Description And Evaluation Of An Open Source Method To Guide Toric Intraocular Lens Realignment Based On Vectorial Analysis Of Astigmatism.

To develop an evaluate an open-source method to assist toric intraocular lens (TIOL) rotation and to compare its results to the Berdahl-Hardten calculator.

Department of Opthalmology, General University Hospital of Elche (Spain)

A vectorial open-code method for calculating TIOL rotation was developed. To evaluate this method, 1,000 simulated calculations were performed using both the Berdahl-Hardten calculator and the developed method. The outcome variables for both methods included the ideal position of the TIOL (defined as the position where residual cylinder was minimum), residual spherical equivalent, residual cylinder, and axis of the residual cylinder at the ideal TIOL position. Student-t tests were conducted for hypothesis testing. Interclass correlation coefficients (ICC) and correlations were calculated for each included variable, and Bland-Altman plots were generated for every outcome variable.

We found no significant differences between both methods for none of the outcome variables: ideal position of TIOL, residual spherical equivalent, residual cylinder and axis of the residual cylinder at the ideal TIOL position (p = 0.999; p = 0.995; p = 0.972; p = 0.822). Outcomes provided by both methods were significantly correlated values (ICC = 1 for all outcome variables).  

An almost perfect correlation between the open-source calculator developed and the state-of-the-art method (the Berdahl-Hardten calculator) was found. The development and open exposition of the method to guide TIOL rotation could improve our understanding about the effect of TIOL decentration and will ease the development of further innovations and research on its bases.