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27-03-2013 | Internal medicine | Article

Toric intraocular lenses improve vision, wellbeing in patients with astigmatism


Free abstract

medwireNews: Toric intraocular lenses (IOL) offer significant advantages in terms of both vision and quality of life when compared with spherical non-toric lenses, results of a study in patients with corneal astigmatism shows.

Toric IOLs are thus "an important option for decreasing astigmatism, giving predictable results and increasing the chance of spectacle independence postoperatively," the study authors write.

Rita Mencucci (University of Florence, Italy) and colleagues evaluated visual and other outcomes in 120 patients who underwent surgery for the treatment of cataracts and correction of refractive astigmatism.

Patients were divided into three groups in a nonrandomized manner, according to the degree of preoperative topographic corneal astigmatism. Patients with astigmatism of more than 1.5 D received either an SN60TT toric IOL (toric group) or a spherical monofocal SN60AT IOL (non-toric group) while 40 patients without astigmatism (<1.0 D) received the spherical monofocal SN60AT IOL (control group).

All operations were performed by the same surgeon using the same protocol, and there were no intraoperative or postoperative complications. IOL axis orientation changed by 3.2 degrees, on average, at 3 months post-surgery and no postoperative realignment was needed.

Writing in the British Journal of Ophthalmology, Mencucci et al report that while uncorrected distance visual acuity (UDVA) was similar among the three groups at baseline, at 3 months postoperatively this value was significantly better in the toric and control groups than in the non-toric group, at 0.07 and 0.04 versus 0.25 LogMAR, respectively.

Similarly, aberrometric values (modulation transfer function area ratio, Strehl ratio, and second order astigmatism) were significantly better and mean postoperative spherical equivalent was significantly lower in the toric and control groups compared with the non-toric group.

Finally, quality of life, measured using the National Eye Institute Refractive Error Quality of Life Instrument, was significantly better in the toric group than in the non-toric group. This difference was driven by significant improvements in items such as clarity of vision, far vision, glare, and satisfaction with correction.

Mencucci and colleagues say that their data "indicate gains in objective optical quality, retinal image quality and visual performance in eyes that underwent toric IOL implantation compared with eyes that underwent non-toric spherical IOL implantation, and this was likely related to reduced astigmatism in the toric group."

They write that toric IOLs are "an important option for decreasing astigmatism, giving predictable results and increasing the chance of spectacle independence postoperatively."

However, they also note that aspheric IOLs offer a range of advantages over spherical IOLs and are "rapidly replacing monofocal spherical IOLs as the standard of care". Therefore, "further studies are necessary to evaluate if the addition of the aspheric profile to toric IOLs will confer greater advantages."

By Joanna Lyford, Senior medwireNews Reporter