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 evaluate the relative factors of effect of vitrectomy on corneal endothelial cells. Methods Retrospective analysis of the results of corneal endothelium microscopy performed on 213 eyes of 213 patients undergone vetrectomy operations including single vitrectomy (78 eyes), vitrectomy combined with cataract extraction (135 eyes), silicone oil injection (34 eyes), and C3F8 injection (53 eyes) before and after 1 week, 1 and 3 moths of these surgical procedures. Results There was no significant difference between pre- and postoperative corneal endothelium density in single vitrectomy group and vitrectomy combined with cataract extraction with posterior capsule integrity group (Pgt;0.05). The corneal endothelium density significantly decreased postoperatively in C3F8or silicone oil injection group with broken posterior capsule (Plt;0.05). Conclusion C3F8 and silicone oil may damnify corneal endothelium in patients undergo vitrectom y combined with cataract extraction with broken posterior capsule. (Chin J Ocul Fundus Dis，2004，20：101-103)
Study of the mechanical properties of in vivo corneal materials is an important basis for further study of corneal physiological and pathological phenomena by means of finite element method. In this paper, the elastic coefficient (E) and viscous coefficient (η) of normal cornea and keratoconus under pulse pressure are calculated by using standard linear solid model with the data provided by corneal visualization scheimpflug technology. The results showed that there was a significant difference of E and η between normal cornea and keratoconus cornea (P < 0.05). Receiver operating characteristic curve analysis showed that the area under curve (AUC) for E, η and their combined indicators were 0.776, 0.895 and 0.948, respectively, which indicated that keratoconus could be predicted by E and η. The results of this study may provide a reference for the early diagnosis of keratoconus and avoid the occurrence of keratoconus after operation, so it has a certain clinical value.
ObjectiveTo investigate the feasibility of adipose-derived mesenchymal stem cells (ADMSCs) differentiating into corneal epithelium-like cells after transfection with Pax6 gene. MethodsThe adipose tissue from bilateral inguinal of healthy C57BL/6 mice (5-6 weeks old) was used to isolate and culture ADMSCs.The 3rd passage ADMSCs were subjected to treatments of non-transfection (group A),pcDNA3.1 empty vector transfection (group B),and recombinant plasmid of pcDNA3.1-Pax6 transfection (group C),respectively.At 48 hours after transfection,the cells in groups B and C were selected with G418.The cell morphology changes were observed under the inverted microscope.Pax6 protein and level of corneal epithelial cells specific molecular-cytokeratin 12 (CK-12) were measured by Western blot.Real-time fluorescence quantitative PCR was applied to measure the mRNA expression of CK-12. ResultsNo morphology change was observed in groups A and B.Two different cell clones were found in group C.No.1 selected clone showed a flagstone-like appearance that was similar to that of corneal epithelial cells;No.2 selected clone showed a net-like appearance,with 3-7 cell processes.The Western blot results showed the Pax6 protein expression in 2 clones of group C,but no expression in groups A and B; and CK-12 protein expression was only observed in No.1 selected clone of group C,and no expression in the others.The real-time fluorescence quantitative PCR results showed that the CK-12 mRNA expression level of No.1 selected clone of group C was 8.64±0.73,which was significantly higher than that of No.2 selected clone of group C (0.55±0.42),group B (1.36±0.40),and group A (1.00±0.00) (P<0.05),and there was no significant difference among groups A,B and No.2 selected clone of group C (P>0.05). ConclusionPax6 gene transfection could induce differentiation of ADMSCs into corneal epithelium-like cells which express CK-12 at both the mRNA and protein levels.This result provides a promising strategy of generating corneal epithelilcm-like cells for construction of tissue engineered cornea.
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.
The decrease of corneal stiffness is the key factor leading to keratoconus, and the corneal collagen fiber stiffness and fiber dispersion are closely related to the corneal biomechanical properties. In this paper, a finite element model of human cornea based on corneal microstructure, namely collagen fiber, was established before and after laser assisted in situ keratomileusis (LASIK). By simulating the Corvis ST process and comparing with the actual clinical results, the hyperelastic constitutive parameters and corneal collagen fiber stiffness modulus of the corneal material were determined before and after refractive surgery. After LASIK, the corneal collagen fiber stiffness modulus increased significantly, and was highly correlated with central corneal thickness (CCT). The predictive relationship between the corneal collagen fiber stiffness modulus and the corresponding CCT before and after surgery was: k1 before = exp(9.14 − 0.009CCTbefore), k1 after = exp(8.82 − 0.008CCTafter). According to the results of this study, the central corneal thickness of the patient can be used to estimate the preoperative and postoperative collagen fiber stiffness modulus, and then a personalized corneal model that is more consistent with the actual situation of the patient can be established, providing a theoretical reference for more accurately predicting the safe surgical cutting amount of the cornea.
Objective To analyze the risk factors for persistent corneal epithelial defects (PCED) after pars plana vitrectomy (PPV) in patients with proliferative diabetic retinopathy (PDR). Methods A total of 201 PDR patients (201 eyes) who received PPV were enrolled in this retrospective study. There were 86 males (86 eyes) and 115 females (115 eyes). The patients aged from 30 to 81 years, with the mean age of (57.94±9.65) years. Among them, 159 patients were ≥50 years of age, and 42 patients were ＜50 years of age. There were 36 patients with HbA1c ＜7.0%, 165 patients with HbA1c ≥7.0%. There were 93 right eyes and 108 left eyes. There were 93 right eyes and 108 left eyes. The diabetic retinopathy stages were as follows: stage Ⅳ in 24 eyes, stage Ⅴ in 78 eyes and stage Ⅵ in 99 eyes. The operation time was ranged from 1 to 4 hours, with an average of 2 hours. Among the 201 eyes, corneal epidermis were scraped on 25 eyes; 70 eyes were combined with cataract surgery; a laser photocoagulation count ＜1000 points was performed in 78 eyes, and ＞1000 points were performed in 123 eyes. Sixty-one eyes involved intravitreal silicone oil tamponade, 18 eyes involved intravitreal tamponade with C3F8, and 122 eyes were not involved with intraocular tamponade. Postoperative persistent intraocular hypertension was defined as an intraocular pressure (IOP) ≥21 mmHg (1 mmHg=0.133 kPa) after PPV with necessary treatment using IOP-lowering medications for ≥2 weeks. The diagnostic criteria for corneal epithelial defects were taken from the Expert Consensus on Clinical Diagnosis and Treatment of Corneal Epithelial Defect in China (2016). The corneal epithelial defect was diagnosed as PCED if it was treated with common methods such as a lacrimal substitute or corneal contact lens, but showed no improvement and no signs of healing for ≥2 weeks. The incidence of PCED after eye surgery was recorded and its related risk factors were analyzed. A multivariate logistic regression was used to analyze the risk factors for PCED, which were expressed as a odds ratio (OR) and a 95% confidence interval (CI). Results Of 201 eyes, 16 eyes (7.96%) presented with PCED after surgery and 185 eyes (92.04%) with no PCED. There was no significant difference in the age, sex, and eyes between the patients with or without PCED (χ2=6.548, 0.927, 0.044; P=0.011, 0.336, 0.833). A multivariate logistic regression showed that intraoperative epithelial debridement (OR=13.239, 95%CI 2.999−58.442, P=0.001), intraoperative treatment in combination with cataract surgery (OR=7.448, 95%CI 1.975−28.091, P=0.003), intravitreal tamponade with C3F8 (OR=11.344, 95%CI 2.169−59.324, P=0.004), and postoperative persistent intraocular hypertension (OR=10.462, 95%CI 2.464−44.414, P=0.001) were risk factors for PCED after PPV. Conclusion Intraoperative epithelial debridement, intraoperative treatment in combination with cataract surgery, intravitreal tamponade with C3F8, and postoperative persistent intraocular hypertension are risk factors for PCED in patients with PDR after PPV.
Objective To review research progress of corneal tissueengineering.Methods The recent articles on corneal tissue engineering focus on source and selection of corneal cells, the effects of growth factors on culture of corneal cells in vitro. The preparation and selection of three-dimensional biomaterial scaffolds and their b and weak points were discussed. Results The corneal tissue engineering cells come from normal human corneal cells. The embryo corneal cell was excellent. Several kinds of growth factors play important roles in culture, growth and proliferation of corneal cell, and incroporated into matrix.Growth factors including basic fibroblast growth factor, keratinocyte growth factor, transforming growth factor β1 and epidermal growth factor was favor to corneal cell. Collagen, chitosan and glycosaninoglycans were chosen as biomaterial scaffolds. Conclusion Human tissue engineering cornea can be reconstructed and transplanted. It has good tissue compatibility and can be used as human corneal equivalents.
Objective To observe the biocompatibility of the acellular corneal stroma materials prepared by three different methods. Methods Three different serial digestion methods were used to produce the acellular corneal stroma materials. The biocompatibility of the materials was investigated by the cell seeding and the materials were implanted into the rabbit corneal stroma layer. Results The cells in the materials 1 and 2 were not decellularized completely. The rabbit corneal fibroblasts died on the materials 1 and 2 after the cell seeding for 3-4 days. An obvious rejection could be observed after the implantation. The cells in material 3 were decellularized completely and the collagen fibers or elastic fibers were reserved integrally，showing a typical three-dimensional net work. The rabbit corneal fibroblasts could expand on the materials in vitro. No obvious rejection could be observed and the materials were gradually absorbed. Conclusion The acellular porcine cornea stroma materials prepared by trypsin-Dnase-Rnase are suitable for reconstruction of the tissue engineered cornea.
As the most important refraction part in the optical system, cornea possesses characteristics which are important parameters in ophthalmology clinical surgery. During the measurement of the cornea in our study, we acquired the corneal data of Orbscan Ⅱ corneal topographer in real time using the Hook technology under Windows, and then took the data into the corneal analysis software. We then further analyzed and calculated the data to obtain individual Q-value of overall corneal 360 semi-meridian. The corneal analysis software took Visual C++6.0 as development environment, used OpenGL graphics technology to draw three-dimensional individual corneal morphological map and the distribution curve of the Q-value, and achieved real-time corneal data query. It could be concluded that the analysis would further extend the function of the corneal topography system, and provide a solid foundation for the further study of automatic screening of corneal diseases.