dorzolamide and Hypoxia

To assess the effects of dorzolamide hydrochloride, a topical carbonic anhydrase inhibitor, on corneal endothelial function.. The authors measured the rate of corneal deswelling and the endothelial permeability to fluorescein after 2 hours of hypoxic contact lens wear in 19 normal human subjects. The study was double-masked; one eye of each subject was randomly assigned to receive 2% dorzolamide drops, and the other eye received placebo drops every 8 hours for 24 hours before the study day and twice during the study day.. Dorzolamide-treated eyes were not significantly different from placebo-treated eyes in corneal deswelling rate, expressed as the percent recovery per hour (55.7% +/- 13.6% versus 59.6% +/- 14.5%; P > or = 0.10), open eye steady state thickness, swelling induced by hypoxia, and corneal autofluorescence. Endothelial permeability to fluorescein was increased in the dorzolamide eyes (4.40 +/- 0.84 x 10(-4) cm/minute versus 4.10 +/- 0.80 x 10(-4) cm/minute; P = 0.01). As expected, the intraocular pressure and aqueous humor flow rate were decreased in the dorzolamide eyes.. Dorzolamide hydrochloride, when topically administered to normal human eyes for 24 hours, had no significant effect on the corneal deswelling rate after hypoxic stress. The corneal endothelial permeability to fluorescein, however, was increased by the drug, although this did not result in increased corneal thickness.

Topics: Adult; Aqueous Humor; Carbonic Anhydrase Inhibitors; Corneal Edema; Double-Blind Method; Endothelium, Corneal; Fluorescein; Fluorophotometry; Humans; Hypoxia; Intraocular Pressure; Microscopy; Middle Aged; Ophthalmic Solutions; Permeability; Sulfonamides; Thiophenes

To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs.. Experimental BRVO was induced by diathermy close to the optic disc. RPO(2) was measured with an oxygen-sensitive electrode 0.5 mm above the BRVO-affected area, which was compared to the retinal areas not affected by BRVO. In one group of five pigs, RPO(2) was measured at baseline, 1 and 3 hours after BRVO, and after intravenous injection of 500 mg dorzolamide. In a second group of five pigs, RPO(2) was measured 1 week after the BRVO, both before and after intravenous injection of 500 mg dorzolamide.. The average baseline RPO(2) was 2.64 +/- 0.09 kPa (mean +/- SD). In the BRVO-affected areas, RPO(2) decreased significantly (by 0.67 +/- 0.29 and 0.94 +/- 0.13 kPa) at 1 hour and 3 hours after BRVO induction. In the non-BRVO areas RPO(2) increased significantly (by 0.51 +/- 0.14 kPa) 1 hour after BRVO induction, but subsequently decreased and reached baseline 3 hours after BRVO induction. One week after BRVO induction, RPO(2) was 0.67 +/- 0.29 kPa lower in affected areas when compared with the non-BRVO areas. In the BRVO-affected areas, dorzolamide increased RPO(2) significantly (by 0.36 +/- 0.21 kPa at 3 to 4 hours and by 0.67 +/- 0.40 kPa) 1 week after BRVO induction.. Retinal hypoxia induced by experimental BRVO remained significant 1 week after BRVO. Dorzolamide increased retinal oxygen tension in the BRVO-affected areas both at 4 hours and 1 week after experimental BRVO in pigs.

Topics: Animals; Carbonic Anhydrase Inhibitors; Disease Models, Animal; Fluorescein Angiography; Hypoxia; Injections, Intravenous; Ion-Selective Electrodes; Ischemia; Oxygen; Oxygen Consumption; Partial Pressure; Retina; Retinal Vein Occlusion; Sulfonamides; Swine; Thiophenes