The swelling tendency of fresh rabbit corneas kept in organ culture was determined by measuring percentage weight increase. Corneal buttons with diameters of 5, 9, 14, and 16 mm had an average weight increase during the first hour of 53%, 35%, 18%, and 8.6%, respectively. Those with diameter 5 and 9 mm had a continuous weight increase up to a maximum of 350% to 450% of start weight after 25 h and 57 h, respectively. Many corneas with 16 mm diameter (including a thin scleral rim) and some with 14 mm, had a temporary stable weight of average 56% (with an individual cornea stabilizing at only 15%) above start weight between day 2 to day 7. Thereafter a phase with approximately linear weight increase ended at a maximum weight of 350% to 450% of start weight after one month. It is concluded that the rate of corneal swelling in cultivation is highly dependent upon the corneal button size.
Endothelial pump activity of rabbit corneas kept under eye bank conditions was examined. Different swelling rates for medium with and without ouabain were used for the calculation of endothelial pump rate. After an initial weight increase during 24 h, the control corneas kept approximately constant weight for 1 week. The ouabain-treated corneas increased continually, and during the time interval 24-48 h the increase was 41% of start weight. This corresponds to a pump activity of 2.3% of the weight of the normal corneal stroma per h, or to 9 microns of the corneal thickness per h. Each endothelial cell pumped fluid corresponding to 200-300% of the cell volume per h between day 1 (24 h) and day 8. The pump activity was gradually reduced after 8 days. The average weight was the same in both groups after 7 weeks.
A weight recording system (Medin & Davanger 1988, 1989), was used to demonstrate possible toxic damage of a medicament to the endothelium of rabbit corneas stored in organ culture. Seven corneas were stored in organ culture medium containing gentamicin (3.0 mg/ml). Seven other corneas stored in identical organ culture medium without gentamicin served as controls. The corneas were followed with weight recordings for up to 76 h. A toxic effect of gentamicin was demonstrated by a rapid weight increase in the corneas stored in the presence of gentamicin. After 5.3 h there was a significant difference (P = 0.0002) between the average weights of the two groups, and this difference increased during the following 2-3 days. Corneas from the two groups were also examined by light microscopy and scanning electron microscopy. There was good accordance between the weight recordings and the morphology. The weight recording system detects clearly the toxic effect of gentamicin (3.0 mg/ml).
ABSTRACT.Purpose: To investigate the influence of storage temperature on corneal swelling and on endothelial morphology in cultured corneas. Material and methods: Forty-eight rabbit corneas were separated into four groups of 12. The corneas were stored in culture medium at 37 (group 37), 34 (group 34), 31 (group 31) and 23 (room temperature) (group 23), respectively. All the corneas were monitored by weight recordings on days 0, 1, 2, 3, 4 and 7. On day 7, corneas were prepared for scanning electron microscopy and endothelial cell counts were performed. Results: Lowering the temperature of the culture medium resulted in less swelling. Both temperature and storage time had significant effects on corneal swelling (p < 0.001). On day 7, the observed mean weight increase was 131.2%, 143.0%, 172.5% and 199.7% in groups 23, 31, 34 and 37, respectively. The estimated mean daily weight increase for the corneas were 2.6%, 4.0%, 9.1% and 16.0% in groups 23, 31, 34 and 37, respectively. Scanning electron microscopy showed an intact endothelial layer in all groups after 7 days and there were no statistically significant differences in endothelial counts between groups 23, 31 and 34. In group 37, the cell borders were difficult to distinguish after 7 days and no meaningful count could be performed. Conclusions: The swelling rate of cultured corneas is significantly less at 23 and 31than it is at 34 and 37 during the first week. This is most likely the result of a greatly increased barrier effect at lower temperatures. Whereas weight recording revealed profound differences between the groups, scanning electron microscopy and endothelial cell counting did not. The results support the hypothesis that storage at 37is not optimal in culturing corneas. Lowering the temperature below body temperature, and even lower than 31, results in less corneal swelling.
ABSTRACT.Purpose: To evaluate the toxic effect of vancomycin on the corneal endothelium related to concentrations of vancomycin. Methods: The toxic effect is assessed with a weighing method that gives a measure of endothelial function. Thirty-three rabbit corneas were divided into four groups. Three groups of seven corneas each were exposed to concentrations of 1.0 mg/ml, 3.0 mg/ml and 5.0 mg/ml vancomycin, respectively. The fourth group of twelve corneas served as a control group. Results: The corneas exposed to 1.0 mg/ml vancomycin showed no significant weight increase, while the corneas exposed to 3.0 mg/ml and 5.0 mg/ml showed a significant weight increase as compared to the control corneas. The weight increase was significantly larger in the group of corneas exposed to 5.0 mg/ml as compared to 3.0 mg/ml. Conclusions: In the interval of tested concentrations there is a dose response relationship between vancomycin concentrations and endothelial toxicity. This experiment shows that vancomycin in the concentration of 1.0 mg/ml is nontoxic to the endothelium, while 3.0 mg/ml and 5.0 mg/ml increasingly impair endothelial function.
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