We investigated the protective effects of
sericin on
corneal damage due to
benzalkonium chloride (BAC) used as a preservative in commercially available
timolol maleate eye drops using rat debrided corneal epithelium and a human cornea epithelial cell line (
HCE-T). Corneal
wounds were monitored using a fundus camera TRC-50X equipped with a digital camera;
eye drops were instilled into the rat eyes five times a day after corneal epithelial abrasion. The viability of
HCE-T cells was calculated by TetraColor One; and Escherichia coli (ATCC 8739) were used to measure antimicrobial activity. The reducing effects on transcorneal penetration and intraocular pressure (IOP) of the
eye drops were determined using rabbits. The corneal wound healing rate and rate constants (kH) as well as cell viability were higher following treatment with 0.005% BAC
solution containing 0.1%
sericin than in the case of treatment with BAC
solution alone; the antimicrobial activity was approximately the same for BAC solutions with and without
sericin. In addition, the kH for rat eyes instilled with commercially available
timolol maleate eye drops containing 0.1%
sericin was significantly higher than that of eyes instilled with
timolol maleate eye drops without
sericin, and the addition of
sericin did not affect the corneal penetration or IOP reducing effect of commercially available
timolol maleate eye drops. A preservative system comprising BAC and
sericin may provide effective
therapy for
glaucoma patients requiring long-term
anti-glaucoma agents.