The Efficacy of Paired Opposite Clear Corneal Incisions Correcting Preexisting Low-to-Moderate Astigmatism in Implantable Collamer Lens Surgery

Abstract

Purpose: To evaluate the efficacy of paired opposite clear corneal incisions (OCCIs) in Implantable Collamer Lens (ICL; STAAR Surgical) implantation surgery for correcting preexisting low-to-moderate astigmatism and observe their influence on corneal aberration. Methods: This prospective controlled randomized study included 123 eyes: 73 eyes in the ICL surgery group (control group) and 50 eyes in the ICL combined with OCCI group (OCCI group). All patients had corneal astigmatism between 0.50 and 3.00 D. Parameters considered included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, keratometry, slit-lamp biomicroscopy, indirect ophthalmoscopy, corneal topography, and higher order aberrations (HOAs). The Alpins method was used to analyze the correction of astigmatism. The follow-up period lasted for 12 months. Results: Both groups showed a statistically significant improvement in mean UDVA and CDVA after surgery. At 1 and 12 months, the OCCI group had statistically better UDVA than the control group ( P = .021 and .01). The OCCI group showed a significant reduction in mean refractive astigmatism from −0.835 ± 0.274 to −0.535 ± 0.353 and −0.450 ± 0.346 D postoperatively ( P < .05) after 1 and 12 months. No significant change was observed in the control group ( P > .05). The average magnitude of surgically induced astigmatism (SIA) was 0.911 ± 0.442 and 0.811 ± 0.397 D at 1 and 12 months postoperatively, respectively, in the OCCI group, which was slightly lower than the target induced astigmatism. The difference in SIA between the OCCI and control groups was significant by the end of 1 and 12 months postoperatively ( P < .0001). The mean correction index was below 1, suggesting an undercorrection effect caused by clear corneal incisions in the opposite direction. HOAs increased in both the control and OCCI groups after surgery ( t = 5.668, P < .0001, t = 3.773, P = .0003, respectively), with oblique trefoil only significantly increasing in the OCCI group. Conclusions: This study demonstrated that OCCIs represent a secure, efficient, reliable, and long-term technique for reducing preexisting low-to-moderate corneal astigmatism during ICL surgery. However, OCCIs did not show any advantageous impact in terms of wavefront aberrations when compared to the traditional single-incision method. The presence of oblique trefoil may be the main contributor to the alteration of HOAs during OCCI surgery. [ J Refract Surg . 2024;40(1):e20–e29.]