Femtosecond laser small incision lenticule extraction (SMILE) with different residual stromal thicknesses (RST) is set to investigate its effect on corneal biomechanical properties of rabbits in vivo. In this study, 24 healthy adult Japanese rabbits were randomly divided into group A and B. The RST of group A was set 30% of the corneal central thickness (CCT), and the RST of group B was 50% of the CCT. The thickness of the corneal cap in both groups was set one third of CCT. Corneal visualization Scheimpflug technology (Corvis ST) and Pentacam three-dimensional anterior segment analyzer were used to determine corneal biomechanical and morphological parameters before surgery, and 1 week, 1 month and 3 months after surgery. Pearson correlation analysis was used to analyze factors affecting corneal biomechanical parameters after SMILE. The results showed that the corneal stiffness of group A was significantly higher than that of group B at 1 week and 1 month after surgery, and most biomechanical parameters returned to preoperative levels at 3 months postoperatively. The results of correlation analysis showed that postoperative CCT and RST were the main factors affecting corneal biomechanical parameters after SMILE. There was no significant difference in corneal posterior surface height (PE) between 3 months after surgery and before surgery in both two groups. It indicates that although the ability to resist deformation of cornea decreases in SMILE with thicker corneal cap and less RST, there is no tendency to keratoconus, which may be related to the preservation of more anterior stromal layer.
Animals ; Biomechanical Phenomena ; Cornea/surgery* ; Postoperative Period ; Rabbits

OBJECTIVE: To determine the effect of Laser Assisted Keratomileusis (LASIK) on intraocular pressure (IOP) measurement METHODS: Central and temporal corneal Goldmann tonometry and pneumotonometry were done before and after LASIK. Corneal thickness was also measured before and after surgery RESULTS: Results showed a mean IOP drop of 1.47mmHg+ 1.36 between the central and temporal measurements in post-operative patients using Goldmann applanation tonometer. This value was not significant (P = 0.548112). There was a mean IOP drop of 2.75mmHg+ 1.49 between the central and temporal measurements in post-operative patients using Pneumotonometer. This was significant (P=0.419025). The difference between pre-operative central corneal thickness and the post-operative central corneal thickness was 41.42um+ 18.22. This value was compared with the IOP drop in central IOP measurement in post-operative patients using Goldmann applanation tonometer and the result showed no significant correlation (P=0.386000). It was also compared with the IOP drop in central IOP measurement and, likewise, showed no significant correlation between ablation depth and IOP drop using both Goldmann and Pneumotonometer (P=0.610471 and P=0.141398, respectively) CONCLUSION: Goldmann Applanation tonometry and Pneumotonometry can be used to determine IOP after myopic LASIK treatment. Ablation depth does not influence post-operative IOP measurements using the two tonometers. (Author)
Human ; Male ; Female ; Middle Aged ; Adult ; Young Adult ; SURGERY ; CORNEA

Cornea ; surgery ; Corneal Injuries ; Equipment Design ; Eye Foreign Bodies ; surgery ; Humans ; Surgical Instruments

BACKGROUNDThe limiting factor to corneal transplantation is the availability of donors. Research has suggested that xenogenic acellular corneal scaffolds (XACS) may be a possible alternative to transplantation. This study aimed to investigate the viability of performing lamellar corneal transplantation (LCT) in rabbits using canine XACS.

METHODSFresh dog corneas were decellularized by serial digestion, and LCT was performed on rabbit eyes using xenogeneic decellularized corneal matrix. Cellular and morphological changes were observed by slit-lamp, light, and scanning electron microscopy at 7, 30 and 90 days postoperatively. Immunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft.

RESULTSDecellularized xenogenic corneal matrix remained transparent for about 1-month after LCT. The recipient cells were able to survive and proliferate into the grafts. Three months after transplantation, grafts had merged with host tissue, and graft epithelialization and vascularization had occurred. Corneal nerve fibers were able to grow into the graft in rabbits transplanted with XACS.

CONCLUSIONSXenogenic acellular corneal scaffolds can maintain the transparency of corneal grafts about 1-month and permit growth of cells and nerve fibers, and is, therefore, a potential substitute or carrier for a replacement cornea.

Animals ; Cornea ; surgery ; Corneal Stroma ; surgery ; Corneal Transplantation ; methods ; Dogs ; Microscopy, Confocal ; Rabbits ; Tissue Engineering

OBJECTIVES: To investigate angle Kappa and diopter distribution in myopic patients and the changes of angle Kappa and corneal morphology after Sub-Bowman-Keratomileusis (SBK), and to analyze the effects of the surgery on corneal morphologic changes and the patients' near fixation characteristics. METHODS: The clinical data of 134 myopic patients (268 eyes) undergoing SBK from August 2015 to August 2016 were retrospectively analyzed. Angle Kappa, corneal curvature in the central corneal region of 3 mm, and post-corneal Diff value were measured by Orbscan IIz Corneal Topography System before operation, 1 month and 6 months after operation. According to the values of angle Kappa before SBK, the patients were divided into 2 groups: the large K group (angle Kappa≥5°, 71 eyes) and the small K group (angle Kappa<5°, 197 eyes). Correlation analysis of the factors influencing angle Kappa at 6 months after operation was performed. RESULTS: In the large K group, angle Kappa was (5.67±0.65)°, spherical equivalent was (-4.84±2.32) D, and angle Kappa was decreased after operation (both CONCLUSIONS The angle Kappa is decreased in low-moderate myopia patients with large angle Kappa, while is increased in high myopia patients with small angle Kappa after SBK. Myopia patients after SBK will look for the new balance of the binocular accommodation and vergence function for improving the comfort in the near-work situations.
Cornea/surgery* ; Humans ; Keratomileusis, Laser In Situ ; Myopia/surgery* ; Refraction, Ocular ; Retrospective Studies

OBJECTIVETo evaluate the static and dynamic contrast sensitivity changes in myopic patients before and after laser in situ keratomileusis (LASIK).

METHODSSeventy-three eyes in 37 patients with myopia (with or without astigmatism) who received LASIK were tested for static and dynamic contrast sensitivities using the METRO VISION MON ELEC I system at 0.7, 1.4, 2.7, 5.5, 11, and 22 cpd and cps prior to LASIK, and at one-, three-, and six-month intervals after LASIK.

RESULTSAll eyes gained naked visual acuity of more than 0.5 after LASIK. The contrast sensitivity was depressed at all frequencies 1 month after LASIK, as compared to one week prior to LASIK. The depression at 2.7, 5.5, 11 (P < 0.01) and 22 cpd (P < 0.05) was statistically significant for static contrast sensitivity, and also at 5.5 (P < 0.01) and 11 cps (P < 0.05) for dynamic contrast sensitivity. Myopic eyes between 6.25 D and 14.0 D, and astigmatic eyes 2 DC and more, suffered more static and dynamic contrast sensitivity depression than the myopic eyes between 1.25 D and 6.00 D and astigmatic eyes less than 2 DC. Contrast sensitivities were improved and exceeded preoperative levels 3 months after LASIK, and improved even more 6 months after LASIK. All sequences were statistically significant for static contrast sensitivity (P < 0.01), while only 2.7, 5.5, and 11 cps were statistically significant for dynamic contrast sensitivity (P < 0.01). The astigmatic eyes 2 DC and more showed less improvement, even below the preoperative level at 1.4 cps of dynamic contrast sensitivity.

CONCLUSIONSWhile temporary depression of contrast sensitivity for myopic eyes after LASIK was seen, contrast sensitivity soon returned to exceed preoperative levels at 3 months after LASIK, while improving even more 6 months after LASIK.

Adolescent ; Adult ; Astigmatism ; surgery ; Contrast Sensitivity ; Cornea ; surgery ; Female ; Humans ; Keratomileusis, Laser In Situ ; Male ; Myopia ; physiopathology ; surgery ; Visual Acuity

To investigate the safety of subconjunctivally injected mitomycin-C(MMC) as an adjunctive therapy following the glaucoma filtration surgery(GFS), various amounts of MMC have been given to rabbit eyes after the surgery. To the control group, balanced salt solution(BSS) was injected subconjunctivally and 0.05mg MMC dissolved in BSS was given to the I experimental group I, 0.1mg to the group II, and 0.2mg to the group III. When the concentration of MMC in aqueous humor and cornea were measured at 30 min after the administration of MMC by high performance liquid chromatography, while no MMC was detected in aqueous humor, 1.2 +/- 0.5 micro gram of MMC/g of corneal tissue was detected for group III and 0.3 +/- 0.1 micro gram/g was found in group II. No MMC could be detected in corneal tissues of group I. The scanning electron microscopy which was done on the third day after surgery, revealed the most serious destructive changes of corneal endothelium in group III, while slight changes in group II, and no alteration in group I and control group. Based on these observations, subconjunctival injection of low dose(0.05mg) of MMC may be safe as an adjunctive method to enhance the success rate of GFS.
Aqueous Humor ; Chromatography, Liquid ; Cornea ; Endothelium, Corneal ; Filtering Surgery* ; Filtration* ; Glaucoma* ; Microscopy, Electron, Scanning ; Mitomycin* ; Rabbits*

The authors investigated the toxicity of two antimetabolites. 5-fluorouracil(5-FU) and mitomycin-C(MMC) on the rabbit cornea and sclera following glaucoma filtration surgery(GFS). Forty rabbits were divided into four groups; the first control group(I) was the balanced salt solution soaked group(BSS) during GFS, the second(II) was the 5-FU subconjunctival injected group(5-FU SC) after GFS, the third(III) was the 5-FU soaked group(5-FU) during GFS, and the fourth(IV) was the MMC soaked group(MMC) during GFS. At the fifth day after GFS, scanning electron microscopic findings showed that corneal epithelial cells were most seriously damaged in 5-FU SC group, slightly damaged in 5-FU group, and no change in MMC and BSS group. At six months after GFS, transmission electron microscopic observation on sclera revealed the most profound degenerative changes in 5-FU group, and followed by an order of MMC, 5-FU SC, and BSS group. These results suggest that the dosage and application method of antimetabolites should be selected with great caution to prevent ocular toxicity.
Antimetabolites ; Cornea* ; Epithelial Cells ; Filtering Surgery* ; Filtration* ; Fluorouracil* ; Glaucoma* ; Mitomycin* ; Rabbits ; Sclera*

PURPOSE: This study was performed to assess efficiency and stability of astigmatic change by incision size after cataract surgery. METHODS: This work was designed as a retrospective, comparative, nonrandomized interventional study. A total of 121 cases of cataract surgery were reviewed in 98 patients performed by one surgeon at the Oregon Eye Institute in Eugene, OR, USA with 3-year follow-ups. All procedures were performed with the temporal approach of self-sealing incisions. The serial change in surgically induced astigmatisms were examined in all cases of three groups: Group A, cartridge injection of a foldable IOL through a 2.5 mm self-sealing incision; Group B, cartridge injection of a foldable IOL through a 3.0 mm self-sealing incision; Group C, cartridge injection of a foldable IOL through a 3.5 mm self-sealing incision. Keratometric data were obtained preoperatively, and 3 weeks, 3 months, 6 months, 9 months, 12 months, 24 months and 36 months postoperatively. Polar value analysis was performed to calculate the surgically induced astigmatism. RESULTS: The astigmatic change decreased over time in Group B (P<0.05). The other groups tended to remain in induced astigmatism. All groups showed anticlockwise torque at 3 weeks following surgery. Group B showed a decrease in deviation, but the other groups showed increases in their torque value at postoperative 12 months (P<0.05). CONCLUSIONS: The 3.0 mm incision size correlated with the least surgically induced astigmatism.
Retrospective Studies ; Phacoemulsification ; Lens Implantation, Intraocular ; Humans ; Cornea/*surgery ; Cataract Extraction/*adverse effects/*methods ; Astigmatism/*etiology

The pattern and morphology of cellular infiltration of iris melanocytes implanted into the corneal stroma were studied with a rabbit corneal model. Iris melanocytes are transformed into fibroblast-like cells with a loss of pigment granules, which may reflect the in vivo characteristics of iris melanocytes under pathologic conditions. The metaplastic chararter of iris melanocytes appears to be related to the formation of retrocorneal pigmentation and fibrous membrane.
Animals ; Cell Division ; Cornea/*cytology/pathology/surgery ; Iris/*cytology ; Melanocytes/*cytology/physiology/transplantation ; Metaplasia/pathology ; Rabbits