Automated Applanation Tonometry - Updated

Goldmann Applanation Tonometry (GAT) is considered the clinical gold standard for eye pressure measurements and yet it is known to be a subjective measurement with limited repeatability and limited portability. Another clinical standard for checking eye pressure is known as the pneumotonometer. This method is more objective but not portable. The purpose of this study is to develop new methods of measuring eye pressure that are more objective, reproducible and portable. In this study, the investigators will be comparing the eye pressure measurements using 2 investigational methods to GAT and pneuumotonometer.

Study Overview

• Status: Recruiting
• Conditions: Glaucoma; Glaucoma, Suspect
• Intervention / Treatment: Device: Standard GAT; Device: Fixed force GAT; Device: Upright applanating prototype; Device: Pneumotonometer

Detailed Description

This is a prospective study. Patients presenting for their scheduled eye appointments will be recruited by verbal communication. Following informed consent, intraocular pressure (IOP) measurements will be made by the following methods:

Standard Goldmann Applanation Tonometry (GAT): this is the standard method for IOP measurement in clinical practice. The eye is given topical fluorescein/anesthetic, the GAT prism contacts the eye while the observer looks through the slit lamp machine ocular using blue light illumination to visual the applanation mires. The GAT dial is adjusted until mire alignment is achieved and the IOP measurement is read off the GAT dial.

Pneumotonometer: This is what is done in routine eye care. The participant will receive a topical anesthetic (numbing agent). A probe will touch the front of the eye while the machine measures the eye pressure.

Fixed force GAT: From the patient perspective, this method will feel identical to the standard GAT. The eye is given topical fluorescein/anesthetic. The GAT dial is set at 1.8 or 2.0, a complementary metal oxide semiconductor (C-MOS) camera is connected to one of the oculars of the slit lamp machine and under blue light illumination, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance through the ocular. The diameters of the recorded mire images are measured and the IOP is calculated based on the mire diameter. A similar method using an iPod touch camera has been previously published by this PI.

Upright applanating prototype: With this prototype, an applanating prism (custom manufactured with medical grade acrylic in an ISO-13485 certified facility) is attached to a fixed-force spring that creates a force equivalent to 1.8 or 2.0 on the GAT dial. Blue LED lights on the prototype are used to create the blue illumination similar to the blue light used in clinical practice on the slit lamp or Perkins tonometer. A C-MOS camera is aligned with the GAT prism to image the applanation mires. The eye is given topical fluorescein/anesthetic. Like fixed-force GAT, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance. The diameters of the recorded mire images are measured and the IOP is calculated based on the mire diameter.

The order of the above 4 measurements will be randomized.

• Study Type: Interventional
• Enrollment (Estimated): 200
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sarah Jones; Phone Number: 919 681 6584; Email: sarah.jones1@duke.edu

Study Locations

• United States
  • North Carolina
    • Durham, North Carolina, United States, 27710
      • Recruiting
      • Duke Eye Center
      • Contact: Joanne Wen, MD; Phone Number: 919-684-2975; Email: joanne.wen@duke.edu
      • Principal Investigator: Joanne Wen, MD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Criteria:

Inclusion Criteria:

• Presenting for a routine eye exam
• ≥ 18 years of age
• Able and willing to give consent

Exclusion Criteria:

• History of corneal scarring
• Active infection of the eye
• Ocular surface trauma or infection

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Diagnostic
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Fixed-force GAT; From the patient perspective, this method will feel identical to the standard GAT. The eye is given topical fluorescein/anesthetic. The GAT dial is set at 1.8 or 2.0, a C-MOS camera is connected to one of the oculars of the slit lamp machine and under blue light illumination, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance through the ocular. The diameters of the recorded mire images are measured and the IOP is calculated based on the mire diameter	Device: Fixed force GAT; An investigational device similar to standard GAT
Experimental: Upright applanating prototype; With this prototype, an applanating prism (custom manufactured with medical grade acrylic in an ISO-13485 certified facility) is attached to a fixed-force spring that creates a force equivalent to 1.8 or 2.0 on the GAT dial. Blue LED lights on the prototype are used to create the blue illumination similar to the blue light used in clinical practice on the slit lamp or Perkins tonometer. A C-MOS camera is aligned with the GAT prism to image the applanation mires. The eye is given topical fluorescein/anesthetic. Like fixed-force GAT, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance. The diameters of the recorded mire images are measured and the IOP is calculated based on the mire diameter	Device: Upright applanating prototype; An investigational device, prism used in standard and fixed-force GAT is attached to a portable device
Active Comparator: Standard GAT; This is the gold-standard method for IOP measurement in clinical practice	Device: Standard GAT; Standard Goldmann Applanation Tonometry (GAT): this is the standard method for IOP measurement in clinical practice
Active Comparator: Pneumotonometer; This is another standard method for IOP measurement in clinical practice	Device: Pneumotonometer; This is a standard for checking eye pressure. A topical anesthetic (numbing agent). A probe will touch the front of the eye while the machine measures the eye pressure

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Intraocular pressure (IOP) as measured by standard GAT	this is the standard method for IOP measurement in clinical practice. The eye is given topical fluorescein/anesthetic, the GAT prism contacts the eye while the observer looks through the slit lamp machine ocular using blue light illumination to visual the applanation mires. The GAT dial is adjusted until mire alignment is achieved and the IOP measurement is read off the GAT dial.	Baseline
Intraocular pressure (IOP) as measured by fixed force GAT	From the patient perspective, this method will feel identical to the standard GAT. The eye is given topical fluorescein/anesthetic. The GAT dial is set at 1.8 or 2.0, a C-MOS camera is connected to one of the oculars of the slit lamp machine and under blue light illumination, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance through the ocular.	Baseline
Intraocular pressure as measured by upright applanating	With this prototype, an applanating prism (custom manufactured with medical grade acrylic in an ISO-13485 certified facility) is attached to a fixed-force spring that creates a force equivalent to 1.8 or 2.0 on the GAT dial. Blue LED lights on the prototype are used to create the blue illumination similar to the blue light used in clinical practice on the slit lamp or Perkins tonometer. A C-MOS camera is aligned with the GAT prism to image the applanation mires. The eye is given topical fluorescein/anesthetic. Like fixed-force GAT, the GAT prism contacts the eye while the CMOS camera makes a video of the mire appearance. The diameters of the recorded mire images are measured and the IOP is calculated based on the mire diameter.	Baseline
Intraocular pressure as measured by supine Pneumotonometer		Baseline

Collaborators and Investigators

• Sponsor: Duke University
• Investigators: Principal Investigator: Joanne Wen, MD, Duke Eye Center

Study record dates

Study Major Dates

• Study Start (Actual): March 2, 2026
• Primary Completion (Estimated): December 29, 2026
• Study Completion (Estimated): December 29, 2026

Study Registration Dates

• First Submitted: December 19, 2025
• First Submitted That Met QC Criteria: December 19, 2025
• First Posted (Actual): December 23, 2025

Study Record Updates

• Last Update Posted (Actual): March 6, 2026
• Last Update Submitted That Met QC Criteria: March 4, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Eye Diseases; Glaucoma; Ocular Hypertension
• Other Study ID Numbers: Pro00106111_1

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: No Currently, there is no plan to share data with other researchers.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No