Tandem scanning confocal microscopic analysis of differences between epithelial healing in limbal stem cell deficiency and normal corneal reepithelialization in rabbits

Purpose. To analyze the differences in epithelial healing between limbal stem cell-deficient corneas and normal corneas by using in vivo confocal microscopy. Methods. Two different injury models were made in rabbit eyes by using n-heptanol to create a corneal epithelial defect with (limbal stem cell-deficiency model) or without (normal corneal reepithelialization model) peripheral limbal keratectomy. Using a tandem scanning confocal microscope (TSCM), we examined and compared the epithelial healing processes of the two different injury models. Impression cytology and pathologic examination were done on limbal stem cell-deficient corneas. Results. In limbal stem cell-deficient corneas, the healing epithelial cells were smaller and more variable in size compared with those in normal corneas. In limbal stem cell-deficient corneas, the epithelial thickness varied from one to six cell layers, with the middle and basal cell layer cells being lined up in a certain direction in some areas. The basement membrane was uneven and partially deficient; in some areas, the deep basal epithelial cells were mixed with fibrous strands extending from the anterior stroma. New vessels were located in various levels, from epithelium to deep stroma. These findings were not seen in the normal corneal reepithelialization. In both epithelial-healing models, particularly in the normal corneal reepithelialization, the superficial squamous cells in the early healing stage were considerably larger than those in nontraumatized normal corneas. Conclusion. TSCM is a useful technique for studying the in vivo microscopic structure of many corneal diseases and injury models sequentially over time.