A comparison of NCT, Goldman application tonometry values with and without fluorescein

Purpose

The aim of the study was to statistically compare intraocular pressure (IOP) values measured using noncontact tonometer (NCT), Goldmann applanation tonometry (GAT) with fluorescein (fGAT), and GAT without fluorescein (nGAT). The study was also performed to test whether the values obtained using each technique change in accordance with the central corneal thickness (CCT) and refractive and keratometric values.

Study design

This study was a prospective study of 188 eyes of 94 healthy volunteers. Methods: IOP was measured using fGAT, nGAT and NCT. CCT, refractive values, and keratometric values were measured, and the correlations and differences in the IOP for each tonometer were investigated.

Results

The mean IOP values obtained with the NCT, nGAT, and fGAT were 17.5±3.7, 12.3±2.7, and 12.5±2 mmHg. The mean CCT was 538.2±34.4 µm, the mean refractive value was 0.9±1.2 D, and the mean keratometric value was 43.5±1.5 D. NCT was positively correlated with fGAT and GAT values and was significantly higher than both the values. There were no differences between fGAT and GAT values. No correlation was observed between the CCT and keratometric and refractive values and the difference between NCT and nGAT or fGAT.

Conclusion

Differences in the measurements obtained using nGAT and fGAT were insignificant (P>0.05). Both values were positively correlated with NCT measurements (r =0.354, P<0.05) and were independent of CCT, keratometry, and refraction values. nGAT appears to be suitable for use in routine clinic practice.

Comparison of Goldmann Applanation, Noncontact Air Puff, and Tono-Pen XL Tonometry in Normal Controls versus Glaucoma Patients at a University Hospital in Riyadh, Saudi Arabia

PURPOSE:

The purpose of this study is to compare intraocular pressure (IOP) measured by the Goldmann applanation tonometer (GAT), the Tono-Pen XL (TPXL), and a noncontact airpuff tonometer (NCT) in glaucoma patients and normal controls.

METHODOLOGY:

In the current study, two groups of individuals were recruited; the first group included glaucoma patients (glaucoma group) while the second one was a glaucoma-free group. The IOP was measured through GAT, NCT, and TPXL for the same participants by three different physicians in both groups. Measurements through the three devices were compared statistically. Correlations between different methods of assessment were also assessed.

RESULTS:

In the glaucoma group, the mean IOP measured was 16.0 ± 5.5 mmHg (range, 6–40 mmHg) with GAT 20.5 ± 6.9 mmHg (range, 10–52 mmHg) with the TPXL, and 20.2 ± 6.5 mmHg (range, 8–50 mmHg) with the NCT. In the control group, the mean IOP was 14.0 ± 2.7 mmHg (range, 9–19 mmHg) with GAT, 17.3 ± 3.8 mmHg (range 6–30 mmHg) with the TPXL, and 17.9 ± 3.9 mHg (range 10–27 mmHg) with the NCT.

CONCLUSION:

IOP measurements were approved among the three devices with relatively higher readings using both NTC and TPXL. All three methods are required to address different situations that present in the daily clinical and surgical practice.

Comparison of three methods of tonometry in normal subjects: Goldmann applanation tonometer, non-contact airpuff tonometer, and Tono-Pen XL

Objective

We aimed to compare intraocular pressure (IOP) measurements via three different tonometers: the Goldmann applanation tonometer (GAT), the Tono-Pen^® XL (TPXL), and a non-contact airpuff tonometer (NCT).

Methods

This was a cross-sectional study of 200 eyes from 200 patients. Right eyes of all patients were included in this study. IOP was measured via GAT, NCT, and TPXL by three physicians. Each physician used one of the tonometers. Measurements via the three devices were compared.

Results

The mean IOP was 15.5±2.2 mmHg (range 10–22) with the GAT, 16.1±3.0 (range 9–25) with the TPXL, and 16.1±2.8 (range 10–26) with the NCT. Bland–Altman analysis showed that the mean difference between measurements from the NCT and the GAT was 0.6±2.3 mmHg. The mean difference between the TPXL and GAT measurements was 0.7±2.5 mmHg. The mean difference between the NCT and TPXL measurements was −0.02±3.0 mmHg. There was no significant difference between the groups according to a one-way analysis of variance (ANOVA) test. P-values were 0.998 for NCT–TPXL, 0.067 for NCT–GAT, and 0.059 for TPXL–GAT.

Conclusion

The NCT and TPXL provide IOP measurements comparable to those of the gold standard GAT in normotensive eyes.

Comparative evaluation of intraocular pressure with an air-puff tonometer versus a Goldmann applanation tonometer

PURPOSE

Tonometry, or measurement of intraocular pressure (IOP), is one of the most important examination procedures in ophthalmic clinics, and IOP is an important parameter in the diagnosis of glaucoma. Because there are numerous types of tonometer available, it is important to evaluate the differences in readings between different tonometers. Goldmann applanation tonometers (GATs) and noncontact air-puff tonometers (APTs) are largely available in ophthalmic clinics. The purpose of this study was to evaluate the role of AP tonometer by comparing the measurements of IOP made using this device with those made using a GAT.

PATIENTS AND METHODS

This study involved 196 eyes from 98 study participants, all of whom were patients attending an ophthalmic outpatient clinic. Each patient's IOP was measured using both Goldmann applanation tonometry and AP tonometry, and the difference in readings between the two methods was calculated.

RESULTS

The mean IOP as measured by GAT was 13.06 ± 4.774 mmHg, while that as measured by AP tonometer was 15.91 ± 6.955 mmHg. The mean difference between the two methods of measurement was 2.72 ± 2.34 mmHg. The readings obtained by AP tonometer were higher than those obtained by GAT in 74% of patients, and this difference was most obvious when the GAT measurement of IOP exceeded 24 mmHg. No statistically significant variation in IOP was noted between the devices when the patients' age, sex, and laterality (right and left eyes) were considered.

CONCLUSION

There is a significant difference in the measurement of IOP between GATs and AP tonometers. Goldmann applanation tonometry remains the most suitable and reliable method for measuring IOP. Because measurements of IOP by AP tonometer are usually higher than those obtained by GAT regardless of the patient's age, sex, or laterality of eyes, AP tonometry is a suitable method for community or mass screenings of IOP.

Comparison of Keeler Pulsair EasyEye tonometer and Ocular Response Analyzer for measuring intraocular pressure in healthy eyes

Purpose

To evaluate the relationship between intraocular pressure (IOP) measurements obtained with Pulsair EasyEye (PEE) and Ocular Response Analyser (ORA) in healthy patients.

Methods

Sixty-five eyes from 65 patients underwent a full optometric examination, including central corneal thickness (CCT), and IOP measured with PEE and ORA. Differences between IOP measurements between both tonometers were analyzed. Pearson correlation coefficients between IOP values and ORA corneal biomechanics parameters were also obtained.

Results

Statistically significant differences were found between IOP of PEE (IOPk) and Goldmann-corrected IOP of ORA (IOPg; p = 0.001). IOPk and corneal resistance-corrected IOP of ORA (IOPcc) were also found to differ significantly (p = 0.025). Mean differences between IOPg-IOPk, IOPcc-IOPk and IOPg-IOPcc were 0.71 ± 1.66, 0.70 ± 2.46 and 0.01 ± 1.54 mmHg (mean ± standard deviation), respectively.

Pearson correlation coefficients indicated that IOPk, IOPg, and IOPcc were significantly correlated among them (p < 0.001): r = 0.816 for IOPk-IOPg, r = 0.826 for IOPcc-IOPg and r = 0.587 IOPcc-IOPk. IOPk and IOPg were linearly associated with corneal resistance factor (CRF; r = 0.626 and r = 0.619, respectively) and with CCT (r = 0.531 and r = 0.579, respectively). IOPcc had a linear relationship with corneal hysteresis (CH) (r = −0.482) and similar results were found between CRF and CH (r = 0.841), CRF and CCT (r = 0.681) or between CH and CCT (r = 0.466).

Conclusions

Differences between mean values of IOP measured with PEE and ORA are statistically significant, with ORA tonometer taking higher IOP values than PEE in most of the cases. IOPk, IOPcc and IOPg have, al least, moderate positive linear correlations and ORA biomechanics parameters CRF, CH and CCT have a linear positive relation between them.

Comparison of intraocular pressure measurements with the portable PT100 noncontact tonometer and goldmann applanation tonometry

Purpose:

Noncontact tonometers are useful when regulations preclude use of contact tonometers by medical students and other nonophthalmologists. Our study compared the measurements by the portable, noncontact tonometer (PT100) with Goldmann applanation tonometry (GAT).

Methods:

This was a prospective study of 98 eyes from 98 patients. Intraocular pressure (IOP) was measured by GAT and the PT100 (Reichert, Buffalo, NY).

Results:

Mean IOP measurements showed no significant differences in measurements performed by the two tonometers (P = 0.64). Measurements by the two tonometers were in agreement by ≤3 mmHg in 92.8% of eyes. Linear regression analysis of PT100 vs GAT measurements revealed a slope of 0.98 with r² = 0.58. Bland–Altman analysis showed a mean difference of measurements by GAT and PT100 of −0.3 mmHg with two standard deviation = 7.1 mmHg.

Conclusion:

The portable noncontact PT100 tonometer provides IOP measurements comparable to GAT within the normal range of IOP.