Abstract: Objective To compare the correction efficacy of Toric implantable collamer lens (TICL) implantation for high ocular residual astigmatism (HORA) with that for low ocular residual astigmatism (LORA). Design Retrospective case series. Participants A total of 200 eyes of 100 patients underwent TICL implantation from July to December 2020 at Beijing Tongren Eye Center. Methods Total astigmatism was obtained by subjective refraction using corneal topography (iTrace visual function analyzer) before surgery. The difference between total astigmatism and corneal astigmatism was calculated by the vector analysis method to obtain intraocular astigmatism (ocular residual astigmatism, ORA). According to the magnitude of ORA, the surgical eyes were divided into HORA group (ORA≥1.30 D, 94 eyes) and LORA group (ORA<1.30 D, 106 eyes). Then, the standard vector analysis method recommended by the American National Standards Institute (ANSI) was used to calculate the intended refractive correction (IRC) and surgically induced refractive correction (SIRC) in both groups. The ratio of SIRC to IRC is the correction ratio (CR). CR equal to 1 represents the most ideal correction, CR>1 indicates overcorrection of astigmatism, and CR<1 indicates undercorrection of astigmatism. The difference between SIRC and IRC is the error vector (EV), and the ratio between EV and IRC is the error rate (ER). When ER is 0, it represents the most ideal correction, and when ER is 1, it represents no correction at all. The differences of the above parameters between the two groups were compared. Main Outcome Measures IRC, SIRC, CR, EV, ER. Results In the HORA group, the IRC, SIRC, CR, EV, ER was 1.52 (0.88~2.60)D, 1.47 (0.83~2.53)D, 0.91 (0.75~1.16), 0.67 (0.39~1.04)D and 0.43 (0.24~0.90) respectively at 1 week after operation; was 1.52 (0.88~2.60)D, 1.37 (0.68~2.43)D, 0.92 (0.69~1.15) , 0.7 (0.43~1.14)D and 0.49 (0.28~1.02) respectively at 6 months after surgery. In the LORA group, the IRC, SIRC, CR, EV, ER was 1.18 (0.53~1.70)D, 1.1 (0.59~1.91)D, 1.03 (0.66~1.49), 0.57 (0.29~1.00)D and 0.62 (0.31~1.02) respectively at 1 week after operation; was 1.12(0.53~1.68)D, 0.93(0.50~1.67)D, 0.91(0.61~1.24), 0.54(0.28~1.07)D and 0.61(0.32~1.13) respectively at 6 months after surgery. Comparing the HORA group with the LORA group, there were significant differences in IRC and SIKC (P<0.01, 0.01), but no significant difference in CR, EV and ER at 1 week after operation. There were significant differences in IRC, SIRC and EV at 6 months after operation(P<0.01, <0.01, 0.03), but no significant difference in CR and ER. Conclusion Toric Implantable collamer lens (TICL) have the same good correction effect for astigmatism in the HORA group as in the LORA group. (Ophthalmol CHN, 2022, 31: 213-218)

Key words: Toric implantable collamer lens, ocular residual astigmatism