ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The anteroposterior keratocyte density distribution in the rabbit cornea was measured. Unsectioned tissue blocks from the central cornea of five rabbits were stained with propidium iodide and imaged using a Leica laser scanning confocal microscope. A z-series of images was acquired in each sample, from anterior to posterior stroma in either 3− or 8-μm steps. Software was developed to allow interactive marking of the keratocyte nuclei within each section of the z-series and for calculating cell density. For convenience, cell density was expressed as the number of cells per corneal volume element (CVE), where CVE is a newly defined volume unit with x, y, and z dimensions of 250, 250, and 10 μm, respectively. The calculated keratocyte density was 20.2 ± 1.0 cells/CVE (n = 5), which is equivalent to 32,360 ± 1,660 cells/mm3. The greatest density was underneath the epithelium (26.3 ± 2.5 cells/CVE), the density then decreased linearly with depth to 15.2 ± 1.4 cells/CVE; there was a slight increase in density pre-Descemets membrane to 18.5 ± 3.5 cells/CVE. A 30% decrease in cell density over the entire anteroposterior stromal thickness was observed. To facilitate statistical analysis, the cell density was averaged over 5% thickness intervals from anterior to posterior cornea. A significant difference in mean cell density of these intervals was found (ANOVA, n = 20, p < 0.01). To further assess the density distribution, linear regression analysis was performed. A significant correlation was found between keratocyte density and stromal depth (R= −0.94, n = 20, p < 0.05). We conclude that in the rabbit, keratocyte cell density is maximal underlying the epithelium and progressively decreases from anterior to posterior cornea.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

We present eight cases ofAcanthamoebakeratitis. In each case, theAcanthamoebaorganisms were visualized in the epithelium and anterior stroma using tandem scanning confocal microscopy. The organisms were highly reflective, ovoid, and were 10–25 μm in diameter. TheAcanthamoebaorganisms in the human corneas were identical in size and shape toAcanthamoebaorganisms on an agar plate visualized with the same confocal microscope. Confocal microscopy is a useful method for identifying.Acanthamoebaorganisms in vivo within the corneal epithelium and anterior stroma.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Congenital hereditary endothelial dystrophy is characterized by a diffuse bilateral corneal opacity (edema). Its inheritance has been reported to be both autosomal recessive and dominant. All our cases seemed to be autosomal recessive. There seems to be a prevalence of the recessive gene in the Iranian population. The dystrophy might be misdiagnosed as congenital glaucoma, as in several of our cases. We have operated on 37 eyes of 21 patients during the past 10 years. Our visual and anatomical success rate has been very good, with 92% clear grafts and only an 8% rejection rate, in contrast to poor prognosis that has been previously reported. In children, suture removal should be started 3 months postoperatively. Partial amblyopia was preexistent in all cases, but deep amblyopia was not common.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The association of glaucoma and penetrating keratoplasty presents a difficult management problem, particularly when medical therapy and conventional glaucoma surgery have failed. We have found alloplastic tube shunt surgery to be an effective method for intraocular pressure control in glaucomatous eyes subjected to penetrating keratoplasty. We report 46 patients who underwent alloplastic tube shunt implantation before (13 patients, group A), in combination with (17 patients, group B), or after (16 patients, group C) penetrating keratoplasty. All groups had significantly lowered intraocular pressure postoperatively. The most common complication was graft failure, in 31% of patients in group A, 29% in group B, and 44% in group C. Other postoperative complications and results including visual outcome are reviewed. Because the management of advanced glaucoma in patients undergoing keratoplasty is difficult, alloplastic tube shunt implantation should be considered.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

We report our experience with the Eckardt temporary keratoprosthesis including a technique modification allowing use of larger corneal grafts. We combined penetrating keratoplasty with vitreoretinal surgery using the Eckardt keratoprosthesis in 24 eyes of 24 patients in two patient groups: trauma (n = 11) and nontrauma (n = 13). Our technique modification involved centering a larger partial trephination for the donor cornea around the smaller trephination used for the keratoprosthesis. After the keratoprosthesis was removed, we excised host cornea along the larger trephination, and placed a larger corneal graft. With the exception of visual acuity (VA), the outcomes were similar for both trauma and nontrauma groups, and combined results were as follows. Corneal grafts remained clear in 71% of patients at a mean follow-up period of 16 ± 3 (SE) months. For the trauma and nontrauma groups, VA improved in 82 and 23%, and decreased in 18% and 38.5%, respectively. Postoperative loss of VA was due primarily to retinal scarring (47%) and phthisis bulbi (37%). Only one case of graft rejection occurred. Postoperatively, the larger corneal grafts (8.0 and 8.5 mm) were less steep, and residual astigmatism was more easily managed than with the “recommended” (7.2 mm) size. Conclusions: Larger corneal grafts allow less astigmatism and a more normal corneal curvature. Theoretical advantages also include faster rehabilitation of vision, better predictability for intraocular lens implant power calculations, and transplantation of more endothelial cells. The Eckardt will continue to be a useful tool and our technique modification allowing use of larger corneal grafts should enhance its utility.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

During 1992 a questionnaire was sent to 57 cornea transplant centers in the Eurotransplant area, i.e., the Netherlands, Germany, Belgium, and Austria. Questions included the number of grafts transplanted in each center in 1991, the indications for cornea transplants, and surgeons' opinions on risk factors and indications for human leukocyte antigen (HLA)-matched grafts. A response rate of 89% (51 of 57) was achieved. The total number of grafts in the 51 reporting centers was 2,156 [average 42 (range: 3–303)]. In 19.3% of the cases HLA-matched donor tissue was used (range: 0–64%). Matched transplants were performed in high-risk cases. The term high-risk is not standardized by any means. Foremost, HLA-matched donor corneas were requested for regraft after immunologic failure of a previous transplant and in cases showing more than two quadrants of deep stromal vascularization. This survey has shown important differences in management of high-risk cases: variance in indications for HLA-matched grafting and no consistency in the weighing of the importance of HLA-A, HLA-B, and HLA-DR antigens nor consistency in the use of information on circulating antibodies. For proper allocation of available donor tissue for corneal transplants in the Eurotransplant area, a mutually accepted protocol defining indications for matched grafting is needed.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The Collaborative Corneal Transplantation Studies (CCTS) were designed to evaluate the effect of donor-recipient histocompatibility matching and cross-matching on the survival of corneal transplants in high-risk patients. We now report on the role of symptoms in the detection of corneal allograft reactions in the CCTS and on the relationship between symptom reporting and graft survival. The 456 patients transplanted in the CCTS were followed for a minimum of 2 years or until graft failure. The follow-up protocol included 11 scheduled examinations in the first year, four examinations during the second year, and examinations every 6 months thereafter. Interim examinations were performed in response to patient-reported symptoms. At every examination, patients were asked specifically if they had redness, sensitivity to light, loss of vision, or pain (RSVP). Of the 456 patients transplanted, 62% had at least one graft reaction. Patients diagnosed with reactions at scheduled visits in the first postoperative year were 2.5 times more likely to report symptoms than those without reactions. Reports of red eye and vision loss were strongly associated with allograft reaction. However, these symptoms were neither highly sensitive nor specific for reaction (sensitivity = 46%, specificity = 70% at 6 months). The severity of reaction influenced the reporting of symptoms: 69% of patients with severe reactions reported symptoms versus 48% of patients with mild reactions (p < 0.001). The only patient characteristic associated with reliable symptom reporting was age, with younger patients with reactions being more likely to report symptoms. Patients who reported symptoms at the first reaction were more likely to experience graft failure from rejection than patients not reporting symptoms.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Increasing reports of gentamicin-resistant bacteria contaminating donor corneas and causing endophthalmitis have indicated that preservation of corneal storage media with 100 μg/ml of gentamicin alone needs reevaluation. We investigated the stability and possible cytotoxicity of streptomycin as a supplement to gentamicin in Optisol corneal storage medium. The combination of gentamicin and streptomycin in Optisol solution was stable at room temperature for at least 4 weeks and inhibited the growth ofStaphylococcus aureus, S. epidermidis, α hemolytic streptococci,StreptococcusGroup D,Propionibacterium acnes, Escherichia coli, and diphtheroids, but notPseudomonas aeruginosa.The addition of vancomycin did not significantly improve the antibacterial effectiveness of the gentamicin and streptomycin combination when stored at 4°C. The growth of 15 of 20 clinical ocular isolates ofPs. aeruginosawas suppressed by the gentamicin-streptomycin combination. Streptomycin in concentrations of up to 1,000 μg/ml did not decrease the mitotic activity of corneal endothelial cells as evaluated by the in vitro incorporation of tritiated thymidine or cause cytotoxicity. The addition of 200 μg/ml of streptomycin to Optisol corneal storage medium containing 100 μg/ml of gentamicin may significantly improve activity against gentamicin-sensitive and gentamicin-resistant contaminants.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The effect of poloxamer 407 onPseudomonas aeruginosaadherence to cultured epithelial cells from rabbit corneas was investigated. Three methods of bacterial quantification were used to assessP. aeruginosaadherence: scanning electron microscopy (SEM) counts, radioactivity counts, and viable bacteria counts. Confluent monolayers of rabbit corneal epithelial cells were incubated in agitation for 30 min at room temperature with H3-labeled or nonradiolabeledP. aeruginosa(1010bacteria/ml) in a solution of poloxamer 407 [2% or 4% in phosphate-buffered saline (PBS)] or PBS as control. Cell monolayers were washed to remove nonadherent bacteria and fixed with 2.5% glutaraldehyde and processed for SEM or processed for radioactivity counting or for culture on agar plates. The results showed that both solutions of poloxamer 407 inhibited ∼75% of the bacterial adherence to epithelial cells (p < 0.05). Similar percentages of bacterial inhibition were obtained using the three methods of bacterial quantification. The use of an antiadherent agent such as poloxamer 407 in eye drops could possibly be a prophylactic approach toP. aeruginosakeratitis.

ISSN:0277-3740    

出版商:OVID    

年代:1995

数据来源: OVID