Comparison of the effects of preserved and unpreserved formulations of timolol on the ocular surface of albino rabbits

Thirty-six albino rabbits, randomly divided into six groups, were used to s tudy their ocular tolerance to (a) 0.25 and 0.50% Timoptol(R) preserved wit h 0.01% benzalkonium chloride, (b) 0.25 and 0.50% Timoptol-LP(R), a gel-for ming solution preserved with 0.012% benzododecinium bromide, and (c) 0.25 a nd 0.50% Timabak(R) unpreserved in the ABAK(R) eyedrops dispenser, All eyed rops were applied in the right eye for 60 days, A clinical follow-up with s litlamp examination and break-up time evaluation was performed for 2 months . At the end of the experimentation, the animals were sacrificed and their eyes enucleated for histological analyses of the conjunctiva and cornea, Th ere was no significant difference in the clinical examination between each group, except for the break-up time evaluation between Timoptol and Timabak at each concentration which was better with the unpreserved timolol, Histo logical results showed a significant difference in the corneal stroma edema between preserved and unpreserved timolol, This study confirms that using unpreserved timolol may be beneficial for the long-term treatment of glauco matous patients as it increases tear film stability and decreases epithelia l permeability and stromal aggression of the cornea, Copyright (C) 2000 S. Karger AG, Basel.