Use of visual acuity to screen for significant refractive errors in preschool children.

Purpose: To determine the sensitivity and specificity of visual acuity (VA) for the detection of refractive errors in preschool children from the Sydney Pediatric Eye Disease Study.

Methods

Data from both eyes were pooled for a total of 2332 observations. Children aged 3-6 years had a comprehensive eye examination including VA (monocularly tested using the Electronic Visual Acuity HOTV test) and cycloplegic (cyclopentolate 1%) refraction using the table-mounted autorefractor (RK-F1 Auto Ref-Keratometer; Canon, Tokyo, Japan). Clinically significant refractive error was defined as: Myopia ≤-1.00D, Hyperopia ≥+3.00D (Moderate Hyperopia ≥+3.00D - <+5.00D, High Hyperopia ≥+5.00D) and Astigmatism ≥+1.00D. VA cutoffs used were <6/12, <6/9 and <6/7.5. Ethics approval was obtained by the Human Research Committee, University of Sydney and adheres to the tenants of the Declaration of Helsinki.

Results

There was low sensitivity for detection of myopia at a cutoff of <6/12 (41.2%), with moderate sensitivity at <6/9 (58.8%), and high sensitivity (82.4%) and specificity (83.9%) at <6/7.5. Across the three cutoffs, there was low sensitivity for detection of astigmatism (<6/12: 14.7%, <6/9: 22.5%, <6/7.5: 54.3%) and hyperopia (<6/12: 13.8%, <6/9: 21.1%, <6/7.5: 52.3%). This was particularly true for those with moderate levels of hyperopia (sensitivity <6/12: 5.0%, <6/9: 8.8%, <6/7.5: 45.0%). High hyperopia was better detected, particularly at the <6/7.5 cutoff (72.4%); however, had low sensitivity at <6/12 (37.9%) and <6/9 (55.2%). ROC analysis for detection of clinically significant refractive error revealed an area under the curve (AUC) of 0.708 (p < .001) for <6/7.5. This was comparatively lower at <6/9 (AUC = .606) and <6/12 (AUC = .572, all p < .001).

Conclusion

VA was valid for detecting myopia at the <6/7.5 cutoff for preschool children. Astigmatism and hyperopia, even at high levels, did not consistently impact VA. This remains a challenge for detecting significant refractive errors when screening in preschool children.