Effect of timolol on aqueous humor protein concentration in the human eye
M. Stur, G. Grabner, V. Huber-Spitzy, J. Schreiner and R. Haddad
We performed a double-masked, controlled study investigating the increase
in the protein concentration in aqueous humor after topical timolol maleate
administration. Forty patients scheduled to undergo intracapsular cataract
surgery were included in the study. Either timolol ophthalmic solution or
the vehicle of timolol alone (control) were applied topically in a
randomized fashion, and aqueous humor was collected during surgery. Protein
concentrations were determined by gel-filtration chromatography. The total
protein concentration as well as the concentration of high and medium
molecular weight proteins were significantly elevated in the
timolol-treated group. The relation of the levels of the three different
molecular weight classes did not differ significantly between the two
groups, indicating that undisturbed protein filtration in the face of
reduced aqueous humor production--and not a change in the permeability of
the blood-aqueous barrier--is responsible for the increase in
concentration.
