98th Annual Meeting DOG 2000

P 358

Measurement of intraocular pressure with the Tono-Pen in comparision to Goldmann applanation tonometry

C. M. E. Deuter, T. Schlote, M. Derse, G. Stroman, T. Bende, B. Jean

Purpose: To investigate the precision of two equal Tono-Pens in the measurement of intraocular pressure (IOP) in comparision to Goldmann applanation tonometry (GT).

Methods: Measurement of IOP was done in 100 eyes of 52 patients (mean age 63 ± 15 years) with ocular hypertension or glaucoma. According to a random table either right or left eye was measured using GT firstly and the Tono-Pen secondly. For the fellow eye the measurement was reversed. One of the two equal Tono-Pens (Mentor, USA) was used according to a second random table. Three measurements were obtained with each instrument on both eyes within 15 minutes, subsequently. Patients were placed in an upright position for all measurements.

Results: Even for well-trained ophthalmologists a learning curve of approximately 10 measurements when using the Tono-Pen was observed. The Tono-Pens measured an average IOP of 16,9 mmHg in all 100 eyes. The GT measured an average IOP of 17,7 mmHg. This difference between the two instruments was not statistically significant. The standard deviation for all measurements was better for the Tono-Pen (4,7 mmHg vs. 5,8 mmHg for GT). No reduction of the IOP after Tono-Pen measurement was observed (in contrast to GT). The reproducibility on the same eye was worse by a factor of two for the Tono-Pen when compared to GT. There was a significant difference in variation between the Tono-Pens.

Conclusions: Measurement of IOP with the Tono-Pen is comparable to GT. The difference between the two equal Tono-Pens indicates the need for improvement of quality check in the manufacturing.

University Eye Hospital, Department I (General Ophthalmology), Schleichstr. 12, D-72076 Tübingen