Evaluation of Decentration, Tilt and Angular Orientation of Toric Intraocular Lens

Abstract

Purpose

The aim of this study was to develop software for the universal objective evaluation of factors influencing intraocular correction of astigmatism, such as decentration, tilt, axial position and angular orientation the toric intraocular lens (IOL).

Patients and Methods

Software was developed using the MS Visual Studio environment. The analysis was presented using images of 67 eyes with an implanted IOLs of the SN6ATx model series. Decentration and angular position of the lens were obtained from images of the anterior segment of the eye, using a Visucam unit. Tilt was measured on tomographic images from OCT Avanti (in meridian of highest tilt and perpendicular meridian) and preoperative biometry parameters of eye (axial length, anterior chamber depth – ACD, ocular lens thickness – LT, limbus diameter and mean keratometry value) including postoperative anterior chamber depth (pACD) were measured using Lenstar LS900.

Results

Applying the software methodology to the evaluation of individual toric IOL parameters, the following results were obtained: mean decentration 0.25 ± 0.17 mm which was observed in 61.19% of eyes, mean misalignment to the planned axis equal to 3.8 ± 3.6 degrees, mean highest inclination equal to 3.7 ± 1.2 degrees and mean difference of pACD and ACD was equal to 1.46 ± 0.31 mm. There was only a weak nonsignificant correlation between preoperative ACD versus decentration and tilt of IOL or a weak significant correlation between preoperative LT and both decentration and misalignment of IOL.

Conclusion

The use of the presented methodology for determining the positional parameters of the toric IOL provided comparable results with the results of recent studies. Software design can be considered as a suitable alternative to previously published techniques, with the significant advantage of the possibility of using universal input images, their graphical editing and especially the possibility of comprehensive analysis of all parameters.

Keywords:

• astigmatism and cataract
• toric IOL centration
• toric IOL tilt
• toric IOL axis misalignment

Ethics Approval

This work was performed in accordance with the Declaration of Helsinki and the internal Code of Ethics of the Czech Technical University in Prague. All participants gave informed consent to participate in this study, which was approved and approved by the internal ethics committee of the Ophthalmology Clinic JL, V Hůrkách 1296/10, 15800 Prague 5 - Nové Butovice, Czech Republic.

Acknowledgments

This work was supported by the Grant Agency of the Czech Technical University in Prague, grant No. SGS21/139/OHK4/2T/17

Disclosure

The authors report no conflicts of interest in this work.