Vision Screening in Schoolchildren: Two Years Results
Napaporn Tananuvat MD, Anita Manassakorn MD*, Apaporn Worapong BS*, Jarassri Kupat BA*, Jenjitr Chuwuttayakorn MD*, Sopa Wattananikorn MD*
Affiliation : * Department of Ophthalmology, Chiang Mai University Presented in part as poster presentation at the Royal College of Ophthalmologists of Thailand Annual Scientific Meeting, Bangkok, November 28-29, 2002
Objective : To assess the prevalence of visual impairment and ocular abnormalities among schoolchildren
in Chiang Mai.
Design : A community-based survey.
Subjects and Method : The vision screening project was conducted from June 2000 to March 2002. Students
in grade I in the Chiang Mai municipal area were examined for visual acuity (VA), color vision, ocular
alignment, anterior segment and fundus. Subjective refraction was done in students with subnormal vision
(VA 20/30 or less). Referral to the hospital for further evaluation and treatment was made for students with
strabismus, amblyopia and other ocular abnormalities.
Results : A total of 3,431 and 3,467 students were enrolled in 2000 and 2001, respectively. The prevalence of
normal vision (VA 20/20), VA 20/30 or better in at least one eye and 20/40 or less in at least one eye were
similar in both years (87%, 5.7%, 7.3% and 85%, 6.4%, 8.7%, respectively). There was no statistically
significant difference in visual acuity among boys and girls in either year (p = 0.6 and p = 0.2). Prevalence
of abnormal color vision was 4.2%. Other causes of visual impairment in both years included strabismus
(1.5% and 6.2%), amblyopia (1.1% and 1.4%) and some congenital abnormalities. Most cases of amblyopia
were due to uncorrected refractive errors.
Conclusion : The authors found that over 10% of school-aged children had subnormal vision. The important
causes of visual deterioration came from refractive errors, strabismus and amblyopia. The authors concluded
that vision screening is a cost-effective way of reducing visual morbidity from preventable visual impairment,
which is a tragedy that cannot be ignored.
Keywords : Vision screening, Refractive error, Schoolchildren, Amblyopia, Strabismus
