ObjectiveTo compare the changes of corneal astigmatism after long-term spherical and toric orthokeratology wearing, and to investigate the effects of different orthokeratology design on corneal astigmatism.MethodsThe medical records of myopic adolescent patients who have been prescribed spherical and toric orthokeratology in the contact lens clinic of West China Hospital, Sichuan University between January 2019 and December 2021 were analyzed retrospectively.The differences of corneal astigmatism changes after wearing spherical and toric orthokeratology for a long time and one month discontinuation were compared. The influencing factors of corneal astigmatism changes were analyzed. ResultsA total of 156 patients were included. There were 76 cases (76 eyes) in spherical orthokeratology group and 80 cases (80 eyes) in toric orthokeratology group. There was no significant difference between the two groups in age, gender, baseline myopia diopter and total lens wearing time (P>0.05). There were statistically significant differences between the spherical orthokeratology group and the toric orthokeratology group in the baseline corneal flat K value [42.1 (41.3, 43.3) vs. 43.1 (42.0, 44.1) D], baseline corneal steep K value [(43.4±1.3) vs. (44.6±1.5) D], baseline corneal astigmatism [(1.1±0.5) vs. (1.6±0.6) D], and baseline total eye astigmatism [−0.6 (−1.2, 0.0) vs. −1.4 (−1.8, −1.0) D] before wearing the orthokeratology (P<0.05). Compared with the baseline value, 1 month after the two groups stopped wearing the orthokeratology, the corneal flat K values became flatter [spherical orthokeratology group: 42.09 (41.28, 43.34) vs. 41.73 (40.98, 43.16) D, toric orthokeratology group: 43.09 (41.95, 44.10) vs. 42.61 (41.52, 43.56) D; P<0.05], the changes of corneal steep K values were not statistically significant (P>0.05), but the corneal astigmatism values increased [spherical orthokeratology group: (1.05±0.49) vs. (1.37±0.56) D, toric orthokeratology group: (1.62±0.57) vs. (1.99±0.63) D; P<0.05]. There was no significant difference in the changes of corneal flat K value, corneal steep K value and corneal astigmatism between the two groups (P>0.05). Multivariate analysis showed that age (P=0.011) and the total duration of orthokeratology wearing (P=0.004) were the main factors affecting the changes of corneal astigmatism. ConclusionAfter 1 month of non-wearing, the flat K value of the cornea becomes flat, the steep K value remains unchanged, and the corneal astigmatism increases. There is no difference in the effect of the spherical and toric orthokeratology on corneal astigmatism. The change of corneal astigmatism is related to the patient’s age and the total duration of wearing the orthokeratology. The younger the age, the longer the duration of orthokeratology wearing, the more significant the increase of corneal astigmatism after stopping wearing the orthokeratology.
Objective To compare the accuracy of different corneal curvature parameters used in toric intraocular lens (Toric IOL) implantation. Methods Patients who underwent phacoemulsification combined with Toric IOL implantation at the Department of Ophthalmology, the People’s Hospital of Leshan between January and June 2022 were retrospectively included. The following data of all patients were collected: age, sex, axial length, anterior chamber depth, total keratometry (TK) and simulated keratometry (Simk, described as Simk1) measured by IOL Master 700 biometric instrument, total corneal refractive power (TCRP) measured by Pentacam AXL panoramic biometric instrument, Simk measured by iTrace visual function analyzer (described as Simk2), astigmatism of the operative eye, and the optometry (including spherical, cylindrical and axial degrees) of operative eyes three months after operation. According to the different corneal curvature parameters (TK, Simk1, TCRP and Simk2) used in the preoperative degree calculation of Toric IOL, patients were divided into four correspondent groups. By analyzing the differences and consistency in postoperative spherical equivalent, variation of postoperative spherical equivalent and postoperative residual astigmatism among the four groups, the accuracy of the four parameters for Toric IOL implantation was evaluated. Results According to the inclusion and exclusion criteria and after propensity score matching, a total of 47 patients (60 operated eyes) were included, with 15 eyes in each group. The spherical equivalent of the TK group, Simk1 group, TCRP group and Simk2 group after operation were (0.38±0.24), (0.49±0.15), (0.69±0.37) and (0.80±0.27) D, respectively. There was no significant difference between the Simk1 group and the TK group (P=0.52), but the differences between the TCRP group, Simk2 group and TK group were all statistically significant (P<0.01). The 95% consistency boundary width of the Simk1 group and the TK group was the narrowest (1.23). The variations of postoperative spherical equivalent of the four groups were (0.25±0.12), (0.39±0.19), (0.64±0.26) and (0.48±0.12) D, respectively. There was no significant difference between the Simk1 group and the TK group (P=0.11), but the differences between the TCRP group, Simk2 group and TK group were all statistically significant (P<0.01). The 95% consistency boundary width of the Simk2 groups and the TK group was the narrowest (0.64). The postoperative residual astigmatism of the four groups were (−0.33±0.12), (−0.57±0.11), (−0.73±0.18) and (−0.70±0.17) D, respectively. The differences between the last three groups and the TK group were statistically significant (P<0.01). The 95% consistency boundary width between the Simk1 group and the TK group was the narrowest (0.58). Conclusion It is a reliable and effective method to use TK to reflect the total corneal curvature and calculate the degree of Toric IOL.