Which are the Optimal Tonometers for Different Animal Species?

—Dogs—

Abstract

To determine the optimal tonometer for dogs, the Keeler pulsair, Perkins hand-held applanation tonometer MKII, Tono-PenXL and Alcon applanation pneumatonograph (AlconPTG) were compared using male beagles. The primary emphasis was centered on determining 1) the characteristics of the four tonometers and if they are applicable to dogs, 2) if variation of intraocular pressure (IOP) is observed among multiple operators, 3) if variation of IOP is observed by a single operator when measured over five days, 4) if there are any variations of IOP in different age groups of dogs, and 5) if there are any correlation among tonometers.

Tono-PenXL and AlconPTG were applicable to dogs, and Tono-PenXL was superior in handling when IOP was measured in the animal room. The variation in IOP obtained by five operators using these two tonometers was minimal and no statistically significant difference was noted in either tonometer. The coefficient of variation of IOP over five days was smaller in Tono-PenXL than in AlconPTG, indicating that IOP determined by Tono-PenXL was more stable in repeated measurements. IOP obtained by Tono-PenXL showed no statistically significant difference among 9, 32 and 45-month-old dogs. Statistically significant positive correlation (r=0.550, p<0.001) was observed between Tono-PenXL and AlconPTG.

We concluded that of four tonometers tested, Tono-PenXL was the most applicable to dogs.