Date of Award

January 2025

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Paul C. Kang

Abstract

Background: The rotational stability of a toric intraocular lens (IOL) is key for optimizing postoperative visual outcomes as even a minor deviation of the lens from its target axis can result in a significant reduction of astigmatic correction. This study systematically reviews and conducts meta-analyses to address two key questions: 1) Which lens models and haptic designs promote stable toric IOL positioning? 2) How does combined phacovitrectomy, with its altered intraocular fluid dynamics during and after vitrectomy, impact the rotational stability of toric IOLs? Quantifying and better understanding toric IOL stability can aid in future toric IOL design, and the assessment of toric stability in the setting of altered fluidics during a phacovitrectomy will aid in the management of astigmatic patients with vitreoretinal pathologies.

Methods: All published studies and clinical trials in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), OVID Medline, OVID Embase, and Web of Science databases that investigate postoperative rotation of toric IOLs were searched and evaluated. Quality of studies was assessed using the Methodological Index for Nonrandomized Studies (MINORS) scale. A single-arm meta-analysis was performed in R4.3.1 software with subgroup analysis based on lens model and haptic design.

Results: A total of 51 studies of 4863 eyes were included in the first meta-analysis assessing isolated cataract surgeries in patients with regular corneal astigmatism. The pooled mean absolute rotation of all toric IOLs was 2.36° (95% CI: 2.08-2.64). Subgroup analysis by lens model showed AcrySof IQ SN60TT, AcrySof IQ SN6ATT, AT TORBI 709M, Tecnis Toric I, and Tecnis Toric II to have pooled mean absolute rotations and 95% CI of 2.94° (1.72, 4.16), 2.55° (1.70, 3.40), 3.32° (0.42, 6.22), 3.11° (2.21, 4.00), and 1.01° (0.63, 1.39) respectively. Subgroup analysis by haptic design showed loop, double loop, plate loop, and plate haptics to have pooled mean absolute rotations and 95% CI of 2.48° (2.12, 2.84), 1.83° (0.90, 2.75), 1.91° (1.51, 2.31), 2.83° (1.61, 4.05) respectively. In the second meta-analysis assessing toric performance in combined phacovitrectomy, six studies of 136 eyes were included with a mean follow-up of 8.3 months. The pooled mean absolute misalignment was 3.64° (95% CI: 2.16-5.11). The pooled mean preoperative and postoperative logMAR CDVA was 0.51 (95% CI: 0.22-0.79) and 0.12 (95% CI: 0.04-0.21) respectively, yielding an aggregate safety index of 2.45.

Conclusion: Postoperative rotation is dependent on many aspects of lens material and design. Generally speaking, IOLs with double loop or plate loop haptics that increase contact surface area with the capsular bag tend to be more stable. Modern commercially available toric IOLs exhibit exceptional rotational stability, even in the setting of combined phacovitrectomy.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 05/14/2027

Download

Share

COinS