Eye (1988) 2, 343-357
BOWMAN LECTURE
Current Concepts of Infantile Esotropia
G. K. VON NOORDEN
Houston, Texas
Summary Several forms of esotropia with a different pathophysiology that meet the criterion of an onset early in life must be distinguished from essential infantile esotropia. A hypothesis is presented, according to which a delayed development or a congenital defect of retinal disparity sensitivity (motor fusion) in an otherwise normal infant with immatur� sensory functions causes esotropia under the influence of various strabismogenic factors. Some of these factors are genetically determined, hence the familial occurrence of essential infantile esotropia. The absence or marked decrease of stereopsis and the asymmetry of optokinetic nystagmus are interpreted as the consequence of ocular misalignment early in life rather than of structural anomalies in the afferent visual pathways of esotropic patients. The therapeutic results after surgery are clas sified into four groups: subnormal binocular vision, microtropia, small angle eso- or exotropia and large angle residual or consecutive eso- or exodeviations. Analysis of data from 358 oper ated patients with a documented onset of esotropia prior to the sixth month of life has shown that the probability of obtaining an optimal functional result is increased when surgical align ment is completed before completion of the second year of life. However, surgery after the age of two or even four years of life does not preclude the development of binocular vision on a sub normal or anomalous basis.
William Eddowes 'Bowman was born in 1816 under Robert Hentley Todd. Thus began a 5 in Nantwich, Cheshire. After schooling at year period during which Bowman, still in his Hazelwood college in Birmingham he was early twenties, made an extraordinary series appointed, at the age of 17, apprentice to of anatomic discoveries while working with Joseph Hodgson, a well known surgeon at Todd on two monumental volumes, the the General Hospital in Birmingham. As Physiological Anatomy and Physiology of Hodgson was also the founder of the Birmin Man and the CyClopaedia of Anatomy and gham Eye Infirmary we may assume that the Physiology. During this time occurred the young Bowman received an early exposure to description of the anterior limiting mem the art of ophthalmic surgery. After five brane which has immortalised his name. He years of apprenticeship he joined Kings Col made major contributions to the histology of lege in London as an anatomic demonstrator striated muscle and of the inner ear, of the
From the Cullen Eye Institute, Baylor College of Medicine and the Ophthalmology Service, Texas Children's Hospital, Houston, Texas. Supported in part by grants EY 07001, EY 01120 and EY 02520 from the National Institutes of Health.
I'resented at the Annual Meeting of the Ophthalmological Society of the United Kingdom, Harrogate, April, t988.
Correspondence to: G. K. von Noorden, M. D., Ophthalmology Service, Texas Children's Hospital, Box 20269, Houston, Texas 77225, USA 344 G. K. von NOORDEN ciliary muscle and the musculature of the iris. ous thinking about this entity began in this Indeed, as Sir Arthur Keith put it in his 1930 country and third, because there exists uncer Bowman Lecture: 'in the first President of tainty in the ophthalmological community this Society England had one of the greatest with regard to the aetiology, what may be anatomists she had ever produced'!. In 1884, expected from treatment and when to oper at the age of 30, Bowman began his career ate on children with this disorder. as an ophthalmologist by joining the staff of Kings College Hospital in London. During Definition his lifetime he advanced our science substan Infantile esotropia may be defined as a con tially, notably the surgery of the lacrimal sys stant esotropia with onset occurring during tem and of the anterior segment. He was a the first 6 months of life. Another term, often genius of great versatility and the praise of used synonymously is congenital esotropia his work has been sung so many times and so which carries the implication that th� eso competently that I shall not attempt to do it tropia is present at birth. In the light of pre again. However, in reviewing his work I was sent knowledge it is highly relevant whether a astonished to learn that Bowman performed child is born with crossed eyes or whether the brow suspension of the upper lid nearly 100 eyes cross after a period of initial alignment. years before the Friedenwald-Guyton suture Animal experiments have taught us, during and determined the angle of strabismus the past 20 years, about the extraordinary quantitatively long before this became a sensitivity of the infantile visual system and routine clinical procedure. In 1851 William the behavioural, physiological and structural Bowman, already famous and well estab consequences of abnormal visual stimulation lished at Moorfields received the visit of two during visual immaturity. It is reasonable to young colleagues from the Continent, assume from these data that an infant whose Albrecht von Graefe and Frans Cornelius eyes are crossed from birth has little chance Donders. They were given a warm and hos of developing binocularity. On the other pitable welcome, staying as guests in Bow hand, an esotropia preceded by a brief period man's house. Thus began a close friendship of normal eye alignment may cause less dam that united the three greatest ophthal age to a patient's ability to recover at least mologists of the 19th century for a lifetime. some binocular functions. Several authors After a long, happy and fulfilled life Bowman have expressed doubt that the esotropia actu died at the age of 76. As Frank Law com ally occurs at birth.4,p.87;5,6 However, it was mented in the history of this society, 'he was not until Nixon and co-workers from Indiana a whole man in every sense, thorough and University7 and Friedrich and de Decker painstaking, honest and fair, modest and from the University of Kiel8 published their abstemious, punctual and business-like. He observations in a total of 2200 physically nor was everybody's friend and a unique figure in mal and alert newborns that such suspicions many fields'2. For Donders' obituary Bow were confirmed and became facts. These man wrote: 'he had the fortune to have con authors reported that while strabismus, usu tributed considerably to the advancement of ally intermittent exotropia but occasionally his specialty and lived long enough to see the also a transient esotropia, was found in about fruits of his work universally recognised'3 a third of all newborn infants during the first Indeed, what he said about his great Dutch few days of life the eyes of these infants had friend could well have been written about aligned themselves over an interval of three Bowman himself. months. When re-examining the children in I have chosen the ·topic of infantile esot the series from Indiana at the age of six ropia for three reasons. First, and foremost, months only three who had been exotropic or because Brian Harcourt had suggested that I orthotropic at birth had developed a clincal speak about this subject which was of special picture consistent with infantile esotropia.9 fascination to him while, at the same time, Thus, true congenital esotropia, if it exists at holding the interest of general ophthal all, must be exceedingly rare and it is for this mologists. Second, because much of the seri- reason that we prefer the term 'infantile' to CURRENT CONCEPTS OF INFANTILE ESOTROPIA 345 describe this condition, and add the prefix pathophysiology the clinical management 'essential' to distinguish it from other forms and the treatment results cannot be expected of esotropia that occur in infancy. However, to be the same. Next to obvious congenital we must not lose sight of the probability that esotropias such as the retraction syndrome of congenital and hereditary factors contribute Stilling, Turk and Duane or Moebius syn to the development of infantile esotropia. drome there are other forms of infantile eso tropia which must be distinguished from Clinical Characteristics essential 'infantile esotropia. These condi Although certain variations are common the tions are listed in Table II and will be discus clinical findings in essential infantile eso sed here only as they pertain to the differen tropia are fairly consistent and are sum tial diagnosis of essential infantile esotropia. marised in Table I. This Table is a modifica tion of a consensus of opinions from Euro Nystagmus dampening by convergence (nys pean and North American strabismologists tagmus blocking or compensation syndrome) during an informal gathering in Modena, The relationship between congenital nystag Italy in 1984 and to which I have added asym mus and infantile esotropia and a possible metry of the optokinetic response and latent aetiologic association between these two con or manifest nystagmus. ditions has been mentioned often in recent years. However, the literature is often con Differential Diagnosis fusing because of failure to differentiate When studying essential infantile esotropia it clearly between latent and manifest congeni becomes mandatory to exclude similar condi tal nystagmus. Why is this distinction so tions III which because of different important? Because the roles of manifest and of latent nystagmus in infantile esotropia are Table I Characteristics of essential infantile eso entirely different: in the case of manifest nys tropia tagmus the infantile esotropia may be a con sequence of the nystagmus, in latent nystag Onset birth - 6 months mus both conditions though frequently Large angle (>30 prism dioptres) occurring in the same patient have no appa Stable angle rent aetiological link. Normal central nervous system Manifest nystagmus is of equal intensity May be associated with regardless whether both eyes are open or -asymmetric optokinetic nystagmus ---defective abduction either eye is covered (Fig 1). The nystagmus ---excessive abduction is called latent when it can be provoked only ---dysfunction of oblique muscles by covering either eye (Fig 2). SorsbyJO was ---dissociated vertical deviation (DVD) first to note, however, that even in latent nys -latent or manifest-latent nystagmus tagmus the eyes are rarely entirely at rest Initial alternation with crossed fixation under binocular viewing conditions. In other Potential for normal binocular vision words, latent nystagmus often has a manifest limited phase and true latent nystagmus occurs infrequently. Dell'Osso and co-workers, 11 Table II Esotropia with onset during infancy therefore, substituted the term latent nystag mus with 'manifest-latent' nystagmus, a term Essential infantile esotropia which in spite of its oxymoronic connotation Nystagmus blocking syndrome has become firmly established in the nystag Abducens palsy mus literature. Manifest and manifest-latent Refractive accommodative esotropia congenital nystagmus have uniquely distinc Infantile esotropia with central tive waveform characteristics which suggest a nervous system disorders different aetiology for each nystagmus type. 11 Sensory esotropia Since manifest-latent nystagmus occurs fre Duane's syndrome type I Moebius syndrome quently and manifest nystagmus infrequently with infantile esotropia it is highly probable 346 G. K. von NOORDEN that many esotropes who in the past were tal nystagmus, an onset of esotropia within classified as having manifest nystagmus actu the first few months of life, a variable angle, ally had the manifest-latent form.12 pseudo abducens paralysis and an inverse The possibility that congenital nystagmus relationship between the angle of strabismus may cause an esotropia was first suggested by and the intensity of the nystagmus (Fig 3). Adelstein and Cuppers!3 who coined the Because of the rather unique aetiology of the term nystagmus blockage syndrome. These esotropia in these cases, nystagmus blocking authors proposed that the esotropia occurs syndrome must be considered an entity diffe from hypertonicity of the medial recti, rent from essential infantile esotropia. caused by sustained adduction. Adduction of both eyes is provoked by a convergence
impulse, the purpose of which is to decrease R (or to 'block') the nystagmus and thus to t--i 120' 1 increase visual acuity. This blockage syn L sec. drome is characterised by manifest congeni- Eyes Open t Occlude 00
f---i 1 sec.
Eyes Open Eyes Open
Fig. 2. Binocular electronystagmogram of man ifest-latent nystagmus. Note minimal nystagmus with both eyes open and marked increase of jerk nystagmus upon covering either eye. The nystag mus with both eyes open was not seen on clinical examination in this patient. From von Noorden, Munoz, and Wong12'. • Published with permission from The American Journal of Ophthalmology. Copyright by the Ophthalmic Publishing Company. OD Occluded
20/400 20/100
OD r"'l��M.I''''Mlli/ll
OS Occluded 2oo/sec�I 20° !----i L 1 sec. Fig. 1. Binocular electronystagmogram of man ifest nystagmus. Note mostly pendular wave form Fig. 3. Binocular nystagmogram showing dam and no significant change in intensity upon cover pening of manifest nystagmus by convergence with ing either eye. From von Noorden, Munoz and improvement of visual acuity during esotropic Wong12'. phase. From von Noorden, Munoz and Wong12'. • Published with permission from The American • Published with permission from The American Journal of Ophthalmology. Copyright by the Journal of Ophthalmology. Copyright by the Ophthalmic Publishing Company. Ophthalmic Publishing Company. CURRENT CONCEPTS OF INFANTILE ESOTROPIA 347
Unfortunately, Adelstein and Clippers did infancy is in my experience exceedingly rare not distinguish clearly between manifest and although I find, not infrequently, that latent congenital nystagmus. Their nystag patients with essential infantile esotropia are mus blockage syndrome has become con referred to us with this diagnosis. In most fused with a much more common condition instancet the apparent inability to abduct described by Ciancia 14 and consisting of either eye beyond the midline is caused by infantile esotropia associated with manifest crossed fixation, the right eye fixating in left latent nystagmus. In this syndrome the gaze and the left eye in right gaze. After relationship between the esotropia and the occlusion of either eye for a few hours or nystagmus is, as far as we know, purely coin when applying the doll's head manoeuvre cidental. Such patients may present with a abduction becomes normal. Pseudoparalysis head turn toward the side of the fixating, of the lateral recti is also a frequent finding in adducted eye and have a jerky nystagmus the nystagmus blocking syndromeI3 and in with a neutral point in adduction and increas esotropia with manifest-latent nystagmus.14 ing amplitude as the eye abducts (Fig. 4). Whether esotropia associated with manifest Refractive accommodative esotropia latent nystagmus as described by Cianci a rep Even though the majority of children with resents a nosologically viable subgroup in the refractive accommodative esotropia develop essential infantile esotropia syndrome their squint between the ages of 2 and 3 years remains an intriguing subject for future a refractive accommodative esotropia fully research. correctible with glasses may occasionally occur as early as during the first 6 months of Abducens paralysis lifel5,16 and thus be confused with essential A unilateral or bilateral abducens paralysis in infantile esotropia. The earlier view that accommodation is inactive in infants can no 30° ____20/30 �20/60 longer be upheld, as anyone can attest to who LevoverSion has done refractions in newborn infants. In fact, accommodation may reach adult capac ity by the 4th month of life. 17 10° Levoversion � Infantile esotropia with central nervous system disorders Pnmary Position The infantile esotropia occurring in patients with Down's syndrome, hydrocephalus, ocu 10° lar or oculo-cutaneous albinism, cerebral DextroverSion � palsy, meningomyelocoele etc. must be con sidered separately from essential infantile esotropia as different aetiologies may be
Dextt rslon 20/60 20/50 involved. It is noteworthy, however, that ��: � ---- these conditions are frequently associated 00 as Fixatmg Fncating with manifest nystagmus. We have recently f------; examined 15 children with strabismus and 1 sec. ocular or oculo-cutaneous albinism. All had Fig. 4. Monocular electronystagmogram of man manifest nystagmus and all but three had a ifest-latent nystagmus in different gaze positions. nystagmus blocking syndrome! It seems, Note increase of jerk nystagmus in abduction with therefore, that esotropia, seen so frequently fast phase beating toward side of fixating eye and improvement of visual acuity when each eye fixates with the central nervous system anomalies in adduction. From von Noorden, Munoz, and just mentioned may often have a common Wong12'. cause, namely the manifest nystagmus. • Published with permission from The American Journal of Ophthalmology. Copyright by the Sensory esotropia Ophthalmic Publishing Company. Before returning to the principal subject of 348 G, K, Yon NOORDEN this discussion we must consider sensory treatment of infantile esotropia to creating, esotropia because it also may have its onset at best, a cosmetic improvement. On the in infancy. It is a common misconception other hand, removal of the obstacles that originating with Chavasse18,p, 172,19 that an eye prevent the development of normal binocular blind at birth, or blinded during the first few reflexes by surgery at a young age improves weeks or months of life, diverges. Actually, the chances for a functional cure. Indeed, it eso- and exotropias are encountered with was the teaching of Chavasse that has equal frequency if the onset of the visual loss triggered a current trend, which began in the is between birth and the age of 5 years.2 0 United States with Costenbader,22 to operate Thus, a careful fundus examination, if neces on infantile esotropes before completion of sary under anaesthesia, belongs at the very their second year of life to prevent deteriora beginning of an evaluation of any esotropic tion of binocular functions. infant. Let us remember the observation of In examining the writings of Worth and Ellsworth that esotropia is the second most Chavasse the contrast between their theories common sign of retinoblastoma.21 appears less profound than generally assumed and their views have held up Aetiology remarkably well in the light of current know The aetiology of essential infantile esotropia ledge. When speaking of a congenital fusion has been the subject of much speculation. defect Worth does not clarify, however, Our current concepts have been substantially whether he is referring to a sensory or motor moulded by the work of two great English fusion defect, nor whether he was aware that strabismologists, Claud Worth and Francis such a difference existed. Yet, a clear distinc Bernard Chavasse. Worth, a native of Lanca tion between these two important compo shire who founded the first Orthoptic Clinic nents of normal binocular vision is indispens at Moorfields, instilled sound scientific think able in the evaluation of treatment results. ing and meticulous observation into the prac As such distinction is often lacking in the tice of strabismology at a time when squint modern literature but essential for communi was still considered by some as an affliction cation I must digress for a moment and brought on by malignant spirits or as a sign of clarify our terminology which is based on the an evil disposition. His classical text, pub classical concepts of sensory physiology and lished first in 1903 has passed through nine thus on the foundations laid down by Hering, editions, was re-written after his death by Helmholtz, Tschermak and Bielschowsky. I Chavasse and survived into our time through define sensory fusion as the unification of vis its latest edition by Keith Lyle and Bridge ual excitations from corresponding retinal man. Worth's concept of a congenital defect elements of similar size and brightness into a of the fusion faculty was derided by Chavasse single mental percept. These excitations arise of Liverpool, an equally profound and from the two foveas but also from the retinal enthusiastic strabismologist, who saw the periphery. Thus, one cannot, as is commonly aetiology of squint in obstacles preventing done, equate sensory fusion with 'central' the development of binocular reflexes in an fusion and 'peripheral' fusion with motor otherwise normal visual system. In his fusion because the retinal periphery is also delightfully poignant prose Chavasse consi involved with sensory fusion. The term cent dered the defect in 'fusion faculty 'a supersti ral fusion, so frequently encountered in the tion that may have had its uses in the past' , or current literature, should be avoided 'a fireless altar before which we need no altogether since the entire process of fusion, longer vainly gesticulate' . 18,pp,Yiii,2 The sensory and motor, is a central one. For sta theories of Worth and ChilVasse have often ble sensory fusion to c-ome about motor been contrasted with regards to their fusion is essential. Motor fusion is evoked by therapeutic implications which may be sum retinal image disparity outside Panum's area. marised as follows: an inborn defect in the Such disparity elicits fusional vergence move fusion faculty precludes normalisation of ments with the purpose to keep the eyes binocular vision and banishes the surgical aligned so that sensory fusion can be main- CURRENT CONCEPTS OF INFANTILE ESOTROPIA 349 tained. It is important to note here that sen development or a permanent defect of motor sory and motor fusion may be independently fusional vergences in a sensorially normal impaired. We have observed patients with infant causes esotropia during the vulnerable the ability to have momentary sensory fusion first three months of visual immaturity under with normal stereoacuity but with defective the influence of factors that de stabilise the motor fusion because of a post-traumatic oculomotor equilibrium. What is the nature motor fusion deficiency. 23 Likewise, motor of these factors? In addition to uncorrected fusion may be normal and stable in the hypermetropia and anisometropia already absence of bifoveal sensory fusion but not in mentioned by Worth, excessive tonic con the absence of peripheral sensory fusion. vergence, an abnormally high AC/A ratio, or When speaking of 'the instinctive tendency anomalies of the neural integrators for ver to blend the images formed in the two eyes' gence movements which were recently disco Worth may have referred to sensory fusion. vered in the brainstem32 need to be consi However, when he described 'the desire for dered here. Claud Worth already recognised binocular vision' that keeps the eyes fully that once fusion is firmly established straight,24.p.54 or when he comments that he none of these potentially strabismogenic fac could not elicit fusional vergence movements tors short of an extraocular muscle paralysis on a haploscope in an esotropic patient24,p.60 can cause squint. 24,p.54 In view of the frequent it appears that he was referring to motor occurrence of infantile esotropia in members fusion instead. Be this as it may, according to of the same family some of these components Worth the development of this fusion faculty or, perhaps, the defect of motor fusion itself in squinters is either delayed, functions must be hereditary. imperfectly, or not at all. The eyes are then Two findings in essential infantile eso 'in state of unstable equilibrium, ready to tropia are seemingly at odds with our work squint either inwards or outwards on slight ing hypothesis, namely the defective or provocation'.24,p.55 The factors mentioned by absent stereopsis in the treated patient and Worth as causing strabismus in the presence the asymmetry of the optokinetic nystagmus. of defective fusion, such as uncorrected The fact that not a single patient with hypermetropia or anisometropia are similar essential infantile esotropia has ever been to those which, according to Chavasse, per recorded as having normal stereopsis when vert the development of normal binocular measured with random dot tests has often reflexes. been taken as evidence for a primary sensory On the basis of current knowledge it has defect that precludes the development of become possible to add to the theories of normal binocular vision. Since stereopsis has Worth and Chavasse. Worth already sus been linked to the presence of binocular pected that vergence movements lack preci neurons in the visual cortex33,34 we must at sion in newborns and modern psychophysical least consider the possibility that a congenital research in infants has shown indeed that the absence of binocular cells at birth may lead to motor and sensory components of binocular instability of binocular vision which, in turn, vision are only incompletely developed at causes the strabismus. In the absence of a birth.25,26 For instance, visual acuity,27 con valid animal model for essential infantile trast sensitivity2S,29 and stereopsis30,3I during esotropia this argument is difficult to prove the first few months of life are far from hav or disprove but there are several observa ing reached their adult levels of accuracy. tions that cannot be reconciled with this Since the development of stable ocular align theory. First, recent data suggest that ran ment may depend on a high quality visual dom dot stereopsis does, at least transiently, input26 binocular vision may be vulnerable occur in esotropes during infancy wht
PA THOGENESIS OF INFANTILE ESOTROPIA
Normal sensory anlage Immaturity of sensory and motor functions during first 3m OKN asymmetry Motor instability Vulnerability of system
DEFECTIVE MOTOR FUSION �� ��ORMAL MOTOR FUSION delayed development T or primary defect of STRABISMOGENIC FACTORS fusional vergences? Excessive tonic convergence + High AC/A ESOTROPIA Hypermetropia Anisometropia � Unknown Decimated Arrest of Maturation of binocular OKN development and cens sensory 1 motor blnoc. J. functions. Loss of Persistent asym. OKN symmetry normal OKN stereopSiS J. ORTHOTROPIA Fig. 7. Working hypothesis of aetiology ofessential infantileesotropia. For explanation see text. 352 G. K. von NOORDEN of spectacles on alternative days, blurring approach has undergone periodic changes either the right or the left eye with a +3.00 over the years. Initially, we favoured a reces spherical lens. sionlresection operation on the non-domin Once infantile esotropia has become firmly ant eye, combined with inferior oblique established correction of a mild or moderate myectomies if indicated, to be followed, if hypermetropic refractive error is rarely of necessary, by a recessionlresection on the fel benefit to the patient. However, we do low eye. The amount of surgery varied recommend a trial with spectacles or miotics according to the size of the deviation and on prior to surgery when the refractive error the basis of observations made during exami exceeds two and a half dioptres. nation of the ductions of the eyes57 and Finally, we must draw attention to the fre ranged from 3-5 mm recessions and 5-8 mm quent occurrences of a dissociated vertical resections. However, the number of reopera deviation (DVD) and/or upshoot of the tions required to gain or maintain alignment adducted eye, apparently caused by a prim was discouraging. In 1972 we reported that ary overaction of the inferior oblique mus an average of 2.1 operations per patient was cle(s). DVD occurred in 51% and upshoot in required to align the eyes.5R Ing and cowor adduction in 68% of our patients.53 These kers,59 who used 3-5 mm recessions of both figures are in accord with prevalences medial recti required as many as 2.6 opera reported by other authors. 56 The results of tions per patient to achieve this goal. In quantitative measurements obtained in 170 recent years we have changed our method of 408 patients with essential infantile esot and now employ recessions of the medial ropia and DVD are presented in Table Ill. recti ranging from 5-8 mm.60 This more The reason for the frequent occurrence of aggressive approach has decreased the need DVD or of inferior oblique overact ion in for additional surgery and, contrary to our patients with essential infantile esotropia is initial concern, does not cause limitation of not at all clear. It is of interest to note, how adduction. Initial reports show that by doing ever, that overacting inferior obliques, usu these unconventionally large recessions of ally associated with a V -pattern, are com both medial recti 73-84% of the patients are monly detected during the initial examina successfully aligned with one operation. 61-63 tion of the child. DVD, on the other hand, is Botulinum injection il).to the medial recti rarely present in infancy and occurs, as a has been mentioned as an alternative to 64.65 rule, between the ages of 3-5 years and often surgery. While chemodenervation with several years after surgical alignment of the Botulinum has been most effective in the eyes. treatment of essential blepharospasm and We now treat a cosmetically significant may also be useful in certain cases of paraly DVD with a 7-8 mm recession of the superior tic strabismus caution is advised with regard rectus muscle. This amount is varied with to its role in infantile esotropia. The need for asymmetric involvement. frequent injections under anaesthesia, the common complication of ptosis and transient Surgical Treatment vertical deviations, the conspicuous lack of The aim of surgery for essential infantile prolonged follow-up and of controlled esotropia is to align the eyes as closely to the studies comparing the results of surgery ver orthotropic position as possible with the least sus injections"" have kept us from accepting number of operations. My own surgical Botulinum as a valid treatment option at this time. Table III Characteristics of DVD in essential infantile esotropia Results of Treatment What can be expected from surgery in terms (n=170) of restoration of binocular vision and how critical is it to perform surgery in early Unilateral 24(14 % ) symmetrical 13 ( 9%) Bilateral 146 (86%) asymmetrical 133 (91 %) infancy? These questions are difficult to ans wer from the literature because of a deplora- CURRENT CONCEPTS OF INFANTILE ESOTROPIA 353 ble lack of precise terminology in describing microtropias or residual small angle eso- or treatment results. Most current authors use exodeviations. These patients maintain one or several of the following findings as binocular vision on the basis of anomalous criteria for the restoration of binocular func retinal correspondence,73-75 , require no tions: the presence of gross stereopsis,67,68 further treatment except for amblyopia and fusion on the Worth 4 dot test,6H>9 apprecia are considered to have an acceptable treat tion of both stripes on the Bagolini striate ment result. lens test61,67,69, alignment of within 10 prism Anomalous retinal correspondence, was dioptres of the orthotropic position56,59,67 or once seen as an unsurmountable obstacle to the presence of a fusional vergence move normal binocular vision and treated with ment on the cover-uncover test.70 However, there is no single test that provides all the Table IV Subnormal binocular vision answers about the extent of recovery of motor and sensory binocular functions. Nor Orthotropia or asymptomatic heterop horia are any of the tests just mentioned, without Normal visual acuity in both ey es the application of additional tests, capable of Fusional amplitudes detecting subtle but functionally important Normal retinal correspondence vanatlOns between normal, subnormal, Foveal suppression in one eye in binocular vision abnormal or absent binocular vision.71 Reduced or absent stereopsis Stability of alignment The current lamentable practice of group No treatment ing together normal and abnormal retinal correspondence has done little to advance our knowledge. By distinguishing clearly, Table V Microtropia whenever this is possible, between the vari ous types of binocular cooperation in the Inconspicious shift or no shift on cover test treated patient a more meaningful analysis of Mi ld am blyopia frequent treatment results becomes possible. Fixation parafoveolar We classify our results into four categories: Fusional am plitudes subnormal binocular vision, microt Anomalous retinal correspondence (1) (2) Reduced or absent stereopsis ropia, residual small angle eso- or exo (3) Some stability of alignment tropia and (4) large angle esotropias or con Amblyopia treatment up to school age secutive exotropias that may require further surgery and have described elsewhere the combination of sensory and motor tests Table VI Small angle esolexotropia «20 prism required to diagnose these conditions.71 The dioptres) clinical characteristics of each of these four end stages of surgical therapy are listed in Cosmetically acceptable Tables IV-VII. While there is unanimous 80% have anomalous retinal agreement that a complete normalisation of correspondence Less stability of angle all binocular functions including normal ran No treatment except for dom dot stereo acuity is an unattainable goal amblyopia in essential infantile esotropia we shall see that a state of near normalcy is by no means beyond the reach of the therapist. Subnormal Table VII Large angle esolexotropia (>20 prism binocular vision, a term introduced into the dioptres) strabismus literature by the late Keith Lyle72 must be considered as an optimal outcome of Usually cosmetically unacceptable treatment. Retinal correspondence is normal Less chance for anomalous retinal correspondence, suppression and with the exception of normal random dot prevails stereopsis and bifoveal sensory fusion, such Unstable angle patients have nearly normal binocular vision. Further surgery often required More common endstages of treatment are 354 G. K. von NOORDEN great zeal and conviction by many orthop and in Europe largely under the influence of tists. It is now viewed in an entirely different Lyle, Hugonnier and Arruga, surgery was light. The patient with anomalous correspon usually performed beween the ages of two dence gains many functional benefits from and five years of age. The current tendency this sensorial adaptation to a residual angle to attempt alignment earlier and preferably of squint. These benefits include an intact prior to the age of 18 months began in the binocular field of vision, stability of the United States with Costenbader and his residual angle, fusional vergences,7&--7?; nor schooP9.R2 Many authors claim that only by mal distance judgemenel),RO and even gross operating at this age can a functionally useful stereopsis. 73,75,81 Above all, it permits a result be obtained59,68M and that surgery per patient with a residual manifest strabismus to formed later precludes such an outcome.4.p.89 enjoy single binocular vision. This is the prin We have recently published our results in 358 cipal reason why I am opposed to treating patients operated on for essential infantile anomalous correspondence by orthoptics, a esotropia53 and I will only summarise these practice still rampant in various parts of the data here. The mean follow-up was 39.4 world. Anyone who has ever had to deal with months (1-203 months), The onset of the the unfortunate patient who by lengthy and squint prior to the age of six months was con often costly eye exercises is now incapaci firmed by an ophthalmological examination tated by constant diplopia will agree with this or, in the few caes where this was not possi assessment. ble, documented on photographs supplied by Finally, we must discuss the optimal age at the parents. The results are presented in which surgery should be performed, In my Figure 8 and show that, as the age at comple professional lifetime I have seen a progres tion of surgery increases, the probability of sive shift towards early surgery. In the sixties, achieving subnormal binocular vision,
PREY ALENCE OF FUNCTIONAL STATE ACCORDING TO AGE AT ALIGNMENT (358 Patients) 50 188 SBV � ET > 20d • Microtropia o XT > 20d 40 m ET/XT < 20d
- c: 30 Q) (J ... Q) 0.. 20
10
4m - 2y - 4y (n=71) 4y and > (n=97) Age at Last Surgery Fig. 8. Prevalence of surgical results in 358 patients with essential infantile esotropia according to age at alignment. ,)'BV, subnormal binocular vision, ET, esotropia, XT, exotropia. From von Noorden53". CURRENT CONCEPTS OF INFANTILE ESOTROPIA 355 defined by us as an optimal result decreases Abducensl1ihmung (Das sogenannte 'Bloc (p=O.002). Increasing age at the completion kierungssyndrom'). Buch Augenarzt 19 66, 46: of treatment tends to move the patients into 271-78. the less favourable though still acceptable 14 Ciancia A: La esotropia con limitacion bilateral categories of microtropia or small angle eso de la abduccion en el lactante. Arch O/talmol B.A. 1962,37: 207-11. or exotropia. Thus our findings are in sup 15 Pollard ZF: Accommodative esotropia during port of the current tendency to complete sur the first year of life. Arch Ophthalmol 197 6 . gical alignment prior to the age of two years. 94: 1912-13. However, they also show that many patients 16 Baker 1D and Parks MM: Early onset accom achieved satisfactory results when surgery modative esotropia. Am J Ophthalmol 198 0, was delayed until after the ages of two or 90: 11-18 . even four years. 17 Haynes H. White B. Held R: Visual accommo dation in human infants. Science 1965 , 148: 528-30. 8 References 1 Chavasse FB: Worth's squint or the binocular 1 Keith A: The genius of William Bowman. Trans reflexes and the treatment of strabismus. 7th Ophthalmol Soc UK 1930,50: 32-5l. ed. London. Bailliere, Tindall and Cox. 1939 . 2 Law FW: The Ophthalmological Society of the 19 Duke-Elder Sand Wybar K: Ocular motility United Kingdom. A hundred years of history. and strabismus. System of Ophthalmology. London. Headley Brothers, p. 4. St. Louis. C V Mosby. 1973: 2 38 . 3 Hirschberg J: The history of ophthalmology. 20 Sidikaro Y and von Noorden GK: Observations Vol. 8 (A) The first half of the nineteenth cen in sensory heterotropia. J Pediat Ophthalmol tury (part 4) Great Britain (A). Translated by Strabismus 1982, 19: 12-19. F. C. Blodi. Bohn. J. P. Wayenborgh, 1987: 21 Ellsworth RM: The practical management of 2 33. retinoblastoma. Trans Am Ophthalmol Soc 4 Taylor DM: Congenital esotropia. Management 19 69 . 67: 462-534. 22 and prognosis. New York. Intercontinental Costenbader F: Infantile esotropia. Trans Am Medical Book Corporation, 1973. Ophthalmol Soc 1961. 59: 397-429. 5 Foster RS, Paul TO, Jampolsky A: Manage 23 Avilla CW and von Noorden GK: Post-trauma ment of infantile esotropia. Am J Ophthalmol tic fusion deficiency. In Ravault A and Lenk 1976,82: 291-9. M eds. Transactions of the 5th International 6 Keiner GBJ: cited from Crone RA, Orthoptic Congress, Lyon: LIPS 1984: 143- Symptomatology in convergent strabismus. In 47 . Evens, Led. Bull Soc BeIge Ophthalmo/1981, 2·\ Worth C: Squint: its causes, pathology. and 195: 125-77. treatment. 6th ed. Philadelphia. R. B1akis 7 Nixon RB, Helveston EM, Miller K, Archer ton's Son and Co. 1929. SM, Ellis FD: Incidence of strabismus in 25 Slater AM and Findlay 1M: Binocular fixation in neonates. Am J Ophthalmol 1985, 100: 79'11,- the newborn baby. J Exp Child Psychol 1975, 80l. 20: 2 48-7 3 . 8 Friedrich D and de Decker W: Prospective 2" Aslin RN: Development of binocular fixation in study of the development of strabismus during human infants . .I Exp Child PsycheJ/1977. 23: the first 6 months of life. In Lenk-Schafer. M. U3-50. ed. Trans. 6th Int. Orthop. Congress. 1987, 27 Held R: Development of acuity in infants with 21-8. Burmal and anomalous visual experience. In 9 Helveston EM: Personal Communication (Au Aslin RN, Alberts 1R, Peterson MR cds. gust 22,1987). Development of perception. Vol 2: The visual III Sorsby A: Latent nystagmus. Br J Ophrhalmol system. New York: Academic Press 1981: 1931,15: 1-18. 279-96. 11 Dell'Osso L, Schmidt D, Daroff RD: Latent. 2S Atkinson 1. Braddick 0, Moar K: Development manifest latent and congenital nystagmus. of contrast sensitivity over the first 3 months Arch Ophthalmol1979, 97.1877-85. of life in the human infant. Vision Res 1977. 12 von Noorden GK. Munoz M, Wong SY: Com 17: \037 -44 . pensatory mechanisms in congenital nystag 29 Banks MS and Salapatek P: Acuity and contrast mus. Am J Ophthalmol1987, 104: 387-97. sensitivity in 1-, 2- and 3-month-old human 13 Adelstein F and Clippers C: Zum Problem der infants. Invest Ophthalmol Vis Sci 1978, 17: echten und der scheinbaren 361 -65. 356 G. K. von NOORDEN
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