Table 5 Main findings on accuracy of vision screening tests
Screening tests for visual impairment | Included studies | Main findings |
|---|---|---|
Visual acuity tests (assessment of picture identification tests (LEA Symbols chart) and HOTV eye test) | 6 studies [6] | When screening test cut-offs were set to achieve specificities of 90%: • Positive LR: 6.1 (95% CI 4.8 to 7.6); ‘an abnormal result moderately increased the likelihood of amblyopia, amblyopia risk factors (strabismus, astigmatism, hyperopia, myopia, anisometropia), or significant nonamblyogenic refractive error’ • Negative LR: 0.43 (95% CI 0.38 to 0.50); ‘a normal result indicated a small decrease in the likelihood’ |
Ocular alignment tests (Cover-uncover test) | 1 study [6] (n = 3121) | Sensitivity to detect strabismus was 60% for specificity set to 90% • Positive LR: 7.9 (95% CI 4.6 to 14.0) • Negative LR: 0.73 (95% CI 0.15 to 0.85) |
|  | 1 study [5] | For detecting strabismus in children at 37 months: • Sensitivity of 75% (95% CI: 57.7 to 89.9%) • Specificity of 100% |
Stereoacuity tests | 4 studies [6] (n = 7801) | • Positive LRs: range from 3.6 to 4.9 • Negative LRs: in the minimal range for detecting amblyopia risk factors or significant nonamblyogenic refractive error and in the moderate range for detecting refractive error or strabismus |
Combination of clinical tests (visual acuity, ocular alignment and stereoacuity tests) | • Positive LRs: median of 14; range from 12 to 17 (3 studies); 4.8 (95% CI 2.8 to 8.4; 1 study; n = 141) • Negative LRs: median of 0.28; range from 0.10 to 0.91 • In one study, the cover-uncover test performed by professionals or a stereoacuity test showed an increased detection of strabismus when combined with visual acuity tests. | |
Autorefractors | 16 studies [6] (n = 16,712) (5 studies recruited children < 3 years of age) | • Positive LRs: ‘most studies reported moderate positive LRs’, ‘some studies reported large positive LRs’ • Negative LRs: ‘most studies reported small negative LRs’, ‘some studies reported large negative LRs’ |
Photo-screeners | 11 studies [6] (n = 6187) | • Positive LRs: ‘most studies reported moderate positive LRs’ • Negative LRs: ‘most studies reported small negative LRs’ |
|  | 1 study [16] | Prospective study that evaluated the diagnostic accuracy of a digital photo-screener in a school screening programme in Canada [16, 22]. Among the 335 recruited children (98% were 4 or 5 years of age), 271 completed both the screening test and the reference standard test (ophthalmic examination by a physician who was blinded to the photo-screening findings). Results from both tests agreed in 94% of cases. • Sensitivity and specificity in detecting amblyopia risk factors were 83 and 95% respectively • Positive and negative predictive values were 73 and 97%, respectively. When looking more specifically at detection of strabismus, sensitivity and specificity were 46 and 97% respectively, with 13 children detected by reference standard test. The estimated prevalence of strabismus in the population was 4.8%. |
Retinal birefringence scanning (assessment of the Pediatric Vision Scanner (REBIScan)) | 1 study [6] (n = 102) | • Positive LR: 10.4 (95% CI 5.6 to 19.4) • Negative LR: 0.0 |