||The Faculty of Optometry at Rangsit University performed a retrospective study using records from the eye clinic at Rangsit University (RSU) Healthcare. The objective of the study was to evaluate the relationships between refractive errors and glaucoma and between systemic diseases and glaucoma. Participants were patients attending the eye clinic between 2015 and 2019, aged 40-80 years, who had complete eye examinations and regular follow-up. The total number of subjects was 3,468 (mean age 60.19 ±10.63 years). The examination included measurement of the presenting and best-corrected visual acuity, auto and manifest refraction, applanation intraocular pressure measurement, gonioscopy, cup-to-disc ratio, nerve fiber layer analysis, and perimeter and central corneal thickness measurement. Glaucoma was diagnosed via standardized criteria of the American Academy of Ophthalmology. Cases of refractive error, expressed as spherical equivalent (SE), included 1,154 cases of myopia (mild, moderate and severe), 1,381 cases of hyperopia (mild, moderate and severe) and 359 cases of astigmatism. Subjects also included 302 emmetropic individuals, 139 subjects with pseudophakia and 133 individuals who had undergone refractive surgery. A total of 555 glaucoma cases (19.56%) were identified, including 354 cases of primary open-angle glaucoma (POAG), 50 instances of primary angle-closure glaucoma (PACG), 106 cases of normotension glaucoma (NTG), and 45 cases of secondary glaucoma (SOAG). Subjects with glaucoma-related conditions included 41 post-glaucoma surgery cases, 81 ocular hypertension (OHT) cases, 186 primary open-angle glaucoma-suspect (POAGS) cases, 178 individuals with primary angle closure (PAC) and 166 subjects who had undergone laser peripheral iridotomy (LPI). The results indicated that the prevalence of some types of glaucoma and glaucoma-related conditions (PAC, NTG, OHT and SOAG) increased with advancing age (p = 0.022, 0.001, 0.001, 0.021 respectively). Relationships between refractive error and glaucoma subtypes were found. Mild, moderate and high myopia ( 0.50 to -3.00 D, -3.25 to -5.00 D, and -5.25 D or greater, respectively) were correlated with POAG and NTG (p = 0.001). Mild and moderate hyperopia (+0.50 to +2.00 D and +2.25 to +5.00 D, respectively), were correlated with POAG and NTG (p = 0.001). PACG was correlated with mild, moderate and high myopia and mild to moderate hyperopia (p = 0.001). The lack of relationship between high hyperopia with PACG may be due to fact that 5.85 % of the studied population had already undergone laser peripheral iridotomy. Among glaucoma subtypes, NTG patients were most advanced in age (68.82 ± 10.73 years) and SOAG patients were the youngest (58.36 ± 13.88.79 years). Compared to previous reports, our study revealed an increased glaucoma prevalence in individuals with myopia and hyperopia due to methodological differences and possibly due to our patients being older (60 years vs. 58 years). Diabetes was significantly correlated with SOAG (p = 0.041). Hypertension was not related to any type of glaucoma. Dyslipidemia was significantly correlated with SOAG (p = 0.046). In conclusion, this study found myopia and hyperopia to be related to an increased prevalence of all forms of open-angle glaucoma, including normal-tension glaucoma and angle-closure glaucoma, even after laser peripheral iridotomy. Diabetes and dyslipidemia were correlated with secondary open-angle glaucoma.