[Correction of low to moderate corneal astigmatism by steep-axis incision in image-guided cataract surgery].

Abstract

Objective: To explore the corrective effect of cataract extraction surgery combined with a 2.8 mm steep-axis corneal incision under ophthalmic surgical navigation on low-to-moderate corneal astigmatism and different types of corneal astigmatism. Methods: A prospective cohort study was conducted. Patients with age-related cataract who underwent cataract extraction combined with single-focus intraocular lens implantation in the Department of Ophthalmology at the Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from June to October 2023 and had a total corneal regular astigmatism degree of ≥0.50 D and <1.50 D were continuously collected. Patients were divided into a low-degree group (<1.00 D) and a moderate-degree group (≥1.00 D) according to corneal astigmatism degree. Simultaneously, they were classified into with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism based on preoperative corneal astigmatism axis position. Subjective refraction and anterior segment biometer examination were performed before and 3 months after surgery, respectively. Vector analysis of corneal astigmatism was conducted using the Alpins vector analysis method. The main observational indicators included target induced astigmatism, surgically induced astigmatism, and the correction index. Results: A total of 95 patients (110 eyes) were collected in this study. Thirteen patients (18 eyes) were lost to follow-up, and finally 82 patients (92 eyes) were included. In the low-degree group, there were 14 males (16 eyes) and 26 females (23 eyes), with an age of (69.62±12.22) years. In the moderate-degree group, there were 13 males (15 eyes) and 33 females (35 eyes), with an age of (72.98±8.28) years. The target astigmatism correction amount, surgically induced astigmatism, and deviation vector in the low-degree group were all smaller than those in the moderate-degree group (all P<0.05). Postoperative corneal astigmatism in both groups was undercorrected. The correction index in the low-degree group (0.88±0.44) was greater than that in the moderate-degree group (0.59±0.34) (P=0.001), and the undercorrection proportion in the moderate-degree group (90.00%, 45/50) was much higher than that in the low-degree group (57.14%, 24/42). In the low-degree group, the correction index from high to low was WTR (1.07±0.41), oblique (0.90±0.58), and ATR astigmatism eyes (0.69±0.37). After multiple comparison analysis, the correction index of WTR astigmatism eyes was significantly higher than that of ATR astigmatism eyes (P<0.05). The success index from high to low was oblique (0.82±0.57), ATR (0.74±0.39), and WTR astigmatism eyes (0.68±0.43). In the moderate-degree group, the order of the correction index from high to low was the same as that in the low-degree group, also WTR (0.79±0.33), oblique (0.71±0.50), and ATR astigmatism eyes (0.53±0.30), but there was no statistical significance among the three (P>0.05). In the low-degree group, there were 6 WTR astigmatism eyes undercorrected, fewer than 12 overcorrected eyes; there were 16 ATR astigmatism eyes undercorrected, more than 3 overcorrected eyes. In the moderate-degree group, there were 6 WTR astigmatism eyes undercorrected, more than 2 overcorrected eyes, but there were 2 ATR astigmatism eyes overcorrected, fewer than 34 undercorrected eyes. Conclusions: Cataract extraction surgery combined with a steep-axis corneal incision can achieve a certain astigmatism correction effect in patients with preoperative low-to-moderate corneal astigmatism. Patients with a preoperative corneal astigmatism degree of mild can achieve a better astigmatism correction effect than those with moderate, especially in the WTR astigmatism population. However, for cataract patients with preoperative corneal astigmatism of moderate and WTR astigmatism, a steep-axis corneal incision can also be combined to correct astigmatism as it can achieve the expected postoperative "with-the-rule undercorrection".