Ray-Tracing Calculation Using Scheimpflug Tomography For Non-Diffractive Wavefront Shaping Extended Depth Of Focus Iols Following Myopic Lasik

To evaluate intraocular lens (IOL) calculation using a ray-tracing formula of a new non-diffractive wavefront shaping extended depth-of-focus (EDoF) IOL after myopic laser in situ keratomileusis (LASIK) compared to formulas from an online calculator.

Retrospective, consecutive case series

This retrospective, consecutive case series included patients with a history of myopic LASIK after cataract surgery with implantation of a EDoF IOL (AcrySof IQ Vivity). Preoperatively, biometry (IOLMaster; Carl Zeiss Meditec) and corneal tomography (Pentacam; Oculus Optikgeräte GmbH) were assessed, including true net power (TNP). Evaluation of IOL calculation included the number of eyes within ±0.50, ±1.00, and ±2.00 diopters (D), as well as the mean prediction error, mean absolute prediction error and the median absolute prediction error for the formulas Haigis-L, Shammas and Barrett True K No History. These were compared to the Hill Potvin Shammas PM formula that uses TNP (Pentacam).

Twenty-four eyes matched our inclusion criteria. The preoperative mean spherical equivalent (SE) was -0.41 ± 1.68 diopters (D) and postoperative -0.24 ± 0.63 D. Sorted by MedAE, the best formulas were Hill Potvin Shammas PM and Barrett True K (0.24 ± 0.54 D and 0.27 ± 0.48 D). Most eyes within ±0.50 D were achieved by the Hill Potvin Shammas PM formula (71%) and the Haigis-L formula (71%). For MAE and percentage of eyes within ±0.50 D, Hill Potvin Shammas PM, Barrett True K No History and Haigis-L were significantly better than Shammas (P < 0.05).

Our limited data suggests that using ray-tracing with the Hill Potvin Shammas PM formula for calculation of a nondiffractive wavefront shaping EDoF IOL after myopic LASIK yields good results. IOL calculation after myopic LASIK is still challenging.