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).
This observational case series included 135 consecutive patients with uveal melanoma treated with Iodine125 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.
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.
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.