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AMBLYOPIA AND THE RETINA

1962; BMJ; Volume: 46; Issue: 4 Linguagem: Inglês

10.1136/bjo.46.4.193

1468-2079

Mary Jo Pugh,

Ophthalmology and Visual Impairment Studies

THIs communication is concerned with patients who had the profound type of amblyopia which was resistant to usual routine methods of treatment (facultative amblyopes being excluded); no obvious pathological lesion was present to account for the poor vision.The investigation was directed to analysing the vision present in the defective eye.The results are discussed with reference to the probable site of the defects which could give rise to these particular effects.Three sites have been favoured by different workers as the main one con- cerned in the development of amblyopia, the cortex, the geniculate body, and the retina.Vogt (1939), Wald and Burian (1944), and Dyer and Bierman (1952) thought that the cortex was chiefly affected.Clarke (1941) suggested that, since the cells of the lateral geniculate body rely for their vitality on the link between cortical and retinal activity, an atrophy from disuse might occur in these cells.Since suppression of one image is so essential a part of the mechanism found in the binocular vision of these cases, the higher centres must obviously be involved to a greater or less degree.This is demonstrable in the child whose amblyopic eye recovers normal sight by the simple expedi- ent of covering the dominant eye, but in whom the dominant eye in turn becomes amblyopic from disuse if occlusion is continued too long.Facul- tative amblyopia is another instance.Harms (1949), judging by the lowered response to light in an amblyopic eye, thought that the reaction of the retina was at fault.Enoch (1957) found abnormal retinal response.Since normal binocular vision depends first on the retinal reaction to light of each eye separately, secondly on the passage of the information so received through the tracts and geniculate bodies, and thirdly on the final integration in the cortex, all sites are implicated when one becomes defective.Even so, the initial reaction of the retinal cells to light entering the eye must be the first step to be considered.The kind of asymmetrical vision described