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    K Number
    K991840
    Device Name
    FRESCO PHOSPHENE TONOMETER AND OR PHOSPHENE TONOMETER AND OR FPT AND OR EYELID TONOMETER
    Manufacturer
    BERNARD B. FRESCO
    Date Cleared
    2000-03-20

    (297 days)

    Product Code
    HKY
    Regulation Number
    886.1930
    Type
    Traditional
    Panel
    Ophthalmic
    Reference & Predicate Devices
    N/A
    Predicate For
    N/A
    AI/MLSaMDIVD (In Vitro Diagnostic)TherapeuticDiagnosticis PCCP AuthorizedThirdpartyExpeditedreview
    Intended Use

    Clinical testing of intraocular pressure . Self testing of intraocular pressure. Home monitoring of intraocular pressure. Screening studies, and outreach clinics. For Glaucoma, Ocular hypertensive, and general population groups.

    Device Description

    The phosphene tonometer is a pressure measuring device which consists of three ABS plastic components which are moulded, and a stainless 312 metal spring. These fit together and comprise the body of the instrument, a probe with the spring within and a fiduciary, with reset potential.

    AI/ML Overview

    The FPT/Fresco Phosphene Tonometer is a pressure measuring device intended for measuring intraocular pressure in clinical and home test use, allowing for self-testing.

    Here's an analysis of its acceptance criteria and the supporting study:

    1. Acceptance Criteria and Reported Device Performance

    Acceptance Criteria (Implicit)Reported Device Performance
    Accuracy: Measurements generally within ±3 mm Hg of Goldmann tonometry in general population.Clinically, 90% of measurements with the device were within ±3 mm Hg of Goldmann tonometry measurements, when measured by a clinician, or in self-testing of non-diagnostically specific patients.
    Accuracy: Measurements generally within ±3 mm Hg of Goldmann tonometry in glaucoma subgroups.Glaucoma sub-groups yielded 82% within ±3 mm Hg of Goldmann tonometry.
    Reproducibility/Precision: Low variation in home self-testing.Home self-testing for a ten-day period was undertaken in a group of controlled glaucoma patients as well as non-glaucoma cases. Over 2000 measurements were obtained. For two days, measurements were taken every hour. For the remaining eight days, pressure was measured 6 times a day. The standard deviation for readings taken 6 times daily yielded 0.7 mm Hg for 500 weekly readings. This indicates good precision and reproducibility in a real-world home setting.
    Stability/Repeatability: Consistent readings over short time intervals.Successive measurements with the phosphene tonometer yielded no statistically significant difference in repeat testing at 1, 3, 5, 8, 10, and 15 minutes.
    Safety: No adverse effects.There were no adverse effects evident in any of the studies that were evaluated.
    Addressing specific patient populations (e.g., advanced visual field loss).In cases of advanced visual field loss [greater than 14dB on central 24-2 Humphrey], the phosphene tonometer yielded higher readings than Goldmann tonometry [mean difference of 7 mm Hg.]. In these cases, a calibration correction is necessary for home monitoring, which compensates for the individual difference on a case-by-case basis. This demonstrates an understanding of the device's limitations and a proposed solution.

    2. Sample Size Used for the Test Set and Data Provenance

    The provided information does not explicitly state a single "test set" and its exact sample size or detailed provenance (country of origin, retrospective/prospective). However, the information can be inferred from the study results:

    • Clinically 90% accuracy: "non-diagnostically specific patients" - no specific sample size given for this group.
    • Glaucoma subgroup 82% accuracy: Again, no specific sample size provided for this subgroup.
    • Home self-testing: "a group of controlled glaucoma patients as well as non-glaucoma cases." Over 2000 measurements were obtained over a ten-day period (500 weekly readings mentioned for standard deviation). This implies a significant number of individuals participated to generate 2000+ measurements.
    • The data would likely be prospective given the nature of tonometer comparisons and home monitoring. The country of origin is not specified, but the applicant's address is in Canada.

    3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications

    The document does not explicitly state the number of experts used to establish ground truth or their specific qualifications (e.g., "radiologist with 10 years of experience").

    • The ground truth reference in the accuracy studies is Goldmann tonometry measurements, performed by a clinician. This implies that qualified medical professionals (likely ophthalmologists or trained technicians) performed the Goldmann tonometry, which serves as the gold standard.

    4. Adjudication Method

    The document does not describe any specific adjudication method (e.g., 2+1, 3+1) for the test set.

    5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

    The document does not describe an MRMC comparative effectiveness study comparing human readers with and without AI assistance. The device is a tonometer, not an AI-assisted diagnostic tool for image interpretation. It measures pressure and relies on a subjective response (perception of a phosphene), but does not involve AI for interpretation or decision support for human readers.

    6. Standalone Performance

    Yes, a standalone performance was done, in the sense that the device's performance was compared directly to a reference standard (Goldmann tonometry). The FPT/Fresco Phosphene Tonometer is itself a standalone device that provides a measurement; it is not presented as an AI algorithm augmenting human performance.

    • The accuracy studies (90% and 82% within ±3 mm Hg of Goldmann) directly assess the device's standalone ability to measure intraocular pressure relative to the established standard.

    7. Type of Ground Truth Used

    The primary ground truth used is measurements from Goldmann tonometry. Goldmann tonometry is the widely accepted clinical gold standard for measuring intraocular pressure.

    8. Sample Size for the Training Set

    The document does not mention a "training set" in the context of an algorithm or AI model development. The FPT/Fresco Phosphene Tonometer is a mechanical device, not a software algorithm that requires a training set. The various study results reflect validation of the device's performance against a known standard.

    9. How the Ground Truth for the Training Set Was Established

    Since there is no mention of a "training set" or an AI algorithm, the ground truth establishment for a training set is not applicable to this device. The validation involves comparing the device's readings to directly measured Goldmann tonometry.

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