Evaluation of applanation tonometers for the dog eye

The Mackay-Marg, pneumatonograph, TonAir, and EMT-20 tonometers were evaluated in the normal dog eye. Tonometric scale readings were compared to the manometric recordings from the anterior chamber. The Mackay-Marg tonometer evaluated in open and closed systems was the most reliable (goodness of fit [r2] = 0.96) with intraocular pressure up to 100 mm. Hg. The pneumatonograph also exhibited high reliability (r2 = 0.92) but tended to underestimate intraocular pressures above 40 to 50 mm. Hg. The TonAir and EMT-20 tonometers were the least satisfactory for the dog, with r2 of 0.77 and 0.66 to 0.81, respectively. The Mackay-Marg is the most satisfactory tonometer for the dog.