Mechanisms of optic disc swelling with diffuse choroidal melanomas: clinicopathologic correlations.

The clinical and histopathological findings in the eyes of 2 patients with diffuse malignant melanoma of the choroid are described. The tumours were minimally elevated and nonpigmented in the peripapillary area, and both had an associated nonrhegmatogenous retinal detachment. Extension of the tumour into the region of the lamina choroidalis in each eye appeared to cause a localised constriction of the optic nerve and subsequent swelling of the optic nerve head. In addition tumour infiltration of the nerve head was present in one eye. Ophthalmoscopic, fluorescein angiographic, and ultrasonographic characteristics that differentiate between extensive tumour infiltration of the optic nerve head and swelling secondary to other causes are presented. The importance of appreciating this difference clinically is discussed.