Of 39 members in a family with autosomal dominant aniridia with variable expressivity, 16 members, representing 50% (15 out of 30) of those at risk, were affected. Of these, ten of 16 (63%) had visual acuity of 6/12 (20/40) or better in at least one eye, and six of 16 (37%) had visual acuity between 6/15 (20/50) and 6/60 (20/200) in at least one eye. Affected patients had nystagmus (12, 75%), cataracts (nine, 56%), strabismus (15, 94%), amblyopia (six, 37%), corneal pannus (one, 6%) glaucoma (one, 6%), macular hypoplasia (five, 31%), and optic nerve hypoplasia (one, 6%). The good visual acuity in this family indicates that absence of iris tissue is not responsible for the decreased visual acuity usually associated with aniridia. The decreased visual acuity correlates instead with a decreased macular reflex and with a decreased electroretinogram amplitude. Affected family members have abnormal persistence of vessels in the macular region angiographically, and when sufficient iris tissue is present to be studied angiographically, there are abnormal vascular loops and leakage of dye at the pupillary border.