Evaluation of rebound tonometer iCare IC200 as compared with IcarePRO and Goldmann applanation tonometer in patients with glaucoma

Effects of Phenylcapsaicin on Intraocular and Ocular Perfusion Pressure During a 30-Min Cycling Task: A Placebo-Controlled, Triple-Blind, Balanced Crossover Study

The main objective of this placebo-controlled, triple-blind, balanced crossover study was to assess the acute effects of phenylcapsaicin (PC) intake (2.5 mg) on intraocular pressure (IOP), ocular perfusion pressure (OPP), and heart rate (HR) during a 30-min cycling task performed at 15% of the individual maximal power. Twenty-two healthy young adults performed the cycling task 45 min after ingesting PC or placebo. IOP was measured with a rebound tonometer before exercise, during cycling (every 6 min), and after 5 and 10 min of recovery. OPP was assessed before and after exercise. HR was monitored throughout the cycling task. We found an acute increase of IOP levels related to PC consumption while cycling (mean difference = 1.91 ± 2.24 mmHg; p = .007, ηp2=.30), whereas no differences were observed for OPP levels between the PC and placebo conditions (mean difference = 1.33 ± 8.70 mmHg; p = .608). Mean HR values were higher after PC in comparison with placebo intake (mean difference = 3.11 ± 15.87 bpm, p = .019, ηp2=.24), whereas maximum HR did not differ between both experimental conditions (p = .199). These findings suggest that PC intake before exercise should be avoided when reducing IOP levels is desired (e.g., glaucoma patients or those at risk). Future studies should determine the effects of different ergogenic aids on IOP and OPP levels with other exercise configurations and in the long term.

A comparison of intraocular pressure measurement using SUOER SW-500 rebound tonometer and conventional reusable Goldmann prisms

Introduction

To determine the agreement between intraocular pressure (IOP) measurements using conventional Goldmann applanation tonometry (GA1,2T) and SUOER SW-500 Rebound Tonometer.

Methods

This was a retrospective observational study where 205 eyes of 106 glaucoma patients had their IOPs measured by 2 fellowship trained ophthalmologists. Data were analyzed using the Bland-Altman method of differences. Correlation was measured using the Pearson coefficient.

Results

Most of our patients were Chinese (88.7%) and female (51.9%). The average age was 66.9 years. The range of IOPs as measured by GAT was 2 to 58 mm Hg. Using the Bland-Altman method to compare GAT and SUOER SW-500 Rebound Tonometer. The tonometer overestimated the IOP by 0.5 mm Hg in the right eye and underestimated it by 0.1 mm Hg in the left eye. Overall, the tonometer overestimated the IOP by 0.2 mmHg. The Tonometer IOP correlated well with GAT, with a Pearson coefficient of correlation(r) of 0.89 (p < 0.001) for the right eye and 0.86 (p < 0.001) for the left eye, respectively. In patients with GAT IOP ≥ 21 mm Hg (n = 25), the Tonometer underestimated the IOP by 2.96 mm Hg.

Discussion

The IOP measurements from the SUOER SW-500 Rebound Tonometer correlates well with the conventional GAT in measuring the IOP within normal ranges of IOP. SUOER SW-500 Rebound Tonometer may be of use, especially if the risk of transmission of infection is high considering that the probes are disposable. It is easy to use and its small size and portability makes it useful in situations where the patient is unable to be examined at the slit lamp.

A new mouse-fixation device for IOP measurement in awake mice

Glaucoma is an irreversible blinding eye disease. The mechanisms underlying glaucoma are complex. Up to now, no successful remedy has been found to completely cure the condition. High intraocular pressure (IOP) is an established risk factor for glaucoma and the only known modifiable factor for glaucoma treatment. Mice have been widely used to study glaucoma pathogenesis. IOP measurement is an important tool for monitoring the potential development of glaucomatous phenotypes in glaucoma mouse models. Currently, there are two methods of IOP measurement in mice: invasive and non-invasive. As the invasive method can cause corneal damage and inflammation, and most of the noninvasive method involves the use of anesthetics. In the course of our research, we designed a mouse fixation device to facilitate non-invasive measurements of mouse IOPs. Using this device, mouse IOPs can be accurately measured in awake mice. This device will help researchers to accurately assess mouse IOP without the use of anesthetics.

Effect of digital ocular massage on intraocular pressure and Schlemm's canal dimensions

Digital ocular massage has been reported to temporarily lower intraocular pressure (IOP). This could be related to an enhanced aqueous humor outflow; however, the mechanism is not clearly understood. Using anterior segment optical coherence tomography, the Schlemm's canal (SC) and trabecular meshwork (TM) can be imaged and measured. Here, 66 healthy adults underwent digital ocular massage for 10 min in their right eyes. The IOP and dimensions of the SC and TM were measured before and after ocular massage. All subjects demonstrated IOP reduction from 15.7 ± 2.5 mmHg at baseline to 9.6 ± 2.2 mmHg immediately after, and median of 11.6 mmHg 5-min after ocular massage (Friedman's test, p < 0.001). There was significant change in SC area (median 10,063.5 μm2 at baseline to median 10,151.0 μm2 after ocular massage, Wilcoxon test, p = 0.02), and TM thickness (median 149.8 μm at baseline to 144.6 ± 25.3 μm after ocular massage, Wilcoxon test, p = 0.036). One-third of the subjects demonstrated collapse of the SC area (-2 to -52%), while two-thirds showed expansion of the SC area (2 to 168%). There were no significant changes in SC diameter (270.4 ± 84.1 μm vs. 276.5 ± 68.7 μm, paired t-test, p = 0.499), and TM width (733.3 ± 110.1 μm vs. 733.5 ± 111.6 μm, paired t-test, p = 0.988). Eyes with a higher baseline IOP demonstrated a greater IOP reduction (Pearson correlation coefficient r = -0.521, p < 0.001). Eyes with smaller SC area at baseline showed greater SC area expansion (Pearson correlation coefficient = -0.389, p < 0.001). Greater IOP reduction appeared in eyes with greater SC area expansion (Pearson correlation coefficient r = -0.306, p = 0.01). Association between change in IOP and change in TM thickness was not significant (Spearman's ρ = 0.015, p = 0.902). Simple digital ocular massage is an effective method to lower IOP values, and change in the SC area was significantly associated with IOP changes.

Assessing Agreement and Variability Among Alternative Devices for Intraocular Pressure Measurement: A Comparative Study

Purpose

Intraocular pressure (IOP) measurement is critical in diagnosing and managing eye conditions. This study aims to assess the comparability of three alternative devices for measuring IOP: Noncontact tonometer, Icare rebound tonometer, and Tono-Pen.

Patients and Methods

A cross-sectional study included 172 adult participants (87 males and 85 females) who underwent IOP and central corneal thickness (CCT) assessments. IOP was measured using Noncontact (Canon TX-20), Icare (Icare TA01i), and Tono-Pen (Tonopen XL). CCT was measured with the built-in pachymetry of the Noncontact tonometer. Correlation coefficients and Bland-Altman analyses were conducted to assess the relationships and agreements between these tonometers. Participants were grouped based on IOP and CCT levels. The mean of the standard deviation of the three tonometer results was calculated to evaluate measurement result variability. One-way analysis of variance was conducted for comparing between the groups.

Results

IOP measurements among the three devices were not significantly different, indicating their comparability. Correlation analysis revealed strong correlations between the tonometers. Bland-Altman analysis showed good agreement, with the Icare rebound tonometer and Tono-Pen exhibiting narrower limits of agreement. Furthermore, IOP levels influenced measurement result variability, with higher IOP levels associated with greater variance.

Conclusion

This study demonstrates that the alternative devices examined can provide reliable IOP measurements. It highlights the potential of these alternative devices for IOP measurement. These findings have implications for clinical practice, offering practitioners additional tools for accurate IOP assessment.

Comparison of intraocular pressure measured by iCare tonometers and Goldmann applanation tonometer

OBJECTIVE

To evaluate the relationship between the Goldmann applanation tonometer (GAT) and the iCare PRO and iCare IC200 tonometers in measuring intraocular pressure (IOP) in adult eyes with a diagnosis of glaucoma or glaucoma suspect.

PARTICIPANTS AND METHODS

One hundred and one eyes from 101 participants diagnosed with glaucoma or glaucoma suspect were evaluated in this study. IOP was measured by iCare PRO and iCare IC200 tonometers in a randomized sequence followed by IOP measurements by the GAT tonometer and then central corneal thickness measurements. After the IOP measurements, participants scored their comfort level using a visual analog scale with each tonometer. Intraclass correlation coefficient (ICC) and Bland-Altman analysis were used to investigate the agreement among tonometers. SPSS and Microsoft Excel programs were used for statistical analysis.

RESULTS

Overall, there was good agreement among the 3 tonometers used in this study. The ICC for the iCare PRO and the iCare IC200 was 0.95 (p < 0.001), and the ICC for the iCare PRO and the GAT and the iCare IC200 and the GAT was >0.80 (p < 0.001). However, both iCare tonometers underestimated IOP by approximately 2 mm Hg compared with the GAT. Furthermore, 84% of iCare readings fall within ±5 mm Hg of GAT measurements. Neither body mass index nor central corneal thickness affected the IOP agreement among the tonometers. Participant response on visual analog scale rated IOP measurements by iCare tonometers to be more comfortable than the GAT.

CONCLUSION

Our results demonstrated a good agreement between iCare tonometers and GAT; but iCare tonometers underestimated IOP compared to the GAT.

Evaluation of the agreement and reliability of Transpalpebral Tonometers compared with Goldmann Applanation Tonometer - A systematic Review and Meta-Analysis Protocol

In 2020, the global prevalence of glaucoma was estimated to be 76 million and it was projected to increase to 111.8 million by 2040. Accurate intraocular pressure (IOP) measurement is imperative in glaucoma management since it is the only modifiable risk factor. Numerous studies have compared the reliability of IOP measured using transpalpebral tonometers and Goldmann applanation tonometry (GAT). This systematic review and meta-analysis aims to update the existing literature with a reliability and agreement comparison of transpalpebral tonometers against the gold standard GAT for IOP measurement among individuals presenting for ophthalmic examinations. The data collection will be performed using a predefined search strategy through electronic databases. Prospective methods-comparison studies published between January 2000 and September 2022 will be included. Studies will be deemed eligible if they report empirical findings on the agreement between transpalpebral tonometry and Goldmann applanation tonometry. The standard deviation and limits of agreement between each study and their pooled estimate along with weights and percentage of error will be reported using a forest plot. Cochrane's Q test and the I² statistic will be used to assess heterogeneity, and the publication bias will be investigated using a funnel plot, Begg's and Egger's tests. The review results will provide additional evidence on the reliability of transpalpebral tonometers that, in turn, could possibly assist practitioners to make informed decision about using it as a screening or diagnostic device for clinical practice, outreach camps, or home-based screening. Institutional Ethics Committee registration number: RET202200390. PROSPERO Registration Number: CRD42022321693.

Influence of the body positions adopted for resistance training on intraocular pressure: a comparison between the supine and seated positions

OBJECTIVES

A variety of factors are known to mediate on the intraocular pressure (IOP) response to resistance training. However, the influence of the body position adopted during resistance training on IOP remain unknown. The objective of this study was to determine the IOP response to the bench press exercise at three levels of intensity when performed in supine and seated positions.

METHODS

Twenty-three physically active healthy young adults (10 men and 13 women) performed 6 sets of 10 repetitions against the 10-RM (repetition maximum) load during the bench press exercise against three levels of intensity (high intensity: 10-RM load; medium intensity: 50% of the 10-RM load; and control: no external load) and while adopting two different body positions (supine and seated). A rebound tonometer was employed to measure IOP in baseline conditions (after 60 s in the corresponding body position), after each of the 10 repetitions, and after 10 s of recovery.

RESULTS

The body position adopted during the execution of the bench press exercise significantly affected the changes in IOP (p < 0.001, η_p² = 0.83), with the seated position providing lower increases in IOP levels compared to the supine position. There was an association between IOP and exercise intensity, with greater IOP values in the more physically demanding conditions (p < 0.001, η_p² = 0.80).

CONCLUSIONS

The use of seated positions, instead of supine positions, for the execution of resistance training should be prioritized for maintaining more stable IOP levels. This set of findings incorporates novel insights into the mediating factors on the IOP response to resistance training. In future studies, the inclusion of glaucoma patients would allow to assess the generalizability of these findings.

Accuracy of Intraocular Pressure Measurements of Eyes with Therapeutic Contact Lenses after Vitrectomy

Purpose: To evaluate the accuracy of intraocular pressure (IOP) measurements obtained by a rebound and non-contact tonometer in eyes with a therapeutic contact lens (CL) after vitrectomy.Methods: In 60 eyes of 60 patients who underwent vitrectomy for vitreoretinal disease, IOP was measured using a rebound tonometer (iCare ic200®; IOPRT) and non-contact computerized air puff tonometer (CT-80, IOPNCT), before and after wearing a CL (Purevision2®, +0.0 diopter). The mean IOP of three consecutive measurements were analyzed, and a comparative analysis with IOP measured by a Goldman applanation tonometer (IOPGAT) was performed.Results: The mean IOPRT without and with the CL was 12.55 ± 5.43 and 13.12 ± 5.13 mmHg, respectively, showing a statistically significant difference (p = 0.02) and strong positive correlation (r = 0.90, p < 0.001). The mean IOPNCT with and without the CL was 12.18 ± 3.24 and 12.17 ± 3.14 mmHg, showing no statistically significant difference (p = 0.17). The consistency with IOPGAT (12.57 ± 5.22 mmHg) was highest in IOPRT without the CL, followed by IOPRT with the CL, IOPNCT without the CL, and IOPNCT with the CL (intraclass correlation coefficients = 0.955, 0.945, 0.856, and 0.850, respectively). In addition, the rebound tonometer successfully measured IOP, regardless of whether the CL was worn; however, the non-contact tonometer failed to measure IOP in seven eyes without the CL and nine with the CL. No difference was observed according to intraocular tamponade type.Conclusions: A rebound tonometer can be used as an alternative IOL measuring method in eyes for which it is difficult to use a Goldman applanation tonometer due to the postoperative presence of a therapeutic CL.

How should we measure intraocular pressure in the era of coronavirus disease 2019? Balancing infectious risk, cleaning requirements, and accuracy

PURPOSE OF REVIEW

Accurate and precise measurement of intraocular pressure (IOP) is a vitally important component of the ophthalmic examination. There are multiple methods of tonometry, each of which has considerations in light of the ongoing severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic. This review discusses these considerations and compares various tonometer methods with the gold standard of Goldmann applanation tonometry (GAT).

RECENT FINDINGS

The SARS-CoV-2 virus may spread via droplets, microaerosols, or direct contact in the ophthalmology clinic. Tonometry poses a high risk of contamination. The accuracy and reliability of various methods of tonometry with single-use disposable equipment has been compared with Goldmann applanation tonometry.

SUMMARY

Goldmann applanation tonometry with disposable applanation tips, Tono-pen, and iCare employ single use tips to decrease the risk of cross-contamination of infectious agents. Review of the literature demonstrates good correlation between these devices and GAT, although the published level of agreement between devices varies.

How to Measure Intraocular Pressure: An Updated Review of Various Tonometers

Intraocular pressure (IOP) is an important measurement that needs to be taken during ophthalmic examinations, especially in ocular hypertension subjects, glaucoma patients and in patients with risk factors for developing glaucoma. The gold standard technique in measuring IOP is still Goldmann applanation tonometry (GAT); however, this procedure requires local anesthetics, can be difficult in patients with scarce compliance, surgical patients and children, and is influenced by several corneal parameters. Numerous tonometers have been proposed in the past to address the problems related to GAT. The authors review the various devices currently in use for the measurement of intraocular pressure (IOP), highlighting the main advantages and limits of the various tools. The continuous monitoring of IOP, which is still under evaluation, will be an important step for a more complete and reliable management of patients affected by glaucoma.