Efficacy of Vision Screenings in Waterloo Region

Abstract

Purpose: In 2018, the province of Ontario (Ontario) mandated a universal vision screening program for all senior kindergarten (SK) children (age 4-6 years). The purpose of the vision screening program is to detect children with risk factors for amblyopia, strabismus, and/or high refractive errors. The overarching aim of this thesis is to evaluate the effectiveness of Ontario’s universal vision screening program for SK children and how accurate the program is in identifying vision problems. These objectives are explored through two studies: parental adherence to vision screening recommendations survey, and investigation of the ability of Ontario’s vision screening program in identifying a SK child with a vision problem combined with determination of overall referral rates. Methods: All parents/guardians (parents) of SK students who participated in Ontario’s vision screening program in the Region of Waterloo (ROW) from October 2022 to December 2023 were invited to participate in the initial study to evaluate parental compliance to vision screening recommendations and barriers to seeking vision care. Following the first study, parents who reported taking their child to an optometrist following the vision screening were invited to participate in a follow-up study, evaluating the program sensitivity and specificity and overall screening accuracy. For the second study, the vision screening results were compared to the eye exam results, and all vision screening data (visual acuity, stereoacuity and autorefraction) for children who participated in the 2022-23 vision screening program were analyzed to determine the screening program’s overall referral rate and for all three screening tools. Results: 108 parents from 67 schools in the ROW responded to the survey to evaluate parental compliance in seeking vision services following the screening. The results of the survey found that over half (58/108, 54%) of the children screened were already under the care of an optometrist prior to the screening and less than half (48/108, 44%) of parents were prompted to obtain eye care, including 25% (27/108) who had already had a previous optometric examination. For the follow-up study that examined vision screening accuracy, 65 individuals participated. The vision screening program demonstrated a sensitivity of 0.935 and specificity of 0.406, producing a high rate of false positives (30%). Paired t-tests revealed significant differences in the accuracy of the vision screening tools compared with eye exam findings, particularly for refraction – sphere (OD: p = 0.005, OS: p < 0.001), cylinder (OD: p = < 0.001, OS: p < 0.001), and spherical equivalent (OD: p = 0.016, OS: p = 0.004). The retrospective review of the screening data included a total of 4837 vision screening results from 135 schools in ROW. The screening had an overall referral rate of 54% (2606/4837) and children were most commonly referred for autorefraction (43%; 2099) results followed by stereoacuity (31%; 1510). Conclusion: This analysis of Ontario's vision screening program for SK children in the ROW highlighted key findings. The program was effective at encouraging parents that received a refer to go to the optometrist (64%), though 31% of all parents misreported screening results, suggesting a need for clearer communication. The program showed high sensitivity (0.935) but low specificity (0.406), with a 54% referral rate and 30% false positives which may contribute to lack of public trust over time. Adjusting referral criteria based on evidence could reduce false positives.