Ophthalmologic analysis of COVID-19 long-haulers using optical coherence tomography angiography (OCT-A)

Abstract

Purpose : The mechanism of post-acute sequalae of COVID-19 (PASC) is largely unknown. Using OCT-A, we compared vessel density (VD) and vessel length density (VLD) in a cohort of PASC patients exhibiting neurological symptoms with healthy controls using a prospective, observational cohort study design.

Methods : PASC patients (N=30; 60 eyes) with a positive SARS-CoV2 test and neurological symptoms lasting at least 6 weeks from onset were included following referral from the Northwestern Medicine Neuro COVID-19 clinic. Those with prior COVID-19 hospitalization were excluded. Controls (N=30, 58 eyes) were included if they did not show symptoms suggestive of SARS-CoV-2 infection. Subjects were excluded if they had media opacities or evidence of retinal pathology, glaucoma, or high myopia.

All subjects underwent OCT-A imaging with segmentation of the full retinal slab into the superficial (SCP) and deep (DCP) capillary plexus. Images were exported to FIJI software with averaging of multiple images. The Foveal Avascular Zone (FAZ) was manually delineated on the full slab. A FIJI macro was then used to measure VD and VLD. Current analysis uses data from one rater – data from a second rater is forthcoming.

OCT-A variables were analyzed using linear mixed effects models with fixed effects for PASC status, age, and sex, and a random effect for patient (to account for measurements from both eyes for some patients). Observations were weighted by the number of scans used to obtain the final OCT-A measurement. The coefficient of PASC status was used to determine statistical significance, and p-values were adjusted using the Benjamini-Hochberg procedure.

Results : PASC patients exhibited a statistically significant (p=0.005) reduction in DCP VLD (0.190 +/- 0.010) as compared to healthy controls (0.206 +/- 0.015). No other OCT-A parameters reached statistical significance.

Conclusions : Our results indicate that DCP VLD may be reduced in PASC suggesting preferential involvement of the smallest blood vessels. Differential identification of DCP changes has also been observed in other disease entities such as early diabetic retinopathy. This is the first study to identify anatomic changes in PASC patients and may help elucidate an etiology for this debilitating condition.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Table 1. OCT-A parameters by disease state.

 

Figure 1. A box plot showing the difference in DCP VLD between healthy controls and Neuro-PASC patients.