Abstract
Purpose: :
Astigmatism is a significant cause for referral when using objective screening devices (photoscreeners) for pre-school vision screening programs. Referral rates for astigmatism seem to be higher that that for other refractive conditions such as hyperopia, myopia, and anisometropia. It is unclear if this is an artifact of overestimation by the equipment or if it is perhaps the result of setting referral thresholds too low. The purpose of this study was to investigate concordance of astigmatism measurement by the PlusOptix SO9 Vision Screener versus cycloplegic refraction in preschool children.
Methods: :
Indiana Lions KidSight Program primarily conducts screenings at local, state-registered childcare centers. Using the PlusOptix SO9 Vision Screener, data from preschool children (N=615, mean age=4.5±1.0 years old) was analyzed (quantitative screening results, cycloplegic refraction and visual acuity). Objective screening and follow-up cycloplegic refractions were analyzed as cylinder magnitude (CYL) and spherical equivalent (SE). Difference in CYL and SE between screening and follow up were calculated. Results from the right eye are reported here.
Results: :
Among 615 children, 383 (62%) were referred for astigmatism. In addition, 22 (3%) children were referred for combined reasons including astigmatism. Screening CYL result was 0.91±0.62D and follow-up refraction CYL was 0.73±0.56D. Accordingly, the screening CYL was overestimated by 0.18D (T-test, p<0.001). For children referred for astigmatism (N=383), the CYL was overestimated by 0.23±0.37D, which is significantly higher than that for children referred for other reasons by 0.08±0.27D (T-test, p<0.001); the SE was overestimated by 0.35±1.11D, which is also significantly different than SE for children referred for other reasons (-0.42±1.32D; T-test, p<0.001). In this cohort, 158 (26%) children had amblyopia; in children referred for astigmatism, 64 (17%) children had amblyopia.
Conclusions: :
The PlusOptix SO9 astigmatism measurement generally exceeded that obtained with cycloplegic refraction by 0.2D CYL. Referral criteria of astigmatism should be elevated correspondingly to increase specificity of preschool screening with this device.
Keywords: astigmatism • amblyopia • refractive error development