Structural and functional alterations in corneal nerves after single-step transPRK

Purpose: To evaluate the relationship between structural and functional changes of corneal subbasal nerves after single-step transepithelial photorefractive keratectomy (TransPRK). Setting: Tianjin Medical University Eye Hospital. Design: Prospective observational study. Methods: 51 eligible candidates who underwent TransPRK for moderate myopia were included. The regeneration of corneal subbasal nerves were evaluated by in vivo confocal microscopy (IVCM) prior to surgery and at 1 week and 1 month, 3 months, 6 months, and 12 months postoperatively. The corneal sensitivity was measured by Cochet-Bonnet esthesiometer. The number of complete and incomplete blinks were recorded by LipiView interferometer. A correlation analysis was performed between these variables. Results: 51 eyes of 51 patients were enrolled in this study. IVCM revealed that the density and length of corneal nerve decreased immediately and did not return to preoperative levels by 12 months post-TransPRK ( P < .01). The mean corneal sensitivity was slightly lower compared with preoperative levels at 1 week postoperatively ( P = .001) and then increased to baseline preoperative level within 1 month postoperatively. Mean total blink frequency and the partial blink rates had no statistically significant change postoperatively ( P = .087). There was no direct correlation between postoperative recovery of corneal sensitivity, changes in blink frequency, and regeneration of subbasal corneal nerve. Conclusions: The significant and prolonged decrease in corneal subbasal nerve morphology was accompanied by only a slight and transient reduction in corneal sensitivity to mechanical stimuli within 1 month after TransPRK. The results demonstrated that the structural changes of subbasal nerves were not parallel to their functional changes after TransPRK.