Visual cut off for referral to nearest PHC?

Visual cut off for referral to nearest PHC: <6/9 in either eye. Screening is done by school teachers. Female teachers are preferred. Focus on middle school(5-8th) covering 10-14 years age. 1,50,000 children to be screened per block One trained teacher to handle 150 students 1- day training for the teacher at nearest PHC Teacher Kit: Vision screening cards, referral cards, tape/rope to measure 20 feet