Objective: To study peripapillary retinal capillary circulation in eyes treated with I-125 plaque brachytherapy for uveal melanoma using optical coherence tomography angiography (OCTA).
Design: Cross-sectional study of 10 subjects imaged with OCTA prior to uveal melanoma treatment and 15 subjects imaged after development of radiation retinopathy and/or optic neuropathy.
Participants: Following IRB approval, subjects were enrolled from an academic ocular oncology clinical practice. All subjects had uveal melanoma in one eye and treatment with I-125 plaque brachytherapy was planned or had previously taken place. Patients with low vision at baseline and uncontrolled hypertension were excluded. In the post-treatment group, seven subjects were male and eight were female; age range 38 to 81 years. Visual acuities in the irradiated eyes ranged from 20/20 to counting fingers. Visual acuities in the untreated fellow eyes were 20/25 or better.
Methods: Peripapillary retinal capillary circulation was measured by OCTA (Optovue, Inc). 4.5×4.5 mm optic disc scans were obtained. 10 subjects were imaged prior to brachytherapy treatment and 15 subjects were imaged after development of clinically apparent radiation retinopathy and/or radiation optic neuropathy post-brachytherapy.
Main outcome measures: The relationship of the peripapillary retinal capillary density (PPCD) as measured by OCTA to the calculated dose to the optic nerve (D50, the dose to 50% of the disc) and the LogMAR vision was evaluated.
Results: No significant difference was seen in the PPCD as measured by OCTA when comparing the eye with melanoma to the fellow eye prior to brachytherapy; however the PPCD was significantly lower in treated eyes (52.9% +/- 22.4%) than in fellow eyes that did not receive radiation (73.3% +/- 13.7%, p = 0.004). There was an inverse linear correlation between D50 and the PPCD (Pearson's; r= -0.528, P=0.043) and between visual acuity and the PPCD (Pearson's; r= -0.564, P=0.028).
Conclusions: Among patients with clinically apparent radiation retinopathy and/or radiation optic neuropathy, PPCD was lower in the treated eye and correlated with the radiation dose to the optic nerve and the visual acuity. OCTA provides a measure of capillary changes following radiation, and may serve as a quantitative endpoint to address visual prognosis.