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NCT Number: NCT07298356

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.

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Key information

Conditions

Glaucoma Eye Diseases Glaucoma, Suspect Ocular Hypertension

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Duke Eye Center

Durham, North Carolina, 27710, United States

Location status: Recruiting

Location contact

Joanne Wen, MD

CONTACT

[email protected]

919-684-2975

Joanne Wen, MD

PRINCIPAL_INVESTIGATOR

About this study

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.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Standard GAT

Device

Standard Goldmann Applanation Tonometry (GAT): this is the standard method for IOP measurement in clinical practice

Fixed force GAT

Device

An investigational device similar to standard GAT

Upright applanating prototype

Device

An investigational device, prism used in standard and fixed-force GAT is attached to a portable device

Pneumotonometer

Device

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

Primary outcomes

  1. Intraocular pressure (IOP) as measured by standard GAT

    Time frame: Baseline

    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.

  2. Intraocular pressure (IOP) as measured by fixed force GAT

    Time frame: Baseline

    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.

  3. Intraocular pressure as measured by upright applanating

    Time frame: Baseline

    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.

  4. Intraocular pressure as measured by supine Pneumotonometer

    Time frame: Baseline

Study contacts

Contact information is provided by the study sponsor or research team.

Sarah Jones

CONTACT

[email protected]

919 681 6584

Sponsors and collaborators

Lead sponsor

Duke University

Other

Registry information

Important dates

Study start
2026
Primary completion
2026
Study completion
2026
First posted
Dec 23, 2025
Registry last updated
Mar 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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