Deborah Orel-Bixler


It is frequently difficult to assess visual capabilities objectively in multi-handicapped patients with low vision and the clinician has to rely on clinical observation. We attempted to answer the question of how well clinical observation of the visual behavior of visually impaired patients with multiple handicaps compares to objective measures of vision function in this population. We evaluated over 100 multi-handicapped children with optic nerve hypoplasia and/or optic nerve atrophy of variable severity. Visual acuity and contrast sensitivity were determined using either Visual Evoked Potential techniques or behavioral measures. Patients ranged in age from 1.5 to 40 years (median age was 8 years). Visual acuity varied widely from 20/30 to 20/4000 with 73% having worse than 20/200 acuity. Contrast sensitivity for large targets also showed extreme variability from 0.2-80% Michaelson contrast. Each patient was rated on a visual attentiveness scale based on eye contact and steadiness of fixation, facial recognition of parents without auditory cues, visually guided reaching and mobility. There was a statistically significant correlation between visual acuity and contrast sensitivity (r=0.76). However, this correlation is clinically non-significant because of the wide range of both acuity and contrast sensitivity values. For example, if contrast sensitivity was reduced by a factor of 6 from normal, acuity varied from 20/50 to 20/1000 (a factor of 50) Also, if visual acuity was reduced by a factor of 6 (to 20/120), contrast sensitivity also varied by a factor of 50. Thus, on an individual patient basis, acuity could NOT be predicted from contrast sensitivity or vice versa. Visual attentiveness, however, was a factor of both visual acuity and contrast sensitivity but contrast sensitivity predicted visual attentiveness better than visual acuity. If objective measures of vision function are impossible, rating of visual attention provides a reasonable prediction of visi


Year: 1992

Program Number: 2:15 pm

Author Affiliation: n/a

Co-Authors: Gunilla Haegerstrom-Portnoy, Helen Dornbusch, M. Hoenig

Co-Author Affiliation: n/a

Room: Scotland B