Prevalence of refractive errors; the yazd eye study.

PURPOSE: To determine the prevalence of refractive errors in Yazd, central Iran. METHODS: This population-based study was performed in 2010-2011 and targeted adults aged 40 to 80 years. Multi-stage random cluster sampling was applied to select samples from urban and rural residents of Yazd. Manifest refraction, visual acuity measurement, retinoscopy and funduscopy were performed for all subjects. Myopia, hyperopia, astigmatism and anisometropia were defined as spherical equivalent (SE) <-0.50 diopters (D), SE >+0.50 D, cylindrical error >0.5 D and SE difference ≥1 D between fellow eyes, respectively. RESULTS: From a total of 2,320 selected individuals, 2,098 subjects (90.4%) participated out of which 198 subjects were excluded due to previous eye surgery. The prevalence (95% confidence interval) for myopia, hyperopia, astigmatism, anisometropia, -6 D myopia or worse, and 4 D hyperopia or worse was 36.5% (33.6-39.4%), 20.6% (17.9-23.3%), 53.8% (51.3-56.3%), 11.9% (10.4-13.4%), 2.3% (1.6-2.9%) and 1.2% (0.6-1.8%), respectively. The prevalence of hyperopia, astigmatism and anisometropia increased with age. The prevalence of myopia was significantly higher in female subjects. The prevalence of with-the-rule, against-the-rule and oblique astigmatism was 35.7%, 13.4% and 4.6%, respectively. The prevalence of against-the-rule astigmatism increased with age (P<0.001); with-the-rule astigmatism was more common in women (P=0.038). CONCLUSION: More than half of the study population had refractive errors; the prevalence of myopia and astigmatism was higher than earlier studies in Iran. Since refractive errors are a major cause of avoidable visual impairment, their high prevalence in this survey is important from a public health perspective.

A population-based survey of the prevalence and types of glaucoma in central Iran: the Yazd eye study.

PURPOSE: To describe the prevalence and types of glaucoma in Yazd, central Iran. DESIGN: Population-based, cross-sectional study. PARTICIPANTS: Iranian adults aged 40 to 80 years, residing in Yazd, Iran, in 2010 and 2011. METHODS: Eligible samples were selected using cluster random sampling. Each participant underwent an interview and ophthalmologic examinations, including refraction, determination of uncorrected and best-corrected visual acuity, slit-lamp biomicroscopy, Goldmann applanation tonometry, gonioscopy, dilated fundus examination, central corneal thickness measurement, visual field testing, and stereoscopic fundus photography. MAIN OUTCOME MEASURES: Prevalence of different types of glaucoma. RESULTS: Of 2320 eligible individuals, 2098 (response rate, 90.4%) participated in the study and 1990 completed all evaluations for glaucoma diagnosis. Overall, 47 persons (2.4%) were categorized with ocular hypertension, 32 persons (1.6%) were categorized with primary angle-closure suspect (PACS), and 16 persons (0.8%) were categorized with primary angle closure (PAC). The total number of subjects with glaucoma was 87 (4.4%; 95% confidence interval, 3.3-5.4), consisting of primary open-angle glaucoma (POAG, 3.2%, including high-tension glaucoma [1.7%] and normal-tension glaucoma [NTG], 1.5%]), primary angle-closure glaucoma (PACG, 0.4%), pseudoexfoliation glaucoma (0.4%), and other secondary glaucomas (0.4%). The mean age of subjects with glaucoma was 63.3 ± 11 years, and 57.5% of them were female. Seventy-eight individuals (89.7%) were unaware of their disease. Positive family history of glaucoma was present in 6.9% of glaucoma subjects. CONCLUSIONS: The prevalence of glaucoma in Yazd (4.4%) is comparable to that in other population-based studies in Asia, with POAG accounting for the majority of cases. Most affected subjects were unaware of their disease. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The Yazd Eye Study-a population-based survey of adults aged 40-80 years: rationale, study design and baseline population data.

PURPOSE: To describe the rationale, methodology and baseline data of the Yazd Eye Study, a study in the urban and rural areas of Yazd, a district in the center of Iran. METHODS: This population-based cross-sectional study included adults aged 40-80 years from the non-institutionalized population of the Yazd district, in 2010-2011. Using multi-stage, systematic cluster random sampling and a probability proportional to size strategy, 58 clusters of 40 subjects were selected from 251 clusters in different enumeration areas. A detailed interview and eye examination were performed for each eligible participant. The eye examination included refraction testing, uncorrected and best corrected visual acuity testing, slit lamp biomicroscopy, Goldmann applanation tonometry, gonioscopy, dilated fundus examination, visual field, determination of central corneal thickness, and stereoscopic fundus photography. General health assessments and laboratory tests including hemoglobin, hematocrit, glycosylated hemoglobin, fasting blood sugar, serum lipids, and urine albumin to creatinine ratio were also performed to assess anthropometric and systemic risk factors. RESULTS: Of 2320 eligible individuals, 2098 (response rate 90.4%) participated in the study. The mean ± standard deviation age of participants was 54.1 ± 10.0 years, and included 994 men (47.4%) and 1104 women (52.6%). Most participants lived in urban regions (89.2%) and were younger than 60 years old (72.0%). Among the participants, 20.1% were illiterate, and 40.9%, 28.0%, and 11.0% had primary, secondary and college or university level education, respectively. CONCLUSION: This study is expected to provide an estimate of the prevalence and risk factors of major eye diseases and normal eye indices in the Yazd district.