Vision in albinism

Abstract

Purpose: The purpose of this investigation was to study vision in albinism from 3 perspectives: first, to determine the characteristics of grating acuity development in children with albinism; second, to study the effect of illumination on grating acuity; and third, to define the effect of melanin pigment in the macula on visual acuity.

Methods: I. Binocular and monocular grating acuity was measured with the acuity card procedure in 40 children with albinism during the first 3 years of life. Recognition acuity was eventually measured in 27 of these patients. Ocular pigment was documented by a previously established method of grading iris transillumination and macular transparency. II. Grating acuity under standard and increased illumination levels was measured in 20 adults with albinism (group I) compared with that in 20 adults with nystagmus due to conditions other than albinism (group II) and 20 adults without ocular abnormalities (group III). Recognition acuity measured with the ETDRS charts was also recorded for each group. III. Best-corrected binocular acuity was measured in 29 patients with albinism who were identified with melanin pigment in their maculas by direct ophthalmoscopy.

Results: I. Both binocular and monocular grating acuity was reduced 2 to 3 octaves below the norm for ages 6 months to 3 years. Limited data available in the first 6 months of life did not show failure of vision to develop. Grating acuity measurements overestimated eventual recognition acuity. Mean recognition acuity was 20/111. A relationship between grating acuity development and presence or absence of ocular pigment was not found. II. Grating acuity was significantly better for groups I and II under the condition of increased illumination (P < .03). For patients with albinism, grating acuity under standard illumination was significantly better than recognition acuity (P < .001). For all groups, grating acuity under increased illumination was significantly better than recognition acuity (P < .01). III. Mean recognition acuity in patients with albinism and melanin pigment in their maculas (20/47) was significantly better than measured recognition acuity in Project I (P < .001). All had foveal hypoplasia, but 8 patients had an incompletely developed annular reflex in the macula, 6 patients showed stereoacuity, and 3 patients had no nystagmus.

Conclusions: I. Grating acuity development in albinism seems to progress along a curve that is asymptotic to visual development in a normal population. II. Increasing illumination does not reduce grating acuity in patients with albinism. Grating acuity overestimates recognition acuity in these patients. III. Ophthalmoscopic detection of melanin pigment in the macula in patients with albinism is associated with better vision.