent, and there was no inhibitional palsy of the contralateral superior rectus when he even below it. fixated with the adducted elevated eye. As soon as A DVD may occasionally occur as an isolated the eyes were dissociated, the patient became phenomenon in patients in whom binocular func- aware of diplopia. The red-glass test established that tions are apparently normal, but is found often in the diplopia was in accord with the deviation; that is, the images were uncrossed and had a vertical association with infantile esotropia and less often component, the laterality of which depended on with accommodative acquired esotropia, exotro- which eye was fixating. The diagnosis was residual pia, and heterotropia of sensory origin.64, 72, 109, 132 esotropia with a DVD and absence of suppression. An association with Duane’s syndrome has also No treatment was advocated. been described.17, 95 The high prevalence of DVD in essential infantile esotropia has been discussed Campos and coworkers14 pointed out that sup- in Chapter 16 and it is of interest that a similarly pression is not the only mechanism that accounts high rate of occurrence has been reported in infan- for absence of diplopia in this condition by show- tile exotropia.73 In spite of a careful search the ing that a binocular vertical perceptional adapta- condition is rarely diagnosed in infancy. In our tion may exist in these patients. experience the diagnosis is most commonly made Diplopia can be elicited in most patients with between the ages of 2 and 5 years and often a dark-red glass, and the amount of separation years after surgical alignment of the horizontal between the images is used to measure the ampli- deviation. The age at surgical alignment could not tude of elevation of each eye (see Chapter 12). be correlated with the manifestation of DVD.47 The fact that the patient will localize the red image DVD is usually bilateral and asymmetrical. Of below the fixation light, regardless of whether the 80 the 170 cases observed by us in a group of 408 red glass is held before the right or left eye, children with essential infantile esotropia, only 24 clearly differentiates a DVD from other forms of (14%) were unilateral and only 13 (9%) were cyclovertical anomalies in which the red image symmetrical. However, unilateral occurrence is of- is localized below or above the fixation light, 6 ten observed in deeply amblyopic eyes and in depending on which eye fixates. sensory heterotropia.96, 109 The commonly oc- curring asymmetry between the two eyes is re- versed in the supine position with the head tilted Measurement back: the eye with a larger deviation in the upright An accurate quantitative assessment of DVD may position has a smaller one with the patient supine be obtained provided visual acuity in each eye is and the head tilted back.39 This observation sug- sufficient to visualize the fixation target, using a gests a possible effect of inputs from otolithic and modification of the prism and cover test. As the possibly neck muscle sensors on the amplitude of patient focuses on the fixation target at 6 m dis- a DVD. tance, the occluder is quickly shifted to the fixat- An active suppression mechanism usually will ing eye, allowing the previously dissociated and eliminate diplopia in patients with a spontaneous elevated eye to take up fixation. The cover is then DVD. Exceptions to this rule are rare but do occur returned to the nonfixating eye. As the alternate as shown in Case 18–1. cover test is continued, increasing amounts of Cyclovertical Deviations 381 base-down prisms are held under the occluder in unknown. There is no question, however, that the front of the nonfixating eye until the downward impulse for a DVD must originate in the fixating fixation movement of that eye is neutralized. The eye. Bielschowsky8, p. 36 emphasized the need to procedure is then repeated with the fellow eye differentiate between a hyperdeviation based on fixating. anatomical conditions, that is, an anomalous posi- tion of rest, and the dissociated deviations of in- 116 Etiology nervational origin. Spielmann convincingly con- firmed this difference by showing that DVD does Of the numerous theories advanced to explain the not occur when fixation is prevented by covering mechanism of this intriguing anomaly in the past, both eyes with translucent occluders (Fig. 18–3). only a few will be mentioned in this chapter. Spielmann111–113 assumed that DVD is caused by Elastic preponderance of the elevator or the de- an imbalance of binocular stimulation. Although pressor muscles102; paretic factors25 especially bi- this may explain the frequent occurrence of DVD lateral paresis of the depressor muscles104, p. 183; in essential infantile esotropia and the occasional and imbalances between the amount of innervation occurrence with sensory heterotropias, it does not originating from each vestibular organ87 have been account for DVD in patients with otherwise nor- cited as causes in the older literature. For other mal binocular functions. explanations, see White,127 Verhoeff,125 Posner,91 Several additional explanations were proposed Crone,19 Helveston,46 and Houtman and cowork- in recent years. From the direction of the cycloro- ers.53 It has even been reported that DVD may be tation of the elevating eye (extorsion) and the caused by an abnormal visual pathway routing fixating eye (intorsion) several investigators31, 41, 93 similar to that described in albinism35 (see Chapter have concluded that the vertical vergence move- 9). However, as one may have expected, this find- ment must be predominantly mediated by the ing could not be reproduced.3, 10, 62, 135 oblique muscles because the vertical rectus muscle The results of more recent investigations11, 15, 41, would produce a cyclorotation in the opposite 93, 94, 133 are in basic agreement with what direction. Guyton41 and Cheeseman and Guyton15 Bielschowsky6 so lucidly described in 1931 and believe that this oblique muscle–generated cyclo- in his later publications7, 8: DVD is caused by a version is a purposeful eye movement that damps vertical vergence signal that elevates the occluded latent cylovertical nystagmus to improve visual eye and would depress the fixating eye if it were acuity. The accompanying elevation of the non- not for a simultaneous supraversion impulse that fixating eye, the DVD, is seen as an unavoidable cancels the innervation to depress the fixating eye while at the same time, according to Hering’s law, increasing the innervation flowing to the elevators of the occluded eye. Bielschowsky arrived at this explanation by meticulous clinical observation, sound reasoning, and without the benefit of mod- ern search coil recording techniques that have essentially confirmed the validity of this innerva- tional pattern and sequence41, 93, 133 The origin of the vertical vergence innervation is still a matter of dispute. Bielschowsky6 sus- pected an alternating and intermittent excitation of both subcortical centers that govern vertically divergent eye movements. He cited as examples for such movements and support for the existence of such centers skew deviation and seesaw nystag- mus and felt that the unilaterality of the condition in some cases is ‘‘based on the coincidence of FIGURE 18–3. Combined vertical and horizontal dissoci- the voluntary fixation impulse with the involun- ated deviation in the right eye (A) and predominantly tary action of one of the vertical divergence cen- vertical dissociated deviation in the left eye (B). C, Ab- 8, p. 35 sence of dissociated vertical deviation in the fixation-free ters.’’ The reason for this abnormal excitation position when both eyes are covered with translucent of hypothetical vertical divergence centers remains Spielmann occluders. For details, see text. 382 Clinical Characteristics of Neuromuscular Anomalies of the Eye and undesirable byproduct of this nystagmus vergence is difficult to accept in view of the fact damping mechanism (see Chapter 23). There are that a latent cyclovertical nystagmus is not a con- a number of observations that are difficult to rec- sistent feature of DVD.6, 46, 56, 93 Finally, if DVD oncile with this theory,82 which is based on the were elicited to dampen a latent nystagmus we concept of the inferior oblique muscle being the would expect the nonfixating eye of a patient with primary elevator in vertical vergences. In DVD DVD to elevate each time a patient with latent the dissociated eye elevates not only in adduction nystagmus reads his or her threshold acuity line but also in primary position and abduction (Fig. on the office chart. Not only is this not the case 18–4). In fact, in some cases the elevation in but, on the contrary, DVD manifests itself typi- abduction is greater than in adduction. Clearly, cally when patients are daydreaming and unin- these are gaze positions in which the inferior volved in active visual activities. oblique muscle has little or no elevating power Van Rijn and coworkers94 felt that DVD repre- and the superior rectus muscle must be the princi- sents a form of asymmetrical vertical heterophoria pal elevator. While it is indisputable that excyclo- and could be considered as enhancement of a duction of an elevating eye can only be caused by phenomenon that is present in normal subjects as the inferior oblique muscle, it does not inescap- well. They showed in patients with alternating ably follow that this muscle is also the predomi- hyperphoria, who have a right hyperphoria with nant elevator. One must also consider the possibil- the left eye fixating and a left hyperphoria with ity that both the superior rectus and inferior the right eye fixating, asymmetries of the vertical oblique muscles co-contract during elevation but heterophoria angles, depending on which eye was that the stronger excyclotorsional effect of the fixating. It is true that alternating hyperphoria, inferior oblique overrides the weaker incyclotor- which, incidentally, is an extremely rare clinical sional effect of the superior rectus muscle. More- finding, bears a superficial resemblance to DVD. over, in our experience and that of others45 a However, it is debatable whether these conditions DVD continues unabated after a myectomy of are as closely related as assumed by these authors. the ipsilateral inferior oblique muscle. Also, a A vertical heterophoria becomes manifest as soon nystagmus dampening purpose of the vertical as fusion is disrupted and the eye drifts into its anomalous position of rest. In DVD, the vertical movement is caused by an active vergence in- nervation and fusion is not a factor in controlling the deviation because it may occur in patients without the ability to fuse. Some authors have speculated that DVD is a manifestation of atavistic oculomotor reflexes that are present in birds and fish.11, 14, 20, 41, 46, 94 Crone20 considered that DVD may represent a phyloge- netic residuum of monocular vertical movements present in birds and inhibited in normal humans. Brodsky11 suggested that DVD is a primitive dor- sal light reflex in which asymmetrical visual input to the eyes evokes a vertical divergence move- ment. In lateral-eyed animals this reflex serves as a primitive visual-vestibular righting response. Suppressed in normal humans, it is thought to manifest itself when early-onset strabismus pre- cludes normal binocular development. Can the stimulus for the dorsal reflex in fish be compared FIGURE 18–4. Dissociated vertical deviation in different to the stimulus situation in a human strabismic gaze positions. A, In the case of a dissociated vertical deviation of the left eye, elevation occurs in adduction, infant? A fish illuminated from one side depresses primary position, and, to a lesser degree, in abduction. B, the eye ipsilateral to the light source and elevates When the elevated adducted left eye takes up fixation, the contralateral eye. The stimulus for this reflex the covered right eye will be elevated to an equal degree. (From Noorden GK von: Atlas of Strabismus, ed 4. St eye movement, which does indeed resemble a Louis, Mosby–Year Book, 1983.) vertical vergence response, is a difference in illu- Cyclovertical Deviations 383 mination between the two eyes. However, such Third, when a patient with an overacting infe- differences do not occur in strabismus, as each rior oblique muscle fixates with the involved eye eye receives the same amount of light. In strabis- in the field of action of that muscle (elevation mus, the asymmetry of visual input that disrupts and adduction), the contralateral superior rectus binocularity is caused instead by the incongruity muscle will underact (see Fig. 20–1). This appar- of the retinal images formed in each eye. ent paresis of the superior rectus muscle has been To summarize, it is fair to state that despite discussed under inhibitional palsy (Chapter 20). numerous attempts to clarify it, the etiology of Conversely, in patients with DVD who are tested DVD is still obscure. Bielschowsky’s original ex- in the same manner, underaction of the contralat- planation of this form of strabismus, confirmed by eral yoke muscle does not occur (Fig. 18–4, B). modern eye movement recording techniques, has Fourth, in patients with inferior oblique overac- established indisputably that DVD is a vertical tion, the speed of the refixation movement of the vergence eye movement. However, the stimulus eye after covering the fellow eye is rapid (200Њ to for this movement and its relationship to various 400Њ/s) compared with the much slower infraduc- forms of strabismus, especially to essential infan- tion movements in patients with DVD, which are tile esotropia, have yet to be convincingly identi- usually between 10Њ and 200Њ/s.46 fied. Fifth, the characteristic slow, tonic incycloduc- tion of the eye as it returns from the dissociated to the primary position cannot be observed with Differential Diagnosis equal facility when overaction of the inferior oblique is present. In that case refixation after Even though the pattern of the deviation and the covering the fixating eye is also accompanied by results of the red-glass test are clearly different in incylcoduction but this movement is so fast that it DVD from those in other cyclovertical anomalies, often escapes observation. clinicians sometimes confuse this condition with The differential diagnosis between these two upshoot in adduction caused by overaction of the conditions is summarized in Table 18–1 in which inferior oblique muscles (see p. 386). To be sure, additional distinguishing findings are listed. Clear overaction of the inferior oblique muscle may distinction between them is clinically important; occur in patients with DVD, but such overaction for example, a recession or myectomy of the infe- cannot be held responsible for this anomaly. Sev- rior oblique will have no effect on upshoot in eral clinical findings clearly distinguish DVD from adduction if the patient actually has a DVD. overaction of the inferior oblique muscle. When associated with comitant or paretic First, in DVD the covered eye becomes ele- cyclovertical anomalies the diagnosis of DVD is vated in abduction, primary position, and adduc- more difficult. When evaluating such patients, one tion (Fig. 18–4). Conversely, with overaction of must take into account the starting position of the inferior oblique muscles, each eye becomes each eye before the cover is applied. For instance, elevated primarily in adduction and never in ab- if a right hypertropia is associated with a DVD, duction unless there is coexisting contracture of the right eye will become further elevated under the ipsilateral superior rectus muscle. Unlike the cover, and the fellow left hypotropic eye when DVD, overaction of the inferior obliques is com- covered will move upward the same amount but monly associated with a V-pattern esotropia. The may only reach the midline, since it began its reason for elevation in adduction in a DVD is that movement from a depressed position. Careful ob- the adducted eye becomes occluded by the nasal servation of each eye before, during, and after the bridge and fusion is suspended. In children under cover has been applied is essential to detecting a the age of 2 to 3 years the nasal bridge has not dissociated vertical component in a patient with a yet fully developed and the upshoot in adduction comitant or paretic cyclovertical deviation. is rarely seen. Second, DVD is found also in patients in whom Therapy there is no noticeable overaction of the inferior oblique muscles and actually occurs frequently During the first half of the twentieth century clini- in those with underacting inferior oblique and cians took a rather passive attitude toward treat- overacting superior oblique muscles45, 71 (see Fig. ment of DVD. This conservatism probably finds 18–1). its roots in Bielschowsky’s6 teachings that this 384 Clinical Characteristics of Neuromuscular Anomalies of the Eye

TABLE 18–1. Differential Diagnosis: Dissociated Vertical Deviation vs. Inferior Oblique Overaction

Dissociated Vertical Inferior Oblique Deviation Overaction

Elevation From primary position, adduction Maximal in adduction, never and abduction in abduction Superior oblique action May overact Usually underaction V pattern Absent Often present Pseudoparesis of contralateral superior rectus Absent Present Incycloduction on refixation Present Absent Saccadic velocity of refixation movement 10Њ–200Њ/s 200Њ–400Њ/s Latent nystagmus Often present Absent Bielschowsky phenomenon Often present Absent condition does not lend itself to optical or opera- the two eyes when the deviation is asymmetrical. tive therapy as do comitant or paretic deviations. This approach has yielded a cure or significant Bielschowsky cited cases of torsional diplopia improvement (defined as a cosmetically insignifi- produced by surgery on the superior rectus mus- cant residual angle) in 23 (72%) of 32 patients cles, and stated that therapy, if contemplated at after a follow-up of at least 3 years.32 Contrary to all, should be directed toward strengthening the our earlier concern that such an extensive weaken- fusional mechanism. ing procedure would produce a paresis of the Patients with DVD usually are asymptomatic, superior rectus, we have not observed this compli- and complaints of diplopia have been an infre- cation. The effectiveness of superior rectus muscle quent problem in our experience; however, when recession in terms of correction of a deviation in the patient is daydreaming or tired, the elevated prism diopters per millimeter of recession in other position of either eye may become conspicuous forms of vertical strabismus and the lesser effect and a source of embarassment to the patient. In of this procedure in a DVD of the same magnitude that case surgery may be considered. We have not emphasize the unique position of this anomaly observed DVD in adults as often as we have in among other forms of strabismus. children, and were, perhaps erroneously, under the Several authors have in recent years reported impression that this disorder tends to improve good results with anterior displacement of the with time. However, Harcourt and coworkers44 inferior oblique muscle9, 13, 61, 97, 108, 119, 123 and this followed 100 patients with DVD for as long as treatment has become the procedure of choice for 7.3 years and found no significant decrease in the some. However, we prefer recession of the supe- deviation during this period of observation. rior rectus muscle(s), which is less likely to cause Surgical procedures preferred by various au- some of the complications reported after surgery thors are (1) recession of the superior combined on the inferior oblique insertion (see Chapter 26). with resection of the inferior rectus muscles,59 (2) The question has been debated whether surgery resection of the inferior recti,90 (3) retroequatorial should always be performed in both eyes even myopexy (posterior fixation) of the superior recti though the deviation may be present preopera- combined with27, 46, 58, 117 or without68, 76, 77 a reces- tively only in one eye. It is not uncommon and sion of these muscles, (4) unconventionally large quite disappointing to have a patient return after recessions (7 to 10 mm) of the superior recti,32, 68, surgery in one eye with a DVD in the fellow eye. 70, 124 and (5) anterior displacement of the inferior However, since in our experience this does not oblique insertion, which may be combined with happen in every instance of asymmetrical occur- superior rectus recession.9, 13, 61, 97, 108, 119, 123 rence we operate on both eyes only when a devia- Our initial enthusiasm for using a conventional tion can be diagnosed preoperatively in both eyes. (4 to 5 mm) recession of the superior recti com- Recurrences are not uncommon even after un- bined with a retroequatorial myopexy 12 to 15 conventionally large recessions of the superior mm behind the original insertion27 has waned be- recti and require additional surgery consisting of cause of many recurrences occurring as late as a 4- to 5-mm resection of the inferior rectus mus- several years after an initial satisfactory result. cle. Full correction or improvement, as defined Currently, we prefer 7- to 9-mm recessions of the above, can in our experience be achieved in 92% superior recti and vary the amount of surgery in of the patients after this operation.33 Cyclovertical Deviations 385

Although in most patients with a conspicuous adduct during attempts to neutralize the horizontal DVD surgery is the recommended treatment, the deviation with base-in prisms, and that the exode- possible effectiveness of a conservative approach viation may be strictly unilateral. Moreover, they should not be ignored. This is especially true in described what is similar to the Bielschowsky patients with asymmetrical involvement or those phenomenon in DVD: when neutral density filters accustomed to wearing glasses. For example, a are placed before the fixating eye the abducted patient without binocular vision (after horizontal dissociated eye returns to the primary position and surgical alignment in infantile esotropia) may ex- may even adduct. Since we became aware of this hibit a significant DVD of the left eye when fixat- condition we have observed several patients with ing with the right eye, but only an insignificant a pure dissociated horizontal deviation in one eye deviation of the right eye may occur with the and a pure DVD in the fellow eye. left eye fixating. A slight optical blur induced by For dissociated exodeviations a 5- to 7-mm increasing the power of the lens over the right eye recession of the lateral rectus muscle of the in- sph usually is sufficient) or a contact volved eye is recommended when the size of the 2.00ם) lens (see Case 24–1, p 538) will switch fixation deviation is such that the patient or his or her preference to the left eye, and the DVD is no parents desire correction. Satisfactory results have longer a cosmetic problem. Simon and cowork- been reported using this approach.131 ers110 have confirmed the efficacy of this approach This may be combined with recession of the in selected cases but have used atropine rather superior rectus when associated with a vertical than optical penalization. component. In patients whose dissociated devia- tion is predominantly vertical with only a small horizontal component, we have found a large re- Dissociated Horizontal cession of the superior rectus is usually sufficient Deviations to correct both problems. Spielmann115 described dissociated esodevi- It has only recently been recognized that DVD ations that occur when either eye is covered with may also have a horizontal component. Raab92 the semiopaque occluder. When both eyes are oc- mentioned in 1970 that the vertical movement in cluded (fixation-free position) the eyes remain DVD may be accompanied by abduction. Little aligned, which distinguishes this condition from attention was paid to this observation until the esophoria. In our experience dissociated esodevi- term dissociated horizontal deviations (DHDs) be- ations occur much less frequently than dissociated came established in the literature.30, 113, 130, 134 exodeviations. If the deviation becomes intermit- The condition is characterized by intermittent, tent and a cosmetic consideration, a posterior fix- asymmetrical abduction and elevation of the disso- ation of the medial rectus muscle of the involved ciated eye (see Fig. 18–2A). Occasionally, DHD eye 14 mm behind its insertion is effective. Obser- occurs in an isolated form, not accompanied by a vation rather than surgery has been advocated vertical deviation. As with DVD, latent nystagmus when the esotropia changes to exotropia during and excyclotropia of the deviated eye are fre- visual inattention.132 quently associated findings. Interestingly, and per- In view of the great clinical similarity of disso- haps significantly, Wilson and coworkers132 found ciated vertical, torsional, and horizontal devia- that only two of six patients with a prominent tions, we agree with those who consider these DHD had a history of essential infantile esotropia. strabismus forms as variations on the same theme The remainder had accommodative esotropia, a rather than as different entities sui generis.114, 134 condition that is only infrequently associated with DVD. These authors also reported that when DHD is associated with esotropia the patient may be- Elevation in Adduction come exotropic during periods of visual inatten- (Strabismus tion. Sursoadductorius) In an earlier report Wilson and McClatchey130 had pointed out that unlike in ordinary intermittent Clinical Characteristics exotropia, the alternate cover test reveals less exo- deviation than when the eye abducts spontane- When examining the versions, one may find eleva- ously or under cover, that the fixating eye may tion of an eye as it moves toward adduction (Fig. 386 Clinical Characteristics of Neuromuscular Anomalies of the Eye

18–5). Once in a position of maximal elevation in over the superior rectus muscle of the abducted adduction, the eye will be elevated further than a eye. It is of interest in this connection that Lisch normal eye. This anomaly may be unilateral or and Simonsz66 have reported in normal subjects bilateral and has been termed strabismus sursoad- up- and downshoot in adduction after prolonged ductorius or, if the opposite situation occurs, that monocular patching. This may suggest that there is, the eye shows depression in adduction, strabis- is a natural tendency for elevation and depression mus deorsoadductorius. These Latin terms have in adduction to occur but that under normal condi- never become popular in the English strabismo- tions such eye movements are controlled by fu- logic literature where they are used in their trans- sion.66 Scobee104, p.378 agreed that overaction of the lated forms, elevation (or upshoot) in adduction inferior oblique muscle is normal because of the and depression (or downshoot) in adduction. Up- increased impulse required by the mechanically shoot in adduction in its bilateral form is charac- disadvantaged superior rectus muscle. This strong terized by left hypertropia in dextroversion and impulse is communicated to its yoke muscle, the right hypertropia in levoversion (double or alter- inferior oblique of the adducted eye hidden behind nating hypertropia), but a vertical deviation is the nose. He also stated that the elevating action present infrequently in primary position. Upshoot of the inferior oblique muscle in adduction is in adduction is an isolated phenomenon or occurs greater than the depressing action of the superior with esotropia or exotropia, often associated with oblique muscle. Therefore there would be an im- a V pattern (see Chapter 19). It is frequently balance if the eyes should be dissociated by the observed in infantile esotropia. It is often automat- nose, and the result would be an upshoot of the ically and erroneously assumed that elevation in adducted eye. Lancaster65 agreed with this view. adduction is caused by inferior oblique overac- Guibor40 suggested that inferior oblique overac- tion, that is, by excessive innervation flowing to tions could be caused by a synkinesis of that that muscle. While this is often the case, we shall muscle with the ipsilateral medial rectus muscle see that there are other causes for this condition. owing to an impulse spread within the central nervous system. Etiology None of these older explanations are convinc- ing and it remains quite doubtful whether a true OVERACTION OF THE INFERIOR OBLIQUE primary overaction of an oblique muscle on an MUSCLE. It has been customary to distinguish innervational basis exists at all. The discovery of between primary and secondary overactions of this muscle pulleys (see below) has directed our atten- muscle. Primary overaction of the inferior oblique tion to other etiologic possibilities for this appar- muscle in which there is no evidence for a past or ent overaction. We are in agreement with Clark present ipsilateral superior oblique paralysis or and coworkers16 who lamented the use of diagno- paresis is difficult to explain. A V-pattern type of sis-laden terms for ocular motility disorders except strabismus is often present in such patients and, in cases where the etiology is clear. For this reason typically, the Bielschowsky head tilt test is nega- and because there are several causes for elevation tive. This condition occurs frequently in essential in adduction that are unrelated to excessive infe- infantile esotropia. rior oblique muscle contraction, we recommend The explanations given for apparent primary that the terms primary overaction of the inferior overaction in the older literature are vague, to say oblique (or, for that matter, of the superior oblique the least. Duane,25 for instance, suggested that muscle) should be abandoned in favor of the more there is normally an upshoot of the adducted eye generic elevation (or upshoot) in adduction or because of the greater mechanical advantage of depression (or downshoot) in adduction. the inferior oblique muscle of the adducted eye Secondary overaction of the inferior oblique

FIGURE 18–5. Elevation in adduction. Marked left hypertropia in dextroversion and right hypertropia in levoversion. No vertical deviation in primary position. Cyclovertical Deviations 387 muscle is easier to understand and is caused by but abduct and depress the eye (downshoot). The paresis or paralysis of the ipsilateral superior elevation in adduction is usually more prominent oblique muscle or by paresis or paralysis of the than the depression in abduction, which may even contralateral superior rectus muscle when the pa- be absent. This may be due to structural differ- tient fixates with the paretic eye. In the latter ences between the medial and lateral aspects of situation the upshoot in adduction is actually the orbit. It is of historical interest in this connec- caused by increased innervation flowing to the tion that Bielschowsky8, p.169 documented a case of inferior oblique muscle, according to Hering’s law. an exotropic patient in whom a right hypertropia However, in the former condition the upshoot in caused by an apparently overacting inferior adduction is not caused by excessive innervation oblique muscle disappeared after merely advanc- of the inferior oblique muscle but by a lack of ing and lowering the insertion of the medial rec- tonus of its paralyzed antagonist. In this situation tus muscle. a normal innervational impulse will suffice to DUANE SYNDROME. Another cause of elevation cause the eye to overshoot in the field of action in adduction, unrelated to inferior oblique overac- of the inferior oblique. tion, is the result of co-contraction of the hori- A similar situation exists when the balance zontal rectus muscle in Duane’s syndrome (see of forces between superior and inferior oblique Chapter 21). muscles is offset by anatomical rather than inner- vational causes, as in plagiocephaly (see Chapter DISSOCIATED VERTICAL DEVIATION. Elevation 19). Here, the recessed trochlea has changed the in adduction caused by DVD when fusion is inter- plane of the superior oblique tendon, which places rupted by the nasal bridge has been mentioned the inferior oblique at a functional advantage over above. the superior oblique, which causes an upshoot in Therapy adduction. In the following discussion we shall see that When elevation in adduction is caused by an over- elevation in adduction may be caused by a number acting inferior oblique muscle, treatment, when of other factors. indicated, is surgical and should consist of a weak- ening procedure on that muscle. In view of the HETEROTOPIA OF RECTUS MUSCLE PULLEYS. different etiologies for upshoot in adduction dis- 16 Recent work by Clark and coworkers has pro- cussed above, Spielmann115 warned against the vided evidence that what appears as primary over- indiscriminate use of inferior oblique weakening action of an oblique muscle may actually be a procedures for this condition. It seldom presents a secondary overaction of both elevators caused by cosmetic problem, considering that the eyes rarely heterotopia of muscle pulleys (see Chapter 3). move from primary position more than 15Њ to Because of the significance of these findings with either side under casual conditions of seeing. Sur- respect to the etiology of A and V patterns they gery is done mostly for functional reasons, that is, will be discussed in Chapter 19 when the hypertropia in adduction presents an OCULAR AND ORBITAL TORSION. For a discus- obstacle to fusion in lateral gaze or a V pattern sion of the roles of ocular and orbital torsion exists that disrupts fusion in upward (V exotropia) in producing upshoot in adduction, the reader is or downward (V esotropia) gaze. directed to Chapter 19, where this mechanism is In apparently unilateral overaction of the infe- discussed in connection with the etiology of A- rior oblique muscle, a careful search should al- and V-pattern strabismus. It will suffice to say ways be made in the fellow eye. After myectomy here that excyclotropia of an eye may cause eleva- or recession of an overacting inferior oblique mus- tion in adduction and depression in abduction in cle, it is not unusual for overaction in the fellow 129 the absence of increased innervation of the oblique eye to become manifest. muscles (Fig. 18–6). When the eye is excyclo- torted the medial rectus muscle will no longer act Depression in Adduction as a pure adductor but will gain elevating action (Strabismus as well. Thus, medial rectus contraction will not Deorsoadductorius) only adduct but will also elevate the eye (upshoot) under these circumstances. Likewise, the lateral As mentioned in the preceding paragraph in con- rectus muscle will no longer be a pure abductor nection with elevation, a depression in adduction 388 Clinical Characteristics of Neuromuscular Anomalies of the Eye

FIGURE 18–6. A, Elevation of the adducted and depression of the abducted and right eye in a patient who was orthotropic in primary position and had otherwise normal ductions and versions. B, Fundus photographs show a large right excyclotropia of the right eye.

(Fig. 18–7) may have more than one cause. Again, standing paralysis of the contralateral superior we must distinguish between primary and second- oblique muscle (see p. 435). In view of the relative ary forms. Secondary overaction is well under- frequency of superior oblique paralyses when stood and may occur on the basis of paresis or compared with paralysis of the inferior oblique paralysis of the ipsilateral inferior oblique muscle and inferior rectus muscles, it is not surprising or of the contralateral inferior rectus muscle. An- that depression in adduction occurs less frequently other cause of secondary overaction is contracture than elevation. of the contralateral superior rectus muscle, which As in the case of so-called primary overaction is occasionally seen in conjunction with long- of the inferior oblique muscle the etiology of

FIGURE 18–7. Left, Depression of either eye in adduction. Center, Fusion in primary position. Right, Apparent overaction of both superior oblique muscles with marked exodeviation (A pattern) in downward gaze. (From Noorden GK von: Atlas of Strabismus, ed 4. St Louis, Mosby–Year Book, 1983.) Cyclovertical Deviations 389 apparently primary overaction of the superior such complaints are easily misinterpreted, as oblique is obscure and, analogously to the former, pointed out by Kushner.63 The results of fundus we prefer the more generic term depression in photography (see Fig. 18–6), the Maddox double adduction for this condition. The recent findings rod test, and scotometry67 show that cyclodevi- of heterotopic muscle pulleys to explain a down- ations occur with great regularity and frequency shoot on adduction on a mechanical basis has with any disturbance of the oblique and, to a been mentioned (see p. 387). Ocular or orbital somewhat lesser degree, vertical rectus muscles. incyclotorsion may also cause depression in ad- Curiously, however, with the exception of paretic duction, similar to the elevation produced by ex- conditions of recent onset,42 particularly traumatic cyclotorsion. Duane’s syndrome with co-contrac- unilateral or bilateral superior oblique paralysis, tion of the horizontal rectus muscles and Brown’s symptoms related to cyclotropia—such as tor- syndrome are other causes. sional diplopia, dizziness, and difficulties in nego- tiating stairways, steps, and street curbs—are sel- dom encountered in clinical practice. Cyclodeviations There are several reasons why patients with cyclodeviations are commonly asymptomatic.43, 79 In cyclotropia the eyes are misaligned around the First, we must consider that cyclodeviations re- anteroposterior axis either as an isolated distur- main compensated for by cyclofusion through bance of ocular motility or, more frequently, in cyclovergences.21, 52, 57, 86 In such patients the Mad- association with any other form of strabismus. In dox rods (see Chapter 12) will show various de- most instances, cyclodeviations are caused by an grees of cyclotropia. However, when tested with imbalance between the muscle pair affecting intor- Bagolini lenses and the coexisting vertical or hori- sion (superior oblique and superior rectus mus- zontal deviations are prismatically corrected, cles) and the muscle pair producing extorsion of cyclotropia will be absent.99 This discrepancy in the globe (inferior oblique and inferior rectus mus- testing results is explained by the fact that Maddox cles). Consequently, such deviations are associated rods disrupt fusion, whereas Bagolini lenses do almost invariably with paretic or paralytic cyclo- not. Ruttum and von Noorden99 pointed out that vertical muscle problems, particularly those whereas the Maddox test is of value in substantiat- caused by dysfunction of the oblique muscles. ing and measuring cyclotropia, it addresses the On the other hand, cyclodeviations also occur in position of the eye only under dissociated viewing association with DVD, in the A and V patterns of conditions. The Bagolini test result, on the other strabismus without an obvious paretic component, hand, predicts how a patient will handle a cyclo- in endocrine ophthalmopathy, myasthenia gra- tropia by cyclofusion when coexisting vertical and vis,122 plagiocephaly,55 after surgery for retinal de- horizontal deviations are surgically eliminated. tachment,72 and in heterotopia of the macula, sec- The question whether cyclofusion occurs ondary to retinal traction.105 purely on a sensory basis or has a motor compo- In recent years iatrogenic cyclodeviations have nent has been discussed in Chapter 4. It has been been produced surgically as a consequence of claimed in the literature that in cyclophoria the macular rotation for age-related macular degener- involved eye realigns itself around its anteropos- ation. terior axis under the influence of cyclofusion.1, 26 However, we have been unable to ascertain the Diagnosis presence of such a corrective cycloduction by di- rect observation (see also Jampel and coworkers57) The diagnosis of cyclodeviations is discussed in or by comparison of fundus photographs taken Chapter 12. under monocular and binocular viewing condi- tions.42, 78, 79 Likewise, Locke67 found no change in Clinical Characteristics the position of the vertically displaced blind spot of cyclotropic patients when perimetry was per- No studies are available that reflect the prevalence formed under monocular and binocular conditions. of cyclodeviations. Most ophthalmologists do not On the other hand, Herzau and Joos48 noted varia- routinely test for such anomalies unless the patient tions in position of the blind spot during monocu- specifically complains about torsional diplopia. In lar and binocular perimetry on the phase differ- the absence of a cyclovertical muscle imbalance ence haploscope in patients with cyclovertical 390 Clinical Characteristics of Neuromuscular Anomalies of the Eye strabismus and concluded that cyclofusional movements must exist after all (see also Kol- ling60). However, the velocity of such movements is slow and their amplitudes are small so that they may easily escape detection with the naked eye.49

SENSORIAL ADAPTATIONS. Many patients are unaware of image tilting because of suppression, anomalous retinal correspondence,4 or, in rare in- stances, a compensatory anomalous head pos- ture.85 However, these mechanisms do not explain the common and puzzling finding that a patient whose eye is found to be rotated around the an- teroposterior axis on ophthalmoscopy or fundus photography (see Chapter 12) fails to see a tilted visual environment when the nonparalyzed eye is occluded. The reason for this frequent finding, for instance, in patients with congenital superior oblique palsy, is that adaptations have developed that are quite unique to cyclodeviations. The older literature contains references to the FIGURE 18–8. Reorientation of the retinal meridians in a left eye with excyclotropia (view from behind the globe). fact that the spatial response of retinal elements The image of a cross will no longer be imaged on the can be reordered along new vertical and horizontal normal vertical (V1–V2) and horizontal (H1–H2) retinal me- meridians,50, 51 and the famous case of Sachs and ridians but on the new vertical (Va1–Va2) and horizontal (Ha –Ha ) meridians. Despite the objective excyclotor- 100 1 2 Meller is cited often in this connection. Ruttum sion, a cross imaged on these new retinal meridians will and von Noorden98 and Olivier and von Noorden89 not be seen as tilted by the patient. reinvestigated this phenomenon and confirmed that a spatial reorientation of the horizontal and vertical retinal meridians occurs in certain patients line inclined 45Њ will cause a subsequently viewed with congenital or early acquired cyclodeviations. vertical line to appear inclined in the opposite This spatial adaptation compensates for the image direction. Adaptation to a tilted environment prob- tilt that would otherwise be perceived (Fig. 18–8). ably has a neurophysiologic basis in terms of a It explains why patients with objective cyclotor- change in orientation tuning of the striate cortical 12 sion of one eye continue to see a vertical line as neurons and suggests a certain degree of cortical vertical and a horizontal line as horizontal in the plasticity even in visually mature adults. absence of all other visual clues.98 This adaptation PSYCHOLOGICAL ADAPTATION. Some cyclo- is not irreversible. Patients with a congenital tropic patients may be unaware of a tilted environ- cyclotropia may temporarily note a tilting of the ment because of empirical spatial clues. Experi- environment in the opposite direction after surgi- ence has taught us that familiar objects such as cal correction of the cyclotropia before normal, doors, windows, houses, and trees have a consis- innate spatial orientation of the retinal meridians tent vertical or horizontal orientation in physical reestablishes itself.78, 83 The practical implication space. Such spatial clues from an orderly visual of this finding in connection with postoperative environment are used to correct for image tilting.50 adjustment of a Harada-Ito procedure is mentioned As soon as this normal frame of visual reference at the end of this chapter. is no longer available, for instance, in complete Even in normal subjects there exists a certain darkness, these patients become aware of cyclo- degree of spatial adaptability of the vertical and tropia. Ruttum and von Noorden98 confirmed this horizontal retinal meridians and their central con- by measuring the so-called subjective horizontal nection as demonstrated in the famous ‘‘tilt after- in cyclotropic subjects. The subjective horizontal effect’’ experiment of Vernon126 and Gibson and is defined as a subject’s perception of a horizontal Radner.37 This experiment may be easily repeated plane as opposed to its actual position in physical by the interested reader: monocular observation space. Its determination was once a popular diag- for a few minutes of a fixation mark bisecting a nostic procedure in the diagnosis of cyclovertical Cyclovertical Deviations 391 strabismus. Asymptomatic patients with cyclo- matic trochlear paralysis. A conventional weaken- tropia as diagnosed by fundus photography and ing or strengthening procedure on offending Maddox rods may perceive a faintly illuminated cyclovertical muscles may correct the cyclodevia- horizontal line as tilted when no other visual clues tion in such cases, but it will also produce an are available.98 undesired vertical effect. A procedure is required There is no uniformity in the utilization of that affects the cyclodeviation exclusively. This these physiologic and psychological mechanisms requirement is met by several operations. The ad- that enable a cyclotropic patient to live in relative vancement and lateralization of the superior visual comfort despite a potentially disabling oblique tendon for excyclotropia according to Har- anomaly of ocular motility.48, 60, 98, 118, 120 The vari- ada and Ito43 (see Chapter 26) and its many varia- ous adaptations to cyclodeviations are employed tions has become firmly established in our surgical either exclusively or in combination with each armamentarium. However, this procedure cannot other. This explains the often confusing variety of be performed when the superior oblique tendon is results obtained with different tests and the objec- congenitally absent or has been previously teno- tive finding of cyclotropia in the absence of symp- tomized. In that case nasal transposition of the toms. A spectrum of effectiveness of these adapta- inferior rectus muscle74, 84 is an effective surgical tions exists that includes incomplete adaptation alternative to correct excyclotropia in downward with constant or intermittent torsional diplopia, gaze. When excyclotropia is also present in pri- complete but easily dissociated adaptations in mary position we add a temporal transposition of those with acquired cyclotropia, and deep-seated the superior rectus muscle.84 For incyclotropia, adaptations that are effective under monocular and which occurs much less frequently than excyclo- binocular conditions in patients with congenital tropia, the inferior rectus is shifted templeward cyclotropia. and the superior rectus nasalward.84 In our hands, the average effect of these operations in terms of Therapy rotating the eye around the anteroposterior axis is 10Њ, ranging from 8Њ to 12Њ. Ohmi and coworkers88 The use of cylindrical lenses with their axis placed reported similar results. Other procedures to cor- so as to offset the cyclotropia has been advocated, rect cyclotropia without producing vertical or hori- but the value of this therapy is highly question- zontal strabismus include slanting of the insertion able. The treatment of symptomatic cyclotropia is of all rectus muscles,34, 113 vertical transposition of surgical. When the action of the oblique muscles the horizontal rectus muscles,22 and transpositions is abnormal, cyclotropia usually occurs in associa- of the anterior aspects of the inferior and superior tion with a clinically significant hyperdeviation; oblique tendons.18 The surgical technique for these thus the choice of muscles on which to operate procedures, as well as surgical induction of cyclo- presents no difficulties, since elimination of the tropia to counteract a compensatory head tilt in hyperdeviation also will correct the cyclodevia- patients with congenital nystagmus,81 is discussed tion. For instance, in a patient with paralysis of in Chapters 23 and 26. the homolateral superior oblique muscle, excyclo- An overcorrection after surgery for cyclotropia tropia caused by unopposed action of the inferior (e.g., excyclotropia changing to incyclotropia) oblique muscle can be eliminated by a weakening usually is only temporary and can be explained procedure on the inferior oblique muscle that will by the persistence of sensory adaptation to image correct both the hyertropia and the cyclodeviation. tilting.42, 78 The surgeon should keep this in mind Likewise, if the inferior oblique muscles are not and not be too hasty in planning a reoperation or overacting and the vertical deviation occurs only adjusting the sutures on the first postoperative day in the field of action of the paretic muscle, tucking if adjustable sutures are used for the Harada-Ito of the tendon of the paretic superior oblique mus- procedure. In fact, a slight overcorrection after the cle is similarly effective in eliminating the hyper- Harada-Ito procedure is desirable since the effect tropia and the excyclotropia. of surgery tends to decrease with time. Management of isolated cyclodeviations in pa- A special challenge exists in patients who had tients without a significant associated vertical de- vertical macular translocation for improvement of viation presents a special problem. The most fre- visual acuity of an eye with age-related macular quent cause for an isolated symptomatic degeneration. This operation invariably causes cyclotropia is a residual excylotropia after trau- horizontal and vertical strabismus in addition to 392 Clinical Characteristics of Neuromuscular Anomalies of the Eye cyclotropia. The magnitude of this iatrogenic in- 8. Bielschowsky A: Lectures on Motor Anomalies. Han- over, NH, Dartmouth Publishing Co, 1943/1956. cyclotropia is formidable indeed if compared to 9. Black BC: Results of anterior transposition of the inferior what is usually encountered in cyclovertical stra- oblique muscle in incomitant dissociated vertical devia- bismus and may range from as much as 33 de- tion. J Am Assoc Pediatr Opthalmol Strabismus 1:83, 28, 29, 36 106 1997. grees to 45 degrees. It is all the more 10. Boylan C, Clement RA, Howrie A: Normal visual path- surprising that spontaneous adaptations have been way routing in dissociated vertical deviation. Invest Oph- reported in such patients106, 107 but most will com- thalmol Vis Sci 29:1165, 1988. 11. Brodsky MC: Dissociated vertical divergence, a righting plain about an intolerable shift of the visual envi- reflex gone wrong. Arch Ophthalmol 117:1216, 1996. ronment. Conventional surgery consisting of an 12. Bruce CJ, Isley MR, Shinkman PG: Visual experience advancement and transposition of the inferior and development of interocular orientation disparity in visual cortex. J Neurophysiol 46:215, 1981. oblique and a recession of the superior oblique 13. Burke JP, Scott WE, Kutschke PJ: Anterior transposition muscle, as advocated by Conrad and de Decker18 of the inferior oblique muscle for dissociated vertical and as employed by others,36 or horizontal trans- deviation. Ophthalmology 100:245, 1993. 14. Campos E, Schiavi C, Bolzani R, Cipolli C: Binocular position as used by us, does not suffice to correct vertical perceptual adaptation in essential infantile esotro- a cyclodeviation of this magnitude. Eckardt and pia. Perceptual Mot skills 87:1211, 1998. Eckardt,28, 29 recently recommended adding to the 15. Cheeseman EW, Guyton DL: Vertical fusional vergence. The key to dissociated vertical deviation. Arch Ophthal- surgery on the oblique muscles (according to Con- mol 117: 1188, 1999. rad and de Decker18) a transposition of strips from 16. Clark RA, Miller JM, Rosenbaum AL, Demer JL: Heter- two or from all four rectus muscles to the insertion otopic muscle pulleys or oblique muscle dysfunction? J of the adjoining rectus muscles, similar to a Hum- Am Assoc Pediatr Opthalmol Strabismus 2:17, 1998. 17. Clarke M, Johnson FM, Harcourt B: Left Duane’s retrac- melsheim procedure. This nearly doubled the tion syndrome associated with dissociated vertical cyclorotational effect of the operation to a total divergence—a case report. Br Orthopt J 45:78, 1988. of 30Њ to 40Њ, which about compensated for the 18. Conrad HG, Decker W de: ‘‘Rotatorischer Kestenbaum.’’ Umlagerungschirurgie bei Kopfzwangshaltungen zur cyclotropia produced by macular translocation. Schulter. Klin Monatsbl Augenheilk 173:681, 1978. Freedman and coworkers36 advocated combined 19. Crone RA: Alternating hyperphoria. Br J Ophthalmol superior oblique muscle recession and inferior 38:592, 1954. 20. Crone RA: Diplopia. Amsterdam, Excerpta Medica, oblique advancement for incyclotropia following 1973, p 75. macular translocation. A rotation of only a retinal 21. Crone RA, Everhard-Halm Y: Optically induced eye tor- flap rather than the entire retina apparently causes sion. I. Fusional cyclovergence. Graefes Arch Clin Exp Ophthalmol 195:231, 1975. less of a postoperative image tilt, since patients 22. de Decker W: Rotatorischer Kestenbaum an den geraden operated on in this fashion adjusted to the tilt Augenmuskeln. Z Prakt Augenheilkd 11:11, 1990. without muscle surgery.24, 75 Perhaps this modifi- 23. de Decker W, Dannheim-de Decker E: Unbeachtete Zwangshaltungen beim fru¨hkindlichen Schielsyndrom. cation, if proved to be as effective as total retinal Klin Monatsbl Augenheilkd 215:95, 1999. rotation, will eventually eliminate the need for 24. De Juan E, Loewenstein A, Bressler NM, Alexander A: muscle surgery in conjunction with or following Limited retinal translocation of the retina for management of subfoveal choroidal neovascularization. II. A prelimi- macular translocation. nary report in humans. Am J Ophthalmol 125:635, 1998. 25. Duane A: Binocular movements. Arch Ophthalmol 9:579, 1933. REFERENCES 26. Duke-Elder S, Wybar K: System of Ophthalmology, vol 1. Alpern M: Muscular mechanisms. In Davson H, ed: The 6: Ocular Motility and Strabismus. St Louis, Mosby–Year Eye. New York, Academic Press, 1962, p 177. Book, 1973, p 252. 2. Anderson JR: Ocular Vertical Deviations and the Treat- 27. Duncan L, Noorden GK von: Surgical results in dissoci- ment of Nystagmus, ed 2. London, British Medical Asso- ated vertical deviations. J Pediatr Ophthalmol Strabismus ciation, 1959. 21:25, 1984. 3. Bach M, Kommerell G: Albino-type misrouting of the 28. Eckardt U, Eckardt C: Macular rotation with and without optic nerve fibers not found in dissociated vertical devia- counter rotation of the globe in patients with age related tion. Graefes Arch Clin Exp Ophthalmol 230:158, 1992. macular degeneration. Graefes Arch Clin Exp Ophthal- 4. Bagolini B, Campos E, Chiesi C: Plagiocephaly causing mol 237:313, 1999. superior oblique deficiency and ocular torticollis. Arch 29. Eckardt U, Eckardt C: Orthoptische Probleme nach Ma- Ophthalmol 100:1093, 1982. kularotation mit und ohne Muskelchirurgie. Klin Mo- 5. Bechtel RT, Kushner BJ, Morton GV: The relationship natsbl Augenheilkd; 212:212, 1998. between dissociated vertical divergence (DVD) and head 30. Enke ES, Stewart SA, Scott WE, Wheeler DT: The preva- tilts. J Pediatr Ophthalmol Strabismus 33:303, 1996. lence of dissociated horizontal deviations in congenital 6. Bielschowsky A: Die einseitigen und gegensinnigen esotropia. Am Orthopt J 44:109, 1994. (‘‘dissoziierten’’) Vertikalbewegungen der Augen. 31. Enright JT: Unexpected role of the oblique muscles in Graefes Arch Clin Exp Ophthalmol 125:493, 1931. the human vertical fusional reflex. J Physiol (Lond) 7. Bielschowsky A: Disturbances of the vertical motor mus- 451:279, 1992. cles of the eyes. Arch Ophthalmol 20:175, 1938. 32. Esswein MB, Noorden GK von, Coburn A: Comparison Cyclovertical Deviations 393

of surgical methods in the treatment of dissociated verti- 56. Irving EL, Goltz HC, Steinbach MJ, Kraft SP: Vertical cal deviation. Am J Ophthalmol 113:287, 1992. latent nystagmus component and vertical saccadic asym- 33. Esswein Kapp MB, Noorden GK von: Treatment of resid- metries in subjects with dissociated vertical deviation. J ual dissociated vertical deviation with inferior rectus re- Am Assoc Pediatr Ophthalmol Strabismus 2:344, 1998. section. J Pediatr Ophthalmol Strabismus 31:262, 1994. 57. Jampel RS, Sterns AB, Bugola J: Cyclophoria or cyclo- 34. Fink WH: Surgery of the Vertical Muscles of the Eye, vergence: Illusion or reality. In Moore S, Mein J, Stock- ed 2. Springfield, Il, Charles C Thomas, 1962, p 369. bridge L, eds: Orthoptics: Past, Present, Future: Transac- 35. Fitzgerald BA, Billson FA: Dissociated vertical deviation: tions of the Third International Orthoptic Congress. New Evidence of abnormal visual pathway projection. Br J York, Stratton Intercontinental, 1976, p 403. Ophthalmol 68:801, 1984. 58. Kii T, Ogasawara K, Ohba M, et al: The effectiveness of 36. Freedman SF, Seaber JH, Buckley EG, et al: Combined the Faden operation on the superior rectus muscle com- superior oblique muscle recession and inferior oblique bined with recession of the muscle for the treatment of advancement and transposition for cyclotorsion associ- dissociated vertical deviation. Acta Soc Ophthalmol Jpn ated with macula translocation surgery. J Am Assoc Pedi- 98:98, 1994. atr Ophthalmol Strabismus 4:75 2000. 59. Knapp P: Dissociated vertical deviations. In Fells P, ed: 37. Gibson JJ, Radner M: Adaptation, aftereffect and contrast Second Congress of the International Strabismological in the perception of titled lines. I. Quantitative studies. J Association. Marseilles, Diffusion Ge´ne´rale de Librairie, Exp Psychol 20:453, 1937. 1976, p 185. 38. Gobin, M.H.: Sagittalization of the oblique muscles as a 60. Kolling G: Mo¨glichkeiten und Grenzen der Messung von possible cause for the ‘‘A,’’ ‘‘V,’’ and ‘‘X’’ phenomena. Zyklodeviationen unter besonderer Beru¨cksichtigung des Br J Ophthalmol 52:13, 1968. Deviometers nach Cu¨ppers. Klin Monatsbl Augenheilkd 39. Goltz HC, Irving EL, Hill JA, et al: Dissociated vertical 178:89, 1981. deviation: Head and body orientation affect the amplitude 61. Kratz RE, Rogers GL, Bremer DL, Leguire LE: Anterior and velocity of the vertical drift. J Pediatr Ophthalmol tendon displacement of the inferior oblique for DVD. J Strabismus 33:307, 1996. Pediatr Ophthalmol Strabismus 26:212, 1989. 40. Guibor GP: Synkinetic overaction of the inferior oblique 62. Kriss A, Timms C, Elston J, et al: Visual evoked poten- muscle. Am J Ophthalmol 32:100, 1949. tials in dissociated vertical deviation: A reappraisal. Br J 41. Guyton D: Dissociated vertical deviation: An exaggerated Ophthalmol 73:265, 1989. normal eye movement used to damp cyclovertica nystag- 63. Kushner BJ: Unexpected cyclcotropia simulating disrup- mus. Trans Am Ophthalmol Soc 96:389, 1998. tion of fusion. Arch Ophthalmol 110:1415, 1992. 42. Guyton DL, Noorden GK von: Sensory adaptations to 64. Kutluk S, Avilla CW, Noorden GK von: The prevalence cyclodeviations. In Reinecke RD, ed: Strabismus. New of dissociated vertical deviation in patients with sensory York, Grune & Stratton, 1978. heterotropia. Am J Ophthalmol 119:744, 1995. 43. Harada M, Ito Y: Surgical correction of cyclotropia. Jpn 65. Lancaster WB: Factors underestimated, features overem- J Ophthalmol 8:88, 1964. phasized, and comments on classification. In Allen JE, 44. Harcourt B, Mein J, Johnson F: Natural history and ed: Strabismus Ophthalmic Symposium, II. St Louis, associations of dissociated vertical divergence. Trans Mosby–Year Book, 1958, p 430. Ophthalmol Soc UK 100:495, 1980. 66. Lisch A, Simonsz HJ: Up- and downshoot in adduction 45. Helveston EM: A-exotropia, alternating sursumduction after monocular patching in normal volunteers. Strabis- and superior oblique overaction. Am J Ophthalmol mus 1:25, 1993. 67:377, 1969. 67. Locke JC: Heterotopia of the blind spot in ocular vertical 46. Helveston EM: Dissociated vertical deviation: A clinical muscle imbalance. Am J Ophthalmol 65:362, 1968. and laboratory study. Trans Am Ophthalmol Soc 68. Lorenz B, Raab I, Boergen KP: Dissociated vertical devi- 78:734, 1980. ation: What is the most effective surgical approach? J 47. Helveston EM, Neely DF, Stidham DB, et al: Results of Pediatr Ophthalmol Strabismus 29:21, 1992. early alignment of congenital esotropia. Ophthalmology 69. Lyle TK, Bridgeman GJO: Worth and Chavasse’s Squint. 106:1716, 1999. The Biocular Reflexes and the Treatment of Strabmismus. 48. Herzau V, Joos E: Untersuchungen von Bewegungen und London, Baillie`re, Tindall & Cox, 1959, p 350. Stellungsfehlern der Augen um ihre sagittale Achse Z 70. Magoon E, Cruciger M, Jampolsky A: Dissociated verti- Prakt Augenheilkd 4:270, 1983. 49. Herzau V, Joos-Kratsch E: Objective and subjective eval- cal deviation: An asymmetric condition treated with large uation of cyclovergence and cyclofusion. Doc Ophthal- bilateral superior rectus recession. J Pediatr Ophthalmol mol 58:85, 1984. Strabismus 19:152, 1982. 50. Herzau W: Bestimmung der Medianabweichung des 71. McCall LC, Rosenbaum AL: Incomitant dissociated ver- Auges. Klin Monatsbl Augenheilkd 86:406, 1931. tical deviation and superior oblique overaction. Ophthal- 51. Hofmann FB, Bielschowsky A: U¨ ber die Einstellung der mology 98:911, 1991. scheinbaren Horizontalen und Vertikalen bei Betrachtung 72. Metz HS, Norris H: Cyclotorsional diplopia following eines von schra¨gen Konturen erfu¨llten Gesichtsfeldes. retinal detachment surgery. J Pediatr Ophthalmol Strabis- Arch Ges Physiol 126:453, 1909. mus 24:287, 1987. 52. Hooten K, Myers E, Worall R, Stark L: Cyclovergence: 73. Moore S, Cohen RT: Congenital exotropia. Am Orthopt The motor response to cyclodisparity. Graefes Arch Clin J 35:68, 1985. Exp Ophthalmol 210:65, 1979. 74. Mumma JV: Surgical procedure for congenital absence 53. Houtman WA, Roze JH, De Vries B, Letsch MC: Alter- of the superior oblique. Arch Ophthalmol 92:221, 1974. nating hyperphoria. Dissociated vertical deviation (DVD) 75. Ninomiya Y, Lewis JM, Hasegawa T, Tano Y: Retino- occlusion hyperphoria. Doc Ophthalmol 78:135, 1991. tomy and foveal translocation for surgical management 54. Inoue M, Kita Y: Eye movements in dissociated vertical of subfoveal choroidal neovascular membranes. Am J deviation. Acta Soc Ophthalmol Jpn 97:1312, 1993. Ophthalmol 122:613–621, 1996. 55. Ioannakis K, Herzau V: Cyclodeviation in plagiocephaly. 76. Noorden GK von: Indications of the posterior fixation In Kaufmann H, ed: Transactions of the 16th Meeting operation in strabismus. Ophthalmology 85:512, 1978. of the European Strabismological Association, Giessen, 77. Noorden GK von: Posterior fixation suture in strabismus Germany, 1987, p 297. surgery. In Symposium on Strabismus: Transactions of 394 Clinical Characteristics of Neuromuscular Anomalies of the Eye

the New Orleans Academy of Ophthalmology. St Louis, 103. Scobee RG: Esotropia: Incidence, etiology and results of Mosby–Year Book, 1978, p 307. therapy. Am J Ophthalmol 34:817, 1951. 78. Noorden GK von: Clinical observations in cyclodevi- 104. Scobee RG: The Oculorotary Muscles, ed 2. St Louis, ations. Ophthalmology 86:1451, 1979. Mosby–Year Book, 1952. 79. Noorden GK von: Cyclotropia: Theoretical and practical 105. Schroeder B, Krzizok T, Kaufmann H, Kroll P: Sto¨rung aspects (Costenbader lecture). J Pediatr Ophthalmol Stra- des Binokularsehens bei Makulaheterotopie. Klin Mo- bismus 21:126, 1984. natsbl Augenheilkd 215:135, 1999. 80. Noorden GK von: Current concepts of infantile esotropia 106. Seaber JH, Machemer R: Adaptation to monocular tor- (Bowman Lecture). Eye 2:343, 1988. sion after macular translocation. Graefes Arch Clin Exp 81. Noorden GK von: Horizontal transposition of the vertical Ophthalmolol 235:76, 1997. rectus muscles for treatment of ocular torticollis. J Pediatr 107. Seaber JH, Freedman SF, Toth C: Adaptation to torsion Ophthalmol Strabismus 30:8, 1993. after macular translocation surgery. In Orthoptics in Fo- 82. Noorden GK von: Discussion of paper by Guyton D: cus-Vision for the New Millennium. Transactions of the Dissociated vertical deviation: An exaggerated normal Ninth International Orthoptic Congress, Stockholm, eye movement used to damp cyclovertica nystagmus. 1999, p 25. Trans Am Ophthalmol Soc 46:389, 1998. 108. Seawright AA, Gole GA: Results of anterior transposition 83. Noorden GK von, Brown DJ, Parks M: Clinical observa- of the inferior oblique. Aust N Z J Ophthalmol 24:339, tions in cyclotropia. Presented at the American Orthoptic 1996. Council—American Association of Certified Orthoptists 109. Sidikaro Y, Noorden GK von: Observations in sensory Symposium at the American Academy of Ophthalmology heterotropia. J Pediatr Ophthalmol Strabismus 19:12, and Otolaryngology, Dallas, Sept 16, 1973. 1982. 84. Noorden GK von, Chu MW: Surgical treatment options 110. Simon JW, Bayramlar H, Kamath S: Atropine penaliza- in cyclotropia. J Pediatr Ophthalmol Strabismus 27:291, tion therapy of disscociated vertical deviations. Binocular 1990. Vision Strabismus 11:263, 1996. 85. Noorden GK von, Ruttum M: Torticollis in paralysis of 111. Spielmann A: A translucent occluder for studying eye the trochlear nerve. Am Orthopt J 33:16, 1983. position under unilateral or bilateral cover test. Am Or- 86. Ogle KN, Ellerbrock VJ: Cyclofusional movements. Arch thopt J 36:65, 1986. Ophthalmol 36:700, 1946. 112. Spielmann A: Les divergences verticales dissocie´es: Ex- 87. Ohm J: Schra¨gschielen. Arch Augenheilkd 39:619, 1928. ce`s de sursumversion lie´ a` la fixation. Ophtalmologie 88. Ohmi G, Fujukado T, Ohji M, et al: Horizontal transposi- 1:457, 1987. tion of verical rectus muscles for treatment of excyclo- 113. Spielmann A: The oblique Kestenbaum procedure revis- tropia. Graefes Arch Clin Exp Ophthalmol 235:1, 1997. ited (sloped recession of the recti). In Lenk-Scha¨fer M, 89. Olivier P, Noorden GK von: Excyclotropia of the nonpa- ed: Orthoptic Horizons. Transactions of the Sixth Interna- retic eye in unilateral superior oblique muscle paralysis. tional Orthoptic Congress, Harrogate, England, 1987, p Am J Ophthalmol 93:30, 1982. 433. 90. Parks MM: Personal communication, Oct 5, 1973. 114. Spielmann A: De´se´quilibres verticaux et torsionels dans 91. Posner A: Noncomitant hyperphorias considered as aber- le strabisme pre´ coce. Bull Soc Ophtalmol Fr 90: rations of the postural tonus of the muscular apparatus. 373,381, 1990. Am J Ophthalmol 27:1275, 1944. 115. Spielmann A: Les strabismes. De l’analyse clinique a` la 92. Raab E: Dissociative vertical deviation. J Pediatr Oph- synthe`se chirurgicale, ed 2. Paris, Masson, 1991, p 204. thalmol Strabismus 7:146, 1970. 116. Spielmann A: Les e´le´vation en adduction: Contre une 93. Rijn LJ van, Collewijn H: Eye torsion associated with chirurgie syste´matique du muscle petit oblique. Ophtal- disparity-induced vertical vergences in humans. Vision mologie 5:427, 1991. Res 17:2307, 1994. 117. Sprague JB, Moore S, Eggers H, Knapp P: Dissociated 94. Rijn LJ van, ten Tusscher MPM, Jong I de, Hendrikse vertical deviation: Treatment with the fadenoperation of F: Asymmetrical vertical phorias indicating dissociated Cu¨ppers. Arch Ophthalmol 98:465, 1980. vertical deviation in subjects with normal binocular vi- 118. Sradj H: Rollungsschielen. Physiologie. Instrumentarium. sion. Vision Res 38:2973, 1998. Therapie. Giessen, Germany, Ko¨hler, 1979. 95. Rimmer S, Katz B: Dissociated vertical deviation in a 119. Stager DR, Weakley DR Jr, Stager D: Anterior transposi- patient with Duane’s retraction syndrome. J Clin Neuro tion of the inferior oblique. Anatomic assessment of the Ophthalmol 10:38, 1990. neurovascular bundle. Arch Ophthalmol 110:360, 1992. 96. Romero-Apis D: Comportamiento cli´nico de los estra- 120. Sullivan MJ, Kertesz A: Peripheral stimulation and hu- b´ısmos secundarios. Anal Soc Mex Oftalmol 54:153, man cyclofusional response. Invest Ophthalmol Vis Sci 1980. 18:1287, 1979. 97. Ruttum MS: Anterior transposition of the inferior oblique 121. Swan K, cited by Lancaster WB: Factors underestimated, muscles.Am Orthop J 47:118, 1997. features overemphasized, and comments on classification. 98. Ruttum M, Noorden GK von: Adaptation to tilting of In Allen, JE, ed: Strabismus Ophthalmic Symposium, II. the visual environment in cyclotropia. Am J Ophthalmol St Louis, Mosby–Year Book, 1958. 96:229, 1983. 122. Trobe JD: Cyclodeviations in acquired vertical strabis- 99. Ruttum M, Noorden GK von: The Bagolini striated glass mus. Arch Ophthalmol 102:717, 1984. test for cyclotropia. Doc Ophthalmol 58:131, 1984. 123. Varn MM, Saunders RA, Wilson ME: Combined bilateral 100. Sachs M, Meller J: U¨ ber einige eigentu¨mliche Lokalisa- superior rectus muscle recession and inferior oblique tionspha¨nomene in einem Falle von hochgradiger Netz- muscle weakening for dissociated vertical deviation. J hautinkongruenz. Graefes Arch Clin Exp Ophthalmol Am Assoc Pediatr Ophthalmol Strabismus 1:134, 1996. 57:1, 1904. 124. Velez G: Dissociated vertical deviation. Graefes Arch 101. Santiago AP, Rosenbaum AL: Dissociated vertical devia- Clin Exp Ophthalmol 226:117, 1988. tion and head tilt. Am Assoc Pediatr Ophthalmol Strabis- 125. Verhoeff FH: Occlusion hypertropia. Arch Ophthalmol mus 2:5, 1998. 25:780, 1941. 102. Schweigger C: Die Erfolge der Schieloperation. Arch 126. Vernon MD: The perception of inclined lines. Br J Psy- Augenheilkd 30:165, 1895. chol 25:186, 1934–1935. Cyclovertical Deviations 395

127. White JW: Hyperphoria. Diagnosis and treatment. Arch 132. Wilson ME, Saunders RA, Berland JE: Dissociated hori- Ophthalmol 7:739, 1932. zontal deviation and accommodative esotropia: Treatment 128. White JW, Brown HW: Occurrence of vertical anomalies options when an eso- or exodeviation co-exists. J Pediatr associated with convergent and divergent anomalies. Ophthalmol Strabismus 32:228, 1995. Arch Ophthalmol 21:999, 1939. 133. Zubcov AA, Goldstein HP, Reinecke RD: Dissociated 129. Wieser D: Pseudoeinseitiger Strabismus sursoadductor- vertical deviation (DVD). The saccadic eye movements. ius. Ophthalmologica 170:283, 1975. Strabismus 2:1, 1994. 130. Wilson ME, McClatchey SK: Dissociated horizontal 134. Zubcov A, Reinecke RD, Calhoun JH: Asymmetric hori- deviation. J Pediatr Ophthalmol Strabismus 28:90, zontal tropias, DVD, and manifest latent nystagmus: An 1991. explanation of dissociated horizontal deviation. J Pediatr 131. Wilson ME, Hutchinson AK, Saunders R: Outcomes Ophthalmol Strabismus 27:59, 1990. from surgical therapy for dissociated horizontal devia- 135. Zubcov AA, Fendick MG, Gottlob I, et al: Visual-evoked tions. J Am Assoc Pediatr Ophthalmol Strabismus 4:94, cortical potentials in dissociated vertical deviation. Am J 2000. Ophthalmol 112:714, 1991.