The effect of hEGF and insulin on corneal metabolism during Optisol storage.

We examined the effect of the growth factors, human epidermal growth factor (hEGF) and insulin, on corneal metabolism during storage in Optisol, a chondroitin-sulfate-(CS)-based storage medium. Paired cat corneas, in either Optisol only or Optisol with growth factor(s), were analyzed using ex vivo 31P nuclear magnetic resonance, after storage for 1 week at 4 degrees C. Lysosomal enzyme release into the media at the end of the storage period also was measured fluorometrically. Both epithelial-intact and epithelial-denuded corneal pairs were examined for all conditions. Considering corneas having either intact epithelia or epithelium-denuded corneas, the addition of either growth factor alone to Optisol did not alter the relative corneal concentrations of five of the six phosphatic metabolite spectral bands measured or two metabolic ratios calculated from these bands. Phosphodiesters, however, were significantly lower in corneas stored in Optisol containing both hEGF and insulin (23%) than in corneas stored in Optisol alone (30%). Intracorneal pH was unaffected by the addition of growth factor(s). A significantly higher release of alpha-glucosidase and alpha-mannosidase was noted in those corneas stored in Optisol containing both hEGF and insulin. Optisol maintains high-energy phosphate corneal metabolism similar to other CS-based media, K-Sol and Chondroitin Sulfate Corneal Storage Medium (CSM). The addition of the growth factors hEGF and insulin to Optisol alters corneal metabolic activity during storage in a manner indicative of conserving corneal phospholipids.

Topical fluoroquinolones: antimicrobial activity and in vitro corneal epithelial toxicity.

To assess the potential of fluoroquinolones as topical antimicrobial agents, we evaluated in vitro the antimicrobial activity of five fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin, pefloxacin, and temafloxacin), as well as gentamicin, tobramycin, and cefazolin against 96 isolates of common bacterial corneal pathogens. Ciprofloxacin and temafloxacin were the most active quinolones [minimal inhibitory concentration inhibiting 90% of stains (MIC90) of 1 microgram/ml], followed by ofloxacin (MIC90 2 micrograms/ml), and norfloxacin and pefloxacin (MIC90s 4 micrograms/ml). In contrast, gentamicin and tobramycin MIC90s were 32 and 64 micrograms/ml, respectively; cefazolin MIC90 was greater than 2048 micrograms/ml. The corneal epithelial cytotoxicity of the fluoroquinolones also was evaluated utilizing an in vitro assay of 3H-thymidine uptake of rabbit corneal epithelial cell cultures. The least to greatest toxicity of the fluoroquinolones were as follows: ciprofloxacin and temafloxacin less than norfloxacin less than ofloxacin less than pefloxacin. Our study suggests that the fluoroquinolones, especially ciprofloxacin and temafloxacin, possess excellent in vitro activity against common bacterial corneal pathogens and are less toxic to the corneal epithelium than the aminoglycosides.