Effect of systemic acetazolamide on the fluid movement across the aqueous-vitreous interface

In an attempt to study the effect of systemic acetazolamide on the fluid flow between the aqueous and vitreous in normal eyes, 50 mg kg(-1) acetazolamide was given intravenously every hour for 3 hr and the time change of the aqueous flow rate was calculated in two groups of rabbits, applying one of the following two different methods to each: the fluorescein method II of Jones and Maurice, a classical fluorometric method, or the more recently developed Johnson-Maurice method which entails intravitreal injection of FITC-dextran and measurements of its concentration in the anterior chamber many days after the injection. The flow rate after acetazolamide calculated by the fluorescein method II of Jones and Maurice in one group of rabbits was reduced to 55 +/- 5% (mean +/- S.E. n = 9) of the control on the average. When calculated by the Johnson-Maurice method in another group of rabbits, the reduction was to 80 +/- 4% (n = 11) of the control rate. The difference between the above figures was significant (P less than 0.005). Furthermore, the effect of acetazolamide calculated by the first procedure was significantly greater than that calculated by the second at 1 and 2.33 hr and at later times after the acetazolamide injection (P less than 0.05-0.01). On the other hand, the outflow pressure was reduced by 53-60% in both groups. The difference between the flow rates after acetazolamide determined by the above two methods was best explained by assuming that the FITC-dextran movement from the vitreous into the aqueous was reduced by about 25% after acetazolamide administration.(ABSTRACT TRUNCATED AT 250 WORDS)