Femtosecond laser-assisted capsulotomy marking may deliver better astigmatism correction
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Femtosecond laser-assisted capsulotomy marking produced lower residual astigmatism and better visual outcomes compared with conventional slit lamp-assisted manual marking during toric IOL implantation, according to a study.
Astigmatism correction with capsulotomy marking also delivered significantly higher axis alignment.
“To ensure high accuracy, it is important that toric IOLs have a precise axial position, which, in turn, depends on exact corneal marking. Several methods have been described to determine the best toric IOL position marking,” Qingzhong Chen, MD, and colleague wrote. “A classic (and common) method is based on manual markers, which could be done by slit lamp-assisted marking with a horizontal slit beam, a pendular marker and a nonpendular marker. However, the method has a risk of inaccurate marking of the axis when performed by inexperienced surgeons; the patient’s head position at the time of slit lamp evaluation also affects the accuracy of axis marking.”
Chen and colleague conducted a nonrandomized prospective cohort study to compare outcomes of capsulotomy marking (CM) and manual marking (MM). The study included 57 patients with cataracts and corneal astigmatism greater than 1 D who received a toric IOL between November 2016 and May 2017. Thirty-one eyes received MM, and 26 eyes received CM.
At 1 month and 3 months after surgery, patients in the CM group exhibited lower uncorrected distance visual acuity compared with the MM group (P < .05). Residual astigmatism and IOL misalignment were also lower in the CM group at 1 month and 3 months (both P < .05). There was no significant difference in best corrected distance visual acuity between the groups at 3 months.
“The results suggested that compared with slit lamp-assisted MM, femtosecond laser-assisted CM might have higher accuracy in the alignment of toric IOLs. Because CM determines the axis of the toric IOL based on peripheral iris features, it is not influenced by a change of body position,” Chen and colleague wrote.
Perspective
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The more precisely we can align toric IOLs, the better results we are going to have. Using capsulotomy marking to align toric lenses is another tool in the toolkit, in addition to manual marking, digital marking or aberrometry to try to minimize astigmatism after cataract surgery. I applaud the authors for doing a prospective study and looking at this important issue scientifically. One caution is that IOL rotation is relatively uncommon, so it is hard to draw sweeping conclusions from a small study. Regardless, the results are promising.
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