Macula structural and vascular differences in glaucoma eyes with and without high axial myopia

Aims To assess the thickness of various retinal layers, and the superficial vessel density (sVD) in the macula of glaucomatous eyes and their associations with axial length (AL) and visual field mean deviation (VFMD) to identify parameters useful for glaucoma management in myopic eyes. Methods 248 glaucoma patients (401 eyes) participating in the Diagnostic Innovations in Glaucoma Study observational cohort representing 3 axial myopia groups (non-myopia: n=146 eyes; mild myopia: n=208 eyes; high myopia (AL>26 mm): n=47 eyes) who completed macular OCT and OCT-Angiography imaging were included. The cross-sectional associations of AL and VFMD with the thickness of the ganglion cell inner plexiform layer (GCIPL), macular retinal nerve fiber layer (mRNFL), ganglion cell complex (GCC), sVD and macular choroidal thickness (mCT) were evaluated. Results Thinner Global GCIPL and GCC were significantly associated with worse VFMD (R2=35.1%; and R2=33.4%; respectively p<0.001), but not with AL (all p>0.350). Thicker mRNFL showed a weak association with increasing AL (R2=3.4%; p=0.001) and a positive association with VFMD (global R2=20.5%; p<0.001). Lower sVD was weakly associated with increasing AL (R2=2.3%; p=0.016) and more strongly associated with more severe glaucoma VFMD (R2=31.8%; p<0.001). Thinner mCT was associated with increasing AL (R2=17.3% p<0.001) and not associated with VFMD (P=0.262). mRNFL was thickest while mCT was thinnest in all sectors of high myopic eyes. Conclusions GCIPL and GCC thinned with increasing severity of glaucoma but were not significantly associated with axial length. GCIPL and GCC thickness may be useful clinical parameters to identify glaucoma in myopic eyes.