Changes In Corneal Sensation After Thin-flap LASIK And The Influence Of Ablation Depth Of Corneal Stroma

Objective:To evaluate changes in corneal sensitivity of different position following thin-flap LASIK and to investigate the effect of ablation depth of corneal stroma (ADCS)on the rate of recovery of corneal sensation.Methods:168eyes of84patients underwent thin-flap LASIK to correct myopia.Corneal sensitivity was measured preoperatively and one month and three months after surgery. Sensitivity measurements were taken with an esthesiometer at the central, temporal, inferior, nasal and superior points on the corneal flap. According to the ablation depth of corneal stroma(ADCS)patients were divided into three groups:group1ADCS<50um;group2:ACDS50-80um;group3:ACDS>80umResults:The corneal sensitivity after thin-flap LASIK were reduced during the first month after surgery at any points on the corneal flap(p<0.05).The loss of corneal sensation was greater at the central point and the rate of central corneal sensitivity was slow. The corneal sensitivity of all the positions except the central point were recovered to the preoperative levels by three months.(p>0.05).The superior corneal sensitivity where the corneal flap was hinged was decreased less than other positions and recovered fast. One month after LASIK, the loss of central corneal sensation in group3was greater than that in groups1and group2.The difference between the three groups was statistically significant. Three months after LASIK, the central corneal sensation in three groups was gradually recovered, but still not return to preoperative levels.The differences between the three groups were still statistically significant. It may take a longer time for full recovery.Conclusions:(1) Thin-flap LASIK induced a short-term reduction in corneal sensation, it generally returns to near the preoperative level by three months postoperatively. However, the loss of central corneal sensation was greater than that in other positions and will take a longer time for full recovery.(2)The depth of the corneal ablation affects the extent of loss of central corneal sensitivity and recovery. The groups with deeper ablation showed a greater decrease in sensation and a longer time for full recovery than did the groups with shallow ablation.