To investigate the clinical features of the nevus of Ota in the Korean population.

A retrospective chart review of the medical records from 94 patients (100 eyes), diagnosed to have a nevus of Ota from September 2005 to February 2010, was performed.

The mean age of detection of a nevus of Ota was 8 months, and the mean extent of the nevus was 253 degrees, which covered more than 2 quadrants in most cases. The patients with a faint nevus tended to be younger. Pigmentation did not reach the fornix, but the limbus was mostly pigmented. Combined conjunctival pigmentation was observed in 61.7% of cases. The pigmentation was significantly associated with a greater extent of the nevus. Iris pigmentation was demonstrated in 98.7% of cases.

The clinical features of nevi of Ota were diverse regarding the location, extent, and color of the lesion. Conjunctival pigmentation was associated with the extent of the nevus. Iris pigmentation was revealed in almost all cases; therefore, this feature had the diagnostic value for a nevus of Ota. Young patients with a nevus of Ota may mimic osteogenesis imperfecta, which necessitates careful consideration upon differential diagnosis.