Comparison of intraocular pressure measurements with the Oculab Tono-Pen vs manometry in humans shortly after death.

We compared the Oculab Tono-Pen, a miniaturized Mackay-Marg tonometer, with a Statham membrane manometer in six humans (12 eyes), three to six hours after death. The intraocular pressure was changed in 5- to 10-mm Hg steps in a range between 0 and 60 mm Hg by an infusion system. The correlation coefficient of the relation of Tono-Pen readings vs manometrically determined intraocular pressures was .99. Compared to the manometer, the Tono-Pen gave a small underestimation of intraocular pressure above 17 mm Hg or overestimation below 17 mm Hg. The maximal deviation of the Tono-Pen readings from the manometer readings was 2.5 mm Hg. In our experience the correspondence between Tono-Pen and manometer readings was superior to the correspondence between the readings obtained with the original Mackay-Marg tonometer and manometry.