In vivo confocal microscopy of corneal wound healing after excimer laser photorefractive keratectomy.

We used real-time scanning confocal microscopy to evaluate early changes in corneal wound healing after excimer laser photorefractive keratectomy (PRK). Adult New Zealand White rabbits were given photorefractive keratectomy treatments appropriate for 5.00 to 8.00 D of myopia (44.5 to 71.0 micros depth, with a 5-mm diameter treatment zone). Daily confocal microscopic examinations showed acute loss of keratocytes in the anterior corneal stroma by 5 hours; losses were maximal between 24 and 48 hours for 5.00 D and 6.00 D ablations and between 72 and 96 hours for 7.00 D and 8.00 D ablations. The oval nuclei of normal keratocytes gave way to spindle-shaped fibroblasts accompanied by an accumulation of fibrillary extracellular matrix. Fibroblasts density increased toward the end of the week. Deeper ablations resulted in a longer period of keratocyte depletion and delayed onset of fibroblast activity. No epithelial, deep stromal, or endothelial abnormalities were detected, nor was stromal inflammation found. Light microscopy 1 week after PRK revealed superficial fibroplasia, which correlated with the en face images obtained with real-time in vivo confocal microscopy. The confocal microscope has a number of advantages as a clinical tool for investigation of laser-induced changes in corneal keratocytes and the stromal matrix, which may play a role in determining visual outcome after PRK.