Abstract
Purpose::
Carboxymethylcellulose (CMC) used in artificial tears has been reported to reduce the rate of epithelial defects post-LASIK and has been shown in our previous study to be effective in promoting corneal epithelia wound closure in vitro (Simmons et al. ARVO 2006). This study was to investigate the efficacy of CMC in promoting corneal epithelial wound healing using an animal model.
Methods::
A central corneal epithelial wound of 6mm in diameter was created on the NZ white rabbit eye by epithelial debridement leaving the other eye unwounded. Immediately after ocular surgery was completed and animal had recovered from anaesthesia, 50µl of the sterile PBS in the presence or absence of test compounds (0.2% and 1% w/v CMC) were topically administered to both eyes of the rabbits followed by administration four times a day up to 14 days. At the end of each time point (0, 8, 24, 32, 48, 72 hours, 14, 28 days and 10 weeks post-wounding and treatment), the corneal defect was stained with 1% fluorescein and photographed using a photographic slit-lamp biomicroscope. The wounded eye was then removed for histology. Wound healing rates were determined by the percentage reduction of the fluorescent area at the time point studied as compared to the time "0".
Results::
Twenty four (24) and 32 hours post-wounding, the percentage reduction of the wound area in the CMC-treated groups was significantly greater than the control groups without the CMC-treatment (p<0.05). The wound was closed completely 48 hours post-wounding in the CMC-treated groups whereas the wound remained open in the control groups. The stimulatory effect of CMC on corneal epithelial wound healing appeared to be also dose dependent with 1% CMC having significantly greater effect than 0.2% CMC (p=0.012 & 0.032 for 24 & 32hrs post wounding, respectively). The H&E staining showed the recovered epithelium of CMC-treated eyes was thicker and tighter as compared to the control eyes at 14, 28 days and 10 weeks post-wounding.
Conclusions::
CMC's ability to promote rabbit corneal epithelial wound healing supports its clinical benefits reported with its use in post-surgical (e.g. LASIK) patients to reduce the rate of epithelial defects.
Keywords: cornea: epithelium • wound healing