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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 insufficiency, ill-sustained accommodation, accom- Discussion of results of classi- Description of specific accommodative 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

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