Abstract:AIM: To observe the effect and safety of applying mitomycin C(MMC)in laser-assisted subepithelial keratomileusis(LASEK)for extreme high myopia.
METHODS: LASEK with 0.02% MMC was performed in 364 eyes of 182 patients with extreme high myopia and spherical equivalent was -9.0 to -10.25 D. All the patients were divided into four groups according to the applying time of MMC. The time in Group Ⅰ was 10s, in Group Ⅱ was 25s, in Group Ⅲ was 40s and 55s in Group IV. Uncorrected visual acuity(UCVA), residual refraction, Haze, healing time of corneal epithelium, density and variant index of corneal endothelium was examined in these patients and follow-up 6mo.
RESULTS: At 6mo after surgery, 76.3%, 94.0%, 92.3% and 93.8% of the patients in Group Ⅰ, GroupⅡ, Group Ⅲ and Group IV respectively achieved the UCVA better than 15/20. There was significant difference of UCVA between Group Ⅰ and the other three groups(χ2=19.610, P=0.000). Proportion of the residual refraction between ±0.5D in Group Ⅰ(78.8%)was lower than other groups(95.2% in Group Ⅱ, 93.3% in Group Ⅲ, and 92.7% in Group Ⅳ)at 6mo and there was significant difference(χ2=16.329, P=0.001). Group Ⅰ had more Haze statistically than the other three groups at 6mo postoperatively(Hc=50.110, P=0.000). The healing time of cornea epithelium seem to be no statistically difference between each group at 6mo(χ2=11.611, P>0.05). MMC had no influence on the density of corneal endothelium in each group postoperatively(P>0.05), there were 3 071.3±284.4 cells/mm2 in Group I, 3 105.6±337.8 cells/mm2 in Group Ⅱ, 2 986.3±304.1cells/mm2 in Group Ⅲ and 3 088.7±372.5 cells/mm2 in Group IV respectively. The variant index of corneal endothelium calculated in each group at 6mo after surgery was 24.72±6.52, 22.93±6.74, 24.38±6.63 and 23.14±7.22 repectively, compare with that preoperatively there were no statistically differences(P>0.05).
CONCLUSION: For extreme high myopia LASEK with 0.02% MMC is effective and safe. The MMC applying time of 25s in LASEK can effectively reduce Haze after surgery and decrease potential complications.
