Characteristics of patients with primary open angle glaucoma and normal tension glaucoma at a university hospital: a cross-sectional retrospective study

Yu Yokoyama, Kazuichi Maruyama, Hideyuki Konno, Sayaka Hashimoto, Mai Takahashi, Hiroko Kayaba, Taiki Kokubun, Toru Nakazawa

The characteristics of glaucoma patients and their response to therapy may differ by institution, region and country. Therefore, clinicians should understand the distinctiveness of their patients. Here, we profile primary open angle glaucoma (POAG) and normal tension glaucoma (NTG) patients at a major university hospital in Japan. This study included 523 eyes from 523 POAG and NTG patients who underwent full clinical ophthalmologic evaluations at Tohoku University Hospital. Clinical characteristics such as age, sex, visual acuity, intraocular pressure, Humphrey field analyzer-measured mean deviation (MD) and MD slope were collected retrospectively. MD slope was calculated from MD data that included the first baseline measurement of MD and 4 subsequent, consecutive, reliable measurements of MD. Refractive error was analyzed in a subgroup with no history of refractive surgery, including intraocular lens implantation. Patient characteristics were analyzed separately in the groups of patients with low (<15 mmHg) and high IOP (≥15 mmHg) and in the groups with MD slope ≥-1.0 and <-1.0 dB/year. Mean age, visual acuity (median), IOP, pre-treatment IOP (from patient history), refractive error and MD were 61.7 ± 12.5 years, -0.08 (interquartile range -0.08 to 0.05) LogMAR, 13.87 ± 3.37 mmHg, 18.35 ± 6.26 mmHg, -4.48 ± 3.81 diopters and -11.73 ± 8.83 dB, respectively. POAG and NTG patients had significant differences in mean age (63.4 ± 12.4 vs. 60.7 ± 12.5 years, P < 0.01), visual acuity, IOP (14.95 ± 4.20 vs. 13.21 ± 2.54 mmHg, P < 0.01) and MD (-13.85 ± 9.32 vs. -10.45 ± 8.27 dB, P < 0.01). Interestingly, MD slope was slightly steeper in the low-IOP group than in the high-IOP group, although the difference was not statistically significant (-0.85 vs. -0.70 dB/year, P = 0.31). Baseline MD was significantly worse in the group with MD slope <-1.0 dB/year than in the group with MD slope ≥-1.0 dB/year (-11.56 vs. -7.64 dB/year, P < 0.01). We identified characteristics of glaucoma patients at a university hospital that may reflect the specialized nature of such an institution.