Is There a Relationship Between Blood Pressure and Intraocular Pressure? An Experimental Study in Hypertensive Rats

PURPOSE: Evaluation of relation between blood pressure (BP) and intraocular pressure (IOP) in two hypertensive rat strains: spontaneously hypertensive rats (SHR) and double transgenic (dTGR) (harboring human renin and angiotensinogen genes) rats, and in their normotensive control Wistar Kyoto and Sprague Dawley rats, respectively. METHODS: Each rat strain was divided into medicated and non-medicated groups. Medicated rats were treated orally with an angiotensin II receptor type 1 blocker. IOP was measured using a specific rebound tonometer and BP by a tail-cuff method. Both parameters were determined in conscious animals every second week. For comparison, at the end of the study, IOP was measured in conscious and anesthetized rats. RESULTS: The baseline IOP was higher in hypertensive rats vs their normotensive controls. Eight weeks of treatment with an angiotensin type 1 receptor blocker did not prevent a slight increase in IOP, although it abolished the development of hypertension in SHR. The markedly elevated IOP was reduced in medicated and non-medicated dTGR animals during the short follow-up period. General anesthesia reduced IOP significantly. CONCLUSION: The results suggest a positive relation between BP and IOP in hypertensive rats.