Evaluation of a rebound tonometer for measuring intraocular pressure in dogs and horses.

OBJECTIVE

To compare intraocular pressure (IOP) measurements obtained with a rebound tonometer in dogs and horses with values obtained by means of applanation tonometry and direct manometry.

DESIGN

Prospective study.

ANIMALS

100 dogs and 35 horses with clinically normal eyes, 10 enucleated eyes from 5 dogs, and 6 enucleated eyes from 3 horses.

PROCEDURES

In the enucleated eyes, IOP measured by means of direct manometry was sequentially increased from 5 to 80 mm Hg, and IOP was measured with the rebound tonometer. In the dogs and horses, results of rebound tonometry were compared with results of applanation tonometry.

RESULTS

For the enucleated dog and horse eyes, there was a strong (r2 = 0.99) linear relationship between pressures obtained by means of direct manometry and those obtained by means of rebound tonometry. Mean +/- SD IOPs obtained with the rebound tonometer were 10.8 +/- 3.1 mm Hg (range, 5 to 17 mm Hg) and 22.1 +/- 5.9 mm Hg (range, 10 to 34 mm Hg) for the dogs and horses, respectively. Mean IOPs obtained with the applanation tonometer were 12.9 +/- 2.7 mm Hg (range, 8 to 18 mm Hg) and 21.0 +/- 5.9 mm Hg (range, 9 to 33 mm Hg), respectively. Values obtained with the rebound tonometer were, on average, 2 mm Hg lower in the dogs and 1 mm Hg higher in the horses, compared with values obtained with the applanation tonometer.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the rebound tonometer provides accurate estimates of IOP in clinically normal eyes in dogs and horses.