Comparison of the human and canine Schiotz tonometry conversion tables in clinically normal cats

Paul E. Miller From the Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr West, Madison, WI 53706 (Miller); and the Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University. Blacksburg, VA 24061 (Pickett).

Search for other papers by Paul E. Miller in
Current site
Google Scholar
PubMed
Close
 DVM
and
J. Phillip Pickett From the Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, 2015 Linden Dr West, Madison, WI 53706 (Miller); and the Department of Small Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University. Blacksburg, VA 24061 (Pickett).

Search for other papers by J. Phillip Pickett in
Current site
Google Scholar
PubMed
Close
 DVM

Click on author name to view affiliation information

Summary

Intraocular pressure (iop) was measured in 73 eyes of 37 clinically normal cats with 2 applanation tonometers (Tono-Pen and Mackay-Marg) and the Schiotz indentation tonometer, using the 5.5- and 7.5-g weights. Statistically, the Tono-Pen tonometer underestimated iop compared with the values obtained by use of the Mackay-Marg tonometer (P < 0.0001) and the Schiotz tonometer, with either weight and either the human (P < 0.01) or the canine (P < 0.0001) calibration tables. Estimates of iop using the human calibration table and either the 5.5− or 7.5-g weight were not significantly different from each other or from those obtained with the Mackay-Marg tonometer. Schiotz measurements obtained with either weight and converted using the canine calibration table were not only significantly (P < 0.0001) different from each other, but were also clinically and significantly (P < 0.0001) higher than measurements obtained with the Tono-Pen and Mackay-Marg tonometers or the Schiotz tonometer, using the human calibration table and either weight. Approximately three quarters of clinically normal cats had an iop ≥ 30 mm of Hg when Schiotz tonometer measurements were converted with the canine conversion table. The human calibration table was the most clinically useful table for converting Schiotz measuremenftrsom clinically normal feline eyes to estimates of iop in mm of Hg. Normal mean (±sd) feline readings with the Schiotz tonometer and the 5.5-g weight was 3.9 ± 1.4 tonometer scale units (range, 1.0 to 7.5; 95% confidence interval [ci], 1.1 to 6.7). Converted mean (±sd) iop estimates, using the 5.5-g weight in normal feline eyes, was 21.6 ± 5.0 mm of Hg (range, 11.2 to 34.5; 95% ci, 11.6 to 31.6) with the human conversion table, and 35.0 ± 5.8 mm of Hg (range, 23.0 to 49.3; 95% ci, 23.4 to 46.6) with the canine conversion table

Summary

Intraocular pressure (iop) was measured in 73 eyes of 37 clinically normal cats with 2 applanation tonometers (Tono-Pen and Mackay-Marg) and the Schiotz indentation tonometer, using the 5.5- and 7.5-g weights. Statistically, the Tono-Pen tonometer underestimated iop compared with the values obtained by use of the Mackay-Marg tonometer (P < 0.0001) and the Schiotz tonometer, with either weight and either the human (P < 0.01) or the canine (P < 0.0001) calibration tables. Estimates of iop using the human calibration table and either the 5.5− or 7.5-g weight were not significantly different from each other or from those obtained with the Mackay-Marg tonometer. Schiotz measurements obtained with either weight and converted using the canine calibration table were not only significantly (P < 0.0001) different from each other, but were also clinically and significantly (P < 0.0001) higher than measurements obtained with the Tono-Pen and Mackay-Marg tonometers or the Schiotz tonometer, using the human calibration table and either weight. Approximately three quarters of clinically normal cats had an iop ≥ 30 mm of Hg when Schiotz tonometer measurements were converted with the canine conversion table. The human calibration table was the most clinically useful table for converting Schiotz measuremenftrsom clinically normal feline eyes to estimates of iop in mm of Hg. Normal mean (±sd) feline readings with the Schiotz tonometer and the 5.5-g weight was 3.9 ± 1.4 tonometer scale units (range, 1.0 to 7.5; 95% confidence interval [ci], 1.1 to 6.7). Converted mean (±sd) iop estimates, using the 5.5-g weight in normal feline eyes, was 21.6 ± 5.0 mm of Hg (range, 11.2 to 34.5; 95% ci, 11.6 to 31.6) with the human conversion table, and 35.0 ± 5.8 mm of Hg (range, 23.0 to 49.3; 95% ci, 23.4 to 46.6) with the canine conversion table

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 393 393 81
PDF Downloads 35 35 4
Advertisement