Toxic effect of using twenty percent alcohol on corneal epithelial tight junctions during LASEK

The aim of this study was to determine the effect of using 20% alcohol on corneal epithelial tight junctions during laser epithelial keratomileusis (LASEK). Sixty Sprague-Dawley rats were randomly divided into two equal groups. The central area of the rat corneas in one group were demarcated with a 3-mm trephine, treated with 20% alcohol for 45 sec and washed with sterile balanced salt solution. The epithelium was removed by an epithelial microhoe used in LASEK. In the other group, the rat corneal epithelium in the central area was mechanically scraped. The experimental animals were sacrificed at 24, 48, 72, 96 and 120 h after surgery. The levels of the tight junction proteins, claudin-1 and ZO-1, were determined by immunofluorescence and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) analyses. We found that at approximately 48 h after surgery, the wounded corneas were replaced by corneals with regenerated epithelium. Immunofluorescence analysis demonstrated that the expressions of claudin-1 and ZO-1 in the corneal epithelium of the alcohol-treated group were weaker compared to the mechanical group at the 24 and 48 h time-points. Semi-quantitative RT-PCR analysis showed that the mRNA levels of claudin-1 and ZO-1 in the central cornea after alcohol treatment were lower compared to those in the mechanical group from 24 to 48 h, with no significant difference after 72 h. Thus, we conclude that the treatment with 20% alcohol during LASEK results in damage to the corneal epitheleal tight junctions and prolongs normal recovery time.