Circadian Rhythm of Intraocular Pressure in Cats

DEL SOLE, MARÍA JOSÉ; SANDE, PABLO HORACIO; BERNADES, JOSÉ MARIANO; ABA, MARCELO ALFREDO; ROSENSTEIN, RUTH ESTELA

Buenos Aires

Congreso; XVII International Congress of Eye Research.; 2006

International Society of Eye Research

Objective: To evaluate the circadian rhythm of intraocular pressure (IOP) in healthy domestic cats and to analyze the influence of age, gender, and ocular diseases on day-night variations of cat IOP. Animals: Twelve male adult domestic cats without physical or ocular abnormalities, five adult females, five adult castrated females, eight cats of less than one year old, as well as five cats with uveitis and three cats with secondary glaucoma. Procedure: IOP was assessed with a TonoPen XL at 3 h-intervals during 24 h in healthy adult male cats kept under a photoperiod of 12 h light-12 h darkness. Eight animals from the same group were kept under constant darkness for 48 h and IOP was measured at 3 h-intervals for the following 24 h. In addition, day-night variations of IOP were assessed in females and castrated females, in young cats, as well as in uveitic and glaucomatous cats. Results: Consistent daily variations of IOP were observed in animals exposed to a light-dark cycle, with maximal values during the night. In cats exposed to constant darkness, maximal values of IOP were observed at the subjective night. Day-night variations of IOP persisted in females, castrated females, and young animals, as well as in uveitic and glaucomatous cats. Conclusions: The present results indicate, for the first time, a daily rhythm of cat IOP that persisted in constant darkness, demonstrating a circadian component controlled by an endogenous pacemaker. In addition, daily variations of feline IOP seem to be independent of gender, age, or ocular disease.