ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

We evaluated the precision and predictability of a 1,053-nm picosecond Nd:YLF ophthalmic laser with various combinations of computer-controlled parameters. We utilized epithelium-free corneal-sclera preparations from NZW rabbits, and the 1,053-nm Nd:YLF laser (Intelligent Surgical Lasers, San Diego, CA, U.S.A.). X-line and line patterns were utilized to make linear corneal incisions. Three parameters (layer size, crossing width, and energy level) were evaluated. One parameter was changed for a total of 120 combinations of computer-controlled parameters. Three incisions were performed for each combination. Although the intended depths of the incisions were constant (300 μm), the actual depths of the incisions varied with the change of parameters. Increasing layer size decreased the depth of incisions, and increasing crossing width or energy level increased the depth of incisions. Only three of 120 combinations of parameters achieved depths near 300 μm. Within the same combination of parameters, the depth of the corneal incisions varied. Debris of ablated stromal tissue was observed at the border and partially occupying the incision. Most of the incisions were “funnel”-shaped with the distal treatment zone having a “zigzag” or irregular border. Further improvements are necessary to use this laser system for corneal transverse incisions.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

In this study, we report our clinical experiences and results in performing 193-nm argon fluoride excimer laser phototherapeutic keratectomy (PTK) on 48 eyes of 45 patients with various pathology in the anterior one-third of the cornea, including leukoma, stromal dystrophy, anterior basement membrane dystrophy, and Salzmann's nodular degeneration. The VISX model 20/20 laser was used to ablate the anterior stroma to variable depth, dependent upon pathology. Patients were followed for a minimum of 1 year. Per an FDA-approved protocol vision, refraction, comfort, clarity, rate of reepithelialization, and complications were monitored. Seventy-two percent of patients undergoing excimer laser ablation for visual recovery had documented improvement in Snellen acuity. For the same period, 70% of those patients who were symptomatic prelaser were noted to be more comfortable. Corneal clarity improved in 35 of 48 eyes (73%), remained stable in nine (19%), and worsened in four (8%). Complications arose in 8% and included recurrence of herpetic keratouveitis, episcleritis, and an attack of narrow angle glaucoma secondary to cycloplegic agents. Delayed reepithelialization, >7 days, was noted in nine patients (19%). All complications were successfully treated medically. Excimer PTK appears to be a valuable addition to our therapeutic armamentarium for the treatment of superficial stromal opacification and surface irregularity.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Patients undergoing neodymium:yttrium-aluminum-garnet (Nd:YAG) laser posterior capsulotomy for posterior capsular opacification after penetrating keratoplasty were reviewed retrospectively for incidence of graft rejection. All patients underwent extracapsular cataract extraction with posterior chamber intraocular lens implantation (PC-IOL) performed as a separate or combined procedure. Only one of 20 eyes (4.7%) of 20 patients developed corneal graft rejection over a follow-up period of 6 months to 6 years after capsulotomy. Nd:YAG laser capsulotomy does not appear to increase the risk of corneal graft rejection.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

To determine the expression of matrix metalloproteinases (MMPs) in cornea following excimer laser keratectomy, two sets of experiments were performed. In the first experiment, disciform excimer keratectomy was performed on rat corneas. The central regenerating epithelium was harvested at 3–96 h postwounding. MMP levels were assayed in the regenerated central epithelium and the stroma using zymography and immunoblot assays. In the second set of experiments, deep excimer annular keratectomy was performed on rabbit corneas to induce intrastromal epithelial migration. The effect of β-mercaptomethyl tripeptide, a synthetic inhibitor of metalloproteinase, on the presence and extent of intrastromal epithelial migration was determined. In experiment I, MMP-2 and MMP-9 were expressed in the epithelium of excimer-ablated rat corneas 6–24 h postwounding, but not in the debridement wounds and untreated controls. Only excimer-treated stroma showed MMP-9 activity. In experiment II, intrastromal epithelial migration was delayed by topical application of β-mercaptomethyl tripeptide, a synthetic inhibitor of MMPs (p < 0.05). After excimer wounds, MMPs are expressed in corneal epithelium and stroma during wound closure. They may play an important role in wound healing after excimer laser keratectomy.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

In the systemic mucopolysaccharidoses (MPS) in animals, corneal clouding resulted from storage of glycosaminoglycans (GAG) in stromal keratocytes. The corneal epithelium was normal (MPS VI and VII) or minimally affected (MPS I), and stromal edema was not a feature even though the corneal endothelium demonstrated variable pathology. The MPS I (cat) cornea showed endothelial cells with large numbers of secondary lysosomal inclusions that were vacuolated or had a granular matrix. The endothelium was uniformly affected, but was not markedly hypertrophied. In contrast, the MPS VI (cat) cornea showed no endothelial cell disease. The MPS VII (dog) cornea had the most significant and dramatic endothelial pathology. The cells were massively hypertrophied and contained large numbers of vacuolated lysosomal inclusions. Regardless of the severity of the morphologic disease, the endothelial cells in these animal models functioned normally in maintaining the relative dehydration of the cornea. The corneal clouding was the result of storage in stromal keratocytes rather than corneal edema from endothelial dysfunction.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The scope of this study includes investigations on uptake of dextran and chondroitin sulfate in human donor corneas, and effects of chondroitin sulfate on adhesion and growth of rabbit and cat corneal endothelial cells. Fibronectin and dextrian sulfate served as controls. Nuclear magnetic resonance spectroscopy revealed no detectable osmotic agents in the corneas stored in either Dexsol or Optisol at 4°C for 6 days. The study showed that chondroitin sulfate enhanced cell adhesion marginally at 2.5%, but >40% at 0.5%, comparable to that of 10 μg/ml fibronectin, whereas 2% dextran sulfate abolished ∼70% of cell adhesion capability. In cultures with fibronectin present, the duration for cells to reach confluence was extended from 1.75 to 3 days. Chondroitin sulfate (2%) elicited no apparent cytotoxic effect, with cells becoming polygonal and reaching confluence in ∼9 days. Cell growth was retarded by 2% dextran sulfate, with signs of senescence on day 3 and clear evidence of cell degeneration on day 9. The cells did not survive without serum in cultures, especially at 36°C. These findings suggest that corneal deterioration probably is linked primarily to serum-free storage conditions, not uptake of osmotic agents in the cornea. The highly negatively charged sulfate group, however, may have rendered chondroitin sulfate less effective as an additive.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Possible toxic effects of vancomycin on the corneal endothelium were assessed in rabbit eyes and subsequently in corneal transplant recipients. Fifteen New Zealand White rabbits were divided into five groups of three rabbits each. A paracentesis was performed on right eyes only. One hundred microliters of aqueous humor was removed followed by anterior chamber injection of 100 μl of balanced salt solution (BSS) or varying concentrations of vancomycin (150, 750, 1,875, 7,500 μg/ml). Left eyes served as untreated controls. Endothelial cell morphology and density were assessed by contact specular microscopy 48 h postinjection. There was no statistically significant difference in endothelial cell density between left (control) or right (treated) eyes receiving either BSS or varying concentrations of vancomycin. Transmission electron microscopy of rabbit corneal endothelium exposed to varying concentrations of vancomycin (150, 750, 1,875, 7,500 μg/ml) showed no toxic effects. Six patients undergoing penetrating keratoplasty (PKP) received donor corneas stored in Optisol containing gentamicin to which vancomycin was added to make a final concentration of 150 μg/ml. Eight patients undergoing PKP received corneas stored in Optisol alone. Specular microscopy was performed preoperatively and 3, 6, and 12 months postoperatively. No statistically significant difference in mean endothelial cell change was observed (Wilcoxon signed-rank test) at any time point postoperatively. Endothelial cell morphology and function are not adversely affected by therapeutic doses of vancomycin.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The iridocorneal-endothelial (ICE) syndrome is characterised clinically by a “hammered-silver” appearance of the corneal endothelium, corneal failure, glaucoma, and iris destruction. Specular photomicroscopic studies of the corneal endothelium have demonstrated a population of abnormal cells termed “ICE cells.” The purpose of this study was to define the histological appearances typical of this disease and in particular the ultrastructural morphology of the ICE cell. Thirty-five corneas, 11 trabeculectomy specimens, and 3 failed corneal grafts taken from patients with the ICE syndrome were examined by transmission and scanning electron microscopy. Comparison was made with seven normal corneas. Ten corneas and two trabeculectomy specimens demonstrated a population of well-differentiated cells with epithelial features such as desmosomes, tonofilaments, and microvilli. Other cell types identified were cells that resembled those of normal corneal endothelium, inflammatory cells, and cells with a fibroblast-like morphology. It seems likely that the epithelial cells of our specimens are the histological equivalent of the ICE cell seen by specular photomicroscopy. The other cell types may be either residual normal endothelial cells or else arise from secondary phenenomena of various kinds.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The purpose of our study was to develop a method for detecting herpes simplex virus (HSV) DNA that combined the high sensitivity of the polymerase chain reaction (PCR) with the precise anatomical localization provided by in situ hybridization (ISH). We used in situ PCR (ISPCR), ISH, and standard PCR methods to determine the proportion of Vero cells carrying HSV-1-specific DNA before and after 1, 2, and 4 h of infection with HSV-1 or with HSV-2. Uninfected Vero cells and Vero cells infected with HSV-2 were never found to be positive for HSV-1 DNA by either ISPCR, ISH, or PCR. In contrast, using ISPCR, HSV-1 infected Vero cells showed an increase in the percentage of cells containing HSV-1 DNA from 20% at 1 h to 76% at 4 h after infection. Comparing the ISPCR results with ISH and standard PCR demonstrated that ISPCR was markedly more sensitive than ISH; in fact, the sensitivity of in situ PCR was similar to that seen with standard PCR. These results demonstrate that ISPCR is a highly sensitive method for amplifying genomic DNA sequences within intact single cells. This technique combines the exquisite sensitivity of conventional PCR technology with the precise cellular localization afforded by ISH. In addition, it allows for an accurate quantitative determination of the number of virally infected cells.

ISSN:0277-3740    

出版商:OVID    

年代:1996

数据来源: OVID