Abstract
Purpose: :
To compare the efficacy of topical dry eye medications including topical anti–inflammatory agents and lubricant eyedrops for the treatment of keratoconjunctivitis sicca in a Botulinum toxin B–induced mouse model.
Methods: :
Female 8–week–old CBA mice were randomized into10 groups of 5 animals each. The first 5 groups received a transconjunctival injection of saline into the lacrimal gland, and the remaining groups were injected with 0.05 ml of 20 milliunit (mU) botulinum toxin B (BTX–B) solution. Each group was randomized to receive treatment with either 0.1% fluoromethalone (FML), 0.05% cyclosporine A (CsA), a 50:50 combination of FML and CsA, non–preserved emulsion–based artificial tear or saline three days after intralacrimal gland injections. Tear production without systemic or topical anesthesia measured with phenol red impregnated cotton threads, corneal fluorescein staining and spontaneous blink rate were evaluated for all groups before lacrimal gland injection and then 3 days, 1 week, 2 weeks, 4 weeks, 6 weeks and 8 weeks after the injection.
Results: :
Tear production in the BTX–B injected CsA treated group, BTX–B injected FML treated group and BTX–B injected combined treated group returned to baseline level within 10 days of treatment, while the BTX–B injected mice treated topically with saline or artificial tear still exhibited reduction of lacrimation up to 4 weeks post injection. The use of topical FML dramatically reversed the fluorescein staining score after 4 days of treatment. In comparison, the disappearance of corneal staining in the BTX–B challenged combined treated, and BTX–B challenged CsA treated groups occurred later at days 10 and 24 after treatment, respectively. In the BTX–B injected emulsion treated group, the fluorescein staining score decreased slightly, but not significantly until the 8 week time point when the effect of BTX–B waned. Furthermore, no apparent improvement in corneal staining was observed throughout the experimental period for the BTX–B injected mice treated with saline. No significant changes were noted in blink frequency between the control and study groups undergoing the various dry eye therapies.
Conclusions: :
This mouse model may be potentially useful for further studies regarding the pathophysiology of the ocular surface in dry eye and the efficacy of dry eye therapeutics.
Keywords: cornea: tears/tear film/dry eye • inflammation • lacrimal gland