Open-angle glaucoma (OAG) patients who smoked heavily had a lower density of capillaries in their whole superficial images. The purpose of this study was to use optical coherence tomography angiography to assess the impact that smoking has on capillary density in the optic nerve head in patients with OAG. Patients with perimetric and preperimetric glaucoma who followed optical coherence tomography angiography as part of the Diagnostic Innovations in Glaucoma Study (DIGS) were included in this retrospective cross-sectional study. For this study, researchers analyzed the superficial whole-image capillary density using univariate and multivariate linear mixed analysis to identify the factors contributing to this metric’s variation. There were a total of 432 eyes from 271 patients with glaucoma, with 63 cases of preperimetric glaucoma (106 eyes) and 208 cases of perimetric OAG (326 eyes). A total of 105 people (38.8%) revealed a previous history of tobacco use. Smokers, on average, smoked for 12.8 (10.2, 15.5) pack-years within a 95% (CI). After controlling for age, glaucoma severity, and other covariates, they discovered that each 10-pack-year increase in smoking intensity (95% CI) was linked with a −0.54 (−1.06, −0.02)%  decrease in whole image capillary density (P=0.041). Optic nerve vessel density is lower in glaucoma patients who smoke heavily.