In vivo assessment of corneal stromal toxicity by tandem scanning confocal microscopy.

Epithelial wound closure following superficial corneal abrasions precipitates a complex series of cellular changes in the stroma. Transmission electron microscopy and light microscopy have demonstrated that keratocytes in the anterior stroma show prominent cytoplasmic process and granularity within an hour after this injury. Cell degeneration follows rapidly, with almost complete depletion of these keratocytes by 6-12 hours. Regeneration then occurs by 24-48 hours. These findings were confirmed in-vivo by tandem-scanning confocal light microscopy in rabbits. The optical sectioning capability of this instrument allowed us to demonstrate the three-dimensional array of fibroblast process, their subsequent condensation, and loss by sequential examinations on the same animals. Cell shrinkage and other fixation artifacts common in corneal histological sections were avoided by this technique. Using this method, we investigated the corneal cytotoxicity of an antimitotic agent, mitomycin-C and a muscarinic antagonist, atropine sulphate. Mitomycin-C, an antimetabolite used in pterygium treatment, led to irreversible keratocyte depletion even after four days of observation. However, cellular reaction to the wound were attenuated by atropine sulphate suggesting that it may be useful as a novel inhibitor of fibroblast proliferation.