“…Meta-regression also failed to distinguish the exact source of the heterogeneity. Several factors, such as different characteristics of the populations, different quality of the included studies, different methods used to ascertain outcomes and exposure, different sample 44 Age, sex Chen (2005) 9 Age, SBP, DBP, glucose Motsko (2008) 54 Age, sex Lin (2010) 8 Age, gender, monthly income, and level of urbanization of the community in which the patient resided Lin (2010) 45 Age, sex Imai (2010) 42 Age, maximum temperature, increased abdominal circumference, elevated fasting glucose level, BP Ishikawa (2011) 52 Age, sex, DBP, IOP, and ocular perfusion pressure Newman-Casey (2011) 7 Age, sex, race, education level, household net worth, region of residence at the time of enrollment in the medical plan, cataract, pseudophakia or aphakia, macular degeneration, diabetic retinopathy, systemic hypotension, sleep apnea, and migraine headache Lee (2012) 46 Age, sex, SBP Lin (2012) 33 Age, sex, BMI, waist, SBP, DBP, fasting sugar, and postprandial sugar Kim (2014) 34 Age, sex, impaired glucose tolerance, hypertension, and baseline IOP Aptel (2014) 47 Age, sex, BMI, hypertension, and thyroid dysfunction Kim (2014) 43 Age, sex Chung (2014) 53 Age, sex Kim (2014) 55 Age, sex, myopia, fasting blood glucose Chen (2014) 48 Age, sex, hypertension, diabetes, CAD, and obstructive sleep apnea Sahinoglu-Keskek (2014) 41 Age Fujiwara (2015) 49 Age, sex, SBP, diabetes, cholesterol, HDLcholesterol, BMI, waist circumference, smoking habits, alcohol intake, and regular exercise Shim (2015) 32 Age, sex Chen (2016) 50 Age, sex Chen (2016) 51 Age, gender, and comorbidities of diabetes, hypertension, and CAD Ko (2016) 35 Age, gender, ethnicity, education, insurance, diabetes duration, BMI, hypertension, obstructive sleep apnea, and current smoker Kim (2016) 36 Age, sex, IOP, household income, exercise, education level, smoking status, alcohol consumption, and BMI Yokomichi (2016) 10 Age, sex, SBP, DBP, fasting plasma glucose Rim (2017) 37 Age, sex, hypertension, DM, chronic renal failure, atrial fibrillation, residence, income Lee (2017) 38 Age, sex, hypertension, DM, congestive heart failure, ischemic heart disease, atrial fibrillat...…”