A comparative analysis of the results of corneal astigmatism correction by toric IOL using various markup methods

Abstract

Purpose: to analyze the results of corneal astigmatism correction by cataract surgery using two methods of marking the calculated toric IOL axis with Alpins vector analysis. Materials and methods. The retrospective study group included 212 patients (259 eyes) with cataracts and baseline corneal astigmatism from 0.75 to 8.25 D. The patients were implanted with two varieties of toric IOLs: Alcon Acrysof Toric (113 patients, 135 eyes) and Zeiss AT Torbi 709M (99 patients, 124 eyes). IOL parameters were calculated using an IOLMaster 500 (Carl Zeiss) optical biometer, the target refraction being emmetropy. The axis of toric IOL alignment was determined by online calculators provided by the producers. The patients were divided into two groups in accordance with the marking method: group 1 patients (149 eyes) were marked using by the authors’ techniques that used the angular scale of the slit lamp, while group 2 (110 eyes) was treated with Verion (Alcon) and Callisto Eye (Zeiss) navigation systems. The effectiveness of astigmatism correction was assessed using the Alpins vector analysis method. Results. After surgery, both groups showed a significant increase in uncorrected (UCVA) and best corrected visual acuity (BCVA). In group 1, one month after the operation, the UCVA was 0.67 ± 0.19, and the BCVA was 0.80 ± 0.17. In group 2, UCVA was 0.69 ± 0,07, and BCVA was 0.80 ± 0.49. The success index (IOS) was 0.14 in group 1 and 0.11 in group 2. The difference vector (DV) in the two groups was 0.37 and 0.31 D, respectively, suggesting highly precise astigmatism correction. The average error angle (AOfE) in group 1 was 3.29°, and in group 2 — 3.29°. The average value of the TIA vector was 2.69 ± 1.01 D along the axis of 87.3°, in group 1, while that of group 2 was 2.75 ± 1.09 D along the axis of 95.1°. The average values of the SIA vector were 2.32 ± 0.99 D along the axis of 870 in group 1 and — 2.44 ± 1.03 D along the axis of 99.6° in group 2. Conclusion. The authors’ markup method using the angular scale of the slit lamp yields high functional results of corneal astigmatism correction. The comparative vector analysis of the two study groups shows similar results in applying the authors’ type of markup and that of intraoperative navigation systems.