Change in the Foveal Avascular Zone and Macular Capillary Network Density after Hyperbaric Oxygen Therapy in Healthy Retina.

Sadık Görkem Çevik,Bekir Selim Bağlı

doi:10.18502/jovr.v16i3.9436

Sadık Görkem Çevik, Bekir Selim Bağlı

Open Access

https://doi.org/10.18502/jovr.v16i3.9436

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Abstract

PurposeThis study aimed to evaluate responses in retinal tissue by swept source OCT angiography (OCT-A) to hyperoxia after hyperbaric oxygen (HBO2) therapy.Methods The study was conducted in volunteers who received HBO2 treatment but did not have any eye disease. Patients underwent detailed eye examinations including dilated fundus examination, visual acuity, and refraction before being admitted for HBO2 therapy. Measurements were made before and immediately after HBO2 therapy. Enface images of the retinal vasculature were obtained from the superficial and deep retinal plexus (SP/DP). Quantitative analysis of the vessel density (VD) and foveal avascular zone (FAZ) area was performed.Results In total, 31 patients (15 female) with healthy retina were included in the study. The mean age was 42.8 years. The mean SP vascular density measurements before HBO2 therapy for the right and left eyes were 15.18 1.2 mm and 15.01 1.3 mm, respectively; the measurements after HBO2 therapy for the right and left eyes were 14.34 1.4 mm and 14.48 1.19 mm. The mean DP vascular density measurements before HBO2 therapy for the right and left eyes were 16.03 1.69 mm and 16.1 1.45 mm, respectively; the measurements after HBO2 therapy for the right and left eyes were 15.02 1.65 mm and 15.12 2.16 mm, respectively. Reduction of mean VD in superficial and deep plexus after HBO2 was statistically significant (P = 0.001 and P = 0.000, respectively). Changes in mean FAZ area before and after HBO2 therapy were not statistically significant (P = 0.719).Conclusion The healthy retina responds to oxygen supersaturation with HBO2 therapy by eventually decreasing vascular density in all layers. These findings may be important for further studies especially related to retina and choroidal oxygenation.

Highlights

METHODSHyperbaric oxygen (HBO2) therapy is a medical treatment method that aims to increase the level of dissolved oxygen in tissues
Macular microvasculature is a complex system consisting of three capillary plexuses for the blood supply of the inner retina: the superficial retinal plexus (SP) located in the retinal nerve fiber layer and the two-plexus located at the inner and outer border of the inner nuclear layer (INL), which constitute the deep retinal plexus (DP).[10]
The present study aimed to evaluate changes in foveal avascular zone (FAZ) area and perifoveal capillary network density in SP and DP, with the aid of swept source OCT angiography (OCT-A) in patients undergoing HBO2 therapy

Summary

Introduction

Hyperbaric oxygen (HBO2) therapy is a medical treatment method that aims to increase the level of dissolved oxygen in tissues. Patients intermittently breathe near 100% oxygen while inside a hyperbaric chamber that is pressurized to greater than sea level pressure (1 atmosphere absolute [ATA]) and high tissue oxygen level remains high for up to 4 hr after the therapy.[1]. The retina has an internal autoregulatory system that preserves blood flow and stable oxygenation by altering it in response to unexpected conditions.[2]. This regulatory system changes blood flow and vascular density for unexpected conditions and may not work correctly under some conditions, such as diabetic retinopathy or age-related macular degeneration.[3–9]. Noninvasive retinal blood-flow imaging techniques, such as scanning laser Doppler and Doppler OCT, have previously been described.[11–14]. Noninvasive retinal blood-flow imaging techniques, such as scanning laser Doppler and Doppler OCT, have previously been described.[11–14] OCT angiography (OCT-A) is a novel, noninvasive technique for retinal vasculature imaging that allows segmentation and quantification of the retinal microvasculature.[15]

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