The Tehran Eye Study: research design and eye examination protocol.

"Competing interests None declared."

"AcknowledgementsSpecial thanks are given to Dr Ronald Klein, the Beaver Dam Eye Study; Dr Rupert Bourne, the National Blindness and Low Vision Prevalence Survey of Bangladesh; Dr Leon Ellwein and Dr Praveen K Nirmalan, the Tirunelveli eye survey; Dr Montserrat Martin-Baranera, Survey of blindness in Bioko, Equatorial Guinea, all who kindly have provided us the protocols and data forms of their studies. We also thank Dr Kamran Hojat Jalali and Dr Azam Alimardani for their helps in preparation of the eye examination protocol.This project is supported in part by Noor Vision Correction Center, and a grant from the Iranian National Research Center for Medical Sciences. The selection of clusters is done based on blocks enumeration of the national census of 1996 by the Iranian Statistics Center."