Physiology of suppression in strabismic amblyopia.

It is 100 years since von Graefe first demonstrated a suppression scotoma in an amblyopic eye.' A review of publications on the subject of suppression in strabismus reveals that this has not been a very active area of research and that what literature there is contains many apparent contradictions. Early workers found strong suppression at the fovea of the deviating eye in strabismic amblyopia (the point of confusion) and also at the diplopic point (the point on the retina of the deviating eye where the image of the target being fixated by the other eye falls).23 They made no attempt to describe the fate of images of objects in the rest of the visual field of the deviating eye. Subsequent experimental results have been conflicting: Pratt-Johnson and Tillson found the entire visual field of the deviating eye except the temporal crescent was suppressed in all strabismic subjects except those with monofixation syndrome4; Jampolsky reported hemiretinal suppression,5 and Sireteanu and Fronius described discrete areas of suppression surrounded by regions of facilitation and stereopsis in patients with monofixation syndrome.6 The area of suppression in the amblyopic eye depends on the nature of the stimuli used in the experiment2 4 7; patches of grating, different coloured lights,6 and geometrical patterns5 have all been used by various authors. There has been a tendency by some authors to generalise from data collected from a few patients with a particular type of amblyopia in