A prospective study to compare the safety and efficacy of toric intra-ocular lens vs. opposite clear corneal incision in patients undergoing phacoemulsification for age-related cataract with pre-existing corneal astigmatism

Abstract

Purpose: This study aimed to compare the safety and efficacy of toric intra ocular lens (IOL) implantation vs. opposite clear corneal incision (OCCI) during cataract surgery to correct preexisting corneal astigmatism in patients with age related cataract by comparing the postoperative residual astigmatism, the uncorrected distance visual acuity and the adverse effects following both the procedures.

Methods: A pilot prospective study was conducted at a tertiary hospital among patients undergoing cataract surgery over two years. A total of 150 eyes with pre-existing corneal astigmatism between 1 to 2.5 D were divided into two groups of 75 each by permuted block randomization. Group A underwent implantation of AcrySof Toric IOLSN6AT4 (Alcon Labs, Fort Worth, Tx), and Group B underwent implantation of normal non-toric aspheric AcrySof IOL SN60WF with OCCI on steep axis. Both groups were followed up for 24 weeks.

Results: In the OCCI Group, the difference between mean K1-K2 preoperative and 12 weeks postoperative (mean ± SD) of patients was 1.55 ± 0.17D. In the TORIC IOL Group, the difference between the mean K1-K2 preoperative and 12-week postoperative values (mean ± SD) for patients was 0.53 ± 0.11. The difference in mean K1-K2 pre-operatively and at 12 weeks was statistically significant for both groups (p < 0.0001). There was a significant reduction in corneal astigmatism in the OCCI group at 01 week.

Discussion: In our study, the difference in mean K1-K2 at 1 week between the two Groups was statistically significant (p < 0.0001), as OCCI acts directly on the corneal plane, whereas Toric IOLs reduce astigmatism at the lens plane without affecting corneal curvature. There was a significant reduction in corneal astigmatism in the OCCI group at 1 week. This reduction continued to stabilize at 12 weeks. The corneal astigmatism remained stable in the post-operative period in the Toric IOL group. The decrease in astigmatism was more significant in the toric IOL group than in the OCCI group.

Conclusions: These results demonstrate a similar efficacy of OCCI in reducing corneal astigmatism of up to 1.5 D compared to Toric IOLs. The uncorrected visual acuity was superior in the Toric IOL group. However, this difference was reduced significantly by 12 weeks.

Keywords: BCVA = best-corrected visual acuity; CCI = clear corneal incision; IOLs = intraocular lenses; LASIK = laser in situ keratomileusis; OCCI = opposite clear corneal incision; Opposite Clear Corneal Incision; PEA = Preexisting astigmatism; SIA = surgically induced astigmatism; Toric Intra Ocular Lens; UCVA = uncorrected visual acuity; phacoemulsification; pre-existing astigmatism.

Fig. 1

Standard Axis marking

Fig. 2

Steep/Toric Axis marking on Table

Fig. 3

Toric IOL placed at pre-determined Axis

Fig. 4

OCCI created after IOL implantation on Table