Suitability and calibration of a rebound tonometer to measure IOP in rabbit and pig eyes

Abstract

To utilize the Icare tonometer TAO1 for intraocular pressure (IOP) determination in experimental animals. To calculate true IOP calibration functions for rabbit and porcine eyes. Enucleated eyes of 3-year-old healthy experimental rabbits (New Zealand white), and healthy 1 year old experimental pigs (Deutsche Landrasse) were used for the determination of IOP. Manometric (Geuder GmbH, Heidelberg/Germany) and rebound tonometry (Icare tonometer TAO1, Icare, Helsinki/Finland) were used to record IOP in enucleated animal eyes (rabbit n=2, pig n=3). The Icare tonometer TAO1 measurements underestimated true IOP by 37-60% in rabbit eyes and 17-63% in porcine eyes. IOP values obtained by both rebound and manometric tonometry for rabbit and porcine eyes followed a linear regression curve. Linear functions were calculated to correct the Icare tonometer TAO1 measurements to true IOP for both rabbit (p=1.4244p(ic) + 4.2421) and porcine eyes (p=1.0799p(ic) + 5.8557). The Icare tonometer TAO1 can be utilized for IOP determination in rabbit and porcine eyes when measured values are corrected with the appropriate linear function.