CORNEAL SENSATION FOLLOWING EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMYIN HUMANS

BACKGROUND: For the correction of myopia, small amounts of corneal tis sue-including corneal nerves-are removed, resulting in flattening of t he central cornea. METHODS: We studied the changes in corneal sensatio n in five regions of the cornea following photorefractive keratectomy at varying depths. We examined and compared the recovery of sensation in 17 sighted myopic eyes, with preoperative refractive ranges from -1 .00 to -7.25 D. Eyes were divided into shallow (0 to 30 mum) or deep ( 31 to 70 mum) ablation groups depending on the attempted laser correct ion. Corneal sensation was measured in the central ablated area and th e temporal, inferior, nasal, and superior unablated regions preoperati vely and at 1, 3, and 6 months postoperatively. RESULTS: Central and i nferior sensation were significantly reduced in the deep ablations at 1 month and continued in the central cornea 6 months postoperatively. There were no overall differences in the sensations in the unablated n asal, temporal, and superior regions between either group or over time . There was a significant second order trend (p = .034) in these three regions, indicating a sharper increase in sensation from baseline in the deeper group at 1 month than the gradual upward trend of the shall ow group. CONCLUSIONS: Corneal sensation of both the central ablated a rea and the unablated peripheral cornea is decreased after deep anteri or stromal excimer laser ablations and does not recover within 1 month . Although the deeper group showed isolated areas in the periphery of significant second order trends in sensation, the overall trends were not large, indicating no significant anesthetic effect. Fluctuations i n sensation can be detected in the five regions even 6 months after ex cimer laser keratectomy. The clinical importance of these data remain to be defined.