Impact of preoperative corneal astigmatism on visual performance after multifocal intraocular lens implantation

In their study, Lee et al.¹ evaluated the outcomes of conventional phacoemulsification and femtosecond laser–assisted cataract surgery with multifocal intraocular lens (IOL) implantation. In the study, patients were divided into the following 3 groups: (1) femtosecond, (2) femtosecond with arcuate keratotomy, and (3) conventional phacoemulsification.

The authors reported that the difference in preoperative corneal astigmatism was significant between the 3 groups (P = .017). Patients in the femtosecond group with corneal astigmatism greater than 0.75 diopter (D) had arcuate keratotomy; however, there were no details regarding the correction of astigmatism in the conventional phacoemulsification group. Although the mean preoperative corneal astigmatism in the conventional group was 0.76 D ± 0.42 (SD) (maximum value 1.75 D), patients in this group had no surgery to correct astigmatism, an issue that confounds the study’s results. There was a major difference in the methodology used in these 2 groups, and this is problematic because any residual astigmatism would likely result in worse visual outcomes.²

Hayashi et al.³ found that the presence of residual astigmatism in eyes with diffractive multifocal IOLs had a detrimental effect on all distance visual acuities, suggesting that astigmatism greater than 1.00 D should be corrected. Although in general patient satisfaction with multifocal IOLs is high, residual refractive errors can negatively affect this.^4,5

Thus, we cannot comment on the comparative strengths and weaknesses of the methods used in the Lee et al. study because the approaches regarding astigmatism in the conventional group and the femtosecond group were different. The data obtained from the questionnaire are presented in paramaters—glare, halo—that seem to be incomparable, which might be resolved under more controlled conditions.