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Abstract #10269 Published in IGR 6-1
Effect of corneal parameters on measurements using the pulsatile ocular blood flow tonograph and Goldmann applanation tonometer
Gunvant P; Baskaran M; Vijaya L; Joseph IS; Watkins RJ; Nallapothula M; Broadway DC; O'Leary DJBritish Journal of Ophthalmology 2004; 88: 518-522
AIMS: To investigate the effect of central corneal thickness and corneal curvature on intraocular pressure (IOP) measurements using the pulsatile ocular blood flow tonograph and the Goldmann applanation tonometer, and to assess the agreement between the pulsatile ocular blood flow tonograph and the Goldmann applanation tonometer in IOP measurement. METHODS: Four hundred and seventy-nine subjects underwent IOP measurements with the Goldmann applanation tonometer and the pulsatile ocular blood flow tonograph. Of these, 334 patients underwent additional measurement of central corneal thickness with an ultrasonic pachymeter and corneal curvature measurement with a keratometer. RESULTS: The IOP measurements obtained with both the Goldmann applanation tonometer and the pulsatile ocular blood flow tonograph varied with central corneal thickness and mean keratometric reading. IOP measured using the Goldmann applanation tonometer increased by 0.027 mmHg per μm increase in central corneal thickness. IOP measured using the pulsatile ocular blood flow tonograph increased by 0.048 mmHg per μm increase in central corneal thickness. For an increase of 1 mm of mean corneal curvature there was rise in IOP of 1.14 mmHg measured by the Goldmann applanation tonometer, and of 2.6 mmHg measured by the pulsatile ocular blood flow tonograph. When compared to the Goldmann applanation tonometer, the pulsatile ocular blood flow tonograph underestimated at low IOP and overestimated at higher IOP. CONCLUSION: Central corneal thickness and corneal curvature affected measurements obtained with the pulsatile ocular blood flow tonograph more than they affected measurements obtained with the Goldmann applanation tonometer.
Dr. P. Gunvant, Vision Science Group, Department of Psychological and Brain Science, University of Louisville, KY 40292, USA
Classification:
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
