Assessment of superficial retinal microvascular density in healthy myopia

To evaluate retinal microvasculature in healthy myopia and investigate the correlation between microvascular density and ocular factors.

A total of 174 eyes from 174 healthy Korean subjects were included. The eyes were divided into four groups according to refraction: emmetropia [21 eyes, - 1.00 D ≤ mean spherical equivalent (MSE) < + 0.75 D], mild myopia (32 eyes, - 3.00 D ≤ MSE < - 1.00 D), moderate myopia (76 eyes, - 6.00 D ≤ MSE < - 3.00 D), and high myopia (45 eyes, MSE < - 6.00 D). Images of retinal vasculature in parapapillary and parafoveal area were obtained using optical coherence tomography angiography. Superficial retinal microvascular density was measured for correlation analysis with ocular parameters.

High myopia was found to have a lower superficial parapapillary microvascular density compared with the other groups in total parapapillary area, and in sectors of nasal and inferonasal (all p ≤ 0.001). The superficial parapapillary microvascular density showed a negative correlation with axial length (AL) and intraocular pressure (IOP) (β = - 0.479, p = 0.008 and β = - 0.160, p = 0.048, respectively), and a positive correlation with parapapillary retinal nerve fiber layer (RNFL) thickness (β = 0.140, p < 0.001). However, there was no significant difference in superficial parafoveal microvascular density among all groups (p > 0.05).

This study reveals that superficial parapapillary microvascular density is lower in high myopia and has correlation with AL, IOP, and parapapillary RNFL thickness. It also indicates that superficial parafoveal microvascular density tends to be unaffected by healthy myopia. These retinal microvascular alterations may facilitate understanding the pathogenesis of glaucomatous optic nerve damage in high myopia.