After each surgery, corneal epithelial cells were collected, and total RNA was isolated with an extraction reagent (TRIzol; Invitrogen-Gibco, Gaithersburg, MD). A 5-μg portion of total RNA was used for reverse-transcription (RT) with reverse transcriptase (SuperScript II; Invitrogen-Gibco). Then, 50 ng of reverse-transcribed DNA and 80 ng of genomic DNA were amplified using PCR with 1.0 U of Taq DNA polymerase (Perkin Elmer, Boston, MA) in a mixture containing 0.4 μM of each primer, 0.2 mM dNTPs, and 1.5mM MgCl2. Primer sequences were as follows: MMP-9 (380 bp) sense, 5′-AAC TCA GCC TTT GAG GAT CC-3′, and antisense, 5′-CAG TAT CCA GTG CAT CCG GT-3′; SRY (351 bp) sense, 5′-TGG CTC AAC AGA ATC CCA GC-3′, and antisense, 5′-TGG GGA TGT CCA CAG GCT GT-3′; AQP5 (730 bp) sense, 5′-C AAG GCG GTG TTC GCA GAG TTC C-3′, and antisense, 5′-C CTC TCG ATG ATC TTC CCA GTC C-3′; MUC1 (286 bp) sense, 5′-TCG ACA GGC AAT GGC AGT AG-3′, and antisense, 5′-TCT GAG AGC CAC CAC TAC CC-3′; and β-actin (350 bp) sense, 5′-AGG CCA ACC GCG AGA AGA TGA CC-3′, and antisense, 5′-GAA GTC CAG GGC GAC GTA GCA C-3′. β-Actin was used to control for RNA quality. The amplification reaction was performed in a thermal cycler (PTC-100; MJ Research, Watertown, MA). The conditions consisted of an initial denaturation for 5 minutes at 94°C, followed by 30 cycles (25 cycles for AQP5) of denaturation for 30 seconds at 94°C, amplification for 1 minute at 58°C (at 55°C for AQP5), and extension for 1 minute at 72°C. A final extension was performed for 10 minutes at 72°C. The PCR products were analyzed by electrophoresis on a 1% agarose gel and viewed using ethidium bromide staining.