Evaluating Refractive Outcomes after Cataract Surgery.

Abstract

To compare methods for evaluating refractive outcomes after cataract surgery to detect outliers. Case series database study of the evaluation of diagnostic technology. Consecutive patients who had uneventful cataract operations over a 5-year period. The intended and postoperative refractive outcome and differences between these were analyzed as a spherical equivalent, cylinder, and spherocylinder. The average keratometry and differences between steep and flat keratometric meridians were used to calculate the intended refractive error. Outliers were defined as patients for whom the difference between the intended and postoperative refractive errors was more than 3 standard deviations (SDs) away from the mean. A total of 9000 patients were included. Twelve patients had missing data and were excluded. The mean intended refractive outcome was -0.12+0.12×2 (95% lower confidence limit [LCL], -1.94+1.06×44; 95% upper confidence limit [UCL], +0.77+1.05×140). The actual postoperative refractive error was -0.30+0.47×6 (95% LCL, -2.36+1.31×36; 95% UCL, +1.00+1.18×148) with a difference from the intended of -0.18+0.35×7 (95% LCL, -1.91+1.22×38; 95% UCL, +0.75+1.09×145). Treating the components of the refractive error independently, outliers were observed in 82 eyes (0.91%) based on the sphere, 46 eyes (0.51%) based on the spherical equivalent, 115 eyes (1.28%) based on treating the cylinder as a scalar, and 76 eyes (0.85%) based on treating the cylinder as a vector. When the differences between the intended and postoperative refractive errors were calculated as a compound spherocylinder, outliers were observed for 233 eyes (2.59%). Treating the intended refractive outcome as a spherocylinder improves the precision for detecting clinically significant refractive outliers.