June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Early validation of a novel handheld digital tonometer
Author Affiliations & Notes
  • John Maggiano
    Orange County Retina, Tustin, California, United States
    Western University of Health Sciences, Pomona, California, United States
  • Laz Peterson
    Orange County Retina, Tustin, California, United States
  • Steve Murath
    Orange County Retina, Tustin, California, United States
  • Peter Joson
    Tayani Eye Institute, California, United States
  • Pinakin Gunvant Davey
    Western University of Health Sciences, Pomona, California, United States
  • Footnotes
    Commercial Relationships   John Maggiano, LightTouch (I); Laz Peterson, LightTouch (I); Steve Murath, LightTouch (I); Peter Joson, LightTouch (I); Pinakin Davey, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 4761. doi:
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    • Get Citation

      John Maggiano, Laz Peterson, Steve Murath, Peter Joson, Pinakin Gunvant Davey; Early validation of a novel handheld digital tonometer. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4761.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Post intravitreal injection leads to an acute raise in intraocular pressure (IOP) which provides for a unique model for validation and comparisons of tonometric procedures. LightTouch® tonometer (LT) is a novel prototype contact, hand-held tonometer that estimates intraocular pressure (IOPe) in-vivo under topical anesthesia. Here we present preliminary objective, digital in-vivo data showing early validation of LT’s ability to measure IOPe.

Methods : The LT tonometer records simultaneous corneal apex area and force in 70-80 msec. Area of touch is measured via a decrease in total internal reflection within the device. Force of touch is measured via a proprietary piezoelectric assembly. The device tip contains an acrylic prism with a circular, flat tip of 3.06 mm diameter. Force difference from baseline is noted at the onset of full applanation. The higher the force necessary to achieve the onset of full applanation, the greater the IOPe. This is essentially equivalent to the principle of IOPe via Goldmann Applanation Tonometer (GAT) measurement.
Three patients with choroidal neovasculization due to age-relate macular degeneration underwent routine medically necessary intravitreal injection of 0.1cc aflibercept by a retinal specialist. Both LT and Tono-Pen® Avia measurements are performed every 3-4 minutes in a randomized manner. A time delay of 18-30 seconds occurs between each measurement pair.

Results : There were no complications of measurement using the LT and Tonopen. Figure 1 provides the scatterplots of IOPe obtained using the LT and Tonopen. Pearson correlation coefficient ranged from 0.77 to 0.97 for the three participants. There was a gradual decrease in IOPe seen as expected from prior reports.

Conclusions : The LT output compares favorably to a Tono-Pen Avia. This device comparison gives early validation to the aligned, objective and digital LightTouch technology. Further comparison to other devices and cannulated-eye IOP measurements will assist in establishing the validity of LT at all IOP values. New -objective and digital GAT-based data will enable cohort analysis and improved IOPe accuracy.

This is a 2020 ARVO Annual Meeting abstract.

 

Light touch force estimates compared to Tono-Pen IOP estimates. Each panel is an individual subject's measurments performed in 3-4 minutes.

Light touch force estimates compared to Tono-Pen IOP estimates. Each panel is an individual subject's measurments performed in 3-4 minutes.

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