Comparison of optical nerve head and macular vascular densities measured by optic coherence tomography angiography in healthy participants and patients with ocular hypertension and different stages of glaucoma

Optical cohorence tomography angiography (OCT-A) is a non-invasive diagnostic method that enables the imaging of retinal and choroidal vascular structures. The aim of this study is to investigate the vascular alterations in healthy participants (HP), ocular hypertension (OHT), preperimertric glaucoma (PPG), early-stage glaucoma (EG), middle-stage glaucoma (MG) and advanced-stage glaucoma (AG) and to evaluate the role of OCT-A in the diagnosis and follow-up of glaucoma. Twenty nine eyes of 29 HP, 105 eyes of 62 OHT patients, 69 eyes of 50 PPG patients, 54 eyes of 47 EG patients and 41 eyes of 36 MG patients and 42 eyes of 35 AG patients were investigated in our study. Peripapillary and macular vascular density data of groups were compared with OCT-A and correlations of these data with optical coherence tomography (OCT) and visual field tests were evaluated. In comparisons between groups, statistically significant differences were found in all parameters of rim area, cup volume, mean and vertical cup to disc ratio and retinal nerve fiber layer thicknesses (RNFLT) (p<0,05). There was statistically significant differences between the groups in means of both peripapillary and macular vascular density values and both peripapillary and macular vascular densities decreased as the disease progressed. In subgroup analyzes, statistically significant differences were found in means of both peripapillary and macular vascular densities between HP and EG groups. In the correlation analyzes, an especially high correlation of peripapillary vascular densities with RNFLT were observed except for AG group. In advanced stage disease, it was observed that while RNFLT was not correlated with visual field, peripapillary vascular density was correlated (Mean deviation - whole image peripapillary vascular density (WI-PPVD) r=0,514 r=0,001). According to the receiver operating characteristic (ROC) analysis, the highest discrimination capacity in EG, MG and AG groups was determined in the WI-PPVD values (respectively r=0,873 p=0,037, r=0,824 p=0,037, r=0,989 p=0,009). According to these results, it was revealed that OCT-A can be used in glaucoma diagnosis and follow-up in addition to structural and functional tests. Especially when there are limitations in structural and functional tests OCT-A can be used as a supportive diagnostic test, both in early and advanced stage glaucoma patients. Key words: Glaucoma, optical coherence tomography angiography, vascular density