Choroidal Vascularity Index Changes After Exercise in Patients With Glaucoma

Abstract

Purpose: To investigate the changes in choroidal vascular structures after exercise in patients with glaucoma using an image binarisation algorithm with enhanced-depth imaging optical coherence tomography. Methods: Thirty-four eyes of 19 patients with primary open-angle glaucoma and 40 eyes of 20 normal subjects were included in the glaucoma and control groups, respectively. All subjects were evaluated before, immediately after, and 30 min after 20-min running at moderate speed. The subfoveal choroidal area was segmented into the luminal area (LA) and stromal area (SA), and the choroidal vascularity index (CVI) was measured by calculating the ratio of LA to the total choroidal area (TCA). The mean intraocular pressure (IOP), subfoveal choroidal thickness, CVI, SA, CA, and TCA were compared within and between both groups. The correlation between CVI, IOP, and other vascular indexes was investigated. Results: In the glaucoma group, a significantly lower CVI was found immediately after exercise and recovered 30 min after exercise. Higher TCA and LA levels were demonstrated 30 min after exercise compared to immediately after exercise. In both groups, IOP decreased immediately after exercise but was restored after a 30-min rest. In the glaucoma group, there was a higher correlation between CVI and other choroidal vascular parameters than in the control group. There was no difference in IOP or choroidal parameters between the groups at different time points. Conclusion: In patients with glaucoma, CVI decreased significantly immediately after exercise, indicating that the choroidal layer is affected by exercise and an unhealthy vascular regulatory mechanism.

Keywords: choroidal vascularity index; exercise; glaucoma; optical coherence tomography; primary open-angle glaucoma.

FIGURE 1

Subfoveal choroidal thickness and choroidal vascularity index (CVI) analysis in a patient with glaucoma (A). The enhanced-depth imaging optical coherence tomography (EDI-OCT) image of one eye of patient with glaucoma (B) Choroidal boundaries were automatically identified and assessed by the two operators (red lines) (C) The total choroidal area (TCA) was determined by the binarised EDI-OCT image (D,E) CVI was derived as a proportion of the choroidal vasculature (yellow outlines) against the TCA by image binarisation.

FIGURE 2

Intraocular pressure (IOP) and choroidal parameters before and after exercise in the glaucoma and control groups. T1, before exercise; T2, immediately after exercise; T3, 30 min after exercise. CVI = choroidal vascularity index, CT = choroidal thickness, TCA = total choroidal area, LA = luminal area, SA = stromal area. ^*0.01 ≤ p < 0.05, ^**0.001 ≤ p < 0.01, ^*** p < 0.001.

FIGURE 3

The correlation between the choroidal vascularity index (CVI) and intraocular pressure (IOP) and other choroidal parameters (CT, TCA, LA, and SA) in the glaucoma and control groups. CT = choroidal thickness, TCA = total choroidal area, LA = luminal area, SA = stromal area.