A new surgical technique for deep stromal, anterior lamellar keratoplasty.
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AIMS: To describe a new surgical technique for deep stromal anterior lamellar keratoplasty. METHODS: In eye bank eyes and sighted human eyes, aqueous was exchanged by air, to visualise the posterior corneal surface--that is, the "air to endothelium" interface. Through a 5.0 mm scleral incision, a deep stromal pocket was created across the cornea, using the air to endothelium interface as a reference plane for dissection depth. The pocket was filled with viscoelastic, and an anterior corneal lamella was excised. A full thickness donor button was sutured into the recipient bed after stripping its Descemet's membrane. RESULTS: In 25 consecutive human eye bank eyes, a 12% microperforation rate was found. Corneal dissection depth averaged 95.4% (SD 2.7%). Six patient eyes had uneventful surgeries; in a seventh eye, perforation of the lamellar bed occurred. All transplants cleared. Central pachymetry ranged from 0.62 to 0.73 mm. CONCLUSION: With this technique a deep stromal anterior lamellar keratoplasty can be performed with the donor to recipient interface just anterior to the posterior corneal surface. The technique has the advantage that the dissection can be completed in the event of inadvertent microperforation, or that the procedure can be aborted to perform a planned penetrating keratoplasty. (+info)
Evaluation of potential organ culture media for eye banking using human donor corneas.
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AIM: To evaluate the ability of different commercially available cell culture solutions to preserve human donor corneas during 3 weeks of "closed system" organ culture at physiological temperature. This screening was performed in an attempt to establish a rational basis for the development of a serum-free organ culture medium for eye banking. METHODS: 72 normal human donor corneas were organ cultured for 21 days at 31 degrees C in eight different test media (nine corneas in each group). The basic culture solutions included: minimal essential medium (MEM), MEM with stabilised L-glutamine, M199, DIF-1000, SFM, F99, and F99 with ascorbic acid, insulin, bFGF, transferrin, selenium, and lipids (termed F99-Sr). All media were supplemented with 2% fetal calf serum (FCS), except for MEM, which was also studied at 8% FCS. The evaluation parameters included: (1) the endothelial cell loss as evaluated using trypan blue staining; (2) the ability of keratocytes and endothelial cells to incorporate tritiated uridine into RNA as evaluated using autoradiography and digital image analysis; (3) the leakage of immunogenic keratan sulphate as assessed using ELISA; and (4) changes in storage medium pH, glucose, and lactate content. RESULTS: SFM induced the lowest endothelial cell loss of 14% (SD 2%) and the highest RNA synthesis rates of all test solutions supplemented with 2% FCS. Corneas stored in SFM also showed the least leakage of keratan sulphate and the highest glucose consumption and lactate production. In five media (MEM with 2% FCS, MEM with stabilised L-glutamine, M199, F99, and F99-Sr), comparable and intermediate potentials for organ culture were observed with endothelial cell loss of 16-19%. By contrast, 29% (4%) of the endothelium was lost after storage in DIF-1000. Interestingly, the use of 8% FCS (in MEM) had a marked protective effect on the endothelium, which showed the highest RNA synthetic activity combined with a cell loss of only 11% (4%), compared with 19% (6%) at 2% FCS (p<0.05). CONCLUSION: Among the present test solutions, SFM appears to be the most prominent candidate for a new corneal organ culture medium and should be further tested and possibly refined to effectively substitute serum addition. (+info)
Automated tri-image analysis of stored corneal endothelium.
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BACKGROUND: Endothelial examination of organ culture stored corneas is usually done manually and on several mosaic zones. Some banks use an image analyser that takes account of only one zone. This method is restricted by image quality, and may be inaccurate if endothelial cell density (ECD) within the mosaic is not homogeneous. The authors have developed an analyser that has tools for automatic error detection and correction, and can measure ECD and perform morphometry on multiple zones of three images of the endothelial mosaic. METHODS: 60 human corneas were divided into two equal groups: group 1 with homogeneous mosaics, group 2 with heterogeneous ones. Three standard microscopy video images of the endothelium, graded by quality, were analysed either in isolation (so called mono-image analysis) or simultaneously (so called tri-image analysis), with 50 or 300 endothelial cells (ECs) counted. The automated analysis was compared with the manual analysis, which concerned 10 non-adjacent zones and about 300 cells. For each analysis method, failures and durations were studied according to image quality. RESULTS: All corneas were able to undergo analysis, in about 2 or 7.5 minutes for 50 and 300 ECs respectively. The tri-image analysis did not increase analysis time and never failed, even with mediocre images. The tri-image analysis of 300 ECs was always most highly correlated with the manual count, particularly in the heterogeneous cornea group (r=0.94, p<0.001) and prevented serious count errors. CONCLUSIONS: This analyser allows reliable and rapid analysis of ECD, even for heterogeneous endothelia mosaics and mediocre images. (+info)
Enhancing eye donation rates. Training students to be motivators.
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PURPOSE: Medical professionals could enhance eye donation rates by reminding relatives during grief counseling at the time of patient's death. This study was designed to assess the knowledge and attitudes of final year medical students (future doctors) towards eye donation, prior to instruction in eye banking. METHODS: The responses of 49 final-year medical students to a questionnaire on eye donation were compared with 24 non-medical students (controls). The results were analysed statistically using the chi-square test. RESULTS: More than one-third of students and controls were unaware that eyes are removed within six hours of death. Eight (16.3%) students and 6 (25.0%) controls felt that a close relative's eyes could be donated after death only if he had indicated willingness (P = 0.05). Three (6.1%) students and 3 (12.5%) controls were undecided about donating their own eyes. Nineteen (38.8%) students and 6 (25%) controls did not know where to go in order to pledge/donate eyes. The controls had poorer knowledge of ocular and systemic contraindications, and they did not know that storage could be prolonged (P < 0.001). Only 27 (55.1%) students had knowledge of corneal storage. CONCLUSIONS: Controls were poorly informed about various aspects of eye donation suggesting inadequate dissemination of information by the media. Students and controls alike had misconceptions regarding donation of relatives' eyes and hesitation regarding their own. These aspects should be emphasized during undergraduate teaching to dispel misgivings regarding wastage of donor eyes and to encourage future doctors to promote eye donation. (+info)
Sensitivity and rapidity of blood culture bottles in the detection of cornea organ culture media contamination by bacteria and fungi.
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AIMS: To test the bactericidal activity of standard organ culture medium, and to compare the sensitivity and rapidity of blood culture bottles with conventional microbiological methods for detection of bacteria and fungi inoculated in a standard cornea organ culture medium. METHODS: The bactericidal activity of contaminated standard organ culture medium containing 100 IU/ml penicillin, 0.1 mg/ml streptomycin, and 0.25 micro g/ml amphotericin B was evaluated after 48 hours of incubation at 31 degrees C with five inocula of 14 bacteria. Two yeasts (Candida spp) and one Aspergillus were also tested. Contaminated media were then inoculated in three blood bottles (aerobic, anaerobic, fungal) placed in a Bactec 9240 automat; three conventional microbiological broths were the control. Changes in colour of organ culture medium and growth on conventional broth were screened daily by visual inspection. The sensitivity and rapidity of detection of contamination were compared between the three methods: blood bottle, conventional, and visual. RESULTS: Organ culture medium eradicated five bacteria irrespective of the starting inoculums: Streptococcus pneumoniae, Branhamella catarrhalis, Escherichia coli, Propionibacterium acnes, and Haemophilus influenzae. For micro-organisms where the medium was ineffective or bactericidal only (methicillin resistant Staphylococcus aureus, methicillin sensitive Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Pseudomonas aeruginosa, Acinetobacter baumannii, Bacillus subtilis, Klebsiella pneumoniae, Enterococcus faecalis, Candida albicans, Candida kruzei, Aspergillus fumigatus), the blood bottle, conventional, and visual methods detected microbial growth in 100%, 76.5%, and 70% of cases respectively. Mean detection time using blood bottles was 15.1 hours (SD 13.8, range 2-52). In cases of detection by the blood bottle method and the conventional method, the former was always faster: 95.5% against 65.2% detection within 24 hours (p=0.022) respectively. CONCLUSIONS: Blood bottles detect more efficiently and more rapidly a wider range of bacteria and fungi than the conventional microbiological method and the visual inspection of organ culture media. (+info)
Awareness of eye donation in an adult population of southern India. A pilot study.
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PURPOSE: To determine "awareness of eye donation" and corneal transplantation in an adult population of southern India. METHODS: 507 participants chosen by systematic random sampling were interviewed using a structured questionnaire. Participants were selected among patients attending two community outreach programmes at different sites, and from patients presenting directly to the hospital. RESULTS: 257 participants (50.69%) were aware of eye donations. The major source of awareness was publicity campaigns (n=105). Only 22 (4.34%) participants were aware that eye donation had to be done within 6 hours of death. Four hundred and three (79.50%) participants were not aware of corneal transplantation. Illiteracy and rural residence were more likely predictors of ignorance. CONCLUSION: Although multiple strategies are currently followed to increase awareness of eye donations and corneal transplants, more innovative strategies have to be developed, especially to target illiterate and rural populations. (+info)
Stability of RNA from the retina and retinal pigment epithelium in a porcine model simulating human eye bank conditions.
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PURPOSE: To assess RNA stability after death in a porcine model to simulate current human eye bank techniques. METHODS: Eye bank time interval data were collected from 191 donor specimens: death to refrigeration, enucleation, and tissue processing. A control porcine eye was enucleated, retina and RPE isolated, and specimens frozen (-80 degrees C). Fourteen porcine eyes remained at room temperature for 2 hours and then cooled to 4 degrees C. Retina and RPE were isolated and frozen (-80 degrees C) at 5, 12, 24, 29, 36, 48, and 72 hours. Four globes remained in a moist chamber, five whole and five sectioned globes were immersed in RNAlater (Ambion, Austin, TX) at 5, 12, 24, or 48 hours. RNA was isolated. The 28S and 18S rRNA peaks were analyzed by electrophoresis. RT-PCR was performed on each sample. Messenger RNA for GAPDH, beta-actin, mouse rhodopsin from retina (mRHO), and RPE-65 (from RPE) were analyzed with gel electrophoresis. RESULTS: The average time from death to refrigeration was 4.2 hours, to enucleation 6.4 hours, and to tissue processing 10.7 hours. RT-PCR gel electrophoresis patterns from retinal tissue had bands of similar intensity at each interval from beta-actin, GAPDH, and RHO. Band patterns from RPE demonstrated decay of the RT-PCR gene products after 5 hours. This decay was delayed by at least 24 hours with the use of RNAlater. The 28S rRNA decay was similar for retina and RPE. CONCLUSIONS: Retinal tissue RNA can be analyzed within the time constraints of current eye bank tissue processing, whereas analysis of RPE necessitates either rapid processing or use of RNAlater. These results should aid in future studies in which eye bank tissue is used for RNA analysis. (+info)
Is manual counting of corneal endothelial cell density in eye banks still acceptable? The French experience.
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AIM: To examine the differences in manual endothelial cell counting methods in French eye banks and to analyse whether these differences could explain some substantial discrepancies observed in endothelial cell density (ECD) for corneas made available for transplant. METHODS: A questionnaire was sent to the 22 eye banks asking for details of the technical features of the light microscopes used, the microscope calibration, strategy for cell counting, the technical staff, and the method of presenting endothelial data. RESULTS: All eye banks responded and 91% (20/22) used only manual counting methods, in real time, directly through a microscope, and 62 different technicians, with varying experience, were involved in such counting. Counting of cells within the borders of a grid that were in contact with two adjacent borders was the most common method (17/22, 77%). Of the eight banks (8/22, 36%) that did not calibrate their microscopes, six reported the highest ECD values. Of the 14 others (64%), six applied a "magnification correcting factor" to the initial cell counts. In five of these cases, the corrected ECD was lower than estimated on initial count. Most of the banks (12/22, 55%) counted 100 cells or less in one to six non-adjacent zones of the mosaic. 14 of the banks (14/22, 64%) also graded cell polymegethism while seven (7/22, 32%) also graded pleomorphism ("hexagonality"). CONCLUSIONS: Lack of microscope calibration appears to be the leading cause of variance in ECD estimates in French eye banks. Other factors such as differences in counting strategy, the evaluation of smaller numbers of cells, and the different extent of experience of the technicians may also contribute to intraobserver and interobserver variability. Further comparative studies, including cross checking and the outcome of repeated counts from manual methods, are clearly needed with cross calibration to a computer based image archiving and analysis system. (+info)