Purpose <p>To evaluate macular ganglion cell complex (GCC) thickness and parafoveal vessel density (pfVD) using optical coherence tomography angiography (OCT-A) in patients with ocular hypertension (OHT) and early- to intermediate-stage primary open-angle glaucoma (POAG).</p> Material and methods <p>This cross-sectional study included 150 eyes from 56 patients with POAG and 32 patients with OHT who were under regular follow-up at the Glaucoma Unit of Istanbul University Faculty of Medicine, Department of Ophthalmology. Evaluations were conducted between November and December 2022. Additionally, 50 eyes from 25 healthy individuals were included as a control group. OCT-A imaging was performed using the Topcon DRI OCT Triton system (Topcon Corporation, Japan). Macular GCC thickness and pfVD in the superficial and deep capillary plexuses were measured and compared among groups.</p> Results <p>A total of 113 participants (74 females, 39 males) were included. No significant differences in macular GCC thickness or pfVD were observed between the control and OHT groups. In contrast, both parameters were significantly reduced in POAG eyes, with greater reductions observed in more advanced disease stages. The decrease in pfVD was more pronounced in the superficial capillary plexus compared to the deep plexus. In early-stage POAG, GCC thinning appeared more prominent than pfVD reduction.</p> Conclusıon <p>Our findings suggest that macular GCC thickness and pfVD assessed by OCT-A are associated with glaucomatous changes. In particular, structural alterations in macular GCC may be more pronounced than vascular changes in early-stage POAG. These results indicate that macular GCC assessment may provide complementary information in the evaluation of early glaucomatous damage. However, due to the cross-sectional design of the study, no conclusions can be drawn regarding the temporal relationship between structural and vascular changes.</p>