The effects of protein-free calf blood extract for recovery of corneal nerve after LASEK and LASIK

Abstract

To evaluate the effects of protein-free calf blood extract for recovery of corneal nerve after LASEK and LSEIK. A prospective, randomized, control and double-blind study was carried out from January through February 2009 at Department of Ophthalmology, Eye Ear Nose and Throat Hospital of Fudan University. Forty-nine eyes of 25 patients who underwent LASEK were randomly divided into two groups. One group with 16 patients (32 eyes) was treated by protein-free calf blood extract eye gel which was defined as drug treated group and the other group with 9 patients (17 eyes) was not treated by protein-free calf blood extract eye gel which was defined as no drug treated group. Forty-four eyes of 23 patients who underwent LASIK were also randomly divided into two groups. One group with 13 patients (24 eyes) was treated by protein-free calf blood extract eye gel which was defined as drug treated group and the other group with 10 patients (20 eyes) was not treated by protein-free calf blood extract eye gel which was defined as no drug treated group. Protein-free calf blood extract eye gel was delivered in both drug treated groups 3 times per day for three months after surgery. Laser scanning confocal microscopic examinations were performed on 48 eyes in vivo. Central corneal sensitivity and tear break-up time (BUT) were tested on 93 eyes preoperatively and 1, 3, 6 months, and 1 year after surgery. The obtained dates in the study were analyzed using independent samples t-test, paired t-test and Mann-Whitney Test. The morphology observed by confocal microscope of sub-basal nerve fibers was not different between drug treated group and no drug treated group until the last follow up after LASIK or LASEK (Z = 0.0000, P = 1.00) and (Z = 0.0000, P = 1.00). Nerve fibers with interconnections were observed in drug treated group at 3 months after LASEK. The morphology of sub-basal nerve fibers had not recovered completely until 1 year after surgery. The central corneal sensitivity was better in drug treated group than in no drug treated group at 1 month after LASEK [(4.95 ± 0.84) µm, (3.62 ± 1.38) µm; t = 4.23, P < 0.01] and at 1 and 3 months after LASIK [(3.29 ± 1.40)µm, (2.35 ± 1.51) µm; t = 2.10, P < 0.05], [(4.31 ± 1.61) µm, (3.18 ± 1.62) µm; t = 2.31, P < 0.05]. At 6 months postoperatively, the central corneal sensitivity of both drug treated group and no drug treated group which underwent LASEK was not significantly different from pre-operation [(5.81 ± 0.35) µm; t = -1.26, P > 0.05], [(5.79 ± 0.36) µm; t = -0.70, P > 0.05]. At 6 months postoperatively, the central corneal sensitivity of drug treated group which underwent LASIK was not significantly different from pre-operation [(5.25 ± 0.91) µm; t = -1.87, P > 0.05]. No significant difference was seen in BUT between drug treated group and no drug treated group after LASEK or LASIK until 1 year after surgery [(8.13 ± 2.18) µm, (8.76 ± 1.64) µm; t = -0.90, P > 0.05], [(7.71 ± 2.14) µm, (7.45 ± 2.37) µm; t = 0.30, P > 0.05]. Protein-free calf blood extract could significantly promote the recovery of corneal nerve in the early period after LASEK and LASIK.