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Aesthesiometer for measuring corneal sensitivity

Feasibility study for the development of an aesthesiometer.

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Objectives

The objective of the project is a feasibility study for the development of an aesthesiometer to enable reliable measurement of corneal sensitivity in an everyday clinical environment. The aesthesiometer will be suitable for the following fields of application: to diagnose and evaluate the progress of dry eyes, after refractive surgery and keratoplasty, for corneal dystrophy and degeneration, for peripheral neuropathy and in contact lens wear.

Background

All instruments available for corneal sensitivity measurements are compromised by considerable limitations, such as lack of reproducibility/selectivity of measurement and limited practicality in an everyday clinical setup for routine measurements.

Result

Two potential concepts were identified in discussion with international research partners:

  1. A direct, tactile stimulus based on the classic Cochet Bonnet aesthesiometer using a "tip".
  2. A stimulus using fine, pulsed liquid jet / liquid droplets.

For the first approach, the following conditions should be considered:

  • The tip itself must be disposable or must be easily sterilised.
  • The tip may not compromise the integrity of the ocular surface
  • It must be possible to determine the precise moment of contact between the tip and the cornea
  • The "contact force" and "contact duration" should be determined electronically/electromechanically

For the second approach, it has to be explored how a purely mechanical stimulus can be generated with a fine (pulsed) water jet, without adding too much liquid onto the surface of the eye that may have an influence on the measurement. For this purpose, the following parameters are being examined:

  • Pressure (speed) and size (length) of the water jet (impulse)
  • Frequency and repetition rate of the liquid pulse
  • Temperature of the jet / droplets
  • Salt content of the watery solution used

Project information

Implementation

FHNW Institute of Optometry, FHNW Institute for Sensors and Electronics

Project partners Haag-Streit AG
Duration 33 months
Funding Innosuisse (KTI)
Project management Prof. Dr. Daniela Nosch, Prof. Dr. Markus Loepfe

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