Abstract
Purpose :
Pars plana vitrectomy (PPV) alters oxygen concentration in the posterior segment with implications for vascular growth. We hypothesize that post-PPV pathophysiological changes in retinal and choroidal vasculature can be captured in-vivo with optical coherence tomography angiography (OCTA). This research will broaden our understanding of vitreous humor-regulated homeostasis and advocate for the routine use of OCTA.
Methods :
A retrospective cohort of patients who had PPV at the Vanderbilt Eye Institute from April 2013 to January 2018 was identified with exclusion of cases with expected retinal vasculature abnormalities: proliferative diabetic retinopathy, retinal detachment, previous non-cataract ocular surgery. Using OCTA (RTVue XR 100) the following parameters were measured: flow area of the outer retina, flow area of the choriocapillaris, whole image vessel density, fovea vessel density, parafovea vessel density, parafovea thickness and FAZ area. The averages of each parameter across all post-PPV and non-operative eyes were assessed with a two-sample t-test assuming equal variance, with a p-value for statistical significance of less than .05.
Results :
Twenty-four patients with PPV and subsequent OCTA were identified. Fourteen patients were excluded based on study criteria. The average age was 65.6 +/- 10.2 years. PPV indications were: full thickness macular holes (five patients), epiretinal membranes (four patients), dislocated IOL (one patient). Baseline visual acuity of the operated eye ranged from 20/60 to CF at 1 foot. Surgical timeline between PPV and OCTA was 11.6 months on average. Final visual acuity of the operated eye ranged from 20/20 to 20/80. The foveal vessel density was statistically significantly higher in the post-PPV eye (33.145%) compared to the non-operative eye (27.784%) with a p-value=.032. The other parameters measured yielded no statistically significant differences.
Conclusions :
OCTA uncovered a statistically significantly higher foveal vessel density in post-PPV eyes compared to non-operative eyes. This finding corroborates with evidence for improved oxygenation to the retina post-PPV and supports our hypothesis that OCTA can capture post-PPV changes of the posterior segment. A larger, prospective study is underway to confirm these results.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.