Walther Medin

Wound healing of rabbit cornea in organ culture.

Abstract. A 2 mm perforating cut was made in the central part of 28 rabbit corneas. The corneas were then kept in organ culture from 3 h to 21 days. The healing process was studied by light microscopy and by transmission and scanning electron microscopy. The swelling of the corneal stroma adjacent to the wound created contact between the opposing wound edges within 3 h. Epithelial and endothelial cell migration into the wound was observed after 23 h. Penetration of cells through the perforation was avoided because the opposing wound edges were touching each other, thereby creating contact inhibition of cell proliferation. Cell cover of both the anterior and the posterior surface was completed within 3 days.

Swelling tendency of rabbit cornea in organ culture medium. Influence of button size.

Abstract. 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.

The cell barrier effect in rabbit corneas kept under eye bank conditions

Abstract The influence of endothelial cell pumping and of cell barrier functions on cultivated corneas has been studied by comparing the rate of weight increase in freeze‐treated, ouabain‐treated and fresh corneas. Inhibition of the endothelial cell pump activity increased the swelling rate from 0.5% of start weight per h (fresh corneas) to about 2% per h (ouabain‐treated corneas), as measured after 24 h in culture medium. The cell barrier effect was estimated by comparing the swelling rate of ouabain‐treated corneas after 24 h, and the swelling rate of freeze‐treated corneas with the same swelling pressure. The values are 2 and 9.5% per h, respectively. The swelling rate of freeze‐treated corneas with different button diameters was found to increase with decreasing corneal button diameter.

Endothelial pump function in rabbit corneas kept under eye bank conditions

Abstract 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 μm 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 method for registration of toxic drug effects on corneal endothelium. Effect of gentamicin on rabbit corneal endothelium.

Abstract 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).

Toxic effects of ouabain on the rabbit corneal endothelium

ABSTRACT Rabbit corneas kept in a standard tissue culture medium, were continually exposed to ouabain 10‐3 M, and cultivated for 2, 3, and 4 days The endothelium was still intact with a complete cell cover after 2 days of ouabain exposure Total destruction of the endothelium was found in the corneas cultivated for 3 and 4 days The corneal epithelium, however, appeared to be unaffected Other rabbit corneas were exposed for three days to ouabain concentrations of 10‐4 M, 10‐5 M, 10‐6 M, 10‐7 M, 10‐8 M, and 0 M The corneas exposed to 10‐4 M demonstrated total endothelial cell damage The specimens exposed to concentrations from 10‐5 M to 10‐8 M, presented dose dependant endothelial impairment as compared with the control corneas (0 M) Tracer experiments showed that the endothelial barrier was intact as long as there was a continuous cell cover, as estimated by light, transmission and scanning electron microscopy

The swelling of cornea in bank cultivation. The role of barriers and peripheral edge.

Abstract The swelling of a rabbit cornea in organ culture is caused by influx of fluid via the surface. Data regarding the weight increase rates during the first 4 h of corneal buttons with different diameters, have been used to calculate the net influx per mm2 per h via the anterior + posterior surfaces on one hand, and via the peripheral edge on the other hand. In fresh corneas the contribution to the corneal swelling, of the net fluid uptake via the anterior + the posterior surfaces, is negligible. The influx via the peripheral edge is about the same in fresh and freeze treated buttons. For freeze treated corneas, the resistance for fluid transport via the anterior + posterior surfaces seems to be 4 times higher than the resistance for transport via the peripheral edge. This result indicates that the Descemets membrane and the Bowmans layer may have some barrier effect. An alternative or supplementary explanation is that, at least in swollen corneas, there may be reduced resistance to fluid flow along the corneal plane as compared with the flow vertical to this plane.

An intraocular paraganglioma

Abstract. A tumour of the iris with the morphological and immunohistochemical characteristics of a paraganglioma is presented. Neither this type of tumour, nor the specialized nerve cells giving rise to the tumour, have previously been reported in the eye. A successful local resection was performed. The diagnosis and concept of paragangliomas are discussed briefly.

Further evaluation of a method used for investigation of toxic drug effects. Effect of gentamicin on rabbit corneal endothelium.

Abstract Further evaluation of a method suitable for investigation of toxic drug effect was performed. Rabbit corneas kept in organ culture were exposed to gentamicin for 24 h, and their weights were recorded. The weight increase observed in all specimens was significantly higher (p < 0.0001) in the corneas exposed to gentamicin 0.6 mg/ml (n = 7) than in the controls (n = 14). This was not the case for the corneas exposed to 0.3 mg/ml and 0.1 mg/ml. The accuracy of each weight recording was tested by repeated recordings. The standard deviation (SD) was less than 1%, and there was no significant difference between series performed by two different recorders. The reproducibility of the test was focused upon by calculating the SD of the control group, and by comparing the present results with the results of a control group in a recently published study (Medin 1992). The SD was approximately 2.8%, and no significant difference was found.

Keratoplasties performed at Rikshospitalet, Oslo, Norway A retrospective study

Abstract. Retrospective study was performed of 183 keratoplasties on human patients at Rikshospitalet, Oslo between November 80 and December 86. Penetrating technique others 5. There were 19 reoperations and 9 of these were keratocous 41, bullous keratopathy 35, keratitis herpetica 35, keratitis of unknown origin 23, interstitial/phlyctenular keratitis 20, corneal trauma 13, dystrophia/Fuchs dystrophia 11, others 5. There were 19 reoperations and 9 of these were keratitis herpetica. The patients with keratoconus had the best visual result and keratitis herpetica the poorest.