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Changes in the incidence and management of corneal disorders were the primary factors leading to modifications of grafting until 1987. After 1987, corneal button shortage probably corresponded to the acquired immune deficiency syndrome epidemic. Governmental regulations of eye banking led to a severe corneal button shortage between 1992 and 1997. Despite an increase in the number of PKs performed after 1997, corneal buttons are still preferentially allocated to patients in whom there is a high probability of graft success.

SUMMARY The effect of corticosteroids on the re-epithelialisation of corneas from which the epithelium was removed has been determined by fluorescein staining, photography, and light microscopy. Our results suggest that hydroxymethyl progesterone 1 05% (p<005), prednisolone 1-0% (p<0-001), and dexamethasone 0-1% (p<0001) administered 6 times a day retard the epithelial wound healing compared with control animals which received isotonic NaCl. The method described by Moses et al. " was used for removal of the corneal epithelium. Our tube has an internal diameter of 7-3 mm at the tip.Rabbits were anaesthetised with sodium pentobarbital administered in a marginal ear vein (25 mg per kg body weight). Two drops of Novesine (oxybyprocaine hydrochlorate 0 4%) were instilled into each eye. Each eye was then gently proptosed, and the lip of the iodine tube was wiped on a filter paper and held against the cornea for 3-5 minutes. Recording of the lesion was by photography. The cornea was stained with one drop of 0-5% fluorescein (without preservatives) and then washed with 2 drops of isotonic NaCl solution. The lesions were photographed on Kodak Tri-X film 4 times a day until the complete healing of the corneal epithelial wound, which was determined by the absence of corneal fluorescein uptake. An annular electronic flash covered with a Wratten 47 B filter was fixed round the objective of a slit-lamp, and the objective was covered with a Wratten 12 filter to obtain a good contrast on black-and-white films.With a Quantimet 720 (Cambridge Instruments, UK) the fluorescein-stained areas were measured and converted to square millimeters.For each eye a healing curve was obtained by plotting successive areas of the wound against time. The best fitting curve by the least squares method was obtained by means of a linear regression.The diameter of the first corneal wound for each eye was also measured at 6 hours.Histological study. Four days after treatment 4 eyes from each group were enucleated, stained with haematoxylin and eosin, and prepared for histological examination.Under the microscope we counted the total number of cellular nuclei on the 4 specimens on a 0-35 mm 705 on 10 May 2018 by guest. Protected by copyright.