PARAFOVEAL CAPILLARY DENSITY AFTER PLAQUE RADIOTHERAPY FOR CHOROIDAL MELANOMA: Analysis of Eyes Without Radiation Maculopathy.

Purpose: To study the parafoveal capillary density using optical coherence tomography angiography (OCTA) in eyes treated with plaque radiotherapy.

Research Design: Retrospective comparative case series.

Participants: Ten patients treated with plaque radiotherapy for choroidal melanoma without evident radiation maculopathy on ophthalmoscopy or optical coherence tomography were imaged with OCTA.

Main Outcome Measure: Comparison of the parafoveal capillary density in the superficial and deep capillary plexuses in the irradiated versus fellow nonirradiated eye.

Results: Overall, mean patient age was 55 years (median: 57, range: 45-65 years), and majority were white (9/10, 90%) and female (9/10, 90%). No patient had diabetes mellitus, and 2 (2/10, 20%) had controlled systemic hypertension. The melanoma was located in the choroid in all patients (10/10, 100%), with 2 (2/10, 20%) in the macular region. The mean largest basal diameter was 11 mm (12, 6-16 mm), and mean thickness was 5 mm (5, 2-10 mm). Mean radiation dose to the tumor apex was 72 Gy (median: 70 Gy, range: 70-85 Gy). Mean foveolar radiation dose was 53 Gy (median: 35 Gy, range: 14-110 Gy). Mean follow-up duration after plaque radiotherapy was 17 months (median: 16 months, range: 5-39 months). There was no ophthalmoscopic evidence of radiation maculopathy throughout the follow-up in every case. Optical coherence tomography demonstrated normal foveal contour without edema or subretinal fluid in every case. On OCTA, there was no significant difference in signal strength (P = 0.1151), central macular thickness (P = 0.9316), and foveal avascular zone area in the superficial (P = 0.1595), and deep (P = 0.1534) capillary plexuses between the irradiated versus fellow eyes. However, there was a statistically significant decrease in capillary density in the parafoveal superficial (P = 0.0005) and deep (P = 0.0067) plexuses in the irradiated eye. In addition, mean logMAR visual acuity was 0.2 (0.1, 0.0-0.5) (Snellen equivalent 20/32) in the irradiated eye and 0.0 (0.0, range: 0.0-0.1) (Snellen equivalent 20/20) in the fellow eye (P = 0.0252).

Conclusion: Optical coherence tomography angiography allows qualitative and quantitative analysis of parafoveal capillary density. After plaque radiotherapy for choroidal melanoma, in eyes with normal macular features on ophthalmoscopy and optical coherence tomography, there is a statistically significant decrease in parafoveal capillary density and logMAR visual acuity in irradiated eyes compared with fellow eyes. These subclinical ischemic findings represent the commencement of radiation maculopathy.