Validity of vision screening in schoolchildren of Iran

To determine the sensitivity, specificity, and predictive value of visual screening examination in students living in urban areas of Iran. The first grade students of 7 cities of Iran were randomly selected in a population based cross sectional study in 2013 using multistage cluster sampling. After obtaining consent from the students’ parents, examinations including corrected and uncorrected visual acuity, cycloplegic and non-cycloplegic refraction, and cover test were performed for all students by an optometrist. The criterion for visual problem was a cut point of 20/32 or worse for uncorrected visual acuity. In addition, the validity of the uncorrected visual acuity measured in the national screening program, which is recorded in the students’ health profiles, was calculated. Out of total 4157 individuals who were selected for the study, uncorrected visual acuity was measured in 3645 participants. The sensitivity and specificity of uncorrected visual acuity measured in the national screening program was 35.3% (95% CI 29.2%-41.7%) and 93.9% (95% CI 93.04%-94.7%), respectively. The lowest sensitivity was observed in Dezful (19.6%) and the highest was observed in Ardebil (83.3%). The predictive value of the examinations was 28.8% (95% CI 23.6%-34.3%) and the best cut point of uncorrected visual acuity was recorded as 20/25 in the national screening program. The validity of the visual screening program which is performed before the first grade of primary school is very low. It should be noted that since many families trust these examinations, they do not follow up their children’s condition any more based on the results of these examinations. Therefore, the validity of these examinations, especially their sensitivity, should increase through training the examiners or using more specialized methods.