LRIs vs. Toric IOLs

LRIs are a viable alternative for mild astigmatism. Dermot McGrath reports

Combining cataract surgery with limbal relaxing incisions (LRIs) delivers comparable visual outcomes and quality of life improvements as implantation with toric IOLs for patients with mild to moderate corneal astigmatism, according to the results of a recent randomised, controlled study.

“Our study showed that cataract surgery, combined with astigmatic correction, offers an improvement in quality of life which is comparable for both LRIs and toric lenses, and also offers similar one-year and five-year visual outcomes for mild corneal astigmatism between 0.75 D to 2.5 D,” Ritika Mukhija MD said.

Correcting pre-existing corneal astigmatism can result in significant improvement in visual quality for patients, with LRIs and toric lenses the two most common techniques employed combined with cataract surgery, Dr Mukhija noted. Both methods, however, have their advantages and disadvantages.

“On one hand, the relaxing incisions are simple and low cost. However, they can be less predictable than toric lenses and can only be used for mild astigmatism. Although toric intraocular lenses can be used for a wide range of astigmatism, high cost is often a limiting factor,” she said.

Dr Mukhija’s study included 70 patients with symptomatic cataract with good visual potential and corneal astigmatism between 0.75 D and 2.5 D. Those younger than 18 years or with visually significant comorbidity were excluded. Randomisation was performed using an online random number generator and in two sets to ensure equal spacing throughout the range of astigmatism.

The research team learned of the intervention only before surgery. Manual preoperative marking using a Tomark toric IOL marker (Geuder) and standard zero- and 180-degree marks were performed for all cases. Follow up was at baseline, one month, one year, and five years after surgery.

Anterior keratometric data from a “4-map refractive” display (Pentacam HR) was used for calculation. A single experienced surgeon performed all surgeries. For LRIs, the calculation was done on the standard website using Donenfeld’s nomogram (LRIcalculator.com). A single or double LRI was placed on the limbus after draping and before the start of cataract surgery. The surgeon used a standard 600-micron disposable blade, the Rayner T-flex for toric intraocular lenses, and the company website for calculating IOL power.

The primary outcome was uncorrected distance visual acuity. Secondary outcomes were best-corrected distance visual acuity, residual spherical equivalent, residual refractive astigmatism, and quality of life impact of refractive correction (QIRC) score.

Dr Mukhija said 34 patients had toric lens implantation and 36 LRIs.

“Both groups were comparable in terms of the baseline parameters. Uncorrected logMAR distance visual acuity, which was our primary outcome, significantly improved from baseline in both groups and was comparable at one month, one-year, and five-year follow-up in both groups. The logMAR best-corrected distance visual acuity was significantly better in the LRI group. However, this was only at one month and was not maintained at one-year and five-year follow-ups,” she said.

The residual mean arithmetic refractive spherical equivalent and the residual mean arithmetic cylinder were also comparable in both groups at one year and five years. The mean overall QIRC scores improved in both groups at one month, one year, and five years as compared to the baseline, and there was no statistically significant difference between the two groups at any point, Dr Mukhija said.

Putting the outcomes in context, Dr Mukhija said the main strength of the study lay in the design and the length of follow-up.

“However, there are a few limitations. Other visual properties such as contrast sensitivity, glare, and halos, were not compared. Manual marking technique was used, though it was the same for all cases. Toric intraocular lens power calculation was done using the company’s recommended website, which did not incorporate the posterior corneal astigmatism at the time of study,” she said.

Ultimately, when it comes down to deciding between LRIs or toric IOLs, cost and health economics are definitely major deciding factors, Dr Mukhija told EuroTimes.

“Here, in the UK’s National Health Service, toric IOLs are not routinely available in many trusts, meaning patients may have to go privately and spend much more should they want that option. Not all cataract surgeons perform toric IOL implantation or LRIs, and both have a short learning curve. But LRI being a simple, low-cost technique, may be extremely useful over toric IOL in some situations,” she concluded.

“Our study showed that cataract surgery, combined with astigmatic correction, offers an improvement in quality of life which is comparable for both LRIs and toric lenses.”

Dr Mukhija presented at the ESCRS Virtual Winter Meeting 2022.

Ritika Mukhija MD, FRCOphth, MRCSEd, Cornea & Anterior Segment Fellow, Sussex Eye Hospital, University Hospitals Sussex NHS Foundation Trust, Brighton, UK. ritika.mukhija@nhs.net