Management of strabismus with hemianopic visual field defects

Background

Hemianopia and strabismus leads to severe disturbance of visual orientation and diplopia under binocular conditions if the deviated eye has a normal retinal localization.

Subjects and methods

Four cases with homonymous (two) and bitemporal (two) hemianopia and strabismus will be described with respect to binocular visual field and diplopia/confusion. All of them were recommended for strabismus surgery. Preoperatively, prism adaptation test was carried out to analyze functional results and fusional competence. In three of the four cases, strabismus surgery was successfully performed to avoid diplopia/confusion. All three patients revealed normal retinal correspondence. Furthermore, in two cases surgery led to an extension of binocular visual field; in one case with a bitemporal hemianopia and hemifield-slide phenomenon, blurred central vision and reading problems reduced significantly postoperatively. In one patient with anomalous retinal correspondence due to early childhood trauma exotropia led to an extension of the binocular visual field. In this case, strabismus surgery would have been unfavourable.

Results

Case 1 showed a homonymous hemianopia to the left and acquired exotropia of the right eye, leading to binocular diplopia. Case 2 with homonymous hemianopia to the right and exotropia of right eye revealed anomalous retinal correspondence after history of perinatal brain injury, resulting in absence of diplopia and enlargement of visual field to the right. Cases 3 and 4 with bitemporal hemianopia suffered from sensory disturbances caused by additional acquired strabismus. The exodeviation of the right eye in case 3 led to a restriction of binocular visual field with overlap of the nasal parts causing diplopia, whereas the esodeviation of case 4 resulted in a “gap” between the nasal parts (blind area).

Conclusion

Depending on the extent of visual field defects and on retinal correspondence, functional consequences for binocular vision and binocular visual field should be considered prior to surgery. In normal retinal correspondence, strabismus surgery will be indicated in most cases because of diplopia. However, surgery might result in a reduction of binocular visual field. Preoperatively, it is important to map monocular and binocular visual fields, to examine retinal correspondence, and to undertake prism adaptation test to imitate the postoperative functional result and risk of double vision.     

Causes,background, and characteristics of binocular diplopia in the elderly

Purpose

We evaluated the background and characteristics of elderly patients with binocular diplopia including diseases caused by abnormalities in orbital pulleys.

Study design

Retrospective.

Methods

The participants were 236 patients aged 60 years or older who visited Kitasato University Hospital complaining of binocular diplopia. We classified strabismus by types and investigated the causes for each group. We diagnosed orbital pulley disorders using magnetic resonance imaging (MRI). Patients with orbital pulley disorders exhibited esotropia and/or vertical strabismus and did not present with cranial nerve palsy, systemic illness, or ocular injury.

Results

Classification of strabismus types was: exotropia (24.2%); esotropia (25.0%); vertical strabismus (30.1%), combined strabismus (20.8%). There were 50.9% cases of strabismus associated with vertical deviation. The causes of disease in each group were as follows: in the exotropia group, 50.9% convergence insufficiency exotropia, 21.1% basic exotropia; in the esotropia group: 35.6% orbital pulley disorder 33.9% sixth cranial nerve palsy; in the vertical strabismus group: 32.4% forth cranial nerve palsy, 31.0% orbital pulley disorder; in the combined strabismus group: 28.6% orbital pulley disorder, 28.6% forth cranial nerve palsy.

Conclusions

About half of the elderly patients with binocular diplopia exhibited vertical deviation. In addition, binocular diplopia was often caused by orbital pulley disorders. It is the first epidemiological study focusing on orbital pulley disorders diagnosed on the basis of MRI.

     

周期性内斜视的屈光状态与临床治疗

目的 探讨周期性内斜视的屈光状态与治疗方法。方法 对２４例周期性内斜视者用１％阿托品液散瞳验光检验屈光度。斜视日与正位日用三棱镜测量斜视度,用同视机检验双眼立体视觉。手术量按斜视日最大斜视角有设计。结果 轻度、中度远视２３例。斜视日均有复视。正位日均有双眼立体视觉,斜视矫正术后２３例在斜视日与非斜视日眼位均矫正有正常的立体视觉。结果 为获得正常的双眼立体视功能,应在周期性期间及早手术。手术量控斜视     

Binocularity in comitant strabismus: Binocular visual fields studies

A critical review is made of the literature on binocular perimetry in strabismus. A broad range of results was obtained by various authors, because different testing techniques were used. The concept of sensory testing of strabismic patients in casual seeing condition should be introduced also into binocular perimetry. Therefore a series of experiments is presented in which patients with small-angle comitant strabismus were tested. It was shown that: a) in small-angle esotropia the areas of single vision previously thought to be due to suppression are, instead, areas of binocular vision sustained by anomalous retinal correspondence (ARC); b) this can be seen only when using fusable stimuli as test targets; c) no suppression scotomas were found in patients with smallangle strabismus in the whole visual field; d) appropriate control-marks for binocularity are necessary, i.e. monocularly presented items. They influence the results, as well e) the area of binocular single vision in strabismus (called pseudo-Panum's area) is wider than the Panum's area of normals. Moreover it is easier to disrupt binocular cooperation sustained by ARC causing diplopia than binocular cooperation in normals; f) ARC seems to be more deeply rooted in the center than in the periphery of the visual field; g) superimposable findings were obtained in small-angle constant exotropia; h) in largeangle exotropia wide suppression scotomas were found, which often override the midline. Hemianopic suppression scotomas in exotropia can be found only when dissociating testing techniques are used; i) the same group of patients with small-angle esotropia was examined with the author's technique and with the classical method proposed by Harms. The results were strongly dependent on the method used and the same patient responded differently to the two tests.It is concluded that in small-angle strabismus there is an anomalous type of binocular single vision, which can be tested with binocular visual field techniques. This binocularity can only be found when non-artificial testing conditions are used.The usefulness of this anomalous binocular vision in the every day seeing condition of the patient is discussed.     

Accommodation in strabismus

This paper describes clinical observations of optico-sensori-motor symptomatology prior to and during treatment for strabismus. These findings were compared with theoretical data of the binocular visual function. We consider that binocular function has the structure and the working of a "set" in cybernetic sense. In this psycho-physiological set, the accommodative system constitutes a "sub-set". The classification of accommodative disturbances as "pure or impure" and "typical or atypical" arises from the fact that a rebuilding of the visual function has occurred. Thus in "pure" accommodative strabismus the disturbances of accommodation results from "peripheral" accommodation and is easily reversible. In this situation ocular deviation has been perfectly corrected for and binocular vision normally built up since there is enough compensation of the whole optical correction. In "impure" accommodative strabismus the perturbation of accommodation affects the whole accommodation system and also the sensorial motor system. Thus there is a restructuring of the optico-sensori-motor set that is more or less reversible due to a variety of factors. From these investigations we conclude: every strabismus is accommodative in the sens that in every strabismus there is a disturbance of accommodative mechanism. Furthermore, we oppose believers of "all sensorial" and "all motor" mechanisms. Considering that strabismus is a disturbance of optico-sensori-motor binocularity, nothing can be only "accommodative", only "sensorial" and only "motor". From this it follows that treatment should not be only "motor", only "accommodative" or only "sensorial".     

Strabismus and eye muscle function

Studies of external eye muscle morphology and physiology are reviewed, with respect to both motor and sensory functions in concomitant strabismus. The eye muscles have a more complex fibre composition than other striated muscle, and they are among the fastest and most fatigue-resistant muscles in the body. However, it is not generally believed that concomitant strabismus is due to a primary abnormality of the eye muscles or the ocular motor system. The gross anatomy of eye muscles, including the shape and position of the eye muscle pulleys, was not changed in strabismus. The histology of the eye muscle fibres was also basically the same, but changes have been observed in the cellular and biochemical machinery of the fibres, most notably in the singly innervated orbital fibres. Functionally, this was seen as slower contractions and reduced fatigue resistance of eye muscles in animals with strabismus and defects of binocular vision. Most likely the changes represented an adaptation to modified visual demands on the ocular motor control, because of the defects of binocular vision in strabismus from an early age. Adaptation of eye muscle function to visual demands could be seen also in the adult human ocular motor system, but here the effects could be reversed with treatment in some conditions. External eye muscles in the human have sensory organs, muscle spindles and tendon organs, responding to changes in muscle force and length. It is not known how these proprioceptors are used more specifically in ocular motor control, and there is no stretch reflex in the external eye muscles. However, a clear influence on space localization and eye position can be demonstrated with vibratory stimulation of the eye muscles, presumably activating muscle spindles. Different effects were observed in normal subjects and in adult patients with strabismus, which would indicate that the proprioceptive input from one eye of strabismic patients could be suppressed by the other eye, similar to visual suppression in concomitant strabismus. Such an interaction would most likely occur in the visual cortex, and not in the ocular motor system. Further studies of proprioceptive mechanisms, during the postnatal developmental stage and in adult concomitant strabismus may shed light on the mechanisms of childhood strabismus and may, in this respect, be a more fruitful avenue for further research than eye motor studies.     

Critical study of sectorial occlusion in the treatment of strabismus in children

Sector occlusion, already described in 1953, has been used regularly since Berrondo's first publication on the subject in 1967 by a great number of ophthalmologists and orthoptists for convergent concomitant and sometimes divergent strabismus treatment. Sectors limit the field of fixation of each eye, in order to modify the optomotor reflex to restore and maintain the sensory and motor alternation. The mostly used sector designs are the symmetrical or asymmetrical binasal ones. The way of action of middle, narrow or broad, straight or oblique, or eventually "V" shaped binasal sectors can easily be analysed; their application does'nt present any particular difficulties; their reproduction is easy. Such is not the case of the so called "buridanization", location/observation and other numerous sophisticated shapes suggested by Berrondo. Sector-occlusion indications, advantages and disadvantages, limits and counter-indications are related in details. There is no doubt that binasal sectors represent a major acquisition for concomitant strabismus visual reeducation; they are irreplaceable in the treatment of congenital strabismus.     

Binocular vision with primary microstrabismus

PURPOSE. Patients with primary microstrabismus have a high degree of binocularity, which suggests that their ocular misalignment may have a sensory rather than an oculomotor origin, as in large-angle strabismus. The purpose of these experiments was to determine whether microstrabismic subjects have sensory abnormalities that could give rise to a small angle of strabismus. METHODS. The binocular disparity response functions for sensory and motor processes were compared in seven orthotropic subjects and six strabismic subjects (four with primary microstrabismus and two with infantile esotropia). Binocularity was assessed by disparity vergence (central and peripheral stimuli) and depth discrimination (relative and absolute disparities) measures. Motor and sensory disparity response functions were both determined by psychophysical methods: vergence responses by dichoptic nonius alignment and sensory responses by forced-choice depth discrimination. RESULTS. All the strabismic subjects demonstrated normal retinal correspondence with peripheral binocular stimuli and anomalous retinal correspondence with central fusion stimuli. The microstrabismic subjects' disparity vergence responses with peripheral fusion stimuli were centered on disparities relative to their angle of strabismus. However, with central fusion stimuli, the disparity vergence responses were relative to the subjective angle of strabismus. The microstrabismic subjects' stereoacuities were substantially reduced, but their discrimination responses did not show an asymmetry indicative of an unrepresented population of disparity-selective mechanisms. CONCLUSIONS. The data do not support a sensory abnormality as the primary cause of microstrabismus. The results are not compatible with an oculomotor adaptation to an inherent anomalous correspondence or with a strabismus caused by an absence of a class of disparity-selective mechanisms. Thus, just as in large-angle strabismus, the anomalous retinal correspondence and defective stereopsis of microstrabismus appear to be consequences of abnormal visual experience caused by an interocular deviation.     

先天性眼球震颤的临床特征

背景 先天性眼球震颤是严重影响患者视觉功能的眼科疾病,但目前对其临床特征完整描述的相关报道尚少见. 目的 分析先天性眼球震颤的临床特征. 方法 采用回顾性病例分析的方法,对2005年1月至2011年8月在河南省眼科研究所就诊的先天性眼球震颤患者376例的临床资料进行归纳分析,包括患者家系的系谱分析、眼球震颤类型观察、斜视度测定、视力检查、检影验光、立体视觉测定和对患者有无震动幻觉的调查.结果 本组患者就诊的年龄分布以＞5～ 10岁及＞15～20岁者最多,分别占24.73％和24.20％.本组患者中知觉缺陷型眼球震颤172例,运动缺陷型眼球震颤204例.先天性眼球震颤患者中最常见的遗传方式为常染色体显性遗传;水平眼球震颤为最常见的眼球震颤类型,占73.94％,其次为垂直眼球震颤,占10.11％.本组先天性眼球震颤患者中斜视的患病率为66.36％,知觉缺陷型患者与运动缺陷型患者间斜视的患病率差异无统计学意义(x2=3.048,P=0.081).先天性眼球震颤患者的双眼最佳矫正远视力均较差,知觉缺陷型患者双眼最佳矫正远视力明显低于先天性特发性患者(0.27±0.11 vs 0.50±0.13),差异有统计学意义(t=16.495,P=0.000).先天性眼球震颤患者屈光不正的患病率为77.62％,知觉缺陷型患者与运动缺陷型患者间屈光不正患病率的差异无统计学意义(x2=1.337,P=0.248);散光患病率为75.17％,显著高于近视和远视的患病率.65.18％的先天性眼球震颤患者无立体视觉或立体视觉值在3000”以上,运动缺陷型患者有立体视觉者明显多于知觉缺陷型患者,差异有统计学意义(x2=7.058,P=0.008).313例5岁以上的患者中36例有震动幻觉. 结论 先天性眼球震颤患者最常见的遗传方式为常染色体显性遗传;水平眼球震颤为其最常见的震颤类型;眼球震颤患者的斜视患病率高,视力和立体视觉较差,特别是知觉缺陷型患者;少数先天性眼球震颤患者有震动幻觉.     

Traitement du strabisme par les prismes mise au point 1984

Résumé Entre les perturbations oculomotrices organiques de l'enfant IMOC et les strabismes d'origine strictement fonctionnelle de l'enfant par ailleurs parfaitement normal, on rencontre de plus en plus forme intermédiaire avec intrication de lésionnel et de fonctionnel et qui se présente comme une forme grave de strabisme. Ce type intermédiaire, dont le pourcentage de cas a fortement augmenté depuis 15 ans, est probablement la conséquence d'une souffrance pendant la période embryonnaire ou néo-natale qui a déterminé une atteinte lésionnelle isolée et minime située au niveau des centres moteurs sous corticaux (microlésions décrites par les neuropédiatres).La multiplication de ces formes graves de strabisme, leur irréductibilité aux thérapeutiques en place, nous ont amené à modifier et à adapter nos indications et nos techniques. La mise en place de cette nouvelle thérapeutique a été possible grâce à une meilleure connaissance des processus en cause, à l'utilisation à la foix de méthodes d'exploration plus élaborées et de nouvelles techniques (opératoires en particulier), Les modifications portent surtout sur le moment de l'acte opératoire, la technique opératoire et le fait que 2 ou 3 interventions chirurgicales sont nécessaires. Après avoir brossé une vue d'ensemble sur la variété extrême des formes cliniques de strabisme et sur leurs causes profondes nous présentons les indications et les conduites thérapeutiques à partir de 5 observations types.Les faits cliniques indiquent que dans les formes graves la guèrison (bifovéalité) est possible à condition que l'atteinte organique sous corticale soit très limitée et que le déréglement sous cortical qui en est la conséquence puisse être inhibé par un fonctionnement cortical suffisamment élaboré; toutefois ce traitement qui demande pendant des années la participation étroite de la famille et de l'enfant n'est accepté et suivi que dans un faible pourcentage de cas.

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The use of prisms in treatment of strabismus not only varies according to the author involved but often, a same author will change his opinion on the subject as time goes by. In the first case aetiopathological conceptions and the finality of treatment differ, in the second case improved theoretical knowledge and new possibilities in examination techniques and treatment etc., come into play. For this latter reason we wish to give complementary information and generally revise the publication on the use of prisms published in 1973 (18). The revised version in no way invalidates the previous work, it brings it up to date and gives further information on the severe forms of strabismus which, at the time of the first publication, constituted the failure group.These severe forms (both lesional and functional), the percentage of which has mostly increased during the last 15 years, are probably a consequence of suffering during either the foetal or neo-natal stage. It could be that this suffering gives rise to a minute isolated lesion within the sub-cortical motor centres (microlesions as described by neuropaediatricians).In situation, there are intermediary forms and come between the organic oculomotor disturbances of the cerebral palsied child and the strictly functional strabismus of the child who is otherwise normal. We have modified and adapted our diagnoses and techniques in view of the multiplicity of such forms and their resistance to conventional therapy. A better understanding of the process responsible, use of more sensitive methods of exploration, a longer period of functional readaptation and new techniques (particularly surgery-) all have a part to play in the new therapy. Where operating is concerned changes apply to the time selected, technique and number of operations performed: two or three stages are necessary. We give a general view of the extreme variety of clinical forms of strabismus and their causes and then give diagnoses and outlines for therapy based on four different type-cases. Clinical facts indicate that in severe forms it is possible to obtained a cure (bifoveality) on condition that the sub-cortical organic damage is very slight and that the optomotor dysfunction (which is its consequence) can be inhibited through satisfactory cortical functioning. However, such treatment requires rigourous participation of both the family and the child over a period of years. Unfortunately this treatment is possible only in a small percentage of cases.

     

Saccadic binocular coordination in alternating exotropia.

We studied the coordination of binocular eye movements in human subjects with alternating exotropia (divergent strabismus). Binocular saccades were recorded in six subjects during binocular and monocular viewing. Subjects were instructed to make saccades between two continuously lit targets (LED's) presented in an isovergence array (with the straight-ahead target 130 cm from the eyes) in a dimly lit room. For saccades up to 20 degrees amplitude, there were no large differences in the dynamics of the saccades between control and exotropic subjects. However, for larger amplitudes subjects frequently alternated the eye of fixation during saccades. That is, subjects fixated the left target with the left eye and the right target with the right eye. The alternation in eye fixation at the end of the saccade was taken into account in the programming of the saccades. The amplitudes of the alternating saccades were approximately equal to the target amplitude minus the strabismus angle. We conclude that for those saccades where alternation occurs, there is not only a change in the eye of fixation, but also a change in the target representation provided by either eye. Thus, in this group of strabismic patients, saccades may be programmed in a retina-centered coordinate system, if we assume that for making a saccade to a new target in the contralateral visual field its representation on the temporal retinal field of the currently fixating eye is suppressed and the retinotopic target information is derived from the non-fixating eye. In executing the saccade, the non-fixating eye automatically becomes the fixating eye.     

Paralytic strabismus: the role of botulinum toxin.

Five adults with acute extraocular muscle palsies followed by limited recovery of muscle function were treated with injections of botulinum toxin A to the ipsilateral antagonist of the affected muscle. Three were cases of unilateral sixth nerve palsy, one of bilateral sixth nerve palsy, and one of third nerve palsy. After a period of paralysis, during which the strabismus was overcorrected, the injected muscle recovered and binocular sensory and motor functions were restored and have been maintained for periods of up to 21 months. The treatment is a safe and effective alternative to surgery, particularly in cases in which a general anaesthetic is not advisable.     

‘Rebound-saccade’ in the prism cover test

If the fixing eye of a squinting patient is covered, a saccade to take up fixation follows which corresponds to the eccentricity of the image on the retina of the squinting eye. However, in some strabismus patients one finds a saccade even though the image on the retina of the squinting eye has already been deflected onto the fovea centralis with the aid of prisms. This saccade brings the eye into the primary position and displaces the image of the fixation target to a peripheral retinal point, so that the image must be recentred onto the fovea by a second saccade.We propose to call this movement to and fro a rebound-saccade. This phenomenon indicates that, in patients with alternating strabismus, extraretinal information determined by the angle of squint influences rapid alternation of fixation between the right and left eyes. The rebound-saccade cannot be explained by anomalous retinal correspondence.Supported by the Deutsche Forschungsgemeinschaft, SFB 70, B4.     

The effects of the age of onset of strabismus on monocular and binocular visual function in genetically identical twins

Objective

Both genetic and environmental factors are thought to play a role in the pathogenesis of strabismus and subsequent ocular dominance and amblyopia. Our purpose was to compare the characteristics of sensory visual function in 2 adult monozygotic (genetically identical) twins who presented with esotropia at different ages.

Recurrence of cyclic esotropia after surgical correction

Cyclic esotropia is a rare form of strabismus in which a convergent squint appears and disappears typically, but not always, in a regular 48-hour cycle. Characteristically, the convergent squint, when present, has a large angle with associated suppression and no binocular function. On normal or "nonsquinting" days, no manifest deviation is detectable (although in some cases there may be an esophoria). Physiologic diplopia is appreciated, whereas fusion and stereopsis are all normal. Amblyopia may occur in up to 20% of cases.     

Binocular interactions and steady-state VEPs. A study in normal and defective binocular vision (Part II)

Background: Recent evidence indicates that an index of binocular activity may be found in some properties of steady-state visual evoked potentials (VEPs), such as amplitude facilitation and phase shortening. We evaluated binocular interactions with steady-state VEPs in normal subjects as well as in patients with concomitant strabismus and defective binocular vision. Methods: Steady-state (8-Hz) VEPs to counterphased sinusoidal gratings (1.2 c/deg spatial frequency) of low contrast (3.2%) were recorded in 19 esotropic patients and in 18 age-matched controls. Patients had either anomalous retinal correspondence (ARC, n =10) or suppression (n=9) in casual seeing conditions (striated glasses). In all subjects, both binocular and monocular VEPs displayed a major component at twice the stimulation frequency (second harmonic), whose amplitude and phase were measured. A binocular interaction index was obtained by comparing binocular VEPs (BVEPs) with the sum (vectorial) of the two monocular VEPs (SMVEPs). Results: In normal subjects, BVEPs were larger in amplitude than SMVEPs (facilitation), and shortened in latency (phase). On average, both ARC and suppression patients displayed loss in amplitude facilitation and absence of phase shortening. However, 50% of ARC patients showed clear VEP facilitation. In both ARC and suppression patients, the amplitude ratio BVEP/SMVEP was negatively correlated with the amount of the angle of deviation. Conclusion: These results suggest that losses in amplitude facilitation and phase shortening of binocular steady-state VEPs reflect abnormal binocular interactions associated with different forms of sensorial adaptation in concomitant strabismus.     

Amblyopia resulting from penalisation: neurophysiological studies of kittens reared with atropinisation of one or both eyes.

Atropinisation of the eyes--a clinical method of treating strabismus called "penalisation"--in developing kittens caused a reduction in the spatial resolving power of cells in the lateral geniculate nucleus driven by the penalised eye, regardless of whether 1 eye or both eyes had been atropinised. However, binocularity of cells in the visual cortex was reduced only in monocularly penalised cats. It appears that sharply focused foveal images are important in the development of good visual acuity but synergy of the inputs to the 2 eyes is required for the development of binocular vision.     

Strabismus and diplopia as complications after cataract surgery with IOL implantation

Summary In our Department of Orthoptics we have seen an increasing number of patients suffering from diplopia after cataract surgery with IOL implantation. Between 1993 and 1997 the total number of patients with this problem was 24 (2.7 % of all patients, mean age 71 years, age range 38–88). We addressed the question of whether there is a common pattern of motility dysfunction. Methods: After evaluation of the clinical history and the basic ophthalmological findings the following parameters were examined: binocular function (Bagolini test), squint angles (Maddox cross), ocular motility. Results: The 24 patients could be divided up into three groups. Group 1 consisted of 9 patients (mean age 82 years, range 64–88) who complained about diplopia because of strabismus incomitans with vertical deviation and restricted motility on the first day after surgery. In 8 of the 9 patients strabismus surgery was done. Group II consisted of 10 patients (mean age 66 years, range 38–77) who noticed diplopia and strabismus within 7 days after surgery. We found various kinds of heterotropia. Seven of these patients were operated on and two had a prism correction. Group III consisted of 5 patients (mean age 67 years, range 61–78). Their already known strabismus paralyticus or concomitans deteriorated, leading to diplopia in some cases. All patients in this group were operated on. Discussion: For group I we believe that retro-, para- or peribulbar anesthesia caused the motility dysfunction. In groups II and III it is unlikely that local anesthesia had a causative role. The prolonged disruption of binocular vision and the abrupt change in the sensory situation after the cataract operation with lens implantation may be the leading causes for strabismus or deterioration of a preexisting strabism, respectively. Conclusions: These patients need a subtil meticulous diagnostic work-up and follow-up because of the possibility of early surgical therapy, which has a good prognosis. Evaluation of binocular vision and eye movements prior to cataract surgery appears to be helpful for later strabismic surgery.      

Interocular inhibition in strabismus

Summary Many patients with acquired strabismus do not suffer from diplopia and confusion after an individually and age-dependent interval. They inhibit the image of the deviated eye by binocular rilvary and particularly by the physiological ability to disregard visually disturbing stimuli. In strabismus with early onset, binocular rivalry is also demonstrable, even for stimuli that do not normally lead to suppression. On the basis of anomalous retinal correspondence, this rivalry occurs between retinal points onto which the same object projects. The retinal area with the lesser eccentricity receives the dominance. The fovea of the deviated eye is therefore not suppressed. In small-angle strabismus with smaller functional differences between anomalous corresponding retinal points anomalous fusion and even stereopsis can be possible as long as strong suprathreshold stimuli are presented. Strabismic amblyopia as a consequence of interfoveal suppression can only develop before anomalous retinal correspondence dominates in the strabismic child.      

Quadrantal macular retinal thickness changes in strabismus subjects with abnormal binocular vision development

Purpose

To investigate retinal morphological changes in strabismus patients with abnormal binocular vision development by comparing differences in quadrantal macular retinal thickness.

Methods

Six strabismus patients (6 dominant and 5 non-dominant eyes) with abnormal binocular vision (mean age 22 years), and 11 control subjects (11 dominant and 11 non-dominant eyes) (mean age 21 years) were enrolled. Macular retinal thickness measurements were performed by optical coherence tomography, with total macular retinal (TMR) and ganglion cell complex (GCC) thicknesses measured in 3- and 6-mm regions in each quadrant. Measurement values were then used to determine quadrant ratios.

Results

Compared to the dominant eyes of the controls, the superior/inferior (S/I) ratio of the TMR thickness and GCC thickness in the 3-mm region was significantly lower in the dominant eyes of the strabismus group (P < 0.05, each). The superior temporal/inferior temporal (ST/IT) ratio of the GCC thickness in the dominant eyes of the strabismus group was also significantly lower (P < 0.01).

Conclusions

Dominant eyes of the strabismus group with abnormal binocular vision development exhibited thinner superior temporal GCC thicknesses in the 3-mm region. Retinal ganglion cells in this region might be affected by efferent neural degeneration that originates in the visual pathway responsible for adaptations to the visual experience.