gms | German Medical Science

Background: To evaluate the performance of different intraocular lens calculation formulas provided by an online calculation tool from the American Society of Cataract and Refractive Surgery (ASCRS) for an extended depth of focus IOL after previous myopic laser in situ keratomileusis (LASIK).

Methods: This retrospective consecutive case series took plaxe at the Department of Ophthalmology, Goethe University Frankfurt, Germany. We included patients that underwent cataract surgery with implantation of an extended depth of focus IOL (EDOF) and a history of myopic LASIK. Preoperative assessments included biometria (IOL Master 500 & 700, Carl Zeiss Meditec, Germany). Preoperative refractive data regarding the LASIK, target refraction and postoperative refraction were taken from the clinical files. Prediction error (MPE), absolute prediction error (MAE), and the number of eyes within ±0.5D, ±1.0D, ±1.5D, and ±2.0D were calculated for the following formulas from the ASCRS calculator: Shammas, Haigis L, Barrett True K, Barrett no History, Masket, modified Masket, and the average of all formulas (Average).

Results: We found 25 eyes that matched our inclusion criteria with a mean postoperative spherical equivalent (SE) of -0.81D ± 0.69, the mean pre-LASIK SE was -6.4D ± 3.63. The best performing formulas ranked by MAE were Shammas (0.7D ± 0.75), Haigis L (0.72D ± 0.57), Average (0.79D ± 0.8), Barrett True K (1.14D ± 0.89), mod. Masket (1.4D ± 1.15), Barrett no History (1.45D ± 0.7), and Masket (1.64D ± 1.27). The formulas with the most eyes within ±0.5D were Average (52%), Shammas (48%), and Haigis L (44%), the worst performing was the Barrett no History (12%).

Conclusion: Calculation of IOLs of eyes with a history of refractive surgery remains a challenge. In our study, the Shammas and Haigis L formula performed best, however the Average can deliver reasonable results.