Optimization of intraocular lens constant improves refractive outcomes in combined endothelial keratoplasty and cataract surgery.

PURPOSE: To evaluate the accuracy of intraocular lens (IOL) power calculations with A-constant optimization in Descemet's stripping automated endothelial keratoplasty (DSAEK) combined with cataract extraction and intraocular lens implantation (DSAEK triple procedure). DESIGN: Retrospective case series. PARTICIPANTS: Thirty eyes of 22 patients with Fuchs' endothelial dystrophy who underwent the DSAEK triple procedure performed by a single surgeon. METHODS: Prediction errors were calculated retrospectively for consecutive DSAEK triple procedures. These prediction errors then were used to determine an IOL constant for this cohort of patients. The new optimized IOL constant subsequently was compared with the manufacturer's IOL constant, allowing evaluation and quantification of refractive benefits of optimization. MAIN OUTCOMES MEASURES: The error in diopters (D) of the predicted refraction with the manufacturer's and optimized IOL constants. RESULTS: Optimization of the A constant decreased the mean absolute error (MAE) from 1.09 ± 0.63 D (range, 0.12-2.41 D) to 0.61 ± 0.4 D (range, 0-1.58 D; P = 0.004). Comparing the intended and final postoperative refractions calculated with the original manufacturer's constant and the optimized constant, 20% versus 43% of all eyes were in the less than 0.5-D range and 50% versus 83% of all eyes were in the less than 1.0-D range of the target refraction. Furthermore, optimization decreased the number of eyes that were more than 1.0 D from the target refraction from 50% to 17%. CONCLUSIONS: Optimization of the IOL constant showed significantly improved accuracy of predicted postoperative refraction compared with the manufacturer's IOL constant, which may help improve the postoperative refractive outcomes in patients undergoing the DSAEK triple procedure.

Accuracy of intraocular lens calculations using the IOLMaster in eyes with long axial length and a comparison of various formulas.

PURPOSE: To evaluate the relationship between eyes with long axial length (AL) and postoperative refractive errors as predicted by various commonly used intraocular lens (IOL) formulas using the Zeiss IOLMaster (Carl Zeiss Meditec, Jena, Germany). DESIGN: Retrospective chart review. PARTICIPANTS: A total of 53 eyes of 36 patients with an AL of more than 27 mm who underwent uncomplicated cataract extraction with IOL implantation. METHODS: Data were obtained from patient charts and the IOLMaster. MAIN OUTCOME MEASURES: The main parameters assessed were AL, preoperative best-corrected visual acuity (BCVA), postoperative BCVA, and mean absolute error (actual postoperative spherical equivalent minus predicted postoperative spherical equivalent). Mean absolute error was calculated using predicted spherical equivalents obtained from the Holladay 1, Holladay 2, SRK/T, Hoffer Q, and Haigis formulas. RESULTS: The Haigis formula was found to be the most accurate in predicting postoperative refractive error in long eyes. The SRK/T formula was the second most accurate, followed by the Holladay 2, then the Holladay 1, then the Hoffer Q. All formulas predicted a more myopic outcome than was actually achieved. CONCLUSIONS: These results suggest using the Haigis, SRK/T, or Holladay 2 formulas for very long eyes. It is also advisable to aim for a more myopic result than is intended.