Visual Profile of Children Passing/Failing a UK School Vision Screening Protocol

Purpose : The UK National Screening Committee recommends screening for reduced vision at school entry (4-5 yrs). The recommended protocol tests monocular acuities with a pass criterion of 0.2LogMAR or better in both eyes. The guidance states “amblyopia is the most likely condition to be detected” but that “refractive error and strabismus” are also detected. The present study investigated the visual profile of children who passed/failed vision assessment using this criterion. The aim is to determine how well the protocol detects strabismus and refractive error, how many children with significant visual issues pass and to describe the visual profile of those who fail. Methods : Participants were 295 children (5.2±0.4 yrs; 55% female) recruited and tested in local schools. In addition to the vision screening protocol (crowded LogMAR monoc acuity @3m), ocular posture (cover test), refractive error (cycloplegic autorefraction), stereopsis (random-dot stereogram), and accommodation (dynamic ret) were assessed. These metrics were used to identify children who passed/failed the vision screening protocol, had manifest strabismus and/or significant refractive error (hyperopia SER≥+3.50DS, myopia SER≤-0.50DS; astigmatism ≤-1.50DC; anisometropia diff SER≥+1.50DS). All data were used to identify children with a visual deficit requiring clinical intervention. Results : Of 284 children who completed all tests 79(27.8%) failed to achieve 0.2LogMAR or better in both eyes, 10(3.5%), 55(19.4%) and 60(21.1%) had strabismus, significant refractive error and/or required clinical intervention respectively. The pass/fail criterion for vision screening identified 8 children with strabismus (sensitivity 80% specificity 74.4%), 40 with significant refractive error (sensitivity 71.4% specificity 82.5%) and 42 judged as needing clinical intervention (sensitivity 70% specificity 83.5%). Half (49.4%) of those failing the screening protocol had significant refractive error of which 82% were non-strabismic. The visual profile of almost half (46.8%) of those failing vision screening did not indicate a need for clinical intervention. Conclusions : Vision screening with monocular acuity is reasonably sensitive and specific for detecting refractive error and strabismus. Half of those failing vision screening primarily need refractive intervention and the majority of the remainder are likely to be ‘false positives’ for clinically significant visual deficits.