Effect of Myopia on the Macular Vessel Flow Density in Eyes Using Optical Coherence Tomography Angiography.

Abstract

Purpose : Vessel flow density (VFD) around the fovea in eyes with myopia using OCT angiography (OCTA) has not been reported in literature. The index study investigates the effect of myopia on the VFD in the macular region using OCTA.

Methods : Optovue RTVue XR 100 AVANTI was used to capture OCTA images of 12 myopic and 12 emmetropic eyes. 3x3mm grid centered on the fovea was chosen to scan the parafoveal region. ReVue software (Version: 2015.1.0.71) was used to measure VFD in the regions of interest (ROI). In the macular ROI, VFD was measured in 5 sectors within the inner 2 circles of grid derived from the ETDRS grid (Figure 1A). The mean VFD in the parafoveal and foveal region was correlated with the spherical equivalent in subjects with myopia. The mean VFD in the macular sectors of the myopic eyes were also compared to that of emmetropic eyes.

Results : 12 myopic (mean spherical equivalent: -4.97±1.98) and 12 emmetropic eyes were analyzed (mean age: 33 and 28 years, respectively). Mean VFD in the macular sectors of myopic subjects was 44.2 (±1.9) and 45.6 (±2.4)% and the emmetropic subjects was 42.8 (±6.1) and 45.8 (±6.8)% in superficial and deep retinal plexus, respectively. A negative correlation was found between spherical equivalents of myopic eyes and mean VFD in the parafoveal region at both the superficial and deep plexuses (p<0.05) (Figure 1B and 1C). There was no correlation between spherical equivalent and VFD in the foveal region. Table 1 provides a comparison of mean VFD between myopic and emmetropic eyes. Mean VFD in myopic eyes was found to be significantly lower in the parafoveal region of the deep vascular plexus (p=0.03). This was more significant in the parafoveal nasal and temporal region.

Conclusions : Mean VFD in myopic eyes is lower in the parafoveal deep vascular plexus compared to emmetropics. Additionally, an increase in spherical equivalent of myopic eyes is correlated with a decrease in parafoveal VFD, which may predispose the eyes to neovascularization.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1A: Macular sectors for VFD analysis: A: Fovea; B: Superior; C: Nasal; D: Inferior; E: Temporal; B-E: Parafoveal Region. 1B and 1C: Scatter plots depicting correlation between VFD and spherical equivalent of subjects with myopia in superficial (1B) and deep (3B) plexuses in parafoveal region.

 

Table 1. Comparison of VFD between myopics and emmetropics.