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

Aims To identify clinically relevant parameters for identifying glaucoma in highly myopic eyes, an investigation was conducted of the relationship between the thickness of various retinal layers and the superficial vessel density (sVD) of the macula with axial length (AL) and visual field mean deviation (VFMD). Methods 270 glaucoma patients (438 eyes) participating in the Diagnostic Innovations in Glaucoma cross-sectional study representing three axial myopia groups (non-myopia: n=163 eyes; mild myopia: n=218 eyes; high myopia (AL>26 mm): n=57 eyes) who completed macular optical coherence tomography (OCT) and OCT-angiography imaging were included. Associations of AL and VFMD with the thickness of the ganglion cell inner plexiform layer (GCIPL), macular retinal nerve fibre layer (mRNFL), ganglion cell complex (GCC), macular choroidal thickness (mCT) and sVD were evaluated. Results Thinner Global GCIPL and GCC were significantly associated with worse VFMD (R 2 =34.5% and R 2 =32.9%; respectively p<0.001), but not with AL (all p>0.1). Thicker mRNFL showed a weak association with increasing AL (R 2 =2.4%; p=0.005) and a positive association with VFMD (global R 2 =19.2%; p<0.001). Lower sVD was weakly associated with increasing AL (R 2 =1.8%; p=0.028) and more strongly associated with more severe glaucoma VFMD (R 2 =29.6%; p<0.001). Thinner mCT was associated with increasing AL (R 2 =15.5% p<0.001) and not associated with VFMD (p=0.194). mRNFL was thickest while mCT was thinnest in all sectors of high myopic eyes. Conclusions As thinner GCIPL and GCC were associated with increasing severity of glaucoma but were not significantly associated with AL, they may be useful for monitoring glaucoma in highly myopic eyes.