Anesthesia-Free Tonometer Tips for Glaucoma

Overseen By Joanne Wen, MD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Duke University

Disqualifiers: Corneal scarring, Eye infection, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Approved in 3 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: Unknown

Duration: Baseline

50 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests three new tips for a device that measures eye pressure, crucial for individuals with glaucoma, a condition that damages the optic nerve. The goal is to determine which tip is most comfortable without anesthesia. Participants will compare these new tips, including the anesthesia-free tonometer tip, to the standard one that requires anesthesia. Individuals attending a routine eye exam with no history of corneal problems might be suitable candidates. As an unphased trial, this study allows participants to contribute to advancements in glaucoma care by identifying more comfortable diagnostic tools.

Do I need to stop my current medications for this trial?

The trial protocol does not specify whether you need to stop taking your current medications.

What prior data suggests that these anesthesia-free tonometer tips are safe for use in glaucoma patients?

Research has shown that anesthesia-free tonometer tips, such as the Rebound tonometer and Non-contact Air-puff tonometer, are generally easy to tolerate. They cause minimal discomfort or problems during use. These devices measure eye pressure without requiring numbing drops.

In studies, users of these tips typically report little to no pain. Reports of serious issues or side effects are rare. This suggests that the anesthesia-free tips in the trial are likely safe, based on knowledge of similar devices. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the anesthesia-free tonometer tips for glaucoma because they offer a painless and convenient way to measure eye pressure without the need for numbing eye drops. Traditionally, eye pressure is measured using devices that require anesthesia, which can be uncomfortable and time-consuming. The new tonometer tips are made from medical-grade acrylic coated with silicone or covered by a bandage contact lens, potentially improving comfort. This could make eye exams quicker and more pleasant for patients, leading to more frequent and accurate monitoring of glaucoma.

What evidence suggests that these anesthesia-free tonometer tips are effective for glaucoma?

This trial will compare different anesthesia-free tonometer tips for measuring eye pressure, which function effectively without numbing drops. Research has shown that these devices are crucial for monitoring eye pressure, a key factor in managing glaucoma and preventing vision loss. Studies have confirmed that they measure eye pressure accurately, similar to older methods. Additionally, these new devices offer more comfort, encouraging more frequent at-home testing, which can aid in better glaucoma management. ^{1 2 4 6 7}

Are You a Good Fit for This Trial?

This trial is for individuals with glaucoma. Participants must be willing to have their eye pressure measured using different tonometer tips without anesthesia to find the most comfortable one.

Inclusion Criteria

Presenting for a routine eye exam

Able and willing to give consent

Exclusion Criteria

History of alternated corneal sensitivity

I have an active eye infection.

I have had scarring on my cornea.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants compare the tolerability and comfort of 3 different prototype anesthesia-free tonometer tips with the standard tonometer tip

Baseline

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Anesthesia-free Tonometer Tip

Trial Overview The study is testing three prototype tonometer tips made of medical grade silicone (two varying in thickness) and a sterile bandage contact lens against the standard tip with anesthesia, aiming to identify the best option for home use.

How Is the Trial Designed?

Group I: Medical grade acrylic tip coated with medical grade silicone of a thickness > 100 µm Active Control 1 Intervention

Group II: Medical grade acrylic tip covered by a sterile commercially available bandage contact lens Active Control 1 Intervention

Group III: Medical grade acrylic tip coated with medical grade silicone of a thickness < 100 µm Active Control 1 Intervention

Who Is Running the Clinical Trial?

Duke University

Lead Sponsor

Trials

2,495

Recruited

5,912,000+

Published Research Related to This Trial

The rebound tonometer (RBT) demonstrated the lowest measurement variance compared to other tonometers, indicating its reliability for measuring intraocular pressure (IOP) in rabbits.

IOP measurements with the RBT remained consistent even when the probe was positioned at various distances, angles, and lateral positions from the cornea, suggesting its potential utility in dynamic settings, such as in studies involving human infants.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evaluation of rebound tonometer for measuring intraocular pressure at deviated angle and position. Takenaka, J., Mochizuki, H., Kunihara, E., et al.[2019]

A new handheld non-contact tonometer has been developed that automatically measures eye pressure when properly aligned, making it user-friendly and efficient.

Clinical trials show that this new tonometer correlates well with traditional Goldmann tonometry readings, with a high correlation coefficient (r = 0.88 to 0.95), indicating its potential reliability in measuring intraocular pressure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A new handheld air impulse tonometer. Fisher, JH., Watson, PG., Spaeth, G.[2009]

The non-contact tonometer is a reliable tool for measuring intraocular pressure in individuals with normal levels, offering advantages such as avoiding corneal contact and the need for anesthesia, which reduces risks of corneal abrasion and infection.

However, its reliability decreases in patients with elevated intraocular pressure and can be affected by corneal abnormalities or poor fixation, making it less suitable for all situations despite its usefulness in mass screenings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The non-contact tonometer. Its value and limitations. Shields, MB.[2022]

The iCare rebound tonometer (RBT) is effective for measuring intraocular pressure (IOP) in pediatric patients with childhood glaucoma during general anesthesia, showing comparable results to the handheld Perkins tonometer.

In this study of 45 eyes, the RBT recorded IOP values that were generally higher than those from the Perkins tonometer, with a systemic bias of 1.96 mmHg, indicating that while both methods are useful, the RBT may slightly overestimate IOP.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Rebound tonometry and applanation tonometry during narcosis investigation of pediatric glaucoma]. Rosentreter, A., Schild, AM., Lappas, A., et al.[2021]

The rebound tonometer (Tonovet) is accurate for measuring intraocular pressure (IOP) in normal feline eyes, correlating well with direct manometry, especially at pressures between 25-50 mmHg, making it suitable for glaucoma diagnosis.

In a study of 100 cats, the rebound tonometer showed a mean IOP of 20.74 mmHg, which is 2-3 mmHg higher than the applanation tonometer (18.4 mmHg), indicating that consistent use of the same tonometer is important for follow-up examinations.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Evaluation of a rebound tonometer (Tonovet) in clinically normal cat eyes. Rusanen, E., Florin, M., Hässig, M., et al.[2019]

The rebound tonometer (RT) showed a tendency to overestimate intraocular pressure (IOP) compared to the Goldmann applanation tonometer (GAT), especially at higher IOP levels, indicating that RT readings can be 1 to 3 mm Hg higher than those from noncontact tonometry (NCT) and 2 to 3 mm Hg higher than GAT.

Despite the overestimation, the RT demonstrated reasonable accuracy and concordance with GAT measurements, suggesting it can be a suitable tool for measuring IOP in both normal subjects and patients with glaucoma.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Rebound tonometer: ideal tonometer for measurement of accurate intraocular pressure. Suman, S., Agrawal, A., Pal, VK., et al.[2018]

The Icare® PRO rebound tonometer showed a non-significant mean deviation of -0.14 mm Hg compared to Goldmann applanation tonometry in a systematic review of 6 studies involving 672 eyes, indicating that while the devices generally agree, the differences are clinically irrelevant.

Despite claims of superior accuracy by the manufacturer, the review found significant heterogeneity among studies, with some showing underestimation and others overestimation of intraocular pressure by the Icare® PRO, suggesting that its accuracy may vary in practice.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Meta-analysis of the concordance of Icare&#174; PRO-based rebound and Goldmann applanation tonometry in glaucoma patients. Rödter, TH., Knippschild, S., Baulig, C., et al.[2022]

The Rebound tonometer is a quick and well-tolerated method for measuring intraocular pressure (IOP) in unanesthetized patients, taking significantly less time (about 55 seconds) compared to the Pulsair 3000 (about 138 seconds).

Patients experienced less discomfort with the Rebound tonometer, with only 15% reporting discomfort compared to 36% with the Pulsair 3000, making it a more patient-friendly option for IOP measurement.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Measuring intraocular pressure with the Pulsair 3000 and Rebound tonometers in elderly patients without an anesthetic. Kontiola, A., Puska, P.[2019]

The non-contact air-puff tonometer (NCT) showed a higher mean intraocular pressure (IOP) measurement compared to the Goldmann applanation tonometer (GAT), with significant differences noted in higher pressure ranges (16 mmHg and above) among 180 eyes from 90 patients.

While the NCT provided comparable results to the GAT for IOP measurements in the lower range (10-15 mmHg), it consistently overestimated IOP in higher ranges, suggesting it may not be a reliable alternative for all patients, especially those with elevated pressures.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Comparative Study Between the Goldmann Applanation Tonometer and the Non-Contact Air-Puff Tonometer (Huvitz HNT 7000) in Normal Eyes. Stock, RA., Ströher, C., Sampaio, RR., et al.[2022]

Rebound tonometry (RT) is a safe and well-tolerated method for measuring intraocular pressure (IOP) without anesthesia, showing a mean difference of only 1.0 mm Hg compared to Goldmann applanation tonometry (GAT) in a study of 101 eyes.

RT can be a reliable alternative for clinical screening, especially in situations where traditional methods like GAT are impractical, such as when patients cannot position their heads properly or when avoiding topical anesthetics is necessary.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of rebound tonometry with Goldmann applanation tonometry and correlation with central corneal thickness. Iliev, ME., Goldblum, D., Katsoulis, K., et al.[2021]

The air pulse noncontact tonometer is a safe and reliable method for measuring intraocular pressure (IOP) without the need for topical anesthesia, which can influence IOP readings.

In a study of 212 patients, local anesthetics oxybuprocaine and betoxycaine significantly decreased IOP shortly after application, with reductions observed for up to 15 minutes, while other tested drugs like indomethacin and metipranolol did not show significant immediate effects.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Influence of topical anesthesia on tonometric values of intraocular pressure. Baudouin, C., Gastaud, P.[2018]

In a study of 109 treated glaucoma patients, both the iCare rebound tonometer and the 7CR non-contact tonometer showed strong correlations with Goldmann applanation tonometry for measuring intraocular pressure, indicating they can be reliable alternatives.

However, the iCare rebound tonometer recorded slightly higher pressures in right eyes compared to Goldmann, while the 7CR non-contact tonometer generally provided lower readings, highlighting the need for careful interpretation of results when using different tonometers.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Comparison of intraocular pressure measurement between rebound, non-contact and Goldmann applanation tonometry in treated glaucoma patients. Vincent, SJ., Vincent, RA., Shields, D., et al.[2022]

Citations

1. withpower.com withpower.com/trial/phase-glaucoma-9-2024-39efc

Anesthesia-Free Tonometer Tips for Glaucoma The available research shows that Anesthesia-Free Tonometer Tips, like the non-contact tonometer, are effective for measuring eye pressure in normal ranges ...

2. ncbi.nlm.nih.gov ncbi.nlm.nih.gov/books/NBK493225/

Tonometry - StatPearls - NCBI Bookshelf Tonometry is utilized to measure IOP, which is essential in all forms of glaucoma. Tonometers are most commonly employed as part of a routine clinic visit by ...

3. sciencedirect.com sciencedirect.com/science/article/pii/S2162098923005595

Fundamentals and Advances in Tonometry This review provides a brief historical overview on tonometry and discusses current tonometry instruments.

4. clinconnect.io clinconnect.io/trials/NCT06585423

Tolerability of an Anesthesia-free Tonometer Tip - ClinConnect The purpose of this study is to compare the tolerability and comfort of 3 different prototype anesthesia-free tonometer tips with the standard tonometer tip ...

5. nature.com nature.com/articles/srep42067

Agreement of patient-measured intraocular pressure using ... This study aims to determine the agreement of patient-measured intraocular pressure (IOP) using rebound tonometry with ophthalmologist-measured IOP using ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7335349/

Current Trends in Tonometry and Tonometer Tip Disinfection 10% hypochlorite (dilute bleach) soaks is the only effective tonometer disinfectant and superior to 70% isopropyl alcohol wipes and 3% hydrogen peroxide soaks.

7. reviewofoptometry.com reviewofoptometry.com/article/the-dos-and-donts-of-measuring-iop

The Do's and Don'ts of Measuring IOP The method involves contacting an anesthetized cornea with a tonometer tip approximately 3.06mm in diameter and using fluorescein dye in the ...