Introduction Naevus of Ota is a congenital condition that may involve the skin, eyeball and even intracranial structures usually in the distribution of the ophthalmic and maxillary divisions of the trigeminal cranial nerve. The purpose of this study was to summarise our experience with the ocular clinical presentation, imaging, outcome, treatment of complications and to offer a new classification of patients with naevus of Ota.

Methods We retrospectively reviewed the patients’ medical records and the following parameters were retrieved and analysed: demographics, clinical presentation complications and treatment of complications. Imaging characteristics of patients with naevus of Ota were compared with images from the same period of time of 57 age-matched and gender-matched patients without naevus of Ota (control group).

Results The series was composed of 40 patients (18 males, 22 females) whose mean age at diagnosis was 35.27 years (range 0.5–77 years). Thirty-three patients (82.5%) were type I naevus of Ota according to the Tanino classification, three patients (7.5%) were type II, one patient (2.5%) was type III and three patient (7.5%) were type IV (bilateral naevus of Ota). We further classified all cases in according to the ocular involvement extent. Three patients developed malignant transformation to choroidal melanoma and four patients developed glaucoma.

Conclusions In this study, a new clinical classification based on the involved ocular component and extent of the involvement (in quadrants) of the globe is suggested first. Further studies are needed to assess whether our clinical ocular classification can assist in identifying patients at risk for developing glaucoma and malignant transformation.