Sensory adaptations, such as anomalous retinal correspondence (ARC) and suppression, develop in young children with strabismus to avoid diplopia and confusion. ARC involves a shift in spatial localization between the eyes' retinas such that images from non-corresponding retinal points appear fused. Tests for ARC produce varying results depending on the degree of sensory dissociation. While ARC is initially adaptive, it can become ingrained over time if the strabismus is not treated early in the visual development period from infancy to age 6 years. Suppression involves cortical inhibition of images from the deviating eye to prevent confusion, and its depth and extent can be measured using various tests involving filters, lenses, and stereosc

1. Sensory Adaptation to Strabismus

18. Problems If an adaptive process is present there should be a temporary aftereffect when the adapting process is removed. Though such aftereffects can be observed in ARC (eg monocular diplopia) the findings are often different. HARC is present continuously despite the angle of strabismus changing from distance to near; or with or without spectacle. The instrument used to measure ARC does not indicate the depth of the ARC but represents the influence of the technique on the binocular status.

19. These unsatisfactory aspects of ARC as an adaptive process led Morgan (1961) to propose an alternate motor theory. The theory places emphasis on ego-centric localisation. Oculo-centric localisation refers to the visual direction associated with a particular retinal and cortical point. This direction is not absolute but relative to the ego-centric localisation attributed to the fovea of the eye at that time.

20. Motor Theories the innervation pattern of the extra-ocular muscles gives the potential for change in correspondence by influencing the correction from oculo-centric to ego-centric localisation . Morgan (1961) states “thus anomalous correspondence might depend not on sensory adaptations to a strabismus but rather on whether the basic underlying innervational pattern to the extra-ocular muscles was one which registered itself to consciousness as altering ego-centric direction”. The attraction of this theory is that it has none of the restrictions of the adaptive theories when applied to small angle strabismus and offers the possibility of an instant change in ARC with changed conditions. However the prediction that accommodative esotropia would not have ARC has not been substantiated.

38. Table : provides a comparison of results on the determination of the status of sensory response of strabismic patients using various methods.