A combined prospective and retrospective study of patients with Down's syndrome showed that these patients have narrowed and slanted palpebral fissures but that the fissures are of normal height. Patients with Down's syndrome also had increased prevalences (compared with control subjects) of blepharitis (23 of 53 patients or 46%), strabismus (23 of 53 patients or 43%), nystagmus (five of 53 patients or 9%), light-colored and spotted irides (46 of 53 patients or 87% and 43 of 53 patients or 81%, respectively), keratoconus (eight of 53 patients or 15%), cataracts (seven of 53 patients or 13%), severe myopia (13 of 48 patients or 27%), and astigmatism of more than 3 diopters (12 of 48 patients or 25%).