In cats the aqueous humor is drained essentially into a perilimbal intrascleral venous plexus,1 which, in addition, collects blood from all parts of the uvea.2 The plexus, in turn, is drained by anterior ciliary veins and vortex veins.2 At an intraocular pressure (IOP) artificially stabilized at 20 mm. Hg, the pressure (ISVP) in the intrascleral venous plexus is normally about 7 mm. Hg, but it varies somewhat from one place to another.1 It varies with the blood flow through the uvea, and it may also be influenced by changes in the orbital venous pressure.1,2
Acetazolamide lowers the IOP in cats3-5 as in rabbits and humans,6 and it was generally assumed that this was due essentially to a reduced aqueous humor formation. However, the effect of acetazolamide on other parameters influencing the IOP was little known. In man, Linnér7 found that acetazolamide in therapeutic
BILL A. Acetazolamide and Intrascleral Venous Pressure. Arch Ophthalmol. 1963;69(2):236–240. doi:10.1001/archopht.1963.00960040242016
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