Better visual outcomes with toric IOLs vs. nontoric IOLs, corneal relaxing incisions
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Key takeaways:
- Toric monofocal IOLs resulted in better uncorrected distance visual acuity and lower postoperative cylinder vs. nontoric IOLs.
- Toric IOLs produced better astigmatic correction than corneal relaxing incisions.
Toric monofocal IOLs resulted in better uncorrected distance visual acuity and lower postoperative cylinder compared with nontoric multifocal IOLs and were more effective than corneal relaxing incisions, according to a literature review.
“The purpose of this assessment by the Ophthalmic Technology Assessment Committee Refractive Management/Intervention Panel is to review the published literature on the visual and refractive outcomes and the rotational stability of eyes implanted with toric monofocal IOLs for the correction of astigmatism during cataract surgery and to compare those outcomes with those in eyes implanted with nontoric monofocal IOLs and other astigmatism management methods,” Zaina Al-Mohtaseb, MD, an ophthalmologist and surgeon at Whitsett Vision Group and assistant professor at Baylor College of Medicine, and colleagues wrote in Ophthalmology.
Researchers conducted a PubMed literature search in July 2022 and identified 906 potentially relevant studies, of which 21 were included and rated according to level of evidence. Researchers limited their assessment to toric monofocal IOLs currently available in the U.S. — AcrySof IQ Toric SN6AT (Alcon), Tecnis Toric ZCT (Johnson & Johnson Vision) and enVista Toric MX60ET (Bausch + Lomb) — all of which are hydrophobic acrylic aspheric and block ultraviolent light.
The mean postoperative refractive astigmatism was 0.42 D for the Alcon IOLs, 0.44 D for the Johnson + Johnson IOLs and was not reported for the Bausch + Lomb IOL. Of those with the Alcon lenses, 45% to 86.6% of patients had a postoperative residual refractive astigmatism of less than 0.5 D after IOL implantation. For those with the Johnson & Johnson IOLs, this represented between 52.9% and 85.4% of patients, and for the Bausch + Lomb IOL it represented 57.3% of patients.
Patients with less than 1 D postoperative residual refractive astigmatism after IOL implantation represented 74% to 100% of patients with Alcon IOLs, 84.3% to 100% of patients with Johnson & Johnson IOLs and 100% of patients with a Bausch + Lomb IOL.
The proportion of patients with an uncorrected distance visual acuity of 20/40 or better represented 90% to 100% of those with an Alcon IOL or Johnson & Johnson IOL, and was 95% for the Bausch + Lomb IOL.
All IOLs demonstrated high rotational stability, and toric IOLs outperformed nontoric IOLs with better uncorrected distance visual acuity and lower postoperative cylinder. Toric IOLs also were “more effective and predictable” than corneal relaxing incisions, particularly with high magnitudes of astigmatism.
“All three IOL platforms performed well in most studies with expected outcomes,” Al-Mohtaseb and colleagues wrote. “In addition, all IOLs were rotationally stable. Toric IOLs were more effective in correcting astigmatism compared with using [corneal relaxing incisions], especially in high magnitudes of astigmatism.”
Perspective
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The study reviewed the refractive and visual outcomes of eyes implanted with toric monofocal IOLs among patients undergoing cataract surgery. It aimed to assess the rotational stability of current toric IOLs and compare their outcomes with nontoric monofocal IOLs and other methods of astigmatism management during cataract surgery.
Across 21 studies, toric IOLs consistently demonstrated significant reduction in pre-existing corneal astigmatism and provided satisfactory uncorrected distance visual acuity, with stable rotational performance across different designs. Notably, toric IOLs exhibited superior predictability compared to corneal relaxing incisions, especially in cases of higher astigmatism.
The findings underscore the critical role of precise preoperative calculations and accurate intraoperative placement of toric IOLs for achieving optimal astigmatism correction during cataract surgery. However, variations in measurement techniques and study limitations were acknowledged, suggesting the need for further research.
For practicing optometrists, understanding these results informs decision-making regarding the selection of toric IOLs as a preferred method for astigmatism management. Future studies should focus on comparing different IOL designs and adopting standardized analysis methods to enhance clinical outcomes and improve patient satisfaction.
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