Optometry Reports 2016; volume 6:5626

A review of the classification of and management involves investigation of the underlying etiology in addition to the battery of Correspondence: Charles Darko-Takyi, nonstrabismic binocular vision binocular vision test procedures. Department of Optometry, University of Cape anomalies Coast, Cape Coast, Ghana. Tel. +233.545063571. E-mail: [email protected] Charles Darko-Takyi,1,2 1 1 Naimah Ebrahim Khan, Urvashni Nirghin Introduction Key words: Nonstrabismic binocular dysfunc- 1Department of Optometry, University of tions; Accommodative anomalies; Vergence KwaZulu Natal, South Africa; Many symptomatic patients’ conditions do anomalies. not fit specifically into one diagnostic category 2Department of Optometry, University of because of presence of defects in two or more Contributions: CD-T, conceived the idea, sought Cape Coast, Ghana areas of binocular vision.1 Patient’s with literature and drafted the paper as part of the lit- accommodative disorders may have secondary erature review of a master’s research work; NEK and UN, played a supervisory role, revised the vergence disorders and vice versa due to the Abstract paper critically for important intellectual content, control of the interactive negative feedback and finally approved the paper to be published. loop for these two systems.2,3 For example, There are conflicting and confusing ideas in small degrees of esophoria are usually found Conflict of interest: the authors declare no poten- literature on the different types of accommoda- in cases of accommodative insufficiency;4 in tial conflict of interest. tive and vergence anomalies as different this, patient uses extra innervations to over- authors turn to classify them differently. This come this accommodative disorder causing Acknowledgments: we wish to acknowledge Ms Carrin Martin, English editor for the school of paper sought to review literature on the differ- esophoria due to stimulation of accommoda- health sciences, University of KwaZulu Natal, 4 ent classifications and types of nonstrabismic tive convergence. In spite of these associa- South Africa. binocular vision anomalies and harmonize tions, non-strabismic binocular vision dysfunc- these classifications. Search engines, namely tions are classified as either accommodative Received for publication: 12 November 2015. Google scholar, Medline, Cinahl and Francis anomalies or vergence anomalies.1 The aim of Revision received: 15 February 2016. databases, were used to review literature on this review is to clarify and harmonize the onlyAccepted for publication: 19 February 2016. the classification of accommodative and ver- classification and types of accommodative gence dysfunctions using keywords like binoc- anomalies and vergence anomalies for easy This work is licensed under a Creative Commons Attribution NonCommercial 4.0 License (CC BY- comprehension and diagnosis by optometric ular vision dysfunctions, classification of non- NC 4.0). strabismic binocular vision disorders or anom- practitioners, students and all optometricuse alies, accommodative disorders/anomalies clas- stakeholders. ©Copyright C. Darko-Takyi et al., 2016 sification and vergence disorders/anomalies Licensee PAGEPress, Italy classifications, and included works that Optometry Reports 2016; 5:5626 described these anomalies. Nonstrabismic doi:10.4081/optometry.2016.5626 binocular vision anomalies are classified as Search strategy accommodative and vergence anomalies. There are three different major types of Our search strategy involved using search ent categories, with slight or minor modifica- accommodative anomalies, namely accom- engines like Google scholar, Medline, Cinahl tions or changes in names. The most common modative insufficiency, accommodative infa- and Francis databases to review all literature classifications systems are reviewed below. cility (accommodative inertia), and accom- on the classification of binocular vision anom- modative excess (accommodative spasm), and alies using keywords like binocular vision dys- Donder’s classification seven different types of vergence anomalies commercialfunctions, classification of nonstrabismic The original classification used for accom- (convergence insufficiency, convergence binocular vision disorders or anomalies, modative anomalies was by Donders4,6 and has excess, divergence insufficiency, divergence accommodative disorders/anomalies classifi- been popularized by several authors.4,7-11 It has excess, basic esophoria, basic exophoria and cation and vergence disorders/anomalies clas- the following three categories:7,12 accommoda- fusional vergence dysfunctions), which are sifications. We included works that described functional in origin. Functionally,Non there is a these anomalies. tive insufficiency, accommodative excess and commonly reported interaction between accommodative infacility. accommodative and convergence insufficiency referred to as pseudoconvergence insufficien- Duane’s classification’s cy. Accommodative paralysis (subtype of Accommodative anomalies One of the early attempts to classifying accommodative insufficiency) and vergence accommodative anomalies was by Duane in anomalies – i.e., convergence paralysis, con- Accommodative anomalies are characterized 1915.4,13 Other authors have discussed classifi- vergence spasm and divergence paralysis – are by inadequate accommodative accuracy and sus- cation of accommodative anomalies using non-functional in origin with underlying sys- tainability, inadequate amplitude, flexibility and Duane’s classification with minor modifica- temic disease etiologies. Systemic conver- facility and are non-refractive and non-aging tions. Scheiman and Wick,4 made reference to gence insufficiency, associated with subnor- neuromuscular abnormalities of the visual appa- this system of classification instead of the pop- mal accommodation, is a non-functional inter- ratus.5 This inadequacy affects the eyes ability to ular Duke-Elder’s classification.14 His six cate- action between the accommodative and con- focus objects clearly causing blur retinal gories are:4 Insufficiency of accommodation, vergence insufficiency. The classification of images.1 It is difficult to categorize accommoda- Ill-sustained accommodation, Inertia of accom- nonstrabismic binocular vision anomalies is tive anomalies, as their boundaries are not modation or accommodative infacility, based on the description of the clinical signs clear.5 While there are various classification sys- Excessive accommodation, Inequality of and the underlying etiology either functional tems, confusion arises as different authors clas- accommodation or unequal accommodation, or non-functional in origin. Proper diagnosis sify these disorders into three, five or six differ- and Paralysis of accommodation.

[Optometry Reports 2016; 5:5626] [page 1] Review

Duke-Elder Stewart’s classification temic etiologies, the clinical signs being purely Duke-Elder, making his system the most popu- In American Academy of Optometry evi- descriptive. This system of classification origi- lar. A review of the descriptions of the specific dence-based guidelines on accommodative and nated with Donders, and expanded by Duke- types of accommodative anomalies will vergence dysfunctions,1 accommodative dys- Elder and Abram19 and has been popularized by address the questions raised above, and clarify functions were classified with reference to optometric authors.4 the categories of accommodative anomalies. Duke-Elders Stewart’s classification, as found in his 1949 book The practice of refraction.14 His five categories are: accommodative insuffi- ciency, ill-sustained accommodation, accom- Discussion of results of classi- Description of specific accom- modative infacility, paralysis of accommoda- fications of accommodative modative disorders mentioned tion and spasm of accommodation. disorders above In the book, The practice of refraction,15 Duke-Elder Stewart in 1963 classified accom- In Duke-Elder’s classification in 1949,14 modative anomalies into six distinct cate- Accommodative insufficiency excess of accommodation was not included as gories instead of the five in 1949. This was a A persistently lower accommodation than found in Duane’s classification previously,4,13 minor modification to Duane’s classification, expected for age is accommodative insuffi- and included spasm of accommodation and left and consisted of the following six anomalies: ciency20 and this does not result from crys- out inequality of accommodation. The ques- excessive accommodation, spasm of accommo- talline lens sclerosis.1 In this, the amplitude of tion posed here is Is accommodative excess the dation, insufficiency of accommodation, ill- accommodation is significantly lower than the same as spasm of accommodation or inequality sustained accommodation, inertia of accommo- lower limit of expected for age using of accommodation? If the answer is yes, then it dation, and paralysis of accommodation. Walsh Hofstetter’s formula.4,21 These patients will justifies why the author replaced them with and Hoyt (1969) made reference to the five usually exhibit a reduction in the accommoda- spasm of accommodation. If the answer is no, distinct syndrome categories of anomalies of tive amplitude by 2D or more.4,20 They also then the question posed here is why was accommodation by Duke-Elder.5,16 In the book show a reduced positive relative accommoda- Duane’s classification in 1949 modified? Ophthalmic optics and refraction in 1970,17 as tion, difficulty with minus lens of accommoda- Comparing Duke-Elder’s classification in only well as his publication in 1971,18 Duke-Elder tive facility, and an increased lag of accommo- 196315 to Duane’s classification in 1915,4,13 again emphasis his 1949 classification as: dation.1,4,20 Accommodative insufficiency, Duke-Elder included spasm of accommodation accommodative insufficiency, accommodative though as the commonest accommodative dis- and excluded inequality of accommodation. excess, accommodative fatigue, accommodative order1,4,21 has the main symptom being a gen- Comparing this classification with the classifi- infacility, and accommodative paralysis. useeral asthenopia related to near20 although it cation in 194914, excess of accommodation and also presents with other clinical signs and spasm of accommodation were classified as Duke-Elder and Abram’s classification symptoms.1,4,20 distinct from each other in the 1963 classifica- In their book, The practice of refraction pub- tion15, inferring that the two conditions were 19 lished in 1993, they emphasized Duke-Elder’s not the same. Another question posed here is Ill-sustained accommodation five distinct anomalies specifically naming Is inequality in accommodation similar to any This is an accommodative disorder with nor- them as: insufficiency of accommodation, of these conditions above? mal accommodative amplitude, but repeated 1 fatigue of accommodation, spasm of accommo- Comparing Duke-Elder’s five distinct classi- stimulation of accommodation causes fatigue. dation, paresis of accommodation and infacili- fications in 194914 and 1970 or 1971,18 ill-sus- Ill-sustain accommodation has been catego- ty of accommodation. tained accommodation in 1949 was captured rized as a sub classification of accommodative 1 as fatigue of accommodation in 1970 and 1971. insufficiency and is also known as accom- 20,21 Bertil Sterner’s classification Thiscommercial raises the question as to whether ill-sus- modative fatigue. On occasion, a patient In 2001, While Bertil Sterner5 made refer- tained accommodation is the same as fatigue might have sufficient amplitude of accommo- ence to the classifications by Duke-Elder of accommodation. It can be seen in this clas- dation, but is unable to maintain the response, 1971,18 he maintained that it was clinically sification that spasm of accommodation men- which may be the first stage of accommodative 4,20,21 useful to separate the anomalies of accommo- tioned by Duke-Elder (1963)15 is omitted in his insufficiency. Patients with this disorder dation into one of five distinct syndromeNon cate- 1970 and 197118 publications to form the five initially report the ability to do near work and 20,21 gories: insufficiency of accommodation, fatigue anomalies. Comparing Duke-Elder’s classifica- experience discomforts after some time of accommodation, spasm of accommodation, tion in 1949 to this classification in 1970 and because the accommodative apparatus fails to paresis of accommodation and infacility of 1971, spasm of accommodation mentioned in maintain its effort to accommodate. With con- accommodation. Sterner in 2001 emphasized 1949 was replaced with excess of accommoda- tinuous near work, accommodative system that the five syndromes all constitute different tion in 1970 to form the five. The question loses power and near point recedes causing accommodative disorders, with a range of posed here reads is spasm of accommodation blur near vision; normal amplitudes of accom- 4,21 impact on the accommodative function.5 synonymous with excess of accommodation? modation begin to deteriorate over time. For It can also be seen in Duke-Elder and clinical diagnostic purposes, it is advisable to Scheiman and Wick’s classification Abram’s classifications in 199319 that the name repeat the accommodative amplitude test sev- A more recent classification by Scheiman fatigue of accommodation was maintained eral times to study the trend of results or con- and Wick in 20084 classified accommodative instead of ill-sustained accommodation men- duct the test last in the examination proce- anomalies into four groups namely: accom- tioned in 194914. In their classification again, dure. The average amplitude of accommoda- modative insufficiency, ill-sustained accommo- spasm of accommodation was mentioned as tion is calculated using Hofstetter’s formula, 22 dation (accommodative fatigue), accommoda- compared to excess of accommodation in 18.5-1/3(age). tive excess and accommodative infacility (iner- Duke-Elder’s classification in 1970 and 1971.18 tia of accommodation). This classification is Most of the authors5,16,17,19 from 1969 made Accommodative paralysis functional in origin, with no underlying sys- reference to the five distinct classifications by Accommodative paralysis defines sudden

[page 2] [Optometry Reports 2016; 5:5626] Review onset insufficiencies in accommodation to the other category of accommodative dys- referred to as accommodative spasm, ciliary caused by either organic disorders in the nerv- function called unequal accommodation,4 a spasm and spasm of the near reflex.4 ous system or toxins.23 It has been categorized possible cause of this condition being func- Pseudomyopia is considered as one of the as a sub classification of accommodative insuf- tional amblyopia.4 signs of accommodative excess4 and patients ficiency.4 As a rare disorder,1, 21 there is a fail- with this condition experience discomforts ure of the accommodative apparatus to Accommodative excess with works that require the visual system to respond to stimulus.1 Accommodative paralysis Accommodative excess refers to an inces- relax accommodation.21 The main symptoms can be unilateral or bilateral, sudden or insidi- santly higher accommodative amplitude than are intermittent blurred vision both near and ous,1,4,21 most often unilateral with extra ocular age expected norms20, and is due to spasms of distance; the distance blur becomes worse and pupillary involvement either fixed or dilat- the ciliary muscle.21 Clinical signs include a after prolong near work or towards the end of ed.1 This disorder can result from careless use lead of accommodation and reduced negative the day and is associated with the pseudomy- of cycloplegic drugs, toxicity, accidents, con- relative accommodation.20 It is often secondary opia.21 These symptoms also become worse genital defects and diseases of the system.1,21 It to convergence insufficiency and can also be with dim illumination.21 has also been associated with glaucoma, and regarded as an inability to relax accommoda- has a favorable prognosis for recovery.21 If tion, known as a spasm of accommodation.20 Accommodative infacility accommodative paralysis is unilateral, it leads Accommodative excess is also variously Accommodative infacility, also called Inertia

Table 1. Summary of classification of accommodative anomalies. Anomaly Brief definition Main symptoms Main signs Treatment options Functional Accommodative Persistently lower accommodation Asthenopic symptoms with AOA low for age; Refractive error in origin insufficiency than expected for age near point task high lag of accommodation; correction, low PRA; fails flipperonly test added lenses and with minus lenses; vision therapy sequentially low base out to blur findings at near Ill-sustained Normal accommodative Asthenopic symptoms use Normal AOA on first Refractive error correction, accommodation amplitude, but repeated with near point task administration; added lenses and vision (accommodative stimulation of AOA decreases with therapy sequentially fatigue) accommodation repeated testing; causing fatigue high lag of accommodation; low PRA; fails flipper test with minus lenses Accommodative Difficulty with stimulation Difficulty of switching Fails both monocular Refractive error correction infacility/ and relaxation of the between distance and and binocular flipper and vision therapy accommodative response to accommodation near focus, test with plus and minus lenses; sequentially inertia due to slow down in asthenopia with near task low PRA and NRA; accommodative dynamics low base out to blur findings at near Accommodative Spasms of accommodativecommercial Asthenopia with Variable visual acuity; Refractive error correction excess/ system due to ciliary muscles near task, intermittent variable normal or high AOA; and vision therapy accommodative blur distance and variable results in sequentially spasm near vision objective and subjective refraction; fails flipper Non test with plus lenses; low lag of accommodation/ lead of accommodation; low NRA Non- Accommodative Rare disorder of Sudden onset/sometimes Signs of accommodative Treatment of underlying functional paralysis insufficiency in insidious asthenopic insufficiency; systemic etiology in origin accommodation symtoms with near task extra ocular muscle in which involvement; accommodative fixed or dilated pupil apparatus fails involvement to respond to near stimulus Unequal Unilateral case of Sudden onset/sometimes Accommodative Treatment of underlying accommodation accommodative insidious unilateral insufficiency signs, systemic etiology paralysis asthenopia with near task unilateral extra ocular muscle involvement, unilateral fixed or dilated pupil involvement AOA, autosomal optic atrophy; PRA, positive relative accommodation; NRA, negative relative accommodation.

[Optometry Reports 2016; 5:5626] [page 3] Review of accommodation4, occurs when the accom- two sub classifications of accommodative insuf- exist.4,20 If the esophoria is greater at distance modative dynamics, that is, latency, time con- ficiency as specific types. Functionally, there are and a low AC/A ratio is present, a divergence stant, and peak velocity are slowed.20,21 There is effectively three different major types of accom- insufficiency is said to exist.4,20 If an exo devi- difficulty with stimulation and relaxation of modative anomalies4,12 as first mentioned by ation is higher with near fixation than with the response to accommodation thus the main Donders in 18544,6 and non-functionally there distance fixation, with lower than normal AC/A complain is difficulty changing fixation are two types of accommodative anomalies ratio, then a convergence insufficiency between distance and near.21 With this accom- which are all subtypes of accommodative insuf- exists.4,20 Finally, if the exo deviation is greater modative disorder, the change in accommoda- ficiency (Table 1). at distance and the AC/A ratio is higher than tion between distance and near focus is not normal, a divergence excess exists.4,20 readily achieved and accurate due to abnormal accommodative response.20,21 Changes in Wick’s classification accommodation only occur with effort and dif- Vergence anomalies Wick’s25 classification represents an expan- ficulty in the presence of normal response sion of the classification by Duane, and it con- magnitude,20 with patients exhibiting this con- Vergence anomalies describe disjunctive siders the phoria at distance and AC/A ratio.4,7 dition usually complaining of near-to-far or far- movement of the eye in which there is conver- It takes all possible combinations into consid- to-near blur.20. Even though accommodative gence or divergence, causing the eye to inac- eration, and indicates nine possible diagnoses, amplitude is normal; there is inadequacy in curately fixate and stabilize an image on the rather than the four suggested by Duane,4,25 all the ability of the visual system to quickly use retina.1 Two classification systems exist in lit- of which are horizontal heterophoria prob- this amplitude for longer period.4,21 The diag- erature to help categorize vergence dysfunc- lems. The nine possible diagnoses can be nosis of this disorder can thus be missed if tions, namely Duane’s24 and Wick’s,25 which divided into three main categories of binocular only amplitude of accommodation is measured are explained below with their advantages and vision problems based on the AC/A ratio, the in clinic.21 Other accommodative tests which disadvantages. three categories being low AC/A ratio, normal include monocular and binocular accommoda- AC/A ratio, and high AC/A ratio (Table 2).4,7 tive facility are very vital in the diagnosis of Duane’s classification This classification system was very specific 4 accommodative infacility. This classification divides the disorders into because treatment differs for each of the con- only 4 four main types namely convergence insuffi- ditions mentioned; vertical heterophorias ciency, convergence excess, divergence insuffi- were classified as either right or left hyperpho- ciency and divergence excess.24 This classifica- ria. This is the classification system used by 1 Summary of classification of tion was originally developed by Duane for the American Optometric Association and is use 12 accommodative dysfunctions strabismus, while Tait26 in 1915 extended it to the most common type of classification. The non-strabismic binocular vision anomalies.4,7 conditions are functional in origin with purely Based on the reviews of the description of the This is a descriptive classification and does descriptive clinical signs with no underlying 4 various conditions, it is now certain that not necessarily imply etiology, and Duane system etiologies. unequal accommodation4,13 is a type of accom- described and classified them as binocular modative paralysis which is in turn a sub-classi- commitant convergence syndromes.20 fication of accommodative insufficiency.4 Binocular problems are described according to Accommodative fatigue (a sub-classification of the type of heterophoria measured at distance Comparison of Duane’s classifi- accommodative insufficiency)4 is also called Ill- and at near, so even though there are four cation and Wick’s classification sustained accommodation.20,21 Another name for main types, these could be grouped into two accommodative infacility is accommodative main categories, namely esophoria vergence Other possible combinations exist in Wick’s inertia,4 while accommodative excess is also anomaliescommercial and exophoria vergence classification that do not fit into Duane’s clas- called accommodative spasm.20 Different anomalies.4,7,20 If an esophoria is larger at near sification.4 According to Wick, Duane’s classifi- authors tend to use these terms interchange- than at distance and the accommodative con- cation does not have a category for a deviation ably, with Duke-Elder’s popular 1949 five distinct vergence/accommodation (AC/A) ratio is high- in which the exo deviation and eso deviations accommodative anomalies thus includingNon the er than normal, a convergence excess is said to are equal at distance and near, i.e. basic Table 2. Possible diagnoses of binocular vision problems. Wick’s classification of binocular vision anomalies Anomaly Low AC/A ratio Orthophoria at distance Convergence insufficiency Exophoria at distance Convergence insufficiency Exophoria at distance Divergence insufficiency Normal AC/A ratios Orthophoria at distance Fusional vergence dysfunctions Exophoria at distance Basic exophoria Esophoria at distance Basic esophoria High AC/A ratio Orthophoria at distance Convergence excess Esophoria at distance Convergence excess Exophoria at distance Divergence excess Vertical anomalies Right hyperphoria - Left hyperphoria - AC/A, accommodative convergence/accommodation.

[page 4] [Optometry Reports 2016; 5:5626] Review

Table 3. Summary of classification of vergence anomalies. Anomaly Brief definition Main symptoms Main signs Treatment options Functional Convergence A condition with higher Asthenopic symptoms with Receded NPC; Refractive error correction, in origin insufficiency exophoria at near and reading and near point higher decompensated prisms or vision therapy receded NPC task often long standing exophoria at near than at distance; low AC/A ratio; reduced PFV at near Divergence A condition with high Long standing intermittent Greater esophoria of 2 to 8 Refractive error correction, insufficiency esophoria at distance diplopia, especially at distance, degrees at distance than near; base out prisms, than at near with normal headaches and eyestrain decreased NFV at distance; or vision therapy versions and reduced low AC/A ratio; normal NPC divergence at distance Convergence A condition of a higher Asthenopia with reading Esophoria greater Maximum excess esophoria at near than or near task, at near than at distance; plus refractive error at distance occasional double vision, high AC/A ratio; correction, blur vision reduced NFV at near minimum amount of added lenses for near, prisms and vision therapy Divergence A condition in which Common complaint Exophoria greater Correction of any refractive excess eye turns out is cosmetic appearance, at distance than error, added minus lenses intermittently subjective symptoms rare, at near; high AC/A ratio; at distance, prisms, vision occasional diplopia essentially normal PFV therapy at near and distance; no significant refractive onlyerror Fusional A condition with low Asthenopia with Normal AC/A ratio; Correction of significant vergence or no degree of reading or near task normal phoria refractive errors, vertical dysfunction phoria but lower at distance and near; prisms if vertical deviation fusional vergence use reduced fusional vergence exists and vision therapy reserves at distance reserves at near and distance; and near low PRA and NRA; others Basic A condition Asthenopia with Equal amount of Maximum plus prescription esophoria in which tonic near and distant task esophoria at distance for refractive errors, vergence is and near; normal AC/A ratio; horizontal relieving prisms high and AC/A hyperopia often present and vision therapy ratio is normal Basic exophoria A condition Asthenopia with Receded NPC; Correction of refractive in which tonic near and distant task equal exophoria errors, added lenses vergence is low at near and at distance; in a bifocal format for and AC/A ratio normal AC/A ratio full time wear, normal horizontal relieving prism, commercial vision therapy Non-functional Convergence A case of convergence Recent or sudden All signs of functional Treatment of underlying in origin paralysis insufficiency onset diplopia especially convergence insufficiency; systemic disease associated with at near and asthenopia presence of serious seriousNon systemic systemic disease disease and considered a supranuclear gaze disorder Convergence Over-convergence Headaches, general Episodes of intermittent Treatment of underlying spasm associated with ocular discomfort, maximal convergence; systemic disease accommodative spasm blurring of vision associated and diplopia accommodative spasm; associated pupillary constrictions Divergence A case of high Sudden onset All clinical signs Treatment of underlying paralysis esophoria at distance intermittent diplopia of divergence insufficiency; systemic disease, than at near with at distance, sudden no significant refractive error; e.g. neurological diseases decreased onset headaches, sudden onset eyestrain presence of systemic disease divergence at distance secondary to systemic disease NPC, near point of convergence; AC/A-accommodative convergence over accommodation; PFV, positive fusional vergence; NFV, negative fusional vergence; PRA, positive relative accommodation; NRA, negative relative accommodation.

[Optometry Reports 2016; 5:5626] [page 5] Review exophoria and basic esophoria.4,25 In addition, usually also be reported.30,31 Functionally, modation and the vergence system is pseudo- it does not consider a condition in which there patients with convergence spasm have tubular convergence insufficiency,4 and is a case of is no significant phoria at either distance or field defects; again fixating on an object closer combined insufficiency of convergence and near, but the horizontal fusional vergence to the eye can trigger the spasm and eyes accommodation.22,38 Pseudoconvergence insuf- ranges are reduced in both base-in and base- maintain convergence after the object is ficiency is primarily an accommodative dys- out directions, i.e. fusional vergence dysfunc- removed.22 function.39 In this case, the patient has difficul- tion.4,27 Vergence anomalies have been regard- ty accommodating therefore under accommo- ed as syndromes of deterioration by some Divergence paralysis dates relative to the stimulus.4 As a result, less authors who have proposed a graphical analy- This condition was first described by accommodative convergence is available, the sis-based classification.7,8 However, these clas- Parinaud in 1883 as a clinical entity after he measured exophoria is large, and a greater sifications are purely descriptive, as the mech- observed cases of distance homonymous demand is placed on positive fusional ver- anism of vergence is considered only in its diplopia with normal versions and ductions.22,29 gence.4 The differential diagnosis of true con- open loop state. Some other authors indicate Many subsequent cases have been reported,22 vergence insufficiency vs pseudoconvergence that these models do not estimate the contri- and systemic diseases like tabes, poliomyelitis, insufficiency has been addressed in bution of proximal factor.7,28 Based on this, disseminating sclerosis, pseudotumor cerebri, literature.36 Typically, such patients will also Wick’s classification other than Duane’s clas- encephalitis and influenza,32-34 to mention just have a receded near point of convergence sification specify the binocular system in the a few are known underlying causes because of the reduced amplitude of accommo- presence of fusion.4,7,8 Scheiman and Wick uti- Divergence paralysis presents with all the dation and the lack of accommodative conver- lize Wick’s classification in their recent book.4 clinical signs of divergence insufficiency, but gence.4 This case is purely functional in origin, with abnormal neurological findings22 with with no underlying debilitating systemic dis- presence of systemic disease.32-34 Divergence ease or diseases;4 the classification and diag- paralysis therefore is a non-functional form of nostic clinical signs are thus purely descrip- Non-functional vergence divergence insufficiency but with an underly- tive.4 anomalies ing systemic disease. Systemiconly convergence insufficiency, Discussed below are vergence anomalies associated with subnormal accom- which are non-functional in origin but have Summary discussion of classifi- modation some underlying systemic disease etiologies. 22,40 cation of vergence anomalies First mentioned by Duane in 1916, useBrown later in 1962 described it following Convergence paralysis some systemic diseases.22,41 Brown stated that This condition was first described by Vergence anomalies are classified based on this condition considerably differs from func- Parinaud29 as distinct from convergence insuf- their etiology either functional in origin and tional convergence insufficiency, because ficiency, and is a condition in which diplopia is classification purely descriptive or non-func- symptoms are more severe and the condition present only at near with normal adduction tional in origin with underlying systemic dis- cannot easily resolve. Von Noorden and col- and the inability to converge.4,22 This is a case ease etiology. Functionally, there are seven dif- leagues in 1973also reported cases of this con- of convergence insufficiency with serious ferent types of vergence anomalies (Table 3) dition among patients who were adolescents underlying diseases,4 and is commonly attrib- as proposed by Wick and emphasized by and young adults, who apart from one, did not 4 uted to neurological lesions in the areas of the Scheiman and Wick in a recent book. Non- benefit from conventional orthoptic exercis- third nerve nucleus, Corpa Quadrigemina or functionally vergence anomalies are classified es.22,42 The onset of this condition can be grad- pineal gland (as in Parinaud’s syndrome) or in into three, namely convergence paralysis (case ual over many years or suddenly after an acci- debilitating diseases.22,30 This condition may of commercial convergence insufficiency with systemic dent.22 The only difference between this condi- present with normal, absent or reduced accom- disease etiology), convergence spasm (state of tion and pseudoconvergence insufficiency is modation and the presence or absence of over-convergence with systemic disease etiolo- that, this is not functional in origin; there is pupillary involvement.22 Symptoms include gy) and divergence paralysis (state of diver- always an underlying systemic disease.4,22 crossed diplopia, which presents worse at near, gence insufficiency with disease etiology). usually with a reduction in accommodation.Non30 Brief descriptions of the signs, symptoms and This condition may be intentionally or unin- treatment options for these anomalies are tentionally simulated in uncooperative and indicated (Table 3). Conclusions neurotic patients respectively, as well as in those with debilitating diseases.22 Despite the interaction between the accom- Combined insufficiency of con- modative and vergence systems, nonstrabis- Convergence spasm mic binocular vision anomalies are classified Convergence spasm is a state of over-con- vergence and accommodation as either accommodative anomaly or vergence vergence that is always accompanied by an anomaly. However, specific common interac- accommodative spasm, and occurs almost Discussed below are various conditions that tions between these accommodative and ver- exclusively in hysterical or otherwise neurotic involve an interaction of both convergence gence anomalies have been identified, a com- persons.22 Patients with this condition show insufficiency and accommodative insufficiency. mon example being the interaction between episodes of intermittent maximal convergence accommodative insufficiency and convergence with an associated accommodative spasm and Pseudoconvergence insufficiency insufficiency. These accommodative and ver- pupillary constriction.22 The symptoms are This condition has been long recognized by gence anomalies are either functional in ori- equal to that of an accommodative spasm, and optometrists35,36 and by ophthalmologists.37 A gin and their classification purely descriptive can include headaches, general ocular discom- typical example of a binocular vision anomaly of clinical signs or non-functional in which fort and blurring of vision, but diplopia will where there is an association between accom- case there is an underlying systemic disease

[page 6] [Optometry Reports 2016; 5:5626] Review etiology in addition to the clinical signs of Heinemann; 1987. pp 431-54. 28. Wick B, London R. Analysis of binocular binocular vision. For proper diagnosis and 11. Zellers J, Alpert T, Rouse M. A review of the visual function using tests made under treatment of nonstrabismic binocular vision literature and a normative study of accom- binocular conditions. Am J Optom Physiol anomalies, investigation must be made by way modative facility. J Am Optom Assoc 1984; Opt 1987;64:227-40. of the case history or underlying systemic dis- 55:31-7. ease in addition to the battery of binocular 12. Cacho-Martinez P, Carcia-Munoz A, Ruiz- 29. Parinaud H. Clinique nerveuse: paralysie vision test procedures to ascertain if the cause Cantero MT. Do we really know the preva- des mouvements associés des yeux. Arch is purely functional (innervational) or there is lence of accommodative and nonstrabis- Neurol (Paris) 1883;5:145. a disease etiology. mic binocular dysfunctions? J Optometry 30. Evans B, Doshi S. Binocular vision and 2010;3:185-97. orthoptics. Oxford: Butterworth- 13. Daune A. Anomalies of accommodation Heinemann; 2001. clinically considered. Trans Am References Ophthalmol Soc 1915; 1:386-400. 31. Benjamin WJ. Borish’s clinical refraction. 14. Duke-Elder S. The practice of refraction. 1st ed. Philadelphia, PA: WB Saunders Co; 1. American Optometric Association. Care of 5th ed. St. Louis, MO: CV Mosby; 1949. 1998. the patient with accommodative and ver- 15. Duke-Elder SS. The practice of refraction. 32. Jampolsky A. Ocular divergence mecha- gence dysfunction. Available from 7th ed. St. Louis, MO: CV Mosby; 1963. nisms. Trans Am Ophthalmol Soc 1971 16. Walsh F, Hoyt W. Clinical neuro-ophthal- URL:www.aoa.org/documents/CPG-18.pdf ;68:730. 2. Schor CM. Fixation disparity and vergence mology. 3rd ed. Baltimore, MD: Williams 33. Dunnington JH. Paralysis of divergence adaptation. In: Schor CM, Ciuffreda KJ, and Wilkins; 1969. eds. Vergence eye movements: basic and 17. Duke-Elder S. System of ophthalmology. St with report of cases due to epidemic clinical aspects. Boston, MA: Butterworths, Louis, MO: Mosby; 1970. encephalitis. Arch Ophthalmol 1923;52:39. 1983. pp 465-516. 18. Duke-Elder S. Paresis of accommodation. 34. Walsh FB, Hoyt WF. Clinical neuro-ophthal- 3. Ciuffreda KJ. The scientific basis for and Neuro-ophthalmology. London, UK: Henry mology. Baltimore, MA: Williams & Kimpton; 1971. efficacy of optometric vision therapy in Wilkins; 1969. non-strabismic accommodative and ver- 19. Abrams D, Duke-Elder S. Practice of only 35. Grosvenor T. Primary care optometry, a gence disorders. Optometry 2002;73:735- refraction. Edinburgh: Churchill 62. Livingstone; 1993. clinical manual. Chicago, IL: Professional 4. Scheiman M, Wick B. Clinical manage- 20. Emslie R, Claassens A, Sachs N, Walters I. Press Inc; 1982. ment of binocular vision: heterophoric, The near triad and associated visualuse prob- 36. Richman JE, Cron MT. Guide to vision accommodative, and eye movement disor- lems. S Afr Optom 2007;66:184-91. therapy. South Bend, IN: Bernell ders. Philadelphia, PA: Lippincott Williams 21. Rampersad N. A review of accommodation Cooperation; 1988. & Wilkins; 2008. and its anomalies. Available from: 5. Sterner B. Accommodative facility train- www.eyesite.co.za/magazine/spotlight3.as 37. Press LJ. Pseudoconvergence insufficien- ing. Available from: http://www.oft.gu.se/ p cy discovered by ophthalmologist. J Behav hp/research/theses/licentiate/2001/B_Ster 22. von Noorden GK. Anomalies of conver- Optom 1990;1:196. ner_Lic.pdf gence and divergence. In: Van Norden GK, 38. Barnard S. Anomalies of convergence. 6. Donders F. On the anomalies of accommo- ed. Binocular vision and ocular motility. Investigation and treatment. Available dation and refraction of the eye. London: 4th edition. Maryland Heights, MO: Mosby; from: www.academy.org.uk/lectures New Syndeham Society; 1864. 1990. pp 500-7. 7. Cacho-Martinez P, Garcia-Munoz A, Ruiz- 23. Duke-Elder S. System of ophthalmology. St /barnard8.htm Cantero MT. Is there any evidence for the commercialLouis, MO: Mosby; 1961. 39. University of Missouri. The convergence validity of diagnostic criteria used for 24. Duane A. A new classification of the motor insufficiencies. Available from: accommodative and nonstrabismic binoc- anomalies of the eye based upon physio- http://www.umsl.edu/~garziar/conv_insuf- ular dysfunctions? J Optometry 2012;7:2- logical principles, together with their ficiency.htm 21. symptoms, diagnosis, and treatment. Ann Non 40. Duane A. Anomalies of the accommoda- 8. Dwyer P. Clinical criteria for vergence Ophthalmol 1896;1:969-1008. accommodation dysfunction. Clin Exp 25. Wick B. Horizontal deviation. In: Amos J, tion, clinically considered. Arch Optom 1991;74:112-9. ed. Diagnosis and management in vision Ophthalmol 1915;12:386-402. 9. London R. Accommodation in ocular care. Boston, MA: Butterworth- 41. Brown HW. Strabismus in the adult. In: assessment. In: Barresi B, ed. Ocular Heinemann; 1987. Haik GM, ed. Strabismus. St Louis, MO: assessment: the manual of diagnosis for 26. Tait EF. Accommodative convergence. Am J Mosby; 1962. p 259. office practice. Boston, MA: Butterworth- Ophthalmol 1951;34:1093-107. 42. von Noorden GK, Brown DJ, Parks M. Heinemann; 1984. pp 123-30. 27. Grisham JD. The dynamics of fusional ver- 10. Cooper J. Accommodative dysfunction. In: gence eye movements in binocular dys- Associated convergence and accommoda- Amos J, ed. Diagnosis and management in function. Am J Optom Physiol Opt tion insufficiency. Doc Ophthalmol vision care. Boston, MA: Butterworth- 1980;57:645-55. 1973;34:393.

[Optometry Reports 2016; 5:5626] [page 7]