CONTRAST LETTER THRESHOLDS IN THE NON-AFFECTED EYE OF STRABISMIC AND UNILATERAL EYE ENUCLEATED SUBJECTS

To investigate the effects of visual disruption on contrast letter thr esholds of the non-affected eye, subjects with one eye enucleated, str abismic subjects using the non-deviating eye and normal control subjec ts were asked to identify letters on eye charts and single letter card s which varied in contrast (between 4 and 96%) and size, At all contra sts, contrast letter acuity of eye enucleated subjects was superior to both normal control subjects and strabismic subjects, Early onset str abismic subjects (onset < 24 months) showed inferior performance to no rmal control subjects at all contrasts of 25% and above. Late onset st rabismic subjects showed normal performance at all contrasts, except f or high contrast single letters, where performance was inferior to nor mal control subjects. Further, for all subjects groups, performance on letter charts was similar to performance on single letter cards, We c onclude that disruption to the visual system caused by eye enucleation or strabismus is not equivalent. These differences may be due to intr insic differences between the visual systems of eye enucleated subject s and strabismic subjects and/or to the profound differences in depriv ation caused by the two conditions. Copyright (C) 1996 Elsevier Scienc e Ltd.