Distance judgement in comitant strabismus with anomalous retinal correspondence

Update on strabismus and amblyopia

This review analyzes progress in the field of infantile strabismus and amblyopia. Only works which are of clinical interest have been reviewed. A brief survey is provided also of subjects matter of international debate, as surgery for accommodative esotropia, the prism adaptation test and the use of sectors for amblyopia treatment. Mention is made of new developments in the field which are not yet applicable to clinical practice. Finally, progress in the approach towards ocular nystagmus is considered as well.

Why do the eyes cross? A review and discussion of the nature and origin of essential infantile esotropia, microstrabismus, accommodative esotropia, and acute comitant esotropia

PURPOSE

To try to explain the long-term stability of bilateral medial rectus botulinum toxin (botox) chemo-denervation in essential infantile esotropia; to evaluate divergent fusion amplitude in accommodative esotropia and acute comitant esotropia of emmetropes; to look for accommodation anomalies in high AC/A ratio accommodative esotropia and acute comitant esotropia of myopes; and to discuss characteristics of microstrabismus.

METHODS

Retrospective analysis of 61 essential infantile esotropia patients with early treatment with one botox injection in both medial rectus; measurement of divergent fusion amplitude in accommodative esotropia and acute comitant esotropia; measurement of Near point of accommodation in high AC/A ratio accommodative esotropia and acute comitant esotropia of myopes.

RESULTS

Stable results were found in 85.24% of essential infantile esotropia treated patients; reduced divergent fusion amplitude was detected in accommodative esotropia and acute comitant esotropia; hypo-accommodation was found in some patients with high AC/A ratio accommodative esotropia and a convergence spasm in acute comitant esotropia of myopes.

CONCLUSIONS

Very early botox treatment probably eradicates the effect of an excessive convergence tonus in essential infantile esotropia. A prevention of accommodative esotropia with full retinoscopic correction is only mandatory with a significantly reduced amplitude of fusional divergence. A deficit in accommodation should be looked for in high AC/A ratio accommodative esotropia, before bifocal lenses prescription. Early diagnosed acute comitant esotropia of myopic patients can be treated as a convergence spasm. Only surgery treats acute comitant esotropia, in patients with emmetropia or moderate hypermetropia.

Bowman lecture. Current concepts of infantile esotropia

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 immature 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 classified 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 operated 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 alignment 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 subnormal or anomalous basis.