Recent advancements in ophthalmology have transformed surgical treatment for cataracts into a refractive procedure that delivers optimal visual outcomes. The presence of residual astigmatism remains a barrier to achieving high-quality vision and spectacle independence. Research shows that excessive astigmatism (>0.75 diopters [D]) leads to visual disturbances such as blurring, fatigue, glare, and diplopia. Reducing astigmatism to <0.5 D significantly enhances patient satisfaction.
Several surgical techniques are available for managing preoperative astigmatism, including clear corneal incisions, limbal relaxing incisions, arcuate keratotomy, and toric intraocular lenses (TIOL) implantation. Studies show that TIOL implantation is a widespread viable technique for astigmatic correction procedures. Femtosecond laser arcuate keratotomy (FSAK) is an innovative surgical option because it surpasses manual arcuate keratotomy’s precision while providing consistent results. Recent studies have compared the effectiveness of FSAK and TIOL implantation as astigmatism-reducing techniques following femtosecond laser-assisted cataract surgery (FLACS).
This two-group parallel randomized clinical trial was conducted at the Eye Center of the Second Affiliated Hospital School of Medicine Zhejiang University in China from October 2021 to September 2023. The research frame followed the Declaration of Helsinki guidelines and received authorization from the institutional review board. All potential participants gave informed consent to enter the study before enrolment began.
The research included patients aged 18 to 80 years with regular mild-to-moderate corneal astigmatism, ranging from 0.75 D to 3.0 D prior to undergoing FLACS. The study excluded participants due to irregular corneal astigmatism and patients who experienced ocular trauma or underwent surgical procedures, had coexisting ocular disorders or severe systemic diseases, or inadequately collaborated during the assessment.
Eligible patients were randomized into two groups: FSAK or TIOL implantation. A statistician generated a computer-based random allocation sequence with a 1:1 ratio. The patients and surgeons were not blinded to their treatment, but the outcome observers remained unaware.
A single surgeon performed all procedures using dual platforms like the LenSx femtosecond laser and the Centurion phacoemulsification system. The surgical team performed arcuate incisions in the FSAK group using the Donnenfeld nomogram to determine the 8.5-mm optical zone and depth of incisions, reaching 90% of corneal pachymetry.
Phacoemulsification surgery with the placement of a monofocal IOL (Tecnis ZCB00) was performed postoperatively. In the TIOL group, the surgeons implanted Tecnis Toric ZCT intraocular lenses aligning them according to preoperative calculations.
The primary outcome of this study was the assessment of postoperative refractive astigmatism three months after surgery. Secondary outcomes included the evaluation of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and corneal topography readings. Adverse events were also documented.
A comprehensive screening process identified 220 subjects, who were then randomly assigned into two equal groups consisting of 98 participants each. Patients had a mean age of 68.4 years, and the study included 63% female participants. Nine participants were assigned to the FSAK group, and three participants in the TIOL group withdrew from the study.
Preoperatively, both groups had comparable astigmatism (FSAK: 1.56 [0.77] D; TIOL: 1.67 [0.77] D, P = 0.32). Three-month examination revealed a mean refractive astigmatism of 0.64 (0.64) D for the FSAK group and 0.54 (0.55) D for the TIOL group, showing no statistically significant difference (P = 0.21). Residual astigmatism of less than 0.75 D was more common among patients receiving TIOL treatment at one and three months postoperatively.
Patients in the FSAK group who presented with preoperative astigmatism greater than 1.5 D showed higher remaining astigmatism amounts (0.82 [0.66] D) than TIOL group patients (0.53 [0.58] D, P = 0.009). The FSAK group demonstrated higher residual astigmatism compared to the TIOL group among participants with against-the-rule (ATR) astigmatism at 0.72 (0.62) D versus 0.50 (0.53) D (P = 0.04). A statistical comparison revealed no variations between with-the-rule (WTR) and oblique astigmatism in the study.
Patients in both study groups achieved substantial enhancements in their UDVA and CDVA results. The comparison between groups revealed no significant variations in visual acuity measurements.
Our research found that FSAK, together with TIOL implantation, successfully reduces astigmatism after performing FLACS. TIOL implantation produces better astigmatic results in patients with greater preoperative astigmatism (>1.5 D) and ATR astigmatism. TIOL implantation demonstrates greater reliability than other procedures in producing superior refractive outcomes for these patients.
FSAK shows advantages in precision alongside independence from IOL alignment but delivers slightly lower efficacy than TIOL implantation for controlling astigmatism in higher degrees. TIOL implantation demonstrates improved stability with predictable results, whereas arcuate keratotomy depends on the natural healing response, which can lead to inefficiency.
FSAK and TIOL implantation are effective methods for astigmatism treatment in cataract cases. TIOL implantation provides superior astigmatism correction compared to FSAK in patients requiring astigmatism reduction with higher preoperative and ATR astigmatism levels. Further research with larger study groups and extended follow-up periods is necessary to validate these findings.
References: Zhong Y, Chen S, Wang H, et al. Femtosecond laser arcuate keratotomy vs. toric intraocular lens implantation in cataract surgery: a randomized clinical trial. JAMA Ophthalmol. Published online January 23, 2025. doi:10.1001/jamaophthalmol.2024.5887
