Comprehensive dry eye therapy: overcoming ocular surface barrier and combating inflammation, oxidation, and mitochondrial damage.

BACKGROUND: Dry Eye Disease (DED) is a prevalent multifactorial ocular disease characterized by a vicious cycle of inflammation, oxidative stress, and mitochondrial dysfunction on the ocular surface, all of which lead to DED deterioration and impair the patients' quality of life and social functioning. Currently, anti-inflammatory drugs have shown promising efficacy in treating DED; however, such drugs are associated with side effects. The bioavailability of ocular drugs is less than 5% owing to factors such as rapid tear turnover and the presence of the corneal barrier. This calls for investigations to overcome these challenges associated with ocular drug administration. RESULTS: A novel hierarchical action liposome nanosystem (PHP-DPS@INS) was developed in this study. In terms of delivery, PHP-DPS@INS nanoparticles (NPs) overcame the ocular surface transport barrier by adopting the strategy of "ocular surface electrostatic adhesion-lysosomal site-directed escape". In terms of therapy, PHP-DPS@INS achieved mitochondrial targeting and antioxidant effects through SS-31 peptide, and exerted an anti-inflammatory effect by loading insulin to reduce mitochondrial inflammatory metabolites. Ultimately, the synergistic action of "anti-inflammation-antioxidation-mitochondrial function restoration" breaks the vicious cycle associated with DED. The PHP-DPS@INS demonstrated remarkable cellular uptake, lysosomal escape, and mitochondrial targeting in vitro. Targeted metabolomics analysis revealed that PHP-DPS@INS effectively normalized the elevated level of mitochondrial proinflammatory metabolite fumarate in an in vitro hypertonic model of DED, thereby reducing the levels of key inflammatory factors (IL-1ß, IL-6, and TNF-α). Additionally, PHP-DPS@INS strongly inhibited reactive oxygen species (ROS) production and facilitated mitochondrial structural repair. In vivo, the PHP-DPS@INS treatment significantly enhanced the adhesion duration and corneal permeability of the ocular surface in DED mice, thereby improving insulin bioavailability. It also restored tear secretion, suppressed ocular surface damage, and reduced inflammation in DED mice. Moreover, it demonstrated favorable safety profiles both in vitro and in vivo. CONCLUSION: In summary, this study successfully developed a comprehensive DED management nanosystem that overcame the ocular surface transmission barrier and disrupted the vicious cycle that lead to dry eye pathogenesis. Additionally, it pioneered the regulation of mitochondrial metabolites as an anti-inflammatory treatment for ocular conditions, presenting a safe, efficient, and innovative therapeutic strategy for DED and other inflammatory diseases.

Evaluating the Efficacy of Polyglycolic Acid-Loading Tetrandrine Nanoparticles in the Treatment of Dry Eye.

INTRODUCTION: Dry eye disease (DED) is a multifactor-induced disease accompanied by increased osmolarity of the tear film and inflammation of the ocular surface. Traditional anti-inflammation agent corticosteroids applied in DED treatment could result in high intraocular pressure, especially in long-term treatment. Therefore, we explored a nano drug that aimed to block the formation pathway of DED which had anti-inflammatory, sustained release, and good biocompatibility characteristics in this study. METHODS: We prepared a novel nanomedicine (Tet-ATS@PLGA) by the thin film dispersion-hydration ultrasonic method and detected its nanostructure, particle size, and zeta potential. Flow cytometry was used to detect the cell survival rate of each group after 24 h of drug treatment on inflammed Statens Seruminstitut Rabbit Corneal (SIRC) cells. Observed and recorded corneal epithelial staining, tear film rupture time, and Schirmer test to detect tear secretion on the ocular surface of rabbits. The corneal epithelial thickness, morphology, and number of bulbar conjunctival goblet cells were recorded by H&E staining. Finally, we detected the expression of VEGF, IL-1ß, PGE2, and TNF-α by cellular immunofluorescence staining and enzyme-linked immunosorbent assay (ELISA). RESULTS: The encapsulation efficiency and drug loading of Tet-ATS@PLGA were 79.85% and 32.47%, respectively. At eye surface temperature, Tet can easily release from Tet-ATS@PLGA while that it was difficult to release at storage temperature and room temperature. After 2 weeks medication, Tet-ATS@PLGA can effectively improve the tear film rupture time and tear secretion time in a DED model (p <0.05). Compared with the normal group (62.34 ± 4.86 mm), the thickness of corneal epithelium in ATS (29.47 ± 3.21 mm), Tet-ATS (46.23 ± 2.87 mm), and Tet-ATS@PLGA (55.76 ± 3.95 mm) gradually increased. Furthermore, the flow cytometry indicated that Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory SIRC cells, and the cellular immunofluorescence and ELISA experiments showed that the expression intensity of inflammatory factors such as VEGF, IL-1ß, PGE2, and TNF-α decreased in this process. Interestingly, Tet also had the effect of reducing intraocular pressure. CONCLUSION: Tet-ATS@PLGA can effectively promote the apoptosis of inflammatory corneal epithelial cells, thus inhibiting the expression of inflammatory factors to block the formation of DED and improve the secretion of tear on the ocular surface.

Analysis of potential impact factors of corneal biomechanics in myopia.

PURPOSE: To investigate potential impact factors associated with corneal biomechanical properties in Chinese myopia and further to investigate quantifying corneal biomechanics in clinical work. METHODS: Three hundred fifty-five eyes from 181 healthy myopic subjects with a mean age of 25.1 ± 9.4 were recruited in this study. Each patient carried out a comprehensive ophthalmic examination, including corneal hysteresis(CH), corneal resistance factor(CRF), central corneal thickness(CCT), axial length(AL), intraocular pressure(IOP), spherical equivalence(SE) and corneal curvature (K). CH and CRF were measured with the ocular response analyzer(ORA). To analyze the corneal biomechanical characteristics of myopia patients and their association with other parameters. RESULT: The multiple linear regression analysis showed that CH was positively associated with CCT, and corneal curvature (all with P < 0.05) and negatively associated with SE and AL)(all with P < 0.05); CRF was positively correlated with CCT, corneal curvature and IOP(all with P < 0.05), but negatively correlated with SE and AL(all with P < 0.05). The CH and CRF values in children group were both higher than adults group (≥ 18 years old) (P < 0.05), but it attributed to that the CCT of children was thicker than adults. Excluding factor of CCT, there was no significant difference in CH and CRF between children group and adult group. Excluding factor of CCT, there was no significant difference in CH and CRF among different stage of age (age 18-48). CONCLUSION: The CCT played the most important role of affecting the CH and CRF. The SE, corneal curvature, AL and IOP had a certain influence on corneal biomechanics. Whether the CH and CRF values of individual patient are normal in clinical work, it should refer to the CH and CRF values corresponding CCT sectional range and SE.

Liposome-trimethyl chitosan nanoparticles codeliver insulin and siVEGF to treat corneal alkali burns by inhibiting ferroptosis.

Alkali burns are potentially blinding corneal injuries. Due to the lack of available effective therapies, the prognosis is poor. Thus, effective treatment methods for corneal alkali burns are urgently needed. Codelivery nanoparticles (NPs) with characteristics such as high bioavailability and few side effects have been considered effective therapeutic agents for ocular diseases. In this study, we designed a new combination therapy using liposomes and trimethyl chitosan (TMC) for the codelivery of insulin (INS) and vascular endothelial growth factor small interfering RNA (siVEGF) to treat alkali-burned corneas. We describe the preparation and characterization of siVEGF-TMC-INS-liposome (siVEGF-TIL), drug release characteristics, intraocular tracing, pharmacodynamics, and biosafety. We found that siVEGF-TIL could inhibit oxidative stress, inflammation, and the expression of VEGF in vitro and effectively maintained corneal transparency, accelerated epithelialization, and inhibited corneal neovascularization (CNV) in vivo. Morever, we found that the therapeutic mechanism of siVEGF-TIL is possibly relevant to the inhibition of the ferroptosis signaling pathway by metabolomic analysis. In general, siVEGF-TIL NPs could be a safe and effective therapy for corneal alkali burn.

Physiological and transcriptomic responses to cold waves of the most cold-tolerant mangrove, Kandelia obovata.

Mangrove forests inhabit tropical or subtropical intertidal zones and have remarkable abilities in coastline protection. Kandelia obovata is considered the most cold-tolerant mangrove species and has been widely transplanted to the north subtropical zone of China for ecological restoration. However, the physiological and molecular mechanisms of K. obovata under colder climate was still unclear. Here, we manipulated the typical climate of cold waves in the north subtropical zone with cycles of cold/recovery and analyzed the physiological and transcriptomic responses of seedlings. We found that both physiological traits and gene expression profiles differed between the first and later cold waves, indicating K. obovata seedlings were acclimated by the first cold experience and prepared for latter cold waves. 1,135 cold acclimation-related genes (CARGs) were revealed, related to calcium signaling, cell wall modification, and post-translational modifications of ubiquitination pathways. We identified the roles of CBFs and CBF-independent transcription factors (ZATs and CZF1s) in regulating the expression of CARGs, suggesting both CBF-dependent and CBF- independent pathways functioned in the cold acclimation of K. obovata. Finally, we proposed a molecular mechanism of K. obovata cold acclimation with several key CARGs and transcriptional factors involved. Our experiments reveal strategies of K. obovata coping with cold environments and provide prospects for mangrove rehabilitation and management.

Using Convolutional Neural Network as a Statistical Algorithm to Explore the Therapeutic Effect of Insulin Liposomes on Corneal Inflammation.

Aiming at the disadvantages of easy recurrence of keratitis, difficult eradication by surgery, and easy bacterial resistance, insulin-loaded liposomes were prepared, and convolutional neural network was used as a statistical algorithm to build SD rat corneal inflammation model and study insulin-loaded liposomes, alleviating effect on corneal inflammatory structure in SD rats. The INS/PFOB@LIP was developed by means of thin-film dispersive phacoemulsification, its structure was monitored using a transmission electron microscope, particle size and appearance potential were monitored using a Malvern particle sizer, and ultraviolet consumption spectrum was monitored using a UV spectrophotometer. The encapsulation rate, drug loading, and distribution of insulin liposomes in rat corneal inflammatory model were measured and calculated. The cytotoxicity of liposome materials was evaluated by CCK-8 assay, and the toxic effects of insulin and insulin liposomes on cells were detected. The cornea of SD rats was burned with NaOH solution (1 mol/L), and the SD rat corneal inflammation model was created. The insulin liposome was applied to the corneal inflammation model, and the therapeutic effect of insulin liposome on corneal inflammation was evaluated by slit lamp, corneal immunohistochemistry, corneal HE staining, and corneal Sirius red staining. Insulin-loaded liposomes were successfully constructed with an average particle size of (130.69 ± 3.87) nm and a surface potential of (-38.24 ± 2.57) mV. The encapsulation rate of insulin liposomes was (48.89 ± 1.24)%, and the drug loading rate was (24.45 ± 1.24)%. The SD rat corneal inflammation model was successfully established. After insulin liposome treatment, the staining area of corneal fluorescein sodium was significantly reduced, the corneal epithelium was significantly thickened, the content of corneal collagen was increased, the expression of inflammatory factors was significantly reduced, and new blood vessels (corneal neovascularization, CNV) growth was inhibited.

Combination Nanotherapeutics for Dry Eye Disease Treatment in a Rabbit Model.

PURPOSE: Anti-inflammation is essential for dry eye disease. Traditional anti-inflammation agent corticosteroids applied in dry eye disease (DED) treatment could result in high intraocular pressure, especially in long-term treatment. Thus, we have prepared a liposome loading 1-bromoheptadecafluorooctane and tetrandrine (PFOB@LIP-Tet) to treat DED via anti-inflammation that hardly affects intraocular pressure in this study, which provided another therapy strategy for dry eye disease. METHODS: We firstly detected the physicochemical properties of PFOB@LIP-Tet. Next, we tested the biosafety of synthesized liposomes for corneal epithelium. Then, we explored the accumulations and distribution of PFOB@LIP-Tet both in cellular and animal models. And then, we assessed the therapeutic effects of PFOB@LIP-Tet formulations by laboratory and clinical examinations. Last, we examined the changes in eye pressure before and after treatment. RESULTS: PFOB@LIP-Tet and Tet showed a characteristic absorption peak at 282 nm while PFOB@LIP did not. Large amounts of PFOB@LIP-Tet remained on the ocular surface and accumulated in the corneal epithelial cells in DED rabbits. Corneal staining scores of DED rabbits respectively treated by ATS, PFOB@LIP-ATS, Tet-ATS and PFOB@LIP-Tet-ATS for seven days were 3.7±0.5, 3.2±0.4, 1.5±0.5 and 0.5±0.5. The expressions of related cytokines were correspondingly downregulated significantly, indicating that the inflammation of DED was successfully suppressed. The intraocular pressure changes of DED rabbits before and after treatment by PFOB@LIP-Tet showed no statistical significance. CONCLUSION: We successfully synthesized PFOB@LIP-Tet, and it could effectively treat dry eye disease via anti-inflammation but hardly affected the intraocular pressure.

Polar Value Analysis of Low to Moderate Astigmatism with Wavefront-Guided Sub-Bowman Keratomileusis.

PURPOSE: To evaluate the astigmatic outcomes of wavefront-guided sub-Bowman keratomileusis (WFG-SBK) for low to moderate myopic astigmatism. METHODS: This study enrolled 100 right eyes from 100 patients who underwent WFG-SBK for the correction of myopia and astigmatism. The polar value method was performed with anterior and posterior corneal astigmatism measured with Scheimpflug camera combined with Placido corneal topography (Sirius, CSO) and refractive astigmatism preoperatively and 1 month, 3 months, and 6 months postoperatively. RESULTS: Similar results for surgically induced astigmatism (SIA) and error of the procedure in both anterior corneal astigmatism (ACA) and total ocular astigmatism (TOA). There was a minor undercorrection of the cylinder in both ACA and TOA. Posterior corneal astigmatism (PCA) showed no significant change. CONCLUSIONS: Wavefront-guided SBK could provide good astigmatic outcomes for the correction of low to moderate myopic astigmatism. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after WFG-SBK for myopic astigmatism. Polar value analysis can be used to guide adjustments to the treatment cylinder alongside a nomogram designed to optimize postoperative astigmatic outcomes in myopic WFG-SBK.

The Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Anterior Segment.

Purpose. To evaluate the safety of high-intensity focused ultrasound keratoplasty as a treatment for presbyopia by examining its effect on the rabbit anterior segment. Methods. The right corneas of 36 New Zealand rabbits were treated with HIFU keratoplasty. The animals were sacrificed at 1, 7, 15, 30, 60, and 90 days after operation. Collagen type I, MMP-2, and MMP-9 were evaluated using immunohistochemistry. For the detection of apoptosis, the TUNEL method was applied. The SOD and MDA levels were analyzed with assay kits. Results. Collagen type I, MMP-2, and MMP-9 levels were altered after the operation but returned to normal within 90 days. The apoptotic index (AI) of the corneal cells decreased from 1 to 30 days gradually. No apoptosis was observed in the epithelial cells of the lens, and the SOD and MDA levels were normal at any time point. Conclusion. After HIFU keratoplasty, the histomorphology of the cornea changed, the corneal collagen type I levels decreased, the corneal MMP-2 and MMP-9 levels increased, and the corneal cells underwent apoptosis for a period of time. Ninety days after the operation, the levels returned to normal, and the lenses were not affected. Thus, HIFU presents good biological safety for eyes.

Low-intensity focused ultrasound (LIFU)-induced acoustic droplet vaporization in phase-transition perfluoropentane nanodroplets modified by folate for ultrasound molecular imaging.

The commonly used ultrasound (US) molecular probes, such as targeted microbubbles and perfluorocarbon emulsions, present a number of inherent problems including the conflict between US visualization and particle penetration. This study describes the successful fabrication of phase changeable folate-targeted perfluoropentane nanodroplets (termed FA-NDs), a novel US molecular probe for tumor molecular imaging with US. Notably, these FA-NDs can be triggered by low-intensity focused US (LIFU) sonication, providing excellent US enhancement in B-mode and contrast-enhanced US mode in vitro. After intravenous administration into nude mice bearing SKOV3 ovarian carcinomas, 1,1'-dioctadecyl-3,3,3',3' -tetramethylindotricarbocya-nine iodide-labeled FA-NDs were found to accumulate in the tumor region. FA-NDs injection followed by LIFU sonication exhibited remarkable US contrast enhancement in the tumor region. In conclusion, combining our elaborately developed FA-NDs with LIFU sonication provides a potential protocol for US molecular imaging in folate receptor-overexpressing tumors.

Keratorefractive Effect of High Intensity Focused Ultrasound Keratoplasty on Rabbit Eyes.

Purpose. To evaluate high intensity focused ultrasound (HIFU) as an innovation and noninvasive technique to correct presbyopia by altering corneal curvature in the rabbit eye. Methods. Eighteen enucleated rabbit eyes were treated with a prototype HIFU keratoplasty. According to the therapy power, these eyes were divided three groups: group 1 (1 W), group 2 (2 W), and group 3 (3 W). The change in corneal power was quantified by a Sirius Scheimpflug camera. Light microscopy (LM) and transmission electron microscopy (TEM) were performed to determine the effect on the corneal stroma. Results. In the treated eyes, the corneal curvature increases from 49.42 ± 0.30 diopters (D) and 48.00 ± 1.95 D before procedure to 51.37 ± 1.11 D and 57.00 ± 1.84 D after HIFU keratoplasty application in groups 1 and 3, respectively. The major axis and minor axis of the focal region got longer when the powers of the HIFU got increased; the difference was statistically significant (p < 0.05). LM and TEM showed HIFU-induced shrinkage of corneal stromal collagen with little disturbance to the underlying epithelium. Conclusions. We have preliminarily exploited HIFU to establish a new technique for correcting presbyopia. HIFU keratoplasty will be a good application prospect for treating presbyopia.

[Evaluation of quality of vision in early stage after sub-bowman keratomileusis].

OBJECTIVE: To assess the quality of vision in the early stage after sub-bowman keratomileusis (SBK) for the correction of moderate and high myopia. METHODS: Retrospective case series. Sixty eight myopic eyes of 35 consecutive patients in Chongqing Medal Eye Institute from May to November 2011 were enrolled in this study. All patients were evaluated at 2 weeks, 1 and 3 months postoperatively. The main measurements included visual acuity, corneal and total optical wavefront aberration, photopic and mesopic contrast sensitivity. RESULTS: The median values of preoperative uncorrected central visual acuity (UCVA) and best corrected visual acuity (BCVA) were 0.05 and 1.00, respectively. The median value of postoperative UCVA was 1.20. There was no significant difference between the preoperative and postoperative anterior corneal total aberration (F = 0.712, P > 0.05). Compared with preoperative value (0.47 ± 0.17)µm, the corneal high orders aberrations in 2 weeks after SBK (1.37 ± 0.72) µm increased by 3 times. The total optical aberrations in 2 weeks after SBK (0.99 ± 0.58) µm decreased to one-eighth of preoperative measurements (8.26 ± 2.93) µm. Compared with preoperative value (0.30 ± 0.12)µm, the total high order aberrations in 2 weeks after SBK (0.46 ± 0.19) µm increased by 1.5 times. Although photopic and mesopic contrast sensitivity fluctuated mildly after SBK, the measurements did not decline significantly. Compared with preoperative data, mesopic contrast sensitivity at 3 months increased 0.294 (F = 20.88,P < 0.01) and 0.296 (F = 13.64, P < 0.01) at 12 and 18 c/d, respectively. CONCLUSION: Patients could obtain good quality of vision at the early stage after SBK.

Minor influence of sub-bowman keratomileusis on the posterior corneal surface at early stage.

PURPOSE: To evaluate the changes in posterior corneal surface (Q value and elevation) measured with Pentacam after femtosecond laser assisted Sub-Bowman Keratomileusis (SBK). METHODS: The Q values and elevation of posterior corneal surface were determined in 166 myopic/myopic astigmatism eyes of 88 patients using Scheimpflug imaging (Pentacam; Oculus, Wetzlar, Germany), which estimates asphericity and elevation for several areas of cornea analysed (Q value: 6, 7, 8 and 9 mm; elevation: 2, 4, 6 and 8 mm) before 1 and 3 months after SBK. The correlations between the changes of Q value or elevation and the mean preoperative spherical equivalent (SE), central corneal thickness (CCT), central ablation depth (AD), estimated residual bed thickness (RBT) and RBT/CCT ratio were investigated. RESULTS: Meridian and area differences in Q of posterior surface have been showed. Two major meridians (horizontal/vertical) present the change of significant negative direction before surgery (all p < 0.001), but the alteration of significant positive direction for all post-SBK follow-up visits (all p < 0.05). There was no statistically significant difference in posterior elevation at 2 mm zone (horizontal meridian: p = 0.439; vertical meridian: p = 0.233). Compared with preoperation, minor but significant forward displacements were found in posterior elevation at 4 and 6 mm areas of cornea analyzed (horizontal meridian: all p < 0.001; vertical meridian: p < 0.001, p = 0.024, respectively). However, posterior elevation in two meridians (horizontal/vertical) at 8 mm region was displayed significant backward shift (p = 0.001, p < 0.001, respectively). The Pearson correlation test showed no significant correlation between the changes in the Q values and elevation data in vast majority of areas of cornea analyzed and the SE, CCT, AD, RBT, and RBT/CCT ratio at 1 and 3 months after surgery (all p > 0.05). CONCLUSIONS: The posterior corneal surface showed central flattening and peripheral steepening at early stage post-SBK. To combine the asphericity with the elevation of the posterior corneal surface can overall and accurately understand the posterior corneal shape and its variations after refractive surgery.

Inhibition effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits.

PURPOSE: To observe the inhibitory effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits. MATERIALS AND METHODS: Twenty-seven healthy New Zealand rabbits were selected and underwent Epi-LASIK surgery. According to a self comparison principle, these rabbits were randomly divided into three groups. The first group was treated with tetrandrine eye drops (Tet), the second (negative control, NC) group was treated with pure solvent, and the third group was treated with fluorometholone (FML) solvent. Haze grades of each group were respectively observed by slit lamp exam at half-month, one month, and two months after surgery. After corneal tissues were extracted, optical microscopy, Sirius Red staining, immunohistochemistry, and semi-quantitative RT-PCR tests were conducted, in order to test collagen formation of operated eyes after surgery and expression of transformation growth factor beta 2 (TGF-ß(2)) in corneal stroma. RESULTS: At a half month and one month after surgery, haze grades and type III collagen expression in Tet and FML groups were significantly lower than that in NC groups (P < 0.01). No statistical difference was observed between Tet and FML groups. Immunohistochemistry showed that, at each time point after surgery, expressions of TGF-ß(2) protein in Tet and FML groups were significantly lower than that in the NC group (P < 0.01), whereas there was no statistical difference between Tet and FML groups. The expression level of TGF-ß(2) protein increased, reaching its peak one month after surgery. RT-PCR also showed that, at each point after surgery, the TGF-ß(2) mRNA expression in Tet and FML groups was lower than that in the NC group (P < 0.01), nevertheless no statistical difference was observed between Tet and FML groups. CONCLUSIONS: Like FML, Tet could inhibit haze formation in rabbits after Epi-LASIK surgery, possible through TGF-ß(2)-collagen-III pathway.

[Inhibitory effect of diclofenac sodium on the proliferation of rabbit corneal epithelial cells in vitro].

PURPOSE: To investigate the inhibitory effect of diclofenac sodium on rabbit corneal epithelial cells (RCECs) in vitro and explore its pharmacological mechanism. METHODS: The fresh rabbit cornea was cultured to obtain the primary RCECs, and RCECs of passage 2 were used in this research. The cells were divided into experimental groups, the cells in which were incubated with different concentrations (18.18, 27.27, 36.36, 45.45, 54.55 µg/ml) of diclofenac sodium, and control group. The effect of diclofenac sodium on the proliferation of cells was measured by methyl thiazolyl thiazolium (MTT) assay 24, 48 and 72 h after incubation. While the RCECs were divided into experimental groups, the cells in which were incubated with 9 and 12.5 µg/ml diclofenac sodium, and control group. The cell cycle and apoptotic rate were observed by flow cytometer. RESULTS: MTT assay showed that diclofenac sodium had obvious inhibitory effect on RCECs, and the inhibition rate was increasing along with the increasing concentration of diclofenac sodium and the incubation time(P<0.05). Flow cytometer showed that after incubation with diclofenac sodium, the cells in G0/G1 phase were obviously increased, and the apoptosis cusp and apoptotic rate were increased. CONCLUSION: Diclofenac sodium exerts significant inhibitory effect on RCECs in a dosage-dependent manner, and it may function by inducing cell apoptosis and ceasing cell cycles.

[The early post-operative wound healing mode study of the rabbit cornea after flap-free epiploic laser in-situ keratomileusis].

OBJECTIVE: To evaluate the wound healing mode of rabbit corneal epithelium after Epi-LASIK(epiplolic laser in-situ keratomileusis) and Flap-free Epi-LASIK(Flap-free epiploic laser in-situ keratomileusis). METHODS: Twenty-four New Zealand white rabbits (48 eyes) were randomly divided into four groups. There were six rabbits in every group, which were randomly treated with Epi-LASIK in one eye and Flap-free Epi-LASIK in the other by VISX20/20 excimer laser. Other three rabbits (6 eyes) without any treatment were used as control. The corneal epithelium wound healing mode was observed at 1, 2, 4, 7 days after surgery by light microscope and electron microscope. The number of keratocytes cells in the central anterior stroma were counted by hematoxylin-eosin-stained. The expression of basic fibroblast growth factor (bFGF) in corneal stroma were assessed by Immunohistochemistry staining. Cornea stromal cell apoptosis was evaluated by terminal deoxyribonuc-1-eotidyl transferase-mediated deoxynuridine triphosphate nick end labeling (TUNEL) assay.All the data was analysised by t-test to evaluate the different of wound healing mode after Epi-LASIK and Flap-free Epi-LASIK. RESULTS: The findings of light microscope and electron microscope investigation demonstrated that, at the first day after surgery, there was one layer of neogenesis of the corneal epithelial cells covering the area of surgery in Flap-free Epi-LASIK specimens. It would increase gradually after 7 days. At the first day after the surgery, the base membrane of the corneal epithelium was tightly attached to the stroma in Epi-LASIK specimens. At the second day after the surgery, there was edema observed on the epithelium flap in the Epi-LASIK specimens. There were more keratocytes cells found at 4 days after surgery in Flap-free Epi-LASIK group (33.85 +/- 3.39) than that in Epi-LASIK group (t = -2.315, P < 0.05). The expression of bFGF in Flap-free Epi-LASIK group at 2, 4 days after surgery were 101.75 +/- 8.07 and 110.56 +/- 9.00, which were more than Epi-LASIK (t = -2.339, -2.396, P < 0.05). There was less keratocyte apoptosis cells in Flap-free Epi-LASIK group than Epi-LASIK group at 2, 4 days after surgery (t = 3.332, 2.989, P < 0.05). CONCLUSIONS: Due to the specific way of the epithelium removal resulting in the more rapid epithelium healing, the Flap-free Epi-LASIK technique is advantageous in reducing the stimulative symptoms after the surgery. It's also beneficial for the corneal wound healing.

[The structure and viability analysis of corneal epithelial flap in the rabbit cornea after Epi-LASIK].

OBJECTIVE: To evaluate the changes of ultrastructure and viability in the rabbit corneal epithelial flap after Epi-LASIK (epiploic laser in-situ keratomileusis) surgery and its effect on keratocyte apoptosis and proliferation of peripheral corneal epithelium (out of corneal epithelial flap). METHODS: Fifty-eighty eyes of 29 New Zealand rabbits were used, Epi-LASIK was performed in 28 eyes and Photorefractive keratectomy (PRK) was carried out in 24 eyes. treated-eyes were randomly divided into four groups and were sacrificed at 1, 3, 5, 7 days after surgery, six eyes without treatment were served as blank controls. Histological structure from The specimens of Epi-LASIK and controls eyes were assessed by light, transmission electron microscopy; epithelial cells viability were assessed by enzyme-histochemistry and Immunohistochemistry staining (proliferating cell nuclear antigen, PCNA) were performed to detect proliferation of peripheral corneal epithelial cells. Apoptotic cells were detected by TUNEL assay (TdT-mediated dUTP nick-end labeling) from the specimens of Epi-LASIK and PRK. RESULTS: The study from Transmission electron microscopy demonstrated that epithelial flap separated by KM5000D type epikeratome retained its typical stratification and integrity and the basement membrane including lamina densa and lamina lucida were compaginated with stroma. The expression of ATP enzyme, G-6-P enzyme from epithelial flap to peripheral epithelium of Epi-LASIK-treated eyes were (79%, 58%, 69%, 86%), (79%, 63%, 77%, 97%) at 1, 3, 5, 7 days after surgery respectively. There was no statistically significant difference in the cell Viability and the number of PCNA in peripheral epithelial cells among four Epi-LASIK groups and control group. At 1 day after surgery, no difference in TUNEL positive cells were seen between specimens of Epi-LASIK (3.429 +/- 1.693) and PRK (3.796 +/- 1.998); At 3, 5, 7 days, there was a significant difference in the number of keratocyte apoptosis in PRK compared to Epi-LASIK specimens. CONCLUSIONS: Epithelial flap separated by KM5000D type epikeratome retained its typical stratification and integrity. The flap keeps high viability and no peripheral epithelial cell proliferation and therefore it may play a role in the inhibition of keratocyte apoptosis.

[Advances on surgeries to correct presbyopia].

Surgeries to correct presbyopia are in its initial stage, Conductive Keratoplasty and LASIK multifocal ablation patterns are newly emerging methods. Multifocal IOL or Accommodative IOL provides new method to compensate accommodation of presbyopes, studies on scleral surgeries to restore accommodation are also in progress.

[An analysis about the safe range of thickness of the residual corneal stroma bed after LASIK].

OBJECTIVE: To ascertain the safe range of thickness of the residual corneal stroma bed and the length of stable time after LASIK operation. METHODS: Two hundred and twenty seven eyes were randomly selected from cases treated with LASIK in 2000. The posterior curvature of cornea was measured by Obscan II preoperatively and 1, 2, 3, 6 months, 1 year and 2 year postoperatively. These data were compared and analyzed. RESULTS: Ectasia of central corneal posterior surface was detected at different degrees in all cases at the early postoperative period after LASIK. Ectasia was more prominent in eyes with thinner corneal stroma bed (< 300 microm). In eyes with thicker corneal stroma, ectasia remained stable or reverting obviously during the first year. The posterior curvature of cornea had no significant difference between 1 year and 2 year after operation in all cases. CONCLUSIONS: Ectasia of corneal posterior surface presents in the early postoperative period after LASIK. It is safer to reserve more than 300 microm of the corneal stroma bed. The posterior curvature of cornea of all cases remains stable after one year postoperatively.

[An analysis of measurement error in Orbscan topography system].

OBJECTIVE: To discuss the measurement error and the influence factor of Orbscan Topography to provide more accurate data for clinical application. METHODS: Orbscan Topography System and A-scan ultrasonography were used to measure the corneal thickness and anterior chamber depths pre-operatively and post-operatively, including 200 cases (400 eyes) undergoing laser in situ keratomileusis (Lasik) and 50 cases (100 eyes) undergoing photorefractive keratectomy (PRK). The curvature of posterior corneal surface was measured by Orbscan topography before and after the operations, and the result of measurement was compared. RESULTS: Pre-operatively, the value of corneal thickness was (18.83 - 24.29) microm lower measured by Orbscan topography than that by A-ultrasonography, and post-operatively the value was (56.32 - 139.52) micro m lower than that by A-ultrasonography. The postoperative value was obviously higher than the pre-operative one. The value of central anterior chamber depth was (0.16 - 0.25) mm lower measured by Orbscan system than that by A-ultrasonography pre-operatively and post-operatively. There was no clinical significance. The difference in the comparison of posterior corneal surface curvature before and after Lasik was -0.60 D measured by Orbscan System. The difference in the comparison of posterior corneal surface curvature before and after PRK was -0.51 D in the lower diopter group and -1.12 D in medium diopter group. CONCLUSIONS: It is necessary to improve the accuracy of Orbscan Topography System. The Haze and the change of anterior corneal surface curvature after Lasik and PRK are the main causes of measurement error in Orbscan Topography System. Clinically, it is an un-negligible important problem in the measurement of Orbscan system.