The pneumatonograph and Perkins' tonometer. A clinical study of the reproducibility in glaucomatous eyes.
Reproducibility by means of replicated single pressure readings of 82 eyes of 46 glaucoma patients in the supine position were compared. The standard deviation was 7% for the pneumatonograph compared to 13% for the Perkins hand held applanation tonometer. The difference of the reproducibility is highly significant.