Tina K. Green

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

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 > or =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 > or =6). Ninety-six percent of children had at least 1 measurement (any confidence), and 89% had at least 1 measurement with confidence at the manufacturers recommended value (> or =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 instruments 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 The SureSight does not provide an accurate, quantitative measure of amount of astigmatism. However, it does allow accurate categorization of amount of astigmatism as < or =2.00 D, >2.00 D, or >3.00 D, and it has high measurement success rate in young children.

Accuracy and validity of IK4 handheld video keratometer measurements in children.

The infant keratometer (IK4) is a custom handheld instrument that was designed specifically to allow measurement of corneal astigmatism in infants as young as 6 months of age. In this study, accuracy of IK4 measurements with the use of standard toric surfaces was within 0.25 D. Validity measurements obtained in 860 children aged 3-7 years demonstrated slightly greater astigmatism measurements in the IK4 than in the Retinomax K+. Measurement success was 98% when the IK4 was used. The IK4 may prove to be clinically useful for screening children as young as 3 years of age at high risk for corneal astigmatism.