Abstract
Abstract: :
Purpose: Carbonic anhydrase inhibition (CAI) has been shown to increase blood flow in the optic nerve and retina. Optic nerve oxygen tension is increased in pigs following CAI and we examine the effect of CAI on retinal oxygen tension. Methods: Polarographic oxygen electrodes were placed transvitreally over the retina and optic disc in anaesthetized pigs and oxygen tension recorded continuously. 500 mg dorzolamide HCl was injected intravenously. Results: The baseline retinal PO2 was 25.1 ± 1.5 mmHg. This increased to 27.8 ± 2.0 mmHg (p=0.025, n=6, mean±s.e.m.) following dorzolamide injection. The baseline optic nerve PO2 was 21.6 ± 3.6 mmHg. This increased to 29.3 ± 4.9 mmHg following dorzolamide injection and this change is significantly greater than the retinal effect (p=0.014, n=7). Conclusion: Retinal and optic nerve PO2 is increased with CAI. The oxygen tension of the retina and optic nerve can be elevated with drugs. Dorzolamide has a similar effect on retinal oxygen tension as retinal laser treatment and vitrectomy (Stefánsson, Acta Ophthalmologica 2001). This may offer therapeutic possibilities in diseases of the retina , which have an ischemic or hypoxic component, such as diabetic retinopathy and retinal venous occlusions.
Keywords: 448 ischemia • 554 retina • 390 drug toxicity/drug effects