In the present study, we evaluated nonophthalmologic factors as well as ophthalmologic factors. Emerging evidence indicates that OAG is not localized but influenced by systemic metabolic status.
19 Incorporating information from both ophthalmologic examinations and systemic evaluations would increase the chances of detecting OAG. When all clinical data were available, the presence of OAG was associated with nine risk factors. These factors that were useful in differentiating OAG from GS were sex, age, menopause, duration of hypertension, SERE, IOP, vertical cup-to-disc ratio, and superotemporal and inferotemporal RNFL defects. Thus, we reconfirmed the well-known glaucoma risk factors of age, IOP, vertical cup-to-disc ratio, and superotemporal and inferotemporal RNFL defects.
19 In addition, we discovered the importance of sex, menopause, duration of hypertension, and SERE as glaucoma risk factors. Our data implied that men and postmenopausal women are at greater risk of contracting OAG. Though the relationship between sex and glaucoma still is a controversial issue, current evidence suggests that older women are more vulnerable to glaucoma than men.
20 One possible theory is that estrogen deficiency affects the optic nerve during the aging process. Thasarat et al.
21 hypothesized that the early loss of estrogen leads to glaucomatous damage and degenerative changes in the optic nerve. Hypertension also is a known risk factor of OAG.
22 In our multivariate analysis, the duration of hypertension was a predictive factor of OAG separate from GS. Our data indicated that 5 years or more of hypertension is a risk factor for OAG. Recently, the World Glaucoma Society recognized that lower perfusion pressure is a risk factor for glaucoma; however, there is no consensus about the exact systemic blood pressure characteristics or vascular changes in patients with glaucoma. It is thought that chronic systemic hypertension may have negative effects on vascular changes. Furthermore, we also found that ophthalmic analysis results may be a predictive factor for OAG. Myopia was selected by our prediction model, which has long been suggested as a risk factor for OAG.
23 There is conflicting evidence of the importance of the refractive error range for OAG. In this study, individuals with moderate to high myopia (≤−3.0 diopters) were at risk of OAG from GS. Regarding IOP, we found that 21 mm Hg was an acceptable cutoff value for predicting the risk of OAG. Suh et al.
24 reported that the mean IOP for the South Korean population is 14.10 ± 2.74 mm Hg. This mean value is low in comparison with IOP values reported from European or American populations, yet similar to that of the Japanese population. Generally, ocular hypertension is defined as an IOP greater than 21 mm Hg, but our calculator suggested that an IOP greater than 20 mm Hg is suitable for predicting OAG in the South Korean population. Additionally, a vertical cup-to-disc ratio of 0.7 or greater was found to be a risk factor used in identifying patients with OAG in most studies, and our study showed similar results.
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