Refractive error tudy in children: ampling and meaurement method for a multi-country urvey

PURPOE: The Refractive Error tudy in Children wa deigned to ae the prevalence of refractive error and viion impairment in children of different ethnic origin and cultural etting. METHOD: Population-baed cro-ectional ample of children 5 to 15 year of age were obtained through cluter ampling. Preenting, uncorrected, and bet-corrected viual acuity, along with refractive error under cycloplegia, were the main outcome meaure. Amblyopia and other caue of uncorrectable viion impairment were determined. Abtract REULT: tudy deign and ample ize calculation, urvey enumeration and ophthalmic examination method, quality aurance monitoring, and data analye and tatitical method are decribed. CONCLUION: The tudy deign, ample ize, and meaurement method enure that the prevalence of age-pecific and ex-pecific refractive error can be etimated with reaonable accuracy in the target population. With commonality of method, a comparion of finding between tudie in different ethic origin and cultural etting i poible.