Accuracy of the Welch Allyn SureSight for measurement of magnitude of astigmatism in 3- to 7-year-old children

Abstract

Purpose-To evaluate the accuracy of the Welch Allyn SureSight in noncycloplegic measurements of astigmatism as compared to cycloplegic Retinomax K+ autorefractor measurements of astigmatism in children from a Native American population with a high prevalence of high astigmatism.Methods-Data are reported for 825 3-to 7-year-old children with no ocular abnormalities. Each child had a Retinomax K+ cycloplegic measurement of right eye astigmatism with a confidence rating ≥8 and 3 attempts to obtain a SureSight measurement on the right eye.Results-SureSight measurement success rates did not differ significantly across age or measurement confidence rating (<6 vs ≥6). Ninety-six percent of children had at least 1 measurement (any confidence), and 89% had at least 1 measurement with confidence at the manufacturer's recommended value (≥6). Overall, the SureSight tended to overestimate astigmatism. If the SureSight measurement had any dioptric value (0.00 D to 3.00 D), astigmatism of 2.00 D or less was likely to be present. If the SureSight showed astigmatism beyond the instrument's dioptric range (>3.00 D), Retinomax K+ measurements indicated that >2.00 D of astigmatism was present in 136 of 157 (86.6%). In cooperative children for whom the SureSight would not give a reading, 32 of 34 (94%) had >3.00 D of astigmatism. Conclusions-TheSureSight does not provide an accurate, quantitative measure of amount of astigmatism. However, it does allow accurate categorization of amount of astigmatism as ≤2.00 D, >2.00 D, or >3.00 D, and it has high measurement success rate in young children.Handheld autorefractors have the potential to be useful tools for measurement of refractive error in infants, toddlers, and preschoolers in both screening and research settings. However, when used without cycloplegia, autorefractors tend to have high variability across subjects in accuracy of sphere measurements in children, 1-5 thus eliminating the feasibility of simply applying a single factor to correct for the overestimation of myopia/underestimation of hyperopia that occurs in the absence of cycloplegia. Ste. 108, Tucson, AZ 85711 (emharvey@u.arizona.edu).. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.The authors have no financial interest in any of the tests used in this study. In contrast, while some studies report significant differences between cycloplegic and noncycloplegic measures of astigmatism, these differences tend to be of minimal clinical significance. 1-8 Therefore, non-cycloplegic autorefraction may be useful in measuring astigmatism in infants and toddlers, in both screening...

Beyond Screening for Risk Factors

“…Positive likelihood ratios describe how many more times a “refer” result is likely to be observed in children with the target disorders than in unaffected children. 37 The positive likelihood ratio of 7.7 for a “refer” outcome by the PVS was significantly higher than that for the Sure Sight Autorefractor and represents a moderate, but not conclusive, increase in the likelihood that the child has strabismus or amblyopia. The positive likelihood ratio of 1.9 for the SureSight Autorefractor denotes only a minimal increase in the likelihood that the child has one of these conditions.…”

“…Negative likelihood ratios describe how many fewer times a “pass” result is likely to be observed in children with the target disorders than in unaffected children. 37 The negative likelihood ratio of 0.03 for the PVS was significantly lower than that for the SureSight Autorefractor and represents the low probability that a child with the targeted condition of strabismus or amblyopia will receive a “pass” outcome (ie, affected children have a high probability of being correctly identified by the PVS device).The negative likelihood ratio of 0.42 for the SureSight Autorefractor reflects a moderate probability that children affected by the targeted conditions will be missed by SureSight Autorefractor screening.…”

“…Success rates for SureSight Autorefractor preschool screening of 76% to 89% in private practice and laboratory settings have been reported by numerous authors. 37-39 On the other hand, in multisite vision preschool screening studies, much higher SureSight Autorefractor success rates (>99%) have been described. 16,40 …”

Intertester Agreement in Refractive Error Measurements

“…2 Other researches also have indicated that the Retinomax and the SureSight provided valid measures of refractive error in young children. 4–8 However, data on their intra-tester or inter-tester agreement are scarce. A few, small-sample studies evaluated the intra-tester (i.e., test-retest) agreement of the two instruments in a variety of age groups, 9–14 and results suggested good intra-tester agreement for both instruments in the preschool age group (Table 4).…”

“…The effectiveness of the Retinomax and the SureSight for identifying vision disorders has been well established, 4–8 and these instruments are already used in vision screening and clinical practice by clinicians, nurses and lay screeners. A few studies 9–14 have investigated the intra-tester agreement (i.e.…”