Vessel density, macula thickness and foveal avascular zone measurements in young African adults with moderate myopia: A pilot study.

Purpose: The aim of this study was to investigate the association between macula thickness and vessel density in African myopic and emmetropic eyes through the use of Spectral Domain Optical Coherence Tomography (OCT).

Methods: The study population comprised African adults aged 18-35 years old. The study was conducted at a University eye clinic located in Durban, South Africa. Purposive sampling was utilised to obtain 59 participants of whom 24 were myopes and 35 were emmetropes. Vessel density (VD), foveal avascular zone (FAZ) and retinal thickness (RT) were obtained using the Heidelberg Spectralis OCT with angiography. Thereafter, a multivariate linear regression was used to investigate associations between the spherical equivalent myopic refractive error and VD, FAZ and RT for the myopic group only.

Results: Myopic participants had a mean spherical equivalent (MSE) and standard deviation (SD) of -4.79 D (1.27) while the emmetropic group had an MSE (SD) of -0.32 D (0.46). Both superficial and deep VD were significantly decreased at the central fovea (radius (r) = 0.4 mm), peri-foveal (r = 1.10-1.45 mm) and para-foveal (r = 0.75-1.10 mm) sectors in myopes when compared with emmetropes. Myopes showed a significant reduction in RT in the inner retinal layer across the inferior and temporal zones of the peri-foveal region as well as the inferior and temporal zones of the para-foveal region when compared with emmetropes. A significantly smaller FAZ was found at both the superficial and deep vascular plexuses (p < 0.001). In African myopes, significant associations were not found between MSE and VD or FAZ and macula retinal thickness.

Conclusion: Retinal vascular and thickness reduction may occur in young African adults with moderate myopia. A broad-based study targeting VD and IRT in African myopes is proposed to confirm preclinical myopic macula disruptions in adults of African ethnicity. OCT angiography should be considered when monitoring progressive myopia.