Laser Photocoagulation to Prevent Radiation Maculopathy after Plaque Therapy for Posterior Choroidal Melanoma

Abstract

Abstract: : Purpose: To evaluate the effect of argon laser photocoagulation on plaque radiation retinopathy. Methods: We reviewed the care of 142 consecutive patients with choroidal melanomas extending posterior to the equator. Each had been treated with ophthalmic plaque radiation therapy (Pd–103, I–125) in one brachytherapy session. Forty–five were treated with laser for early onset radiation retinopathy, 14 were treated prior to retinopathy, 3 spontaneously resolved with observation, and 2 are pending treatment. Treatment consisted of scatter argon laser photocoagulation over the radiation–targeted zone (tumor plus 2 mm surround) sparing the fovea over a mean 2 sessions. Early Treatment Diabetic Retinopathy Study (ETDRS) type standardized visual acuity determinations, ophthalmic examinations, and angiography were performed before and after treatment. Clinical evaluations were performed in a non–randomized and unmasked fashion. Results:Firty–nine (34.5%) of the patients developed radiation retinopathy at a mean 26.4 months after plaque irradiation. Vision loss of greater than 3 lines was noted in 21 of the 49 eyes (42.85%), but only 13 (26.53%) were attributable to radiation maculopathy or radiation optic neuropathy. Overall laser photocoagulation appeared to prevent or regress radiation maculopathy in 22 of 45 cases (49%). Other causes of vision loss included: neovascular glaucoma, vitreous hemorrhage, AMD, retinal macroaneurysm, and persistent retinal detachment. One of the 14 patients (7%) who received laser photocoagulation prior to observable radiation retinopathy developed radiation maculopathy 13 months after plaque. With additional laser, his maculopathy regressed with a resultant 2–line loss of vision (at 33 months follow up). Another developed mild radiation retinopathy without maculopathy. Conclusion: Radioactive plaque treated eyes containing choroidal melanomas located posterior to the equator have been shown to be at greatest risk for radiation maculopathy (British Journal of Ophthalmology 2000;84:1068–1070). Scatter argon laser photocoagulation of the radiation–targeted zone prevented or regressed radiation maculopathy in 49% of patients with early onset retinopathy and 93% of those at high risk for radiation maculopathy.

Keywords: melanoma • laser • radiation therapy