Choroidal Microvasculature Dropout is Not Associated With Myopia, But is Associated With Glaucoma.

Abstract

To investigate the frequency of choroidal microvasculature dropout (CMvD) in healthy myopic eyes in comparison with that of myopic open-angle glaucoma (OAG) eyes and determine whether myopia is independently associated with CMvD. Choroidal layer microvasculature images were obtained using optical coherence tomography angiography in 89 myopic OAG patients and 89 age-matched and refractive error-matched healthy myopic eyes. CMvD was defined as a complete loss of the microvasculature network on the choroidal layer vessel density (VD) map. The frequency of CMvD was compared between myopic OAG and healthy myopic eyes. Hemispheric comparisons of various parameters were performed between CMvD-affected and CMvD-unaffected hemiretina. The association of myopia with the presence and angular circumference of CMvD was evaluated using logistic and linear regression analyses. CMvD was identified in 40 eyes (47.6%) with myopic OAG, whereas no CMvD was found in healthy myopic eyes. Mean hemispheric visual field sensitivity (294.9±321.1 vs. 610.5±387.5, P=0.006), retinal nerve fiber layer thickness (68.9±11.5 vs. 82.5±20.6 μm, P=0.001), and circumpapillary VD (50.5%±7.3% vs. 53.9%±8.8%, P=0.048) were significantly worse in the CMvD-affected hemiretina than in the CMvD-unaffected hemiretina. The presence and angular circumference of CMvD was significantly associated with parameters (visual field mean deviation, retinal nerve fiber layer thickness, and circumpapillary VD; P<0.05) representing glaucoma severity rather than parameters (refractive error and axial length; P>0.05) representing myopic change. CMvD was observed only in glaucomatous eyes and associated with severity of glaucomatous damage in myopic OAG subjects. The angular circumference of CMvD was significantly related to glaucoma severity.