Abstract
Purpose: :
To assesses the quality of cataract surgery by third year residents by examining their outcomes using the following parameters: 1) the accuracy of the predicted postoperative refraction (targeted at less than +/- 0.25 diopters) and 2) the change in curvature of the cornea following corneal incisions (targeted at less than 0.50 diopters).
Methods: :
We performed a retrospective chart review of data from the cataract surgeries performed at the Hines Veterans Administration Hospital by 3 senior ophthalmology residents. The data collected included: pre-operative and post-operative keratometry measurements, visual acuity, auto refractions, manifest refractions, and IOL master or A-scan calculations using Holladay I formula for calculating post-operative spherical equivalents (SE) for specific IOL powers. Results from IOL Master and A-Scan measurements were compared. Changes in average keratometry measurements as well as changes in axis were determined 1 month after surgery.
Results: :
96 patients who underwent cataract surgery by 3 senior residents were included in the study. In comparing predicted versus actual SE using a one-sample t-test, there was a mean difference of +0.09 diopters. The 95% confidence interval was -0.04 to +0.23 diopters. The mean difference between pre-op and post-op keratometry readings was -0.11 diopters and the 95% confidence interval was -0.24 to +0.02 diopters. The mean change in axis of astigmatism was 14 degrees.
Conclusions: :
Our results indicated that the 1 month actual SE was within the target range of +/- 0.25 diopters of the predicted SE. The change in average keratometry measurement was also within the targeted range of +/- 0.50 diopters. These results will be important in the future use of premium IOLs and toric IOLs where predicted spherical equivalent and changes in astigmatism must be achieved accurately and consistently.
Keywords: cataract • refraction • astigmatism