Evaluation of electronic tonometers in the rabbit eye

The MacKay-Marg, pneumatonograph, and EMT-20 tonometers were evaluated in the normal rabbit eye. Tonometric scale readings were compared with the manometric recordings from the anterior chamber. Tonometry was performed with the manometric system closed and open to the reservoir column. The MacKay-Marg tonometer evaluated in the closed and the open manometric systems was highly reliable (goodness of fit (r2) = 0.958 and 0.961, respectively) with intraocular pressures (IOP) up to 50 mm of Hg and similarly (r2 = 0.949 and 0.967, respectively) with IOP up to 100 mm of Hg. The pneumatonograph also exhibited high reliability, r2 = 0.936 (closed) and 0.898 (open), at pressures up to 50 mm of Hg and r2 = 0.932 (closed) and 0.948 (open) at IOP up to 100 mm of Hg. The EMT-20 tonometer was least satisfactory for the normal rabbit eye, with r2 ranging from 0.069 to 0.171.