The Effect of Perkins, Tono-Pen, and Schiötz Tonometry on Intraocular Pressure

Comparison of the use of new handheld tonometers and established applanation tonometers in dogs

“…It has been reported 29 that there is an approximately linear decrease of IOP in successive measurements obtained by use of applanation tonometers and that the difference was largest between the first and second measurement. Investigators in 1 study 30 documented that repeated measurements with a commercially available applanation tonometer decreased the IOP. Investigators in another study 6 confirmed that the order of application for applanation tonometers influenced the pressure measurements of a consecutively used tonometer.…”

“…15 Use of the this applanation tonometer by an inexperienced examiner can increase the measured IOP by up to 12 mm Hg. 30 One of the objectives of the study reported here was to evaluate whether we could detect differences between examiners for the I-I tonometer. Because we also wanted to know whether it was easy for a less experienced examiner to acquire the skills needed to use the I-I tonometer, we compared values obtained by an ophthalmologist and those obtained by a general practitioner not experienced in performing tonometry.…”

Comparison of Intraocular Pressure Measurements with the Digital Tonometer TGDc-01 ‘PRA’ and the Goldmann Applanation Tonometer

“…For example, the IOP showed an immediate drop in response to scleral indentation [17]. On the other hand Tono-Pen tonometry produced an increase in IOP so that it should be used with caution in eyes with a weakened cornea or sclera [18].…”

Non-invasive determination of intraocular pressure in the rat eye. Comparison of an electronic tonometer (TonoPen), and a rebound (impact probe) tonometer

“…Such an effect is unlikely for the I/I tonometer, however, as standard deviations of replicate measurements are very close and its contact with the eye is very slight. By contrast, repeated measurements with the TonoPen tonometer could have had such an effect, as the tonometer has been shown to affect IOP [18], and these measurements were therefore made last.…”