ObjectiveTo investigate whether the corneal shape recovered after discontinuation of long-term orthokeratology and whether orthokeratology increased the corneal astigmatism and ocular astigmatism.MethodsFrom December 2016 to April 2018, a retrospective study was conducted on 33 myopic patients who had undergone two times standard orthokeratology in the outpatient department of West China Hospital of Sichuan University, and had stopped wearing the first orthokeratology lens for one month before fitting the second orthokeratology lens. A total of 32 myopia frame glasses wearers were selected by simple random sampling as control. The changes of corneal flat meridian curvature (flat K), corneal steep meridian curvature (steep K), corneal astigmatism and ocular astigmatism before and after discontinuation of orthokeratology were analyzed.ResultsAmong the patients with baseline myopia diopter of ?0.25～?2.75 D, the average annual change of corneal flat K was (?0.03±0.21) D in the frame glasses group and (?0.24±0.14) D in the orthokeratology group, the difference was statistically significant (t=5.555, P<0.001). Among the patients with baseline myopia diopter of ?0.25～?2.75 D, the average annual change of corneal steep K was (0.20±0.42) D in the frame glasses group and (0.15±0.20) D in the orthokeratology group, the difference was not statistically significant (t=0.785, P=0.435). Among the patients with baseline myopia diopter of ?3.00～?5.75 D, the average annual change of corneal steep K was (0.29±0.39) D in the frame glasses group and (?0.01±0.20) D in the orthokeratology group, the difference was statistically significant (t=2.758, P=0.014). The average changes of corneal astigmatism were analyzed according to the difference of eyes, gender, age and baseline corneal astigmatism, the difference was not statistically significant (P>0.05), respectively. For patients with baseline astigmatism absolute value less than or equal to 0.50 D, the astigmatism annual change of the frame glasses group was 0.00 (0.50) D, and that of orthokeratology group was ?0.33 (0.48) D, the difference was statistically significant (Z=?2.301, P=0.021).ConclusionsThe flat K of the cornea becomes flatter and the steep K does not change after one month’s discontinuation of long-term orthokeratology. There was no difference in the increase of corneal astigmatism compared with those wearing frame glasses. When the baseline ocular astigmatism is less than or equal to 0.50 D, the increase of astigmatism may occur after discontinuation of orthokeratology.
ObjectiveTo evaluate the effectiveness of using a six-dimensional eye-tracking system during femtosecond laser-assisted sub-Bowman keratomileusis (FS-SBK) surgery to correct myopia and astigmatism. MethodsA total of 23 patients (36 eyes) with ametropia undergoing FS-SBK were retrospectively analyzed and divided into the static cyclotorsion control (SCC) group (11 patients, 20 eyes) and the non-SCC group (12 patients, 16 eyes). According to the static eyeball rotation degrees, the SCC group was further divided into three subgroups: within ±2° group (5 patients, 9 eyes), ±2°-±5° group (4 patients, 7 eyes), and above ±5° group (2 patients, 4 eyes). The preoprative and postoperative one-month uncorrected visual acuity, best corrected visual acuity, diopter of spherical power, diopter of cylindrical power, corneal curvature, and the rotating degree in SCC were observed; the root-mean-square values of the total higher-order aberrations, spherical aberration, coma, Strehl ratio, etc. when the pupil diameter was 6.5 mm were extracted; and the therapeutic efficacy was observed. ResultsNo severe intraoperative or postoperative complications occurred in any subject. The effectiveness index of the SCC group was 0.947±0.145, and that of the non-SCC group was 1.005±0.141, with no statistically significant difference (P>0.05). Compared with the preoperative levels, in the two groups, the postoperative uncorrected visual acuity was significantly elevated; the postoperative diopter of spherical power, diopter of cylindrical power, and corneal curvature difference were reduced; the postoperative total higher-order aberrations, spherical aberration, and coma increased; all the differences mentioned above were statistically significant (P<0.05). In the SCC group, the difference between the preoperative and the postoperative Strehl ratio was statistically significant (P<0.05). There was no significant difference in postoperative indicators between the SCC group and the non-SCC group (P>0.05). The difference in postoperative increment of coma between the SCC group and the non-SCC group was statistically significant (P<0.05). In the SCC group, no statistically significant difference was found in postoperative increment of any indicator among the three subgroups (P<0.05). ConclusionsFS-SBK of six-dimensional eye-tracking system is effective in correcting myopia and astigmatism. FS-SBK can reduce lower-order aberrations while introducing higher-order aberrations, and whether SCC is performed intraoperatively is meaningless.
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.
【摘要】 目的 探討雙眼散光軸向的關系。 方法 隨機選取2010年1—12月預行準分子激光原位角膜磨鑲術（laser in situ keratomileusis，LASIK）手術患者200例400只眼（散光gt;-0.50 D），收集全眼散光和角膜散光軸向，定性和定量分析雙眼散光軸向的關系。 結果 ①定性分析：雙眼全眼散光性質相同病例在電腦驗光儀結果中占92.5%，在綜合驗光儀結果中占95.0%；雙眼角膜散光性質相同病例在電腦驗光儀結果中占95.5%，在角膜地形圖結果中占97.5%。②定量分析：雙眼全眼散光在電腦驗光儀結果中對稱者為36.5%，近似對稱為25.0%，非對稱為38.5%；在綜合驗光儀結果中對稱者為50.5%，近似對稱為19.5%，非對稱為30.0%。雙眼角膜散光在電腦驗光儀結果中對稱者為37.0%，近似對稱為31.5%，非對稱為31.5%；在角膜地形圖結果中對稱者為43.0%，近似對稱為32.0%，非對稱為25.0%。雙眼散光軸向對稱性指數的中位數在4種檢查結果中分別為：8、6、8、6。 結論 雙眼的全眼和角膜散光在軸向方面都具有同質性，并且具有對稱或近似對稱趨勢。【Abstract】 Objective To analyze the relationship between binocular astigmatism axes. Methods This study included 400 eyes of 200 patients treated by laser in situ keratomileusis (LASIK) between January and December 2010, whose astigmatic degrees were greater than -0.5 D. We collected astigmatic axles coming from either whole eye or cornea. The relationship between binocular astigmatism axes was analyzed qualitatively and quantitatively. Results ① Qualitative analysis: cases of total astigmatism axis with similar quality in autorefraction took up 92.5%, and 95% in subjective refraction. Cases of cornea astigmatism axis with similar quality in autorefraction took up 95.5%, and 97.5% in cornea topography. ② Quantitative analysis: in autorefraction, cases of total astigmatism axes were symmetrical in 36.5%, approximately symmetrical in 25%, and dissymmetrical in 35% of the subjects. In subjective refraction, 50.5% showed symmetry, 19.5% approximate symmetry, and 30% dissymmetry. In autorefraction, cases of cornea astigmatism axis were symmetrical in about 37%, approximately symmetrical in 31.5%, and dissymmetrical in 31.5% of the patients. In cornea topography, 43% of the cases were symmetrical, about 32% were approximately symmetrical, and 25% were dissymmetrical. The middle numbers of the symmetrical index for the four kinds of examinations were respectively 8, 6, 8, and 6. Conclusion The total astigmatism axis and the binocular astigmatism axis of cornea have the characteristic of homogeneity, also the trend of symmetry.
The inverse problem of diffuse optical tomography (DOT) is ill-posed. Traditional method cannot achieve high imaging accuracy and the calculation process is time-consuming, which restricts the clinical application of DOT. Therefore, a method based on stacked auto-encoder (SAE) was proposed and used for the DOT inverse problem. Firstly, a traditional SAE method is used to solved the inverse problem. Then, the output structure of SAE neural network is improved to a single output SAE, which reduce the burden on the neural network. Finally, the improved SAE method is used to compare with traditional SAE method and traditional levenberg-marquardt (LM) iterative method. The result shows that the average time to solve the inverse problem of the method proposed in this paper is only 1.67% of the LM method. The mean square error (MSE) value is 46.21% lower than the traditional iterative method, 61.53% lower than the traditional SAE method, and the image correlation coefficient(ICC) value is 4.03% higher than the traditional iterative method, 18.7% higher than the traditional SAE method and has good noise immunity under 3% noise conditions. The research results in this article prove that the improved SAE method has higher image quality and noise resistance than the traditional SAE method, and at the same time has a faster calculation speed than the traditional iterative method, which is conducive to the application of neural networks in DOT inverse problem calculation.
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.
