1993 Volume 12 Issue 3-4 Pages 3-4_55-3-4_60
In pilot studies of clinically normal eyes in adult horses, we tested the measurement capabilities of the Perkins tonometer, the Keeler Pulsair tonometer, the Tono-Pen XL tonometer (TONO-PEN), and the Alcon Applanation Pneumatonograph (ALCON). These pilot studies showed that the TONO-PEN and the ALCON can be used for eye measurements in horses. We therefore used the TONO-PEN and the ALCON in the following experiments.
Non-anesthetized horses:
Experiment 1:6 eyes of 3 adult thoroughbreds were measured. Measurements were taken by three persons (A, B and C) in the sequence TONO-PEN (1) →ALCON→TONO-PEN (2).
Experiment 2:8 eyes of 3 adult thoroughbreds and 1 heavy draught horse were measured. The measurements were taken by one person (A) in the sequence ALCON (1)→TONO-PEN→ALCON (2).
An average of 4 measurements with each tonometer were taken of the right and left eye alternately in both experiments. The average measurements taken by person A using the TONO-PEN (1) and the ALCON (1) were 29.6±6.2 mmHg and 15.1±3.0 mmHg, respectively.
In both experiments (1 and 2), measurements taken with the TONO-PEN were greater than those taken with the ALCON. The values were more scattered in the TONO-PEN measurements and among the measurements taken by different individuals than in the measurements taken with the ALCON. The correlation of the measurement values for TONO-PEN (2) and ALCON was 0.539.
Anesthetized horses:
8 eyes of 3 adult thoroughbreds and 1 heavy draught horse were measured. TONO-PEN and ALCON measurements were taken ten minutes after administration of xylazine 0.7mg/Kg IV. Both tonometer readings showed a decrease in eye pressure of about 32-33%.
