摘要:

Purpose.To study the management pattern and examine the role of cultures and antibiotic sensitivity testing in infectious keratitis.Methods.A retrospective analysis of the demographic, clinical, and microbiological data was performed in 100 consecutive patients with infectious keratitis. The main parameters evaluated were nature of first contact with the health care services, investigations undertaken, treatment initiated, and the time interval between presentation to the first medical contact and to our center. Finally, the reports of culture and antibiotic sensitivity testing undertaken at our center were evaluated.Results.In 70% of cases, ophthalmologists in independent practice were the first medical contact. Direct microscopy of the corneal scraping was undertaken in only 6% of cases, whereas culture and sensitivity studies had not been performed in any of the patients. Forty-six percent of the patients were prescribed 0.3% ciprofloxacin eyedrops in an inadequate dosage. Broad-spectrum fortified antibiotics eye drops had not been prescribed in any of the cases. At our center, positive cultures were obtained in 73.86% of cases and the most common organism isolated was coagulase-negativeStaphylococcus(33.84%), followed byPseudomonas aeruginosa(15.38%). A large number of the isolates demonstrated resistance to the recommended antibiotic therapy.Conclusions.Failure to implement standard management protocol for infectious keratitis at first contact is a major factor contributing to ocular morbidity in India.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.Quantitatively define and compare the nanoscale topography of the corneal epithelial basement membrane (anterior basement membrane) and Descemet's membrane (posterior basement membrane) of the human.Methods.Human corneas not suitable for transplantation were obtained from the Wisconsin Eye Bank. The corneas were placed in 2.5 mMEDTA for 2.5 h or 30 min. for removal of the epithelium or endothelium, respectively. After removal of the overlying cells, specimens were fixed in 2% glutaraldehyde and either examined in this state by atomic force microscopy only or dehydrated through an ethanol series and prepared for transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM).Results.The subepithelial and subendothelial basement membrane surfaces have a similar appearance that consists of an interwoven meshwork of fibers and pores. Topographic feature sizes were found to be in the nanometer size range with the epithelial basement membrane features larger and less densely packed than Descemet's membrane features. The topographic features are fractile in nature and increase surface area for cell contact.Conclusion.With the use of the TEM, SEM, and AFM, a detailed description of the surface topography of corneal epithelial basement membrane and Descemet's membrane of the human cornea are provided. The significance of differences in corneal basement membrane topography may reflect differences in function of the overlying cells or may be related to differences in cell migration and turnover patterns between the epithelium and endothelium.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To examine the viability of using human amniotic membrane as substrate for culturing corneal epithelial cells and transplanting them onto severely injured rabbit eyes.Methods.An ocular-surface injury was created in the right eye of eight rabbits by a lamellar keratectomy extending 5 mm outside the limbus. Next, from the limbal region of the uninjured left eyes of five of these animals, a small biopsy of corneal epithelial cells was taken and cultured on acellular human amniotic membrane. One month later, the invading conjunctiva that covered the corneal surface of all eight injured eyes was surgically removed. Five of the eyes then received grafts of amniotic membrane containing autologous cultured epithelial cells, whereas the other three received grafts of acellular amniotic membrane alone.Results.A confluent primary culture of limbal corneal epithelial cells was established on acellular human amniotic membrane after 14 days. Cells were partially stratified and fairly well attached to the underlying amniotic membrane, although a fully formed basement membrane was not evident. The three rabbits that received amniotic membrane transplantation alone all had total epithelial defects on the graft in the early postoperative period. Eyes that were grafted with amniotic membrane that contained cultivated epithelial cells, however, were all successfully epithelialized up to 5 days after surgery.Conclusion.Autologous transplantation of cultivated corneal epithelium is feasible by using acellular amniotic membrane as a carrier.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.We sought to determine whether patient meibum fatty acid unsaturation is associated with meibomian gland secretion consistency.Methods.Meibomian gland secretions were dissolved in chloroform and separated into lipid classes by thin-layer chromatography. Fatty acids in individual lipid classes were characterized by gas chromatography after transmethylation.Results.Meibum from patients with meibomian seborrhea was higher, and meibum from patients with meibomian keratoconjunctivitis (meibomianitis) was lower in the monounsaturated fatty acid, oleic acid, than that of other disease groups and normal subjects.Conclusion.Our results strongly suggest that the melting characteristics of meibum, influenced primarily by the amount of oleic acid in wax and sterol esters and free fatty acids, greatly influence the consistency of meibomian gland secretions.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.There are insufficient data on the possible cataractogenic side effects of excimer laser corneal surgery. Higher malondialdehyde (MDA) levels could indicate oxidative events related to the cataractogenic process. We therefore examined MDA levels after refractive laser surgery.Methods.Six white Russian rabbits received laser in situ keratomileusis (LASIK) (Schwind keratome) in the right eye and a 250-&mgr;m-deep microkeratome cut (Schwind microkeratome) in the left eye. Six others underwent photorefractive keratectomy (PRK) in the right eye; the left eye remained untreated. The 180 mJ/cm2fluence applied at a rate of 10 Hz with an optical zone diameter of 5 mm in all rabbits (438 pulses) resulted in an estimated central photoablation depth of 116 &mgr;m. Two weeks later, lenses and aqueous were taken immediately after death. MDA was detected in aqueous and homogenate of lenses after reacting with thiobarbituric acid (TBA). MDA bound to TBA (MDA–TBA) was specifically analyzed by high-performance liquid chromatography (HPLC) (excitation, 525 nm; emission, 551 nm) using phosphate-buffered methanol as eluent.Results.No significant laser-induced MDA alteration was found in either the aqueous or the lens. The microkeratome group, however, had two to three times higher MDA levels in the lenses than the control group (p= 0.12) or the PRK (p= 0.03) group.Conclusion.Elevation of MDA in the lens of the microkeratome group indicates that LASIK, but not PRK, may be a risk factor in cataractogenesis. The increased MDA levels in the LASIK group are probably caused by the microkeratome incision rather than the secondary radiation of the excimer laser. Postoperative inflammation may explain the surprising results.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To count the number of the corneal endothelial cells per unit of tissue area in 25 human fetal eyes ranging from 12–40 weeks of gestation with the histologic method.Methods.The endothelium including Descemet's membrane was stained with hematoxylin–eosin by the flat preparation method. We photographed the endothelium using light microscopy. The number of nuclei was counted on each photograph. A calibrated micrometer was photographed with the light microscopy, and this was used to measure the number of corneal endothelial cells per square millimeter.Results.The prenatal endothelial cell density of the human cornea decreases rapidly from 14,095 cells/mm2(12 weeks of gestation) to 6,820 cells/mm2(40 weeks of gestation).Conclusion.The estimate of the endothelial cell density at 12 weeks of gestation is twofold higher than the estimate at 40 weeks of gestation.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To evaluate the role of nitric oxide (NO) in the pathogenesis of allergic conjunctivitis and the effect of NO-synthase (NOS) inhibitors.Methods.The experimental allergic conjunctivitis was provoked in rabbits and healthy human volunteers by mast cell activators (codeine phosphate, 2.5 mg/mL; compound 48/80, 50 mg/mL; and lipopolysaccharide, 10 ng/eye). NOS inhibitors (aminoguanidine [AG], 1.5%, or NG-nitro-l-arginine methyl ester [L-NAME], 200 &mgr;g/eye) were applied as a pretreatment. In a rabbit model, concentrations of nitrite plus nitrate in the tear were measured colorimetrically using the Griess reaction after 0.5, 1.5, 3, 6, and 9 h. Immunohistochemical study for NOS was performed. The clinical scoring was performed in human volunteers. The vascular permeability was determined by measuring the albumin content in the tear of the challenged human eyes after 1 h.Results.After the instillation of mast cell activator, the NO level and clinical symptoms were markedly increased within 1.5 h. The NOS inhibitors suppressed the NO level. Vascular permeability was also increased in the activator-treated group. The NO-synthase immunoreactivity has been detected in the conjunctival subepithelial area and stroma for brain and endothelial isoform. L-NAME significantly reduces the immunoreactivity for NOS.Conclusion.These results suggest that the expression of NOS mainly contributes to the allergic symptoms. Therefore, NO is an important factor in the induction and progress of the allergic reaction to ocular surface. The NOS inhibitors may have a beneficial effect for allergic conjunctivitis.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To determine whether G-protein-mediated inhibition of secretion by met-enkephalin involves cyclic adenosine monophosphate (cAMP)-dependent events and to identify the G proteins that couple met-enkephalin to inhibition of lacrimal secretion.Methods.Secretion of protein was measured in 3-day primary cultures of rabbit lacrimal acini exposed to vehicle, the cholinergic agonist carbachol (Cch), the &bgr;-adrenergic agonist isoproterenol (Isop), vasoactive intestinal peptide (VIP), or forskolin (FSK) with or without the enkephalin analog D-ala2-met-enkephalinamide (DALA). In separate experiments, cells were pretreated with pertussis toxin or polyclonal antibodies against the &agr; subunits of Gi/Goto determine the physiologic role of G proteins in met-enkephalin inhibition of the release of lacrimal protein. Adenylyl cyclase (AC) activity was measured by a cAMP-dependent protein kinase binding assay in lacrimal membranes in response to the same agonists used in the secretion studies.Results.Cch resulted in a significant increase in protein release from cultured lacrimal acini. Increased secretion also occurred with Isop, VIP, and FSK. Cch-and Isop-stimulated secretion was inhibited by DALA to near-basal values. However, DALA did not inhibit VIP-or FSK-stimulated secretion. The inhibitory effect of DALA on Cch and Isop stimulation of secretion was reversed by pertussis toxin. Inhibition of Cch-stimulated secretion was blocked by antibody specific to a common peptide sequence of Gi&agr;1and Gi&agr;2but was not blocked by anti-Gi&agr;1antibody. The inhibitory effect on Cch-stimulated secretion was also blocked by anti-Gi&agr;3and anti-Go&agr;. Similar experiments resulted in a reversal of DALA inhibition of &bgr;-adrenergic stimulation of secretion by immunoneutralization of Gi&agr;1/2and Go&agr;but not by immunoneutralization of Gi&agr;1or Gi&agr;3. VIP, Isop, and FSK significantly stimulated AC. However, Cch had no effect on the activity of the enzyme. In addition, DALA had no effect on AC activity under any conditions.Conclusions.These results show that enkephalin inhibition of cholinergic and &bgr;-adrenergic stimulation of secretion is mediated by Gi2, Gi3, and Go. The effector coupled by the G proteins is not AC. However, we suggest a role for met-enkephalin in G-protein-coupled modulation of ion channels important for cholinergic and &bgr;-adrenergic stimulation of lacrimal secretion.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.Apoptosis was studied in rabbit corneas as a possible mechanism of cell death after photokeratitis induced by different UV wavelengths.Method.Fourteen albino rabbit corneas were exposed to 280-and 310-nm UV radiation (UVR) in 10-nm full wavebands at doses that cause biomicroscopically significant keratitis (0.12 J/cm2for 280 nm and 0.47 J/cm2for 310 nm). Animals were killed 24 and 76 h after exposure. Corneas were processed for light and transmission electron microscopy and in situ end labeling of fragmented DNA by using a modification of the TUNEL technique.Results.Corneas exposed to 280-nm UVR showed TUNEL-positive staining only in epithelial cells and superficial keratocytes at 24 and 76 h after irradiation. Twenty-four hours after 310-nm UVR exposure, TUNEL-positive staining was present in the epithelial cells, keratocytes throughout the entire thickness of the central stroma, and in endothelial cells. Seventy-six hours after exposure to 310-nm UVR, keratocytes disappeared throughout the whole thickness of the damaged stroma. Only a few epithelial cells were TUNEL positive at that time. Transmission electron microscopy (TEM) verified the occurrence of apoptotic nuclei and cells.Conclusion.Apoptosis appears to be a mechanism of corneal cell death after UVR. The 310-nm UVR caused more extensive damage to the corneal stroma and endothelium than did the 280-nm UVR.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To describe an alternative, novel surgical approach to the repair of a ruptured globe in the second reported patient with keratoglobus, Ehlers–Danlos type VI, and normal lysyl hydroxylase.Methods.Under general anesthesia, a 360° conjunctival peritomy was performed and the epithelium was removed from the keratoglobus cornea. Descemet's membrane and endothelium were removed from a fresh donor corneoscleral ring. An onlay epikeratoplasty was then performed and the entire donor corneoscleral button was secured to the sclera with 9-0 nylon suture. The conjunctiva was brought into position and tacked down over the edge of the donor graft. After 4 months, a full-thickness penetrating keratoplasty was then performed.Results.The patient ultimately had a ruptured globe in the fellow eye and thus required the identical procedure OU. Both eyes were successfully repaired with a final visual acuity OU of 20/100.Conclusion.The described surgical approach allowed successful surgical repair of bilateral ruptured globes in a patient with keratoglobus, Ehlers–Danlos type VI, and normal lysyl hydroxylase levels. In the previous report of such a patient by Judisch et al.(1), the attempt at surgical repair was unsuccessful and ended in enucleation. The described surgical technique may be used to treat advanced keratoglobus or oculus fragilis.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID