Human corneal stromal tissue concentration after consecutive doses of topically applied 3.3% vancomycin

Aims: To evaluate vancomycin penetration into human corneal stromal tissue in patients treated with topical vancomycin eyedrops before penetrating keratoplasty (PKP). Methods: Twenty four patients who underwent PKP, seven patients with keratoconus ( group 1) and 17 patients with corneal scar or corneal decompensation ( group 2). All patients received topical application of vancomycin eyedrops ( concentration: 33 mg/ml) 10, 3, 2, 1 hour, and 15 minutes before the operation. Corneal cumulative vancomycin levels were assessed by bioassay. Results: Mean vancomycin corneal stromal tissue concentration was 46.7 (SE 4.11) mug/g tissue. This value was four to 20-fold in excess of the MIC90 of vancomycin in Staphylococcus aureus (2 - 10 mug/ml). Conclusions: Vancomycin reached high corneal tissue concentrations that significantly exceeded the MIC90 (2 - 10 mug/ ml) for most key Gram positive corneal pathogens. The ratio of vancomycin stromal concentration to protein concentration was statistically higher in group 2 (non-keratoconus).