摘要:

PurposeTo review the current requirements and rationale for serologic testing of cornea donors and to provide guidelines for dealing with results of nonrequired tests. Methods. Eye Bank Association of America (EBAA) and Food and Drug Administration (FDA) regulations are examined with respect to current knowledge of the risk of donor-to-host transmission of systemic infectious diseases via corneal transplantation. Results. Negative screening tests are required for human immunodeficiency virus (HIV) 1 and 2, hepatitis B surface antigen (HBsAg), and hepatitis C virus (HCV) before release of tissue for transplantation. Other tests reported by organ-procurement organizations commonly include hepatitis B core antibody (anti-HBc), syphilis, cytomegalovirus (CMV), and human T-lymphotropic virus (HTLV) I and II. No systemic infectious-disease transmission from donor corneas supplied by EBAA-member eye banks has occurred in the last 12 years, a period during which > 400,000 corneas were provided for transplantation. Conclusion. EBAA donor-screening requirements, including serologic testing, have resulted in an excellent safety record. Requirements for serologic testing should continue to be regularly reviewed as new information becomes available.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Purpose. To report the use of perfluoropropane (C3F8) gas in the repair of Descemet's membrane detachments. Methods. Descemet's membrane detachments after cataract surgery in three eyes and pars plana vitrectomy in a fourth underwent anterior-chamber gas-exchange descemetopexy with an isoexpansile 14% mixture of C3F8to facilitate reattachment of Descemet's membrane. Results. Descemet's membrane detachment was successfully reattached after anterior-chamber gas exchange with 14% C3F8in three of the four eyes treated. The fourth eye treated with 14% C3F8probably failed Descemet's membrane reattachment because of an unrecognized viscoelastic bleb situated anterior to Descemet's membrane. No corneal decompensation or fluctuations in intraocular pressure were believed to be attributable to isoexpansile C3F8gas exchange. Conclusion. Early recognition and repair of Descemet's membrane detachments may prevent complications, such as corneal decompensation, corneal opacities and edema, and an overall decline in visual acuity. Isoexpansile C3F8is demonstrated as a safe and efficacious alternative for the repair of Descemet's membrane detachment.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundApproximately 15–20% ofStreptococcus pneumoniaeclinical isolates in the United States are not susceptible to penicillin. Isolates with a minimum inhibitory concentration (MIC) of 0.12–1.0 mg/ml are intermediately resistant, and those with an MIC > 2.0 μg/ml are classified as having high-level penicillin resistance. Purpose. We determined the proportion of penicillin-resistantS. pneumoniaerecovered from ocular and periocular infections from 1976 through 1995, compared these cases with penicillin-susceptible controls, and evaluated the susceptibility of penicillin-resistant isolates to selected cephalosporins and fluoroquinolones. Methods. MICs for cephalothin, ceftazidime, ciprofloxacin, and ofloxacin were determined for available isolates by the E test. We performed a case-comparison study to evaluate differences between patients with penicillin-susceptible and -nonsusceptible ocular pneumococcal infections. Results. Of 173 ocular isolates ofS. pneumoniaeisolated in the 20-year period, 12 (7%) were not susceptible to penicillin, including eight (5%) intermediate isolates and four (2%) highly resistant isolates. Penicillin-intermediate and -resistant pneumococci were recovered at a rate of none of 46 isolates from 1976 through 1980, one (4%) of 25 from 1981 through 1985, one (2%) of 51 from 1986 through 1990, and 10 (20%) of 51 from 1991 through 1995 (p< 0.0004). We found no significant differences in presenting characteristics between patients with ocular infections due to penicillin-susceptible pneumococci and those caused by nonsusceptible strains. All retested isolates with intermediate susceptibility to penicillin had a cephalothin MIC ≤ 1.5 (μg/ml, and all retested isolates with high-level penicillin resistance had a cephalothin MIC ≥ 4 μg/ml. The ceftazidime MIC for all penicillin-resistant isolates was ≥ 24 μg/ml. All penicillin-nonsusceptible isolates had MICs ≤ 1.5 μg/ml for ciprofloxacin and ≤ μg/ml for ofloxacin. Conclusion. Penicillin resistance has recently emerged among ocularS. pneumoniae.Cephalothin, ciprofloxacin, and ofloxacin have good activity against some ocular isolates with intermediate penicillin susceptibility, although another agent such as vancomycin may be needed for pneumococci with high-level penicillin-resistance.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeA positive donor-recipient crossmatch (CM) due to preexisting recipient lymphocytotoxic antibodies is known to be an important factor in allograft failure in the majority of organ transplantations. However, the effect of positive CM on corneal graft outcome is less known.Method.Between 1982 and 1994, CM was performed by the microlymphocytotoxicity method using donor lymphocytes and recipient pretransplant serum in 759 consecutive corneal transplantations (maximal follow-up, 36 months). Patients were evaluated regarding the type of allospecificity of antibodies involved and their role on corneal graft outcome (rejection and failure). Results. A positive CM was found in 61 patients (8%) and a negative CM in 698 patients (92%). The positive and negative CM groups had similar graft rejection rates at 36 months. Patients with a positive CM due to antibodies directed against donor human leukocyte antigen (HLA) (as defined on the basis of private and public or CREG HLA allele specificities) did not have an increased risk of rejection. However, patients with positive CM and presensitization (previous graft or rejection history) had a statistically significant increase in risk of corneal endothelial rejection. Conclusion. This study shows that donor-recipient CM could be a useful procedure for the selection of recipients for corneal transplantation in patients presensitized by anterior graft or previous corneal rejection.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeThis study quantified the bacterial load and protein deposits on 1− and 15-day disposable contact lenses after use in normal wearers. Methods. Sixteen patients were randomly assigned to a 1-day contact lens (1-Day Acuvue) in one eye and to a 15-day contact lens (Acuvue) in the contralateral eye. Only one specified solution was allowed for the care of 15-day lenses. All patients were evaluated every month for 6 months (at times T1, T2, T3, T4, T5, T6). At times T1, T3, and T5, the lenses were removed in a sterile fashion and sent for laboratory quantification ofStaphylococcus aureusandPseudomonas aeruginosa.At T2, T4, and T6, quantification of protein deposits was determined, and at T0 and T6, impression cytology of the conjunctiva was performed. Results.P. aeruginosawas not identified on any lens. At T1, T3, and T5,S. aureuswas significantly greater on the 1-day versus 15-day lenses (p< 0.001). In contrast, protein deposits were significantly greater on the 15-day lenses at all time points (T2, T6:p< 0.01; T4:p< 0,05). Impression cytology of the 15-day lens eyes revealed a worsening trend compared to the 1-day lens; however, no statistically significant differences were found between the two groups (p= 0.29). Conclusion. Results of this study suggest that the use of cleaning and preservative solutions can alter the ocular surface bacterial environment of the contact lens wearer and that these changes are not a direct consequence of contact lens wear. The bactericidal activity of these solutions could, with time, also affect ocular surface cells, leading to contact lens intolerance and ocular surface disease.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeTo determine the relationships among endothelial morphometric variables and contact lensinduced corneal swelling in a homogeneous sample of adapted contact-lens wearers. Methods. Fifteen male subjects ranging in age from 20 to 40 years, all adapted to daily wear of hydrogel lenses, wore uniform-thickness lenses (Dk/L = 5.78) under unilaterally patched eyes for 4 h. Unpatched fellow eyes served as controls. Central corneal thickness was measured with an optical pachometer. Central endothelial images were obtained with a Topcon SP-1000 Specular Microscope and analyzed by the Topcon IMAGEnet processing system. Thickness and morphometric data were collected on test and control eyes before and after the patching sessions. Results. A strong correlation (r= −0.795;p< 0.001) was found between central corneal swelling and endothelial-cell density. Correlations between swelling and the coefficient of variation in cell area (r= 0.502;p< 0.06) and between swelling and the percentage of six-sided cells (r= −0.200;p< 0.48) were not significant. Correlations among the morphometric variables were not significant. Differences in the morphometric variables between test and control eyes were not significant before or immediately after the patching sessions. Conclusion. Endothelial-cell density is useful in explaining differences in corneal-swelling responses to closed-eye contact-lens wear among adapted wearers, whereas morphometric variables based on cell-size variability and shape are not.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeTo assess alterations in the blood-aqueous barrier after radial keratotomy (RK), photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and photothera-peutic keratectomy (PTK). Methods. Aqueous flare was evaluated using the Kowa FM 500 laser flare meter in a total of 87 eyes from 82 patients who underwent refractive surgery. Measurements were obtained preoperatively in 51 eyes of 51 patients who underwent RK or PRK and again at the end of surgery, and at 1 day and 1 week postoperatively. These patients had been randomized (double masked) to receive topical 0.1% dexamethasone, polymyxin B (6,000 U/ml), and 0.5% neomycin 4 times a day for 1 week after surgery, or polymyxin B (6,000 U/ml) and 0.5% neomycin for 1 week. Aqueous flare measurements were also obtained before surgery in 36 eyes (31 patients) that underwent LASIK and again at 1 day and 1 and 2 weeks postoperatively. All patients in this group received topical 0.1% dexamethasone, polymyxin B (6,000 U/ml), and 0.5% Neomycin 4 times a day for 15 days after surgery. Results. Uneventful RK induced a significant increase in flare immediately after surgery, although this did return to baseline 1 day after surgery (Friedman test). Measurements at 7 days after surgery were similar in steroid-treated and untreated groups. Limbal bleeding, which occurred in 23% (12/51) eyes, did not induce significantly increased flare as compared to uneventful RK. Microperforations, which occurred in 18% (9/51) eyes, did induce significant alterations in the blood-aqueous barrier that persisted for ≥ 1 day, but measurements returned to preoperative levels by day 7. PRK and LASIK induced substantially increased flare in some eyes. Phototherapeutic keratectomy, in particular, induced an elevation in flare measurements that did not return to normal levels even by 15 days after surgery (Friedman test). Conclusions. Using mean results of laser flare meter evaluation, uneventful RK appears to induce short-lasting elevations in aqueous flare in both steroid-treated and untreated patients. Microperforation induced prominent alterations in flare measurements, although limbal bleeding did not. Both PRK and LASIK did appear to increase flare measurements in some eyes, while PTK induced significant elevations in aqueous flare in the majority of eyes.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeTo describe a new manifestation of Peters' anomaly. Methods. We managed four infants with an unusual form of Peters' anomaly. One eye of each patient had a thickened and scarred cornea, mimicking a corneal staphyloma, protruding anteriorly from the corneal plane. The other eye of each patient ranged from normal to having severe ocular anomalies. A corneal transplant was performed in each case. Results. Follow-up ranged from 1 to 3 years. Three eyes maintained graft clarity for at least 1 year. Each of these eyes developed vision. Two of these eyes developed glaucoma. The one eye with graft failure developed an inoperable retinal detachment. The histopathology of each corneal button showed changes consistent with Peters' anomaly. Conclusions. These corneas demonstrated characteristics of both Peters' anomaly and congenital anterior staphyloma. Despite their severe anomalies, surgery successfully restored a more normal cosmetic appearance in all four eyes and vision in three eyes.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeDefects in the iris are associated with clinically significant optical anomalies, such as glare and peripheral light scatter; however, current artificial-iris technology remains inadequate. The purpose of this study was to explore the practicality of a lamellar intrastromal tattoo technique as a treatment modality to correct optical and cosmetic defects resulting from simulated iris abnormalities in eye-bank eyes. Methods. Simulated iris defects (abnormally large pupil, sector iridectomy, iridodialysis, and aniridia) were produced in a series of eye-bank eyes. Depending on the simulated iris defect, one or two lamellar channel(s) were created at 50% depth of the cornea via a peripheral incision (1.8 mm) with specialized proprietary instruments (Kera Vision, Inc., Fremont, CA, U.S.A.). Commercially available tattoo pigment was inserted through the lamellar channel(s) and blended into the detective region of the iris. Results. The tattoo treatment was relatively simple to perform. Tattoo pigment was inserted uniformly through the small incision, and adequate color blending to match the recipient iris was achieved. The intrastromal tattoo effectively obscured light. Conclusion. The lamellar intrastromal tattoo technique appeared to be efficacious for treating different types of iris defects in eye-bank eyes. Further investigation of this technique in nonsighted patient eyes is warranted.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PurposeTo evaluate the predictability of the depth of stromal pockets made in the posterior cornea for the excision of anterior or posterior lamellar corneal buttons with a planned thickness. Methods. Stromal corneal pocket dissections were created in human eye bank eyes by making a peripheral arcuate keratotomy incision at 60, 80, or 95% of central pachymetry and creating a pocket from the bottom of the incision across the cornea. Pocket depth was measured by pachymetry immediately after surgery and by light microscopy. Results. Mean achieved central pocket depth differed by 0.03±0.03 mm from the intended depth. Variation in depth across the pocket decreased from 0.07±0.02 mm for pockets made at 60% of the intended depth to 0.05±0.01 mm for pockets made at 80% depth, and 0.04±0.02 mm for pockets made at 95% depth (p< 0.01). Pachymetric and histological measurements of relative pocket depth averaged 64±9% and 73±7%, respectively, for pockets made at 60% of the intended depth, 82±7% and 86±3% for pockets made at 80% depth, and 91±7% and 92±3% for pockets made at 95% depth. The difference between pachymetric and histological relative pocket depth measurements decreased with deeper pocket depth (p< 0.01). Conclusions. In the posterior cornea, stromal pockets can be created to within 30 μm from the intended depth. Variation in depth throughout the pocket decreases with deeper pocket depth. Pachymetry is a reliable method to check the achieved pocket depth during surgery; the accuracy of pachymetry readings improves with deeper pocket depth.

ISSN:0277-3740    

出版商:OVID    

年代:1998

数据来源: OVID