Effect of Limbal relaxing incisions during implantable collamer lens surgery

The limbal relaxing incisions (LRIs) technique is a safe and an inexpensive procedure, which is simple for experts to perform. It can effectively reduce astigmatism and result in a rapid visual rehabilitation. But there are few reports about reducing pre-existing corneal astigmatism by LRI in ICL surgery. Our research was aimed to study the effect of limbal relaxing inci sions during implantable collamer lens (ICL) surgery.

A prospective analysis reviewing consecutive cases of corneal astigmatism that had either independent ICL surgery (control group) or combined with LRIs (LRIs group). The study population consisted of 45 patients, 85 eyes, with high myopia and regular corneal astigmatism more than 0.50 diopter (D) and less than 3.00 D. The first group received ICL surgery combined with LRIs (limbal relaxing incisions); the control group received only ICL surgery alone. The outcomes considered were uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (BCVA), refraction, keratometry, slit lamp biomicroscopy, indirect ophthalmoscopy, corneal topography, corneal astigmatism, endothelial cell count, and patient satisfaction. The follow-up period covered 12 months.

The mean uncorrected distance visual acuity (UDVA) and the best corrected visual acuity (BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up period, the UCVA was statistically better for the patients with LRIs compared with those underwent ICL surgery alone. The LRIs group showed significant reduction in the mean topographic astigmatism from 1.48 ± 0.35 D preoperatively to 0.37 ± 0.14 D postoperatively (P < .0001) after one month. The control eyes did not show a statistically significant change (P > 0.05). The mean magnitude of the surgically induced astigmatism (SIA) read 1.10 ± 0.35 D,1.13 ± 0.34D,1.13 ± 0.34D,1.11 ± 0.35D by the end of the 1st, the ^3rd, the ^6th and the 12th month postoperatively in LRIs group, which was slightly lower than the target-induced astigmatism (TIA). The difference in SIA between the LRI and the control group was statistically significant by the end of the 1st, the ^3rd, the ^6th and the 12th month postoperatively (P < 0.001). The mean correction index (CI) was less than 1, which indicated undercorrection effect of limbal relaxing incision. No difference was observed in the postoperative endothelial cell count between the two groups. There was no intraoperative and postoperative ocular or systemic complication.

Limbal relaxing incision is an effective method in reducing corneal astigmatism during implantable collamer lens surgery.

The trial was retrospectively registered in 14 April 2017. (NO:ChiCTR-ONR-17011147).