Une nouvelle méthode de mesure de la pression intraoculaire

Abstract

The ocular hypertension (elevation of the intraocular pressure — IOP —) is widespread in the industrialized countries. Its consequences can lead to complete blindness. That is why it is the subject of an attentive surveillance, notably with risky (glaucomatous) patients. Ophthalmologists currently use aplanation tonometers whose utilization induces multiple constraints: (local anaesthesia, additional instrumentations required, …). Our aim was to propose an investigative method both atraumatic and ambulatory. We designed an original device that, putting to profit a physical relation between frequency of mechanical vibration of the ocular globe and the intraocular pressure, combines vibrometry by laser interferometry and spectral analysis of a mechanical impulse transmitted to the eye by a micro hammer located on the temporal edge of the orbital socket. After having scrupulously confirmed that the luminous energy delivered to the eye by the laser source was in agreement with the authorized security norms, we led a survey clinic on 25 patients to test the innocuity and the reliability of this device and to value the reproducibility of measurements. The obtained results are very encouraging: the expressed discomfort is comparable the one felt during analogous sight-testings. Reliability is good (18% of failure in recorded measurements) and the intra individual reproducibility, expressed by the coefficient of interrelationship intraclass, outlines a value qualified of very good (R > 0.93). These first results encourage us to pursue our works to succeed in establishing an correlation between the measured value (the resonance frequency of the eye-ball) and the supervised one (the intraocular pressure).