The Tono-Pen. A manometric and clinical study
W. A. Boothe, D. A. Lee, W. C. Panek and T. H. Pettit
Jules Stein Eye Institute, UCLA Medical Center 90024.
A new miniaturized, digital, electronic tonometer, the Tono-Pen
(Intermedics, Pasadena, Calif), was evaluated for accuracy and
reproducibility of results in the laboratory using enucleated human eyes
with an indwelling pressure transducer (manometric study) and clinically
using 100 eyes in 50 patients with normal corneas. Reproducibility was good
in both the manometric study (SD = 1.09) and in the clinical study (SD =
1.21). Reproducibility of results was similar to that of the MacKay-Marg
tonometer and the pneumotonometer in the manometric study, but less than
that of the Goldmann applanation tonometer and the pneumotonometer in the
clinical study. In the manometric study, the Tono-Pen had less mean error
at high pressure ranges than either the MacKay-Marg tonometer or the
pneumotonometer. In the clinical study, no statistically significant
difference was found between the Tono-Pen and the applanation tonometer at
pressures of 10 to 35 mm Hg (the extent of the data spread). In addition to
being reliable and accurate, this miniaturized tonometer is portable and
easy to use.
