Abstract
Purpose :
EPB is a globe-sparing treatment for choroidal melanoma. Nevertheless, rates of visual morbidity remain high, often due to sequelae of radiation retinopathy. Understanding the development of early retinal vascular changes seen on OCTA may elucidate risk factors and impact the management of preclinical radiation retinopathy.
Methods :
This is a retrospective consecutive series of 29 eyes in 29 adult patients treated with Iodine-125 EPB for choroidal melanoma. As part of standard clinical care, OCTA was performed in both treated and fellow non-irradiated eyes. Semi-automated, quantitative analyses of microvascular abnormalities were performed on images of sufficient quality to grade.
Patients who had other pre-existing retinal vascular disease were excluded from analysis.
Comparison of OCTA metrics in treated and untreated fellow eyes was performed employing the Wilcoxon-Mann-Whitney U-test. Available longitudinal data from patients were analyzed using generalized estimating equation regression.
Results :
Fourteen (48%) participants were female. Median age was 68 years. Median time from plaque placement to first OCTA was 1.9 years, with a median follow-up time of 0.7 years. The median dose of radiation to ocular structures was as follows: 85 Gy (tumor apex), 27 Gy (optic nerve head), and 27 Gy (fovea). Median visual acuity was 20/40 in treated eyes, compared to 20/25 in fellow untreated eyes (p<0.0001).
Median values for OCTA measures in irradiated and untreated eyes, respectively, were: foveal avascular zone area (0.75mm2 vs 0.44mm2, p=0.14), vascular density (39% vs 45%, p<0.0001), branching index (117/mm2 vs 149/mm2, p<0.0001), total vessel length (144mm vs 162mm, p<0.0001), and lacunarity (0.09 vs 0.06, p<0.0001).
Employing multivariate regression by generalized estimating equation to adjust for age, sex, and foveal radiation dose, the mean rate of change of the following indices in treated eyes was: visual acuity (-2 letters/year), FAZ area (0.004mm2/year), vessel density (-0.11%/year), branching index (-0.6/[mm2*year]), total vessel length (-0.8mm/year), and lacunarity (0.005/year).
Conclusions :
Quantitative OCTA analyses demonstrated changes in retinal microvasculature after EPB. Thus, it may have a useful role elucidating the mechanism of and screening for early pathologic changes in preclinical radiation retinopathy.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.