Purpose: To evaluate the time of onset and risk factors for the development of macular edema following plaque radiotherapy for uveal melanoma, using optical coherence tomography (OCT).
Methods: This observational case series included 135 consecutive patients with uveal melanoma treated with Iodine(125) plaque radiotherapy and adjunctive transpupillary thermotherapy (TTT) laser. Patients were evaluated at baseline and 6-month intervals following treatment using ophthalmoscopy, B-scan ultrasonography, fundus photography, and OCT.
Results: Median follow-up was 24 months. The mean time to onset of macular edema by OCT was 12 months. Median best-corrected logMAR visual acuity at the time of onset of OCT-evident macular edema was 0.3 (equivalent to 20/40 Snellen). The development of OCT-evident macular edema was significantly associated with maximum tumor thickness (P = 0.0016), largest tumor base (P < 0.0001), radiation dose, and dose-rate to the tumor base (P = 0.0315 and P = 0.0204, respectively). Neither radiation dose to the foveola nor treatment with adjunctive TTT laser was significantly associated with the development of macular edema.
Conclusions: OCT is useful in the early detection of radiation-induced macular edema, before clinical signs of radiation maculopathy develop and before substantial visual loss occurs. The development of macular edema is significantly associated with larger initial tumor size.