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Vibration tonometry: non-contact IOP measurement from corneal vibration parameters analysis

Poster Details

First Author: P.Bitoun FRANCE

Co Author(s):    Z. Khoueir   K. Bouafia   P. Chapelle   J. Chambard   Y. Lachkar   L. Benzacken     

Abstract Details

Purpose:

A novel non-contact, non-invasive Vibration Tonometry technology with excitation of corneal vibrations and their correlation to GAT IOP was tested in a large clinical trial from which partial results are reported.

Setting:

Clinical trial was registered with national regulatory authorities and approved by local IRB with informed consent. The trial took place in a St Joseph Hospital, Paris, Robert Ballanger Hospital and Paris Glaucoma Institute and was sponsored by i Sonic Medical corporation.

Methods:

470 eyes form 236 volunteers from various ethnic origins at a suburban Paris hospital eye clinic and in the St Joseph Hospital Paris Glaucoma Institute were studied. History, vibration tonometry measurements in triplicate GAT, NIDEK air puff IOP, refractometry, keratometry and Tomey or Lenstar non-contact pachymetry were measured. Algorithm discovery was performed by random draw splitting runs into a discovery sample and a separate validation sample performed 10 times separately on males and females to insure its robustness.

Results:

In 236 patients, 34.6% of eyes had glaucoma, 51% females. 1311 (76%) vibration tonometry measurements were in correct position. Age was 20-92 yo with 48.7% females, mean of 62.1 y in females, 62.5 y in males. CCT mean was 531.2μ in females, 534.8μ in males. In 207 patients AL mean was 23.29 mm in females, 23.73 mm in males. GAT IOP 5.3 to 34 mm Hg, mean15.2 mm Hg in females, 15.2 mm Hg in males. None of these differences were significant. No adverse events were noted. Algorithm for women yielded 98,6% of IOP mean within 5 mm Hg of mean GAT IOP., men 96.4% of IOP mean was within 5mm Hg of mean GAT IOP.

Conclusions:

Current algorithm seems to show no evidence of effect of CCT on measurement precision. Vibration tonometry is a precise and valuable method for non-invasive measurement of IOP without contact with reasonable precision and good reproducibility and independently of CCT. It may thus prove to be a valuable tool for IOP measurement in thin and surgical corneas.

Financial Disclosure:

One or more of the authors is employed by a for-profit company with an interest in the subject of the presentation

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