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Abstract #13019 Published in IGR 7-3
Reproducibility and clinical evaluation of rebound tonometry
Martinez-de-la-Casa JM; Garcia-Feijoo J; Castillo A; Garcia-Sanchez JInvestigative Ophthalmology and Visual Science 2005; 46: 4578-4580
PURPOSE: To establish the reproducibility of a rebound tonometer in humans and the effect of corneal thickness on measurements, comparing it with Goldmann applanation tonometer. METHODS: In a first study designed to examine the reliability of the RBT, three experienced ophthalmologists undertook three consecutive intraocular pressure (IOP) measurements in 12 eyes of 12 normal subjects. A cross-sectional study was then performed to compare measurements obtained using the two tonometers in 147 eyes of 85 patients with ocular hypertension or glaucoma. RESULTS: Intraobserver coefficients of correlation obtained in the reproducibility study were 0.82, 0.73, and 0.87. Interobserver correlation was 0.82. There was a good correlation between IOP readings obtained by the RBT and the GAT (r = 0.865, P < 0.0001). RBT readings were consistently higher than GAT measurements (median difference, 1.8 ± 2.8 mmHg). A Bland-Altman plot indicated the 95% limits of agreement between the two methods were -3.7 to 7.3 mmHg (slope = -0.022, P = 0.618). Using RBT, the point that best discriminated between patients with an IOP ≤ 21 mmHg and those with > 21 mmHg, as determined by the GAT was > 23 mmHg (sensitivity, 70.5%; specificity, 95.1%). In terms of pachymetry, the two tonometers behaved in a similar way, with correlation observed between IOP measurements and central corneal thickness. CONCLUSIONS: Rebound tonometry is a reproducible method of determining IOP in humans. In general, it tends to overestimate IOP compared with Goldmann applanation tonometry. The tonometers used in both methods are similarly affected by pachymetry.
Dr. J.M. Martinez-de-la-Casa, Hospital Clinico San Carlos, Madrid, Instituto de Investigaciones Oftalmologicas Ramon Castroviejo, Universidad Complutense, Madrid, Spain. martinezcasa@ya.com
Classification:
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
