Comparison of intraocular pressure measurements in pig-eyes
A. S. Boros1, I. Theofylaktoupoulos2, S. Dinslage2, C. P. Jonescu-Cuypers2, M. Diestelhorst2
Purpose: Intraocular pressure (IOP) measurements obtained with four commercially available tonometers that are most used in clinical practice (Perkins, Tono-Pen XL, Ocuton A and Pneumotonometer) were compared in pig-eyes after anterior chamber cannulation. We compared the accuracy and the variability of the four tonometers.
Methods: The anterior chamber of adult pig eyes was cannulated with a 25-gauge needle connected to an elevated bottle of balanced salt solution. To control the IOP the bottle was raised and lowered in increments of 10 cm H2O between 0 and 70 cm and backwards. The IOP was recorded with each of these instruments by two different experienced ophthalmologists. Statistical analyses were done.
Results: Comparison of correlation coefficients and regression coefficients showed significant differences between the techniques used for intraocular pressure measurements. Measurements performed with pneumotonometer proved to be the most reliable method, as it showed the least variances between repeated taking of pressure values and smallest regression coefficients. This technique displayed the advantage that it provided reliable data over the largest range of pressure values. Tono - Pen technique, Ocuton - A technique and Perkins technique proved to be less reliable and accurate.
Conclusion: The use of pneumotonometer seems to provide the most reliable results in intraocular pressure measurements. This technique however has the disadvantage of being rather complicated and it requires some not easily portable equipment. The repetition of these experiments on human eye-bulbs would be recommended.
University Eye Clinic of Szeged1 / Hungary, P.O. Box:407 H-6720 Szeged
University Eye Clinic of Cologne2 / Germany