Mechanisms of Optic Nerve Invasion in Primary Choroidal Melanoma.

Aim: 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.

Methods: 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.

Results: 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.

Conclusions: 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.