摘要:

Purpose.The purpose of this article is to review available information regarding development, structure, and function of Bowman's layer in the cornea. Disease-related abnormalities of Bowman's layer are described. A hypothesis is advanced to explain the development and maintenance of Bowman's layer.Methods.Literature review and hypothesis formulation based on previous studies.Results.Information is presented that supports the hypothesis that Bowman's layer forms as a result of cytokine-mediated interactions occurring between corneal epithelial cells and keratocytes that include chemotactic and apoptotic effects on the keratocytes. This hypothesis suggests that Bowman's layer results from such interactions beginning in early development and continuing into adulthood in humans and other animals, such as chickens.Conclusions.Bowman's layer may be a visible indicator of ongoing stromal-epithelial interactions in the human and have no critical function in corneal physiology. Bowman's layer is commonly destroyed in diseases such as advanced bullous keratopathy where stromal-epithelial interactions may be interrupted. Bowman's-like layers often form in response to epithelium, for example when epithelial plugs extend into the stroma in corneas with radial keratotomy incisions.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To bioengineer a corneal surface replacement using ex vivo expanded, cultured corneal epithelial stem cells seeded on a matrix derived from amniotic membrane and use this bioengineered graft to manage difficult ocular surface disease.Methods.Fourteen patients with ocular surface disease unresponsive to standard medical and surgical treatments, including seven patients with presumed limbal stem cell deficiency were chosen for transplantation of a bioengineered composite corneal surface in eye each. Presumed corneal stem cells were harvested from either the patient's or related donor's limbus, expanded ex vivo, and cultivated on a carrier of modified human amniotic membrane. The resulting composite cultured tissue was transplanted to the ocular surface of the diseased eye, from which the abnormal tissue had been surgically removed. Ten patients received autologous grafts, and four received allogeneic grafts.Results.A successful outcome, defined as restoration or improvement of vision, along with maintenance of corneal re-epithelialization and absence or recurrence of surface disease was obtained in 6 of the 10 patients with autologous procedures and in all 4 allogeneic transplants. Follow-up ranged 6–19 months with a mean of 13 months.Conclusions.This novel technique documents that presumed corneal epithelial stem cells can be harvested safely from the limbus, expanded successfully in vitro, and grown on denuded amniotic membrane. The resultant composite cultured tissue can be transplanted and appears to successfully manage eyes with difficult ocular surface disease, including those with stem cell deficiency. This technique minimizes the threat of damage or depletion to the contralateral or donor limbus.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To describe a new surgical technique for deep, anterior lamellar keratoplasty using a viscoelastic for dissection of Descemet's membrane (DM) from the posterior stroma.Methods.Through a paracentesis, aqueous was exchanged by air to visualize the posterior corneal surface—i.e., the air-to-endothelium interface. Using the interface as a reference plane, a 30 gauge needle was inserted into the cornea to just anterior to DM. Viscoelastic was injected to separate DM from the posterior stroma, and a recipient, anterior lamella was excised. A full-thickness donor button was sutured into the recipient bed, after stripping its DM.Results.In 25 eye bank eyes, the procedure could be completed in 20 eyes; in 5 eyes, DM ruptured during visco-dissection. With light microscopy, dissection depth was located at the level of DM. In two patient eyes the procedure could be completed. In a third patient eye DM ruptured during visco-dissection, and the procedure was converted into a penetrating keratoplasty.Conclusion.Using visco-dissection, a lamellar keratoplasty can be performed quickly, with the donor-to-recipient interface just above the recipient DM, i.e., with a nearly perfect anatomical replacement of all corneal stroma. There is substantial risk of rupture or microperforation of DM during surgery.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To determine whether visual acuity (VA) measurements performed at low levels of contrast and glare are a better diagnostic tool for determining whether corneal clouding warrants surgery.Methods.Fifty-nine subjects were recruited from among the candidates for corneal graft. Monocular VA was measured with three Regan contrast VA charts: 96, 25, and 11%, with and without glare provided by the Brightness Acuity Tester (BAT). The discriminative ability of the tests was estimated using the area (AR) under receiver operating characteristic (ROC) curves. Associations between the different VA tests and the Visual Function Index (VF-14) score were studied, using Spearman coefficients.Results.When comparing candidate eyes with contralateral eyes with corneal disease, lower contrasts VA tests provided greater discriminative power. VA measurements made with glare also tended to provide greater discrimination. In fact, discrimination was best with 11% contrast VA with glare, but “testability” was poor. The most practical test in a clinical setting, which retained high discriminative ability (0.798), was the 25% contrast VA with glare. The eye with the best VA correlated strongly with the VF-14, especially at 25% contrast without glare, resulting in an Rsof −0.729.Conclusion.Twenty-five percent contrast VA with BAT could help the practitioner to decide whether a corneal transplant is warranted when symptoms of reduced vision are more important than what high-contrast VA might indicate.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To determine the efficacy of a one-piece lamellar keratolimbal graft for the treatment of ocular surface disorders involving the limbus and cornea.Methods.A retrospective study of a case series including eight patients with either Stevens-Johnson syndrome (four patients), ocular cicatricial pemphigoid (three patients), or familial subepithelial amyloidosis of the cornea (one case) was performed with a mean follow-up period of 18 months after surgery.Results.Of the eight cases, three patients retained a corneal epithelial appearance upon their latest visit. No statistically significant difference was observed between preoperative visual acuity (0.013) and postoperative acuity (0.082). Stromal neovascularization was observed in all cases. Seven of eight cases experienced persistent epithelial defects (PED), four of which evolved secondary infectious ulcers. Two cases required further surgical intervention to treat PED or infectious ulcers. None of the cases developed glaucoma.Conclusion.A one-piece keratolimbal graft does not seem to offer any advantage over a two-piece limbal and corneal graft in the treatment of severe ocular surface disorders involving the limbus and cornea.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Objective.To characterize the clinical and pathologic features of cadaveric keratolimbal allograft (KLAL) rejection.Design.The study design is descriptive.Participants.Four patients (five eyes) with KLAL rejection are reported.Intervention.All patients were subjected to slit-lamp biomicroscopy, treatment of rejection, and ultimately required repeat KLAL surgery. In three patients (four eyes), specimens obtained at the time of repeat surgery were subjected to immunohistochemical staining against the following immune and surface human antigens: CD4, CD8, CD19, CD3, DR, CK19, CK3, and vimentin.Results.Signs of allograft rejection included intense sectoral injection, diffuse or perilimbal conjunctival injection, edema, and infiltration of the KLAL grafts, leading to punctate epithelial erosions, epithelial defects, and surface keratinization. Rejected specimens revealed T-lymphocyte infiltration (CD4:CD8, 2:1) with strong HLA-DR (MHC class II) expression. The epithelium stain results were positive for cytokeratin 19 and weakly positive to absent for cytokeratin 3. The epithelial stain results were weakly positive for vimentin in only one specimen.Conclusions.KLAL rejection is a newly recognized entity. Pathologic findings of rejected specimens indicate that this is a T-cell mediated rejection phenomenon. The pattern of cytokeratin staining provided little evidence that the epithelium covering KLALs had a corneal phenotype. The scarcity of vimentin-positive epithelial cells suggests that the stem-cell/transient-cell pool was probably depleted. Early recognition of clinical rejection is important, as treatment with immunosuppressive therapy may reverse the process.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To reportPropionibacterium acnesas a cause of vision-threatening infectious keratitis and to discuss culture isolation and antibiotic treatment.Methods.Retrospective case series presentation collected from three academic medical centers.Results.Six cases ofP. acnesinfectious keratitis are presented, all of which were associated with a compromised corneal barrier or environment. All cases were culture-positive on thioglycolate broth; none became positive before 7 days of growth. No other organisms were isolated from any culture, and the growth ofP. acnesoccurred in some cases despite negative gram stains.Conclusion.P. acnescan produce vision-debilitating keratitis when the cornea is compromised. Growth in culture should be monitored for at least 10 days to ensure isolation of this fastidious organism.P. acnesmay respond to several different antibiotics that have gram-positive coverage, but it should be treated with vancomycin to enhance clearance of the organism.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To report the ulcer characteristics, microbiologic data, and outcome of infectious keratitis associated with climatic droplet keratopathy (CDK), suggesting that CDK is a predisposing factor for infectious keratitis.Methods.Medical records of 32 patients (34 eyes) in whom infectious keratitis was seen in association with CDK were retrospectively reviewed. Data were collected regarding the nature of CDK lesions, infiltrate characteristics, organisms isolated, and outcome.Results.CDK was peripheral in 16 (47.1%) eyes, central in 8 (23.5%), and diffuse in 10 (29.4%). The CDK lesions were nodular and elevated in all eyes. The infiltrate was adjacent to the CDK lesions in 28 eyes (82.4%). The infiltrate size (widest dimension) ranged 2–6 mm in 18 eyes (52.9%) and was >6 mm in 7 (20.5%). The infiltrate was full thickness in 15 eyes (44.1%) and was involving up to the middle third of the corneal stroma in another 18 (52.8%). Hypopyon was seen in all. Bacteria were commonly isolated.Staphylococcus epidermidis(six eyes) andStreptococcus pneumoniae(five eyes) were the common bacteria isolated. Resolution with medical treatment was seen in 20 (58.8%) eyes.Conclusions.CDK is a predisposing factor for infectious keratitis. Treatment should be considered for advanced and nodular lesions, even if they are peripheral, to prevent infectious keratitis.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

Purpose.To compare the efficacy of antibiotic drops placed in the conjunctival cul-de-sac to antibiotic ointment applied to the lid margin in reduction of bacterial colonization on the lid margin.Methods.A randomized, prospective, single-masked study was conducted on 19 patients with culture-proven colonization of bacteria on the lid margins. Ophthalmic eligibility criteria included the presence of ≥50 colony-forming units/mL (CFU/mL) of bacteria on both right and left lids. Each patient received one drop of ofloxacin in one eye every night for one week, followed by one drop once a week for one month. In the same manner, each patient received bacitracin ointment (erythromycin or gentamicin ointment if lid margin bacteria were resistant to bacitracin) to the lid margin of the fellow eye. Quantitative lid cultures were taken at initial visit, one week, one month, and two months. Fifteen volunteers (30 lids) served as controls. Lid cultures were taken at initial visit, one week, and one month.Results.Both antibiotic drop and ointment reduced average bacterial CFU/mL at one week and one month. Average bacterial CFU/mL reestablished to baseline values at two months. There was no statistically significant difference between antibiotic drop and ointment in reducing bacterial colonization on the lid margin.Conclusion.Antibiotic drops placed in the conjunctival cul-de-sac appear to be as effective as ointment applied to the lid margins in reducing bacterial colonization in patients with ≥50 CFU/mL of bacteria on the lid margins.

ISSN:0277-3740    

出版商:OVID    

年代:2000

数据来源: OVID