To compare the accuracy between two applanation tonometers, Tono-Pen XL® and Perkins®, in ophthalmoscopically normal dogs and cats.Animals|
Both eyes of 25 conscious and healthy dogs and cats were evaluated. Both eyes of five dogs and cats immediately after sacrifice were used as controls for the postmortem study.Procedure|
In conscious animals, the tonometry was performed with topical anesthesia using 0.5% proxymetacaine eye drops for both tonometers and 1% fluorescein eye drops for the Perkins tonometer. Readings of intraocular pressure (IOP) in the postmortem study were taken using manometry and tonometry by Tono-Pen XL® and Perkins®.Results|
The correlation coefficient (r2) in dogs between manometry and applanation tonometers Tono-Pen XL® and Perkins® were, respectively, 0.896 and 0.981 and in cats were 0.905 and 0.988. The mean IOP values in conscious dogs with Tono-Pen XL® and Perkins® were, respectively, 17.5 ± 3.7 mmHg (10.0–25.0 mmHg) and 15.3 ± 2.1 mmHg (12.0–19.8 mmHg) and in conscious cats were 16.8 ± 3.6 mmHg (10.5–24.5 mmHg) and 15.5 ± 1.3 mmHg (13.0–18.5 mmHg).Conclusion|
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.