Posterior vitreous detachment increases macrophage-like cell density

Abstract

Purpose : Optical coherence tomography (OCT) imaging has identified mobile, ramified macrophage-like cells (MLCs) at the vitreoretinal interface in human subjects. The identity of MLCs remains unknown and a potential cell type includes vitreal hyalocytes. We performed OCT and OCT angiography (OCT-A) imaging in patients with and without posterior vitreous detachment (PVD) to determine if MLCs exist in the retina or vitreous, and to determine if PVD status changes MLC detection.

Methods : We imaged 21 eyes from 21 subjects, including 11 eyes with no PVD and 10 eyes with PVD. Repeated foveal-centered 3 x 3 mm OCT-A images were obtained (mean: 6.0 repeats, range: 4–10). The images were segmented, registered, and averaged. The OCT slab segmented from 0 to 3 microns above the internal limiting membrane was used to detect MLCs, which were binarized and quantified using our previously published semi-automated method. The distribution of MLCs in relation to vessels in the superficial capillary plexus was investigated, and MLC density was calculated for 3 vascular regions – on vessels, perivascular, and ischemic (>30 microns from the nearest vessel).

Results : MLC density was 1.8-fold greater in the PVD group (13.21 ± 7.29 cells/mm²) compared to the no PVD group (7.48 ± 4.43 cells/mm²; P = 0.04). MLCs were increased 1.9-fold on-vessel (P = 0.07), 1.9-fold in the perivascular region (P = 0.12), and 2.2-fold in ischemic areas (P = 0.22).

Conclusions : MLCs were detected in both PVD and no PVD eyes, suggesting that MLCs exist in the retina, although we cannot exclude a remnant of the cortical vitreous on the retinal surface. PVD eyes showed a trend toward more MLCs near vessels than ischemic areas, suggesting that MLCs could be extravasating from the vasculature in response to PVD. However, vitreous separation could merely enhance MLC detection. PVD status is an important parameter to consider in future MLC studies.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Registered and averaged MLC en face slab from a representative No PVD (A) and PVD (C) eye. MLC binarization of the representative No PVD (B) and PVD (D) eye with MLCs in white. MLC density was increased 1.8-fold in PVD eyes (E).