Changes of Corneal Nerve Regeneration and Corneal Sensitivity after Corneal Tattooing

ABSTRACT

PURPOSE: To investigate the changes of corneal nerve innervation and sensitivity after corneal tattooing. METHODS: Twelve New Zealand rabbits were divided into two groups of six subjects each. Tissue marking dye or balanced-salt solution was injected into the corneal stroma in one eye of each subject. Corneal nerve innervation was observed at 3 days and 1, 2, 3, 4, and 6 weeks postoperatively and compared with that of the opposite eyes. Corneal sensitivity was evaluated at 1, 2, and 3 days and 1, 2, 3, 4, and 6 weeks postoperatively and compared to the preoperative values in the same subjects. RESULTS: The ratios of corneal nerve density of the study eyes to those of the control fellow eyes were 1.09 in the central area and 1.06 in the peripheral area in subjects injected with tissue marking dye, and 1.11 and 1.23, respectively, in subjects injected with balanced salt solution, which showed no difference between the two groups. The corneal nerve density tends to increase at 3 days postoperatively (p=0.125), but no significant change was found thereafter. Corneal sensitivity assessed using the Cochet-Bonnet esthesiometer was 2.13+/-0.48 cm preoperatively. At three days postoperatively, it was 2.50+/-0.48 cm in subjects injected with tissue marking dye and 2.33+/-0.26 cm in subjects injected with balanced salt solution. It was significantly increased at 3 days postoperatively (2.42+/-0.36 cm, p=0.031), but there were no significant changes at 7 days or more postoperatively. CONCLUSIONS: Corneal nerve density increased at 3 days after corneal tattooing, and this effect is thought to be related to early postoperative hypersensitivity.