Comparison of intraocular pressure measurements between the Tono‐Pen XL^®and Perkins^®applanation tonometers in dogs and cats

Abstract

There was a strong correlation between the IOP values obtained by direct ocular manometry and the Tono-Pen XL(®) and Perkins(®) tonometers in dogs and cats. There was no statistically significant difference between the mean IOP obtained with both tonometers in conscious animals, there was, however, a difference between the minimum and mainly in the maximum values that were on average 5-6 mmHg higher with Tono-Pen XL(®) than those measured with Perkins(®), which justifies a table of normal values differentiated for each tonometer.

Ex vivo and in vivo study of Kowa HA-2 applanation tonometer in the measurement of intraocular pressure in cats

“…These findings are similar to those obtained in an in vivo study conducted with a Perkins tonometer (16.4 ± 2.6 mmHg) and with manometry (15.0 ± 1.7 mmHg) in this species (ANDRADE et al, 2009;ANDRADE et al, 2012).…”

“…The mean IOP value measured with the Kowa HA-2 tonometer in the ambulatory study of healthy cats with healthy eyes was 15.0 ± 1.5 mmHg (11.8 to 18.3), which is similar to the result obtained with a Perkins tonometer (15.5 ± 1.3 mmHg) in a comparative study using a Tono-Pen XL tonometer (16.8 ± 3.6 mmHg) (ANDRADE et al, 2012).…”

“…This correlation is also similar to those from studies in cats with the Perkins tonometer (r² = 0.988) (ANDRADE et al, 2009) and (r² = 0.905) (ANDRADE et al, 2012) using the same Goldmann methodology and those of a comparative study using a Tonopen applanation tonometer (r² = 0.94) and a Tonovet rebound (r² = 0.92) (MCLELLAN et al, 2013).…”

“…Therefore, for an IOP reading 1.6 for example, the tonometer reading would equal x = (1.6-0.0878)/0.0915 = 16.0 mmHg. Therefore, an IOP reading measured with a Kowa HA-2 tonometer can be approximated by multiplying it by 10, which is similar to findings in humans (SCHOTTENSTEIN, 1996), other studies that used Perkins tonometers in dogs, cats, horses and bovines (ANDRADE et al, 2009;ANDRADE et al, 2011;ANDRADE et al, 2012;ANDRADE et al, 2013), and a study that used a Kowa HA-2 tonometer in dogs (ANDRADE et al, 2016).…”

“…In cats, the most commonly used tonometers are portable, e.g., the Tonopen applanation tonometer and more recently the Tonovet, which is a portable rebound tonometer MILLER et al, 1991;MCLELLAN et al, 2013;PASSAGLIA et al, 2004). There are few reports about the use of portable applanation tonometers that use the Goldmann methodology, such as the Perkins and Kowa HA-2 tonometers, in animals (ANDRADE et al, 2009;ANDRADE et al, 2011;ANDRADE et al, 2012;ANDRADE et al, 2013;ANDRADE et al, 2016), and these tonometers are very useful in humans (SCHOTTENSTEIN, 1996). Studies with the Perkins tonometer in animals have been conducted in dogs and cats (ANDRADE et al, 2009;ANDRADE et al, 2012), horses and cattle (ANDRADE et al, 2011;ANDRADE et al, 2013), and there is only one study that describes the use of the Kowa HA-2 tonometer in dogs (ANDRADE et al, 2016).…”