Glaucoma Eye Test through EYELID !

Discussion in 'Eye-Care' started by DevelopAll, Sep 22, 2008.

  1. DevelopAll

    DevelopAll Guest

    DevelopAll, Sep 22, 2008
    #1
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  2. DevelopAll

    Salmon Egg Guest

    Not being in the eye care business, there is no way I would ever buy
    one. On the other hand, I am intrigued about how such a device might be
    implemented. In a way, it sounds like a divining rod.

    It certainly would have made the post credible if a bit was said about
    the principles of operation.

    Bill
     
    Salmon Egg, Sep 23, 2008
    #2
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  3. If you weren't in the business, but had glaucoma, you might consider it.
    It's not a divining rod-- it's FDA approved through a 510K, meaning the
    technology is based on an already-approved device. You can dig up a bunch
    on it by going to FDA.gov and searching for it. You'll see the 510K
    application, then you can search on the devices its based on.
     
    Scott Seidman, Sep 23, 2008
    #3
  4. DevelopAll

    Salmon Egg Guest

    As a matter of fact, I did suffer with glaucoma. I am just finishing up
    with the effects from two trabeculectomies. I am also interested in
    instrumentation and the way things work.

    For example, I was intrigued by how it was possible to have a dashboard
    display of tire pressure problems. I was both surprised by the
    simplicity and the fact that pressure was measured very indirectly. The
    ABS system compared the rolling rates among the various wheels rather
    than actually measuring pressure.

    Getting back to IOP, It should not be difficult to give a one or two
    sentence summary of how the device works and how it gets around the
    eyelid being in the way. A comparison of the accurcies of various
    methods would not hurt. So far, I have not seen that either in the posts
    or on the web site I visited.

    Bill
     
    Salmon Egg, Sep 23, 2008
    #4
  5. DevelopAll

    Dr Judy Guest

    Baush and Lomb has had a through the eyelid tonometer (Proview) on the
    market for years. They tried to market it as a way for glaucoma
    patients to monitor their IOP at home, much like diabetics monitor
    blood sugar. It really never took off. We have one in our office to
    use on those rare patients who refuse any other IOP test and
    occasionally send it home with glaucoma suspects to check diurnal
    variation.

    Studies suggest that it is adequate for checking change but not so
    good at absolute values.

    http://web.njit.edu/~alvarez/CV Papers/Proview Alvarez et al.pdf

    Judy
     
    Dr Judy, Sep 23, 2008
    #5

  6. Here's a start. the TGDc-01 is the "predicate device" listed on the FDA
    510K application that prevented the Diaton not having to go through a
    whole investigation for approval. Try using Google Scholar to find this
    paper, the papers it cites, and the papers that cite it. Eventually, it
    should point you to the technology.




    Auteur(s) / Author(s)
    GARCIA RESUA Carlos (1) ; GIRALDEZ FERNANDEZ Maria J. (1) ; CERVINO
    EXPOSITO Alejandro (2) ; GONZALEZ PEREZ Javier (1) ; YEBRA-PIMENTEL Eva
    (1) ;
    Affiliation(s) du ou des auteurs / Author(s) Affiliation(s)
    (1) Department of Applied Physics (Optometry Group), University of
    Santiago de Compostela, Santiago de Compostela, ESPAGNE
    (2) Neuroscience Research Institute, School ofLife and Health Sciences,
    Aston University, Birmingham, ROYAUME-UNI
    Résumé / Abstract
    Purpose. The TGDc-01 PRA (Ryazan State Instrument, Ryazan, Russia)
    tonometer is a new portable small-sized tonometer that measures
    intraocular pressure (IOP) through the eyelid. The purpose of this study
    is to assess the repeatability of the TGDc-01 IOP measurements by
    comparing them against those obtained with Goldmann tonometer and with
    those from Perkins applanation tonometer, Xpert (Reichert, Depew, NY)
    noncontact tonometer, and Tono-Pen XL (Medtronic Solan, Jacksonville, FL)
    digital tonometer. Methods. Fifty-eight right eyes of 58 young subjects
    were measured with each of the tonometers. Noncontact tonometry was
    performed first, followed by Goldmann and Perkins applanation tonometer
    (in random order), digital Tono-Pen XL, and finally TGDc-01 tonometer
    (sitting and supine position). Correlation analysis was used to evaluate
    the relationship between the Goldmann tonometer and the remaining
    tonometers used in this study. Plotting the difference between the
    methods against mean was also done to compare the tonometers. The
    hypothesis of zero bias was examined by a paired t-test. The 95% limits
    of agreement (LoA) were also calculated. Results. TGDc-01 showed no
    statistical difference between the IOP measurements obtained in sitting
    and supine positions. A poor relationship between the TGDc-01 and
    Goldmann tonometer was found (r2 = 0.173; p = 0.001). Although the mean
    differences between Goldmann and Tonopen XL, Xpert, and TGDc-01 IOP
    measurements were statistically significant, the wider 95% LoA was
    observed when comparing the Goldmann and TGDc-01 tonometers. Computation
    of the 95% LoA resulted in a wide bias range when comparing the TGDc-01
    with all the tonometers used in this study. Conclusions. The TGDc-01 PRA
    tonometer was not comparable with the other techniques used in the study.
    The wide dispersion range of the values obtained shows low repeatability
    of the TGDc-01 for screening purposes. These results could be because of
    the technique of measurement and/or interindividual variables.
    Revue / Journal Title
    Optometry and vision science ISSN 1040-5488 CODEN OVSCET
    Source / Source
    2005, vol. 82, no2, pp. 143-150 [8 page(s) (article)] (44 ref.)
     
    Scott Seidman, Sep 23, 2008
    #6
  7. DevelopAll

    Salmon Egg Guest

    Using phosphenes seems clever. What is the typical pressure variation
    amongst eyes at the onset of phosphenes? What error is introduced by the
    force measurement from outside the eyelid?

    Bill
     
    Salmon Egg, Sep 24, 2008
    #7
  8. DevelopAll

    Dr Judy Guest

    A simple google search using "Proview Tonometer " as the search term
    yielded at least half a dozen comparison reports which would contain
    that information.

    In the one I linked to in the previous post, Proview was repeatable
    with itself, with about a 3mmHg variation measure to measure; that is
    not far off other methods. It did not compare very well to Goldmann
    tonometry. I think its value is in patient self monitoring not in
    intial diagnosis or as an office instrument.

    Judy

    Judy
     
    Dr Judy, Sep 24, 2008
    #8
  9. DevelopAll

    DevelopAll Guest

    Dear Bill,

    There is a lot of information on the actual Diaton website:
    http://www.TonometerDiaton.com

    It Includes Clinical comparison trials with GAT, Tonopen as well as
    other publications.
    http://www.tonometerdiaton.com/inde...meter_Goldmann_Tonopen_Applanation_Tonometers

    Publication/Trials Extracts:


    # 1. Comparison of the Diaton Transpalpebral Tonometer Versus Goldmann
    Applanation
    http://www.tonometerdiaton.com/index.php?do=home.Comparison_Study_Diaton_Tonometer_Goldmann

    R. S. Davidson 1; N. Faberowski2 ; R. J. Noecker3 ; M. Y. Kahook1
    1. Ophthalmology, Rocky Mountain Lions Eye Institute, Aurora, CO, USA.
    2. Ophthalmology, Denver Health Medical Center, Denver, CO, USA.
    3. Ophthalmology, UPMC, Pittsburgh, PA, USA.

    Financial Disclosure
    The authors have no financial interest in the subject matter being
    presented

    Background
    Diaton tonometry is a unique approach to measuring intraocular
    pressure (IOP) through the Eyelid. It is a non-contact (no contact
    with cornea), pen like, hand-held, portable tonometer. It requires no
    anesthesia or sterilization.

    Purpose
    To investigate the agreement in the measurement of intraocular
    pressure (IOP) obtained by transpalpebral tonometry using the Diaton
    tonometer versus Goldmann applanation in adult patients presenting for
    routine eye exams.

    Methods
    Retrospective chart review of consecutive IOP measurements performed
    on 64 eyes of 32 patients age 34-91 years with both the Diaton
    tonometer and Goldmann applanation. Results between groups were
    examined using analysis of variance (ANOVA) where appropriate.

    Results
    Mean IOP was 15.09 +/-4.31 mm Hg in the Goldmann group and 15.70
    +/-4.33 mm Hg in the Diaton group (p=0.43).
    Mean IOP variation between groups was 1.74 +/-1.42 mm Hg (range 0-8).
    83% of all measurements were within 2 mm Hg of each other.

    Conclusions
    The transpalpebral method of measuring IOP with the Diaton tonometer
    correlates well with Goldmann applanation. Diaton applanation may be a
    clinically useful device for measuring IOP in routine eye exams.

    # 2. Comparison of the Diaton Transpalpebral Tonometer Versus Tono-Pen
    Applanation
    http://www.tonometerdiaton.com/index.php?do=home.Comparison_Diaton_Tonometer_Tono_Pen_Applanation

    Theodore H. Curtis, M.D.1, Douglas L Mackenzie, M.D.1, Robert J.
    Noecker M.D.2, and Malik Y. Kahook M.D.1
    1The Rocky Mountain Lions Eye Institute, University of Colorado Health
    Sciences Center, Aurora, CO
    2Eye and Ear Institute, University of Pittsburgh Medical Center,
    Pittsburgh, PA

    Financial Disclosures
    · None of the authors have financial interests relevant to the supject
    discussed.
    Purpose
    · To compare intraocular pressure (IOP) measurements obtained with
    Diaton trans-palpebral tonometry versus Tonopen applanation tonometry
    in children and adults.

    Introduction

    · Goldmann applanation is the gold standard for IOP measurement
    · It has been supplanted by TonoPen applanation in many settings
    because of it's ease of use, portability, convenience, and minimal
    training requirements.
    · The TonoPen requires contact with the corneal surface, and has the
    risks of iatrogenic corneal injury, spread of pathogens, and requires
    topical anesthetics.

    Introduction

    · The newly-developed Diaton tonometer is a handheld device that
    measures pressure through the tarsal plate (Figures 1 & 2).
    · It avoids contact with the cornea and the need for topical
    anesthesia.

    Figure 1: The Diaton Transpalpebral Tonometer
    Figure 2: Using the Diaton Tonometer

    Methods

    · We looked at 74 eyes of 38 consecutive patients who received both
    Tonopen and Diaton tonometry
    · TonoPen measurements were taken in the sitting position following
    topical anesthesia with proparicaine.
    · Diaton measurements were performed in the sitting position with the
    patient gazing at a 45o angle, placing the eyelid margin at the
    superior limbus. If necessary, gentle traction was placed on the brow
    to align the lid with the limbus. The device was activated when the
    signaling mechanism indicated the device was vertical.

    Results

    · Age range 3-91 years of age (mean 47.5 years).
    · The average IOP with the Diaton was 16.24 (+/-5.11 mm Hg; range =
    7-32 mmHg).
    · The average IOP with the TonoPen was 16.37 (+/-4.90 mm Hg; range =
    8-33 mmHg).
    · The mean variation between the two modalities was 1.59 mmHg (+/-1.31
    mm Hg; range = 0-6 mmHg).
    · Eighty-one percent of all measurements were within 2 mmHg of each
    other (Table 1).
    · There was no statistically significant difference in mean IOP values
    obtained with the two devices (p=0.87). Table
    Conclusions

    · The Diaton tonometer pressure measurements correlated well with
    TonoPen measurements in this retrospective review.
    · We did not find problems performing the exam in children, and many
    were reassured by the fact that no drops were needed.
    · There may be a notable benefit in patients after refractive surgery
    or with corneal pathology since the Diaton does not applanate the
    cornea.
    · The Diaton tonometer appears to be a clinically useful device in the
    IOP measurement of both children and adults.


    # 3. Clinical comparison of the Diaton and the Non-contact Tonometers
    with the Goldmann applanation tonometer in glaucoma patients
    http://www.tonometerdiaton.com/inde...parison_Diaton_Non_Contact_Tonometer_Glaucoma

    Nesterov A.P. M.D., Illarionova A.R. M.D., Obruch B.V. M.D.
    Eye Diseases Department, Russian State Medical University, Moscow,
    Russia

    Purpose: Study of intraocular pressure evaluation (IOP) reliability
    using non-invasive devices, which require no anesthesia:
    transpalpebral scleral Diaton tonometer and non-contact
    pneumotonometer (NCT).

    Method: Here the prospective comparative case series clinical study is
    presented. 87 patients (146 eyes) suffered from glaucoma (m:f = 51:36;
    age distribution: 29-85 years) were examined. For comparison IOP
    values received with Goldmann applanation tonometer (GAT) using the
    traditional methodology and digital mean values received with Diaton
    and NTC were used.

    Results: Mean IOP was 17,4±7,6 mmHg with GAT, 16,7±5,58 mmHg with
    Diaton, 21,4±9,13 mmHg with NCT. Minimum IOP value was 6,0 mmHg with
    GAT, 6,0 mmHg with Diaton, 5,0 mmHg with NCT; maximum value was 40,0
    mm Hg with GAT, 36,0 mmHg with Diaton, 47,0 mmHg with NCT. There was
    no significant difference of IOP values (t = -0,51, p < 0,001). The
    Pearson's correlation coefficient was r=0.89, p < 0,001 between GAT
    and Diaton; r=0,87, p < 0,001 between GAT and NCT. There was observed
    high correlation of both tonometers with GAT in IOP range up to 30 mm
    Hg. In case of IOP significant increase NCT showed IOP overestimation
    up to 7 mm Hg; Diaton showed IOP underestimation up to 4 mm Hg.

    Conclusions: The study shows high reliability of transpalpebral
    screral Diaton tonometer enough for clinical purpose. It has both
    accuracy correlating with GAT and NCT's safety and operating speed.
    Diaton advantage is the possibility to evaluate IOP in cornea
    pathology, which is very important in glaucoma patients after corneal
    including laser surgeries.

    ESCRS Meeting, London, September 2006

    # 4. Clinical use of transpalpebral diaton tonometry after
    keratophotorefractive surgeries
    http://www.tonometerdiaton.com/inde...on_Tonometry_Kerato_Photorefractive_Surgeries

    T. Dzhafarli MD., A. Illarionova MD.

    Purpose: The purpose of the study is to evaluate the clinical use of
    transpalpebral scleral tonometry, reliability of its application in
    patients with refraction anomaly in pre- and postoperational periods,
    dynamics of eye morphometric rates (pachymetry of the central corneal
    zone, IOP) and their correlative bond before and after photorefractive
    surgery.

    Setting: Russian State Medical University, Moscow, Russia.

    Methods: The following factors were exclusion criteria from the study:
    cornea, upper eyelid and clera pathology. We have analyzed the results
    of prospective comparative case series clinical study in 98 patients
    (194 eyes) with ametropia, from which 39 persons (76 eyes), who had
    been subjected to excimerlaser vision correction. All patients were
    subject to the comlete refractive examination, including
    keratotopography, wavefront-aberrometry, US-biomicroscopy,pachymetry
    corneal thickness in central zone, IOP was measured with Goldman
    applanation tonometer, pneumotonometer and transpalpebral scleral
    Diaton tonometer using traditional methodology.

    Results: In the patients who had not been subjected to photorefractive
    surgery the mean applanation IOP was 16.1±2.6 mmHg, the mean IOP
    evaluated with Diaton 14.7±2.5 mmHg. At that correlation between
    values of the applanation tonometer and Diaton was highly reliable
    r=0.73. The mean of the real IOP after applanation value conversion
    was 15.4±2.4 mmHg. Pearson correlation coefficient between real IOP
    and the Diaton result was 0.89. In the groups of patients, who
    underwent photorefractive vision correction, the mean applanation IOP
    12.4±2.91 mmHg, modified taking into account keratometry IOP rates
    13.9±3.0 mmHg, mean diaton-tonometry result 15.1±2.75 mm Hg - increase
    of correlation coefficient from 0.51 to 0.81.

    Conclusions: The cornea thickness is an important factor in IOP
    evaluation and monitoring, and necessitates the inclusion of corneal
    pachymetry in the program of examination the patients with suspicion
    of glaucoma and hypertension, especially after various
    keratorefractive surgeries while using the traditional corneal methods
    of ophthalmotonometry. At the same time clinical application of
    transpalpebral scleral diaton tonometer makes it possible to evaluate
    IOP using only one device, the procedure being efficient, economical,
    simple and requires no additional instrument examination.

    XXV Congress of the ESCRS, Stockholm 2007


    Also - the description link has in depth overview on the principles of
    the ballistic tonometry:

    1.4 Advantages of ballistic transpalpebral tonometry with Diaton
    Tonometer.

    1.4.1 During the corneal tonometry it is very difficult to prevent the
    increasing of orbicular and palpebral muscles tone at the moment of
    measuring in reactive patients, that leads to IOP increasing. The
    ophthalmotone increasing may be also connected with the blood pressure
    increasing during the tonometer's bringing near the open eye. Diaton
    tonometer is out of the patient's field of vision.

    1.4.2 It is known that a tear may contain pathogenic bacteria and
    viruses such as hepatitis B virus, herpes, adenoviruses, AIDS. But the
    problem of tonometers sterilization is far from perfection. During
    tonometry with Diaton device the direct contact with the eyeball is
    excluded.

    1.4.3 The corneal tonometry is contraindicative in conjunctivitis,
    erosions, sores, hypostasis and cornea dimness. Using Diaton Tonometer
    the IOP measuring in most of such cases is possible.

    1.4.4 The corneal tonometry is impossible without prior anesthesia,
    which often causes conjunctiva irritation, short-term IOP increasing,
    hypostasis and loosening of cornea epithelium and sometimes allergic
    reaction. These undesirable reactions are excluded while measuring
    with Diaton tonometer.


    For any additional questions - you can contact the company directly
    either by form on the site: email or
    phone: 1-877-diatons (877-342-8667)

    I hope you will find the follow up helpful and useful.

    Best regards,
    DA
     
    DevelopAll, Oct 30, 2008
    #9
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