Choroidal Melanoma Affecting the Optic Nerve

Description

Choroidal melanoma can grow near, touch and even cover the optic nerve. Like other choroidal melanomas, they can exhibit orange pigment on its surface, subretinal fluid (localized retinal detachment), and thickness. The choroidal melanoma in the next photograph exhibits all three findings.

Symptoms

Juxtapapillary choroidal melanoma is typically near the central macular retina and may cause symptoms. Unlike most patients with choroidal melanoma, when the optic nerve is affected patients will have complaints of decreased vision, visual field defects, flashing lights or floaters (spots). Most choroidal melanoma is found on routine eye examination with dilated ophthalmoscopy.

Diagnosis

Choroidal melanoma that affects the optic nerve must be differentiated from optic nerve melanocytoma. The eye care specialist will examine the tumor for evidence of orange pigment (lipofuscin, melanolipofuscin), thickness (as measured by ultrasound), and for leakage (as measured by photography with angiography).

Unlike optic nerve melanocytoma, malignant choroidal melanoma does not typically spread-out along the nerve fiber layer and are lighter in color. It can be difficult to determine the diagnosis of a small tumor. In these cases, the tumor can be closely watched "followed" for evidence of growth or a needle biopsy may be performed.

Dr. Finger has found that circumpapillary melanomas are likely to cause an afferent pupillary defect.

Treatments

Choroidal melanoma that encircles or covers the optic nerve are particulary difficult to treat with eye-sparing plaque radiation therapy. Many are treated by enucleation of the affected eye. Alternatives include external beam radiation (e.g. Proton Beam) or custom made ophthalmic plaque irradiation. The patient must be counseled that with either technique, the entire optic nerve will be within the treated field eventually leaving the patient without vision in the irradiated eye. 

Choroidal Melanoma Affecting the Optic Nerve - The Eye Cancer Network