Mechanisms of Optic Nerve Invasion in Primary Choroidal Melanoma

The aim of this study was to assess morphological risk factors associated with optic nerve invasion of choroidal melanoma and to identify possible mechanisms of optic nerve invasion.

Medical charts and histology slides of patients with primary choroidal melanoma who were treated by enucleation/exenteration and whose pathology showed optic nerve invasion were reviewed.

Twenty-one patients (mean age: 65.67 ± 14.72 years) with primary uveal melanoma arising from the choroid were included in this analysis. A peripapillary location was present in 86% of the cases. Four types of optic nerve invasion were identified: transvitreal invasion (10%); retinal invasion (23%); direct peripapillary invasion (57%); and a combined mechanism (10%). Optic nerve invasion was prelaminar in 67%, laminar in 10%, and retrolaminar in 23% of the cases. Significantly higher largest basal diameter (p = 0.021) and tumor thickness values (p = 0.017) and higher rates of vortex vein (p = 0.022) and retinal invasion (p = 0.007) were observed in the transvitreal/retinal invasion groups when compared to the direct peripapillary invasion group.

A peripapillary tumor location was the most common mechanism of optic nerve invasion of choroidal melanoma. In 43% of the cases, other mechanisms including transvitreal and retinal invasion resulted in optic nerve invasion.