Evidence Gap: No Thailand-Specific Studies Available
The provided evidence contains no peer-reviewed studies from Thailand published between 2018-2025 evaluating school-based vision screening programs. The evidence base consists entirely of international guidelines (primarily U.S.-based from AAP, AAO, and USPSTF) and studies from North America and Europe, with no data addressing program design, coverage, outcomes, cost-effectiveness, or implementation feasibility specific to the Thai context.
What the Evidence Shows Instead
International Guideline Framework for School-Based Screening
The most recent comprehensive guidance from the American Academy of Ophthalmology (2023) emphasizes that optimal pediatric vision care requires organized screening programs in community settings with guaranteed access to comprehensive examinations and provision of refractive correction 1.
Core Program Components
Screening methodology should combine traditional visual acuity testing with instrument-based screening (photoscreening or handheld autorefraction) for children ages 3-5 years, transitioning to visual acuity charts after age 5 when cooperation improves 1.
Age-appropriate visual acuity tests include HOTV charts, Lea symbols, or tumbling E for children 3-5 years old 1.
Instrument-based screening (photoscreening) demonstrates superior sensitivity (85% specificity) compared to traditional acuity testing alone, particularly for detecting amblyogenic risk factors 2.
Critical Implementation Barriers
Follow-up examination rates after failed screening vary dramatically: only 4 of 15 U.S. programs achieved >70% follow-up, while 11 programs fell below 50% 1.
Barriers include inadequate information, lack of access to care, limited financial means, and insurance coverage issues 1.
Providing free spectacles in addition to screening significantly improves the number of children who obtain and wear needed correction compared to prescription-only approaches 1.
Partnering with school nurses to ensure follow-up care proves valuable for minority and low-income children 1.
Evidence-Based Program Design Elements
Screening Protocol
Passive consent models achieve 89% screening participation versus 62% with active consent models (p < 0.001) 3.
Comprehensive screening should include photoscreeners, visual acuity testing, stereoacuity assessment, and eye alignment evaluation 3.
Detection rates in kindergarten populations: 10.7% overall visual problems, 3.4% amblyopia, 6.7% clinically significant refractive errors 3.
For 67.2% of children with detected visual problems, the school screening represented their first eye examination 3.
Cost-Effectiveness Considerations
Photoscreening using digital cameras costs approximately $0.11 per child screened 2.
Vision screening combined with free eyeglasses increases probability of passing standardized achievement tests by 2.0 percentage points, though effects fade without follow-up 4.
Screening alone without provision of eyeglasses is generally insufficient to improve student outcomes 4.
Quality Assurance
Screening personnel require proper training regardless of whether using traditional or instrument-based methods 1, 5.
Evaluators must understand test limitations in relation to the population being tested 1.
Funding mechanisms must include separate payment for vision screening services rather than bundling into general health visits 1.
Common Pitfalls to Avoid
Do not rely on screening alone—comprehensive programs must ensure access to follow-up examinations and treatment 1.
Do not assume referral equals treatment—active follow-up systems are essential to overcome barriers 1, 6.
Do not screen without providing financial support for eyeglasses—prescription-only approaches fail to improve outcomes 1, 4.
Do not perform one-time screening—annual rescreening during school years is recommended 5.
Do not use active consent models if avoidable—passive consent dramatically improves participation 3.
Application to Thailand Context
While no Thailand-specific evidence exists in the provided literature, the international guidelines suggest that successful implementation in any setting requires:
Legislative support with dedicated funding mechanisms separate from general healthcare budgets 1.
Integration of both traditional acuity testing and instrument-based screening methods 1.
Guaranteed provision of free eyeglasses to children who need them 1, 4.
Active follow-up systems to ensure children receive comprehensive examinations after failed screening 1, 3.
Training programs for screening personnel with quality assurance protocols 1, 5.
The absence of Thailand-specific research represents a significant evidence gap that should be addressed through local implementation studies evaluating program design, coverage rates, clinical outcomes, cost-effectiveness, and feasibility within the Thai healthcare and educational systems.