Correlation of ganglion cell complex thinning with baseline deep and superficial macular vessel density in glaucoma

Background/aims To investigate the relationship between ganglion cell complex (GCC) thinning and baseline deep and superficial macular vessel density (VD) in glaucoma. Methods 97 eyes of 69 primary open-angle glaucoma (POAG) and glaucoma suspect patients from the Diagnostics Innovations in Glaucoma Study with a minimum of 4 visits and 2 years of follow-up after baseline optical coherence tomography angiography (OCTA) examination were included. OCTA 3x3 mm(2) macular scans were acquired at each visit and used to calculate superficial and deep parafoveal VD (pfVD) and OCT-based parafoveal GCC (pfGCC) thickness. Association of baseline superficial and deep pfVD with pfGCC thinning rate was evaluated using linear mixed model. Results The included subjects had a baseline mean visual field mean deviation (95% CI) of -2.9 (-3.7 to -2.1) dB and a mean follow-up period of 3.6 years. In the univariable model, lower baseline superficial pfVD and higher mean intraocular pressure (IOP) during follow-up were significantly associated with a faster pfGCC thinning rate (p<0.05 for all), while deep pfVD was not (p=0.177). In the multivariable model, faster pfGCC thinning was correlated with higher mean IOP during follow-up (beta=-0.05, p=0.002) and lower baseline superficial pfVD (beta=-0.04, p=0.011). Eyes with a baseline superficial pfVD in the lowest tertile (<= 46%) had significantly faster pfGCC loss compared with eyes with baseline superficial pfVD greater than 46% (p=0.015). Conclusion Lower baseline superficial pfVD, but not deep pfVD, was associated with faster pfGCC thinning in glaucoma. Moreover, superficial macular VD may help predict central macula thinning in patients with glaucoma.