OCT angiography evaluation of peripapillary vessel density in eyes treated with plaque radiotherapy for uveal melanoma

Abstract

Purpose : To study peripapillary retinal capillary circulation in eyes treated with I-125 plaque radiotherapy for uveal melanoma using OCT angiography (OCTA).

Methods : Cross-sectional study of 16 subjects treated with I-125 plaque radiotherapy one to nine years prior to imaging with OCTA. Subjects were prescribed 85Gy to the tumor apex over 100 hours using I-125 plaque brachytherapy. All subjects had clinically apparent radiation retinopathy and/or radiation optic neuropathy at the time of OCTA imaging. Seven were male and nine were female, with ages ranging from 37 to 81 years. The visual acuities in the irradiated eyes ranged from 20/20 to counting fingers, while visual acuities in the untreated fellow eye were 20/30 or better. Peripapillary retinal capillary circulation was measured by Angio Vue OCTA (Optovue Avanti RTVue XR) in both eyes. 4.5x4.5 mm optic disc scans were obtained. The peripapillary vessel density (PPVD) was calculated for the inner retina (inner limiting membrane to outer plexiform layer) in treated eyes and compared to fellow eyes. The relationship of the PPVD to the calculated dose to the optic nerve was evaluated.

Results : The PPVD as measured by OCTA was significantly lower in treated eyes (52.9% +/- 22.4%) than in fellow eyes which did not receive radiation (73.3% +/- 13.7%, p = 0.004). Every subject was not evaluated pre-radiotherapy, but in those that were (14 of 16), no significant difference was seen between PPVD in eyes with tumor and the fellow eye prior to radiation. A representative OCTA of the peripapillary region in an eye is shown in Figure 1. There was a linear correlation between radiation dose (D50, the dose to 50% of the disc) and the PPVD (Pearson’s; r= -0.528, P=0.043) as shown in Figure 2.

Conclusions : Radiation optic neuropathy is a significant cause of morbidity in patients undergoing radiation therapy for uveal melanoma. OCTA provides a measure of the capillary changes that are occurring following radiation, and may serve as a quantitative endpoint to address visual prognosis in individual patients. Evaluation of a larger series of patients is warranted to further evaluate OCTA as a clinically significant endpoint.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1. Peripapillary OCTA in an eye treated with plaque brachytherapy.

 

Figure 2. Correlation between radiation dose and peripapillary vessel density.