Toric IOL addresses astigmatic issue

December 1, 2011

Multifocal lens more effective for higher levels than non-toric lens plus limbal relaxing incision

The toric IOL was more effective for treating higher amounts of astigmatism. The contrast sensitivity results and rotational stability also were good. Dr Oliver Findl, MBA, presented his results during the annual meeting of the American Society of Cataract and Refractive Surgery.

Astigmatism is a common occurrence in the general population, and 30% of the population can have 1 D or more of astigmatism. In addition, the visual function can decrease substantially, especially with multifocal IOLs, said Dr Findl, chairman, Department of Ophthalmology, Hanusch Hospital, Vienna, Austria, and consultant ophthalmic surgeon, Moorfields Eye Hospital, London.

Dr Findl and his colleagues evaluated the refractive multifocal IOL with a 3 D near add on the lens plane; the IOL is available in two sizes depending on the IOL power. The investigators conducted a randomized, controlled, contralateral eye study that included 60 eyes of 30 patients with corneal astigmatism ranging from 1 to 2.5 D bilaterally. The multifocal toric IOL was implanted into one eye of a patient, and an LRI was created in the fellow eye with a 600 µm steel blade using the Donnenfeld nomogram followed by implantation of the same nontoric IOL.

The purpose of the study was to compare the level of refractive astigmatism after surgery between the two eyes of each patient. Other outcome measures were the corrected near and distance visual acuities, the rotational stability 1 hour and 1 and 3 months postoperatively, and the results of glare and contrast sensitivity measurements under photopic and mesopic conditions.

The patients were asked to fill out a questionnaire that included 17 questions regarding patient satisfaction.

Study results

There were no differences between the two eyes in the preoperative astigmatism, and the astigmatism was evenly distributed between 1 and 2.5 D.

The mean refractive astigmatism with the toric IOL was 0.4 D 3 months after implantation, which was less than the 0.8 D in the eyes treated with an LRI and multifocal IOL, Dr Findl said.

The uncorrected distance and near visual acuities were similar in both groups, but there was a trend toward slightly better, although not significant, results in the eyes with the toric IOL. There were also no differences between the toric and non-toric groups in contrast sensitivity under mesopic and photopic conditions.

The rotational stability was very good, according to Dr Findl, at 2.9° on average, which agrees with results determined with other IOLs. This was evaluated using a dedicated retroillumination photography system that has been shown to have an accuracy of 2°.

The questionnaire results showed that 95% of patients needed spectacles for some visual tasks, especially for periods of long-term reading. Most patients, however, could perform tasks throughout the day without using glasses, Dr Findl added.

No patients reported symptoms of dry eye, which is a potential problem with LRIs. Glare and halos developed in 41% and 35%, respectively. No explantations were performed and patients expressed satisfaction with the outcomes.

"The toric IOL was a bit more effective for addressing moderate corneal astigmatism from 1 to 2.5 D, especially in the subgroup of patients with 2 D and more of astigmatism," Dr Findl concluded. "The uncorrected distance and near visual acuities were similar with both treatments. The rotational stability was excellent. The patient satisfaction was good."