Concordance between TonoVet plus and TonoPen XL tonometers after application in Cavalier King Charles Spaniel dog's healthy eyes

Abstract

Intraocular pressure (IOP) measurement is used during the complete ophthalmologic assessment in dogs and assists in the diagnosis and monitoring of ophthalmopathies. The maintenance of the IOP is due to the balance between the production and the drainage of the aqueous humor, being responsible for the trophic support and the removal of metabolites of the cornea and the lens. Decreased drainage or production of aqueous humor results in IOP changes and factors such as age, blood pressure, dehydration, hypoadrenocorticism, hypovolemic and cardiogenic shock, and most anesthetics may influence IOP. Increased pressure can cause damage to the optic nerve, hydrophthalmia and secundary rupture of the globe, among others. Applanation and rebound tonometers are usually the most commonly used in the routine. Both are portable and easy to use. The applanation tonometer indirectly evaluates IOP by measuring the force required to flatten a constant area of the cornea surface and the rebound tonometer evaluates the IOP through a magnetized probe that makes direct contact with the cornea and detects the deceleration of the cornea produced by the probe. Thus, we aimed to measure the intraocular pressure by the ophthalmologic evaluation of 60 Cavalier King Charles Spaniel dogs eyes, the applanation tonometer (TonoPen XL®) and the rebound tonometer (TonoVet plus®) to analyze the accuracy of each device and obtain reference values considering national conditions and relation between the tonometers.