PURPOSE: To assess if tonometry is influenced by corneal parameters.
MATERIALS AND METHODS: 66 normotensive, 34 ocular hypertensive and 58
glaucomatous patients were selected from routine clinical visits. We performed
computed corneal topography (Eye Sys 2000), pachymetry (Ultrasonic Pachymeter
DGH 2000), applanation tonometry (Goldmann tonometer) and pneumotonometry
(Keeler Pulsair). Among the topographic parameters we considered: the flattest
and the steepest axis, the difference and the mean value; regarding pachymetry
the central corneal thickness was evaluated considering the mean value among 5
measurements. These parameters were compared with the tonometric values
(applanation and pneumotonometry) measured twice a day for 2 successive days.
RESULTS: In normal and in non-treated hypertensive subjects there is a
significative correlation (p<0,05) between tonometry and pachymetry: every
increasing in pachymetric measurements is accompanied by increasing in
tonometric values. No correlation was present in treated hypertensive and in
glaucomatous patients. Topographic parameters showed to have no influence on tonometric
measurements.
CONCLUSIONS: Possible artifacts of tonometric measurements become
essential when the implemented therapy in ocular hypertensive patients is
established on the basis of tonometry. In the clinical practice patients with
high IOP, without other symptoms typical of glaucoma, are classified as ocular
hypertensive on the basis of tonometries that do not take in account corneal
thickness. Probably the best approach is to perform pachymetry in borderline
patients over all the other examinations.