Objective: To evaluate the effect of glaucoma on the mental health of primary open-angle glaucoma patients using Hospital Anxiety and Depression Scale (HADS) Materials and Methods: This was a hospital-based comparative study in which 180 glaucoma patients and controls 18 years and above who met the inclusion criteria were selected consecutively in the Eye Clinic of Federal Medical Centre, Owerri, Imo State, in 2017. Data were collected using a questionnaire and the HADS protocol. All the participants underwent comprehensive ocular examination, and glaucoma was graded using visual field perimetric indices and mean deviation. Results: The mean age for cases was 58.14 ± 13.88 years, whereas that of the control group was 57.19 ± 13.76 years. The majority of glaucoma respondents had the moderate form of the disease followed by the severe form. The glaucoma patients showed evidence of poor mental health with 59 (32.8%) of them anxious and 39 (21.7%) depressed compared to controls ( P < 0.001). The mean scores for anxiety and depression were 6.02 ± 4.8 and 5.20 ± 4.5, respectively, for glaucoma patients, whereas those for the control group were 0.63 ± 1.8 and 0.64 ± 2.1, respectively ( P < 0.001). There was no uniform correlation between the mental health of patients and the variables under study. Conclusion: Primary open-angle glaucoma affects the mental health of patients. This effect is worsened by the severity of the disease and influenced by the occupation and educational level of the patients. Multidisciplinary management of primary open-angle glaucoma patients is recommended.