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Accuracy and comfort of measurement of intraocular pressure by tonopen xl vs. goldman and contact pneumotonometer in patients with primary open angle glaucoma

Poster Details

First Author: N.Kashchenko USA

Co Author(s):    E. Chynn   T. Dovzhuk           

Abstract Details


To compare accuracy and comfort of measurement of intraocular pressure (IOP) of the Tonopen-XL (TPXL) vs. two “gold standards”: Goldman applanation tonometer (GAT), and contact pneumotonometer (CPT) in patients with primary open angle glaucoma (POAG).


Prospective comparative study involving a single glaucoma subspecialty private practice.


IOP of 17 POAG patients (34 eyes; 6 male (35.3%) and 11 female (64.7%)) was measured with Tonopen XL (Medtronic, USA), Goldman applanation tonometry (Haag-Streit, Switzerland), and contact pneumotonometry (Medtronic “classic model 30”, USA). Central corneal thickness (CCT) was measured using ultrasonic pachymeter (DGH, USA). Patients graded their subjective comfort level on a numerical scale (1-10).


Mean CCT was 566 ± 46 μm. Mean IOP (mmHg) for TPXL was 12.5 ± 3.0 (range, 5-18) vs. 14.6 ± 3.3 for GAT (range, 9-24) and 14.7 ± 3.4 (range, 9.5-25.5) for CPT. Average difference between mean IOP for TPXL and GAT was -2.15; TPXL and CPT -2.25; GAT and PTC was -0.1. TPXL readings were strongly correlated to both GAT (r=0.73, p<0.001) and CPT (r= 0.69, p<0.001), CPT and GAT were highly correlated (r=0.89, p<0.001). Mean comfort scores were 6.8 for TPXL, 7.64 for GAT, and 7.70 for CPT; no significant differences in comfort scores between devices


In a population of patients with POAG, Tonopen-XL was shown to be a very accurate method of measuring IOP, as it correlated highly with two “gold standards” for IOP measurement, namely Goldman and contact pneumotonometry. Tonopen-XL read consistently about 2 mm Hg below both Goldman and contact pneumotonometry; clinicians may wish to correct for this difference. Goldman and contact pneumotonometry readings were nearly identical, which supports the use of each as a “gold standard.” All three methods had good comfort scores without any significant differences.

Financial Disclosure:


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