title: The Tehran Eye Study: research design and eye examination protocol.
abstract: BACKGROUND
  Visual impairment has a profound impact on society. The majority of visually impaired people live in developing countries, and since most disorders leading to visual impairment are preventable or curable, their control is a priority in these countries. Considering the complicated epidemiology of visual impairment and the wide variety of factors involved, region specific intervention strategies are required for every community. Therefore, providing appropriate data is one of the first steps in these communities, as it is in Iran. The objectives of this study are to describe the prevalence and causes of visual impairment in the population of Tehran city; the prevalence of refractive errors, lens opacity, ocular hypertension, and color blindness in this population, and also the familial aggregation of refractive errors, lens opacity, ocular hypertension, and color blindness within the study sample.
  
  
  METHODS
  Through a population-based, cross-sectional study, a total of 5300 Tehran citizens will be selected from 160 clusters using a stratified cluster random sampling strategy. The eligible people will be enumerated through a door-to-door household survey in the selected clusters and will be invited. All participants will be transferred to a clinic for measurements of uncorrected, best corrected and presenting visual acuity; manifest, subjective and cycloplegic refraction; color vision test; Goldmann applanation tonometry; examination of the external eye, anterior segment, media, and fundus; and an interview about demographic characteristics and history of eye diseases, eye trauma, diabetes mellitus, high blood pressure, and ophthalmologic cares. The study design and eye examination protocol are described.
  
  
  CONCLUSIONS
  We expect that findings from the TES will show the status of visual problems and their causes in the community. This study can highlight the people who should be targeted by visual impairment prevention programs.
authors.affiliation: Farabi Eye Hospital, School of Medicine, Tehran University of Medical Sciences, Noor Vision Correction Center, Tehran, Iran. hhashemi@noorvision.com
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Akbar
authors.initials: A
authors.lastname: Fotouhi
authors.forename: Kazem
authors.initials: K
authors.lastname: Mohammad
mesh_terms: D001766:Blindness / Q000453:epidemiology*; D002386:Cataract / Q000453:epidemiology; D003119:Color Perception Tests; D003117:Color Vision Defects / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003906:Developing Countries; D005127:Eye Color; D006801:Humans; D007429:Intraocular Pressure; D007492:Iran / Q000453:epidemiology; D009798:Ocular Hypertension / Q000453:epidemiology; D009887:Ophthalmoscopy; D015995:Prevalence; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000453:epidemiology; D012107:Research Design; D014787:Vision Tests / Q000379:methods*; D015354:Vision, Low / Q000453:epidemiology*; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*