WO1994012104A1 - Procede et dispositif permettant d'effectuer des esthesiometries - Google Patents

Procede et dispositif permettant d'effectuer des esthesiometries Download PDF

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Publication number
WO1994012104A1
WO1994012104A1 PCT/ES1993/000091 ES9300091W WO9412104A1 WO 1994012104 A1 WO1994012104 A1 WO 1994012104A1 ES 9300091 W ES9300091 W ES 9300091W WO 9412104 A1 WO9412104 A1 WO 9412104A1
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WO
WIPO (PCT)
Prior art keywords
cornea
gas
acid
air
eye
Prior art date
Application number
PCT/ES1993/000091
Other languages
English (en)
Spanish (es)
Inventor
Carlos Belmonte Martinez
Miguel Angel Pozo Garcia
Chen Xiaojie
Juana Gallar Martinez
Original Assignee
Universidad De Alicante
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universidad De Alicante filed Critical Universidad De Alicante
Priority to AU54666/94A priority Critical patent/AU5466694A/en
Publication of WO1994012104A1 publication Critical patent/WO1994012104A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/48—Other medical applications
    • A61B5/4824—Touch or pain perception evaluation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/16—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for measuring intraocular pressure, e.g. tonometers
    • A61B3/165—Non-contacting tonometers

Definitions

  • the present invention falls within the technical field of the measurement or determination of the sensitivity of the cornea and conjunctiva of the eye and, specifically, refers to a new procedure and its corresponding device for said determination in the that an air stream containing carbon dioxide or an aerosol containing an acid solution is applied.
  • the present invention broadens and improves the possibilities of the currently available mecha-stesiometers, by resorting to a different type of stimulation, chemistry, which activates the sensory nerve fibers of the cornea by a mechanism different from that of mechanical stimuli and which , because it uses a gas stream to transport the stimulus, it also avoids its direct contact with the cornea.
  • tissue including those of the eye, specialized nerve endings that transform the chemical, mechanical or thermal lesion stimuli into a nervous message that ultimately results in pain sensations.
  • These painful endings can be stimulated by the application of chemical irritants or by the action of acid solutions.
  • the present invention relates firstly to a new method for determining the degree of sensitivity of the cornea or ocular conjunctiva by applying a stream of air containing carbon dioxide, which locally modifies the pH of the tissue, or by the application "of an aerosol containing an acid solution that exerts this same action.
  • the change in pH acts as a chemical stimulus on the sensory nerve endings of the cornea, exciting them when the acidity reaches a threshold value. Since the change can be adjusted of pH produced by controlling the concentration of C0 2 in the applied gas or that of the acid substance in the aerosol, it is possible to quantitatively determine the chemical threshold at different points on the anterior surface of the eye.
  • This method can be used to evaluate the Consequential reductions in corneal sensitivity to metabolic or surgical corneal lesions.
  • the procedure of the present invention is characterized in that it comprises the following operations: a) apply at one or more points of the cornea or conjunctiva of the eye, the sensitivity of which is to be determined, a gas stream containing CO 2 and air at varying concentrations, or either an isotonic acid solution at variable pHs; and b) carry out a stesiometry of the local stimulation produced by the application of the stimulating substance, based on the determination of the threshold and the intensity of the pain, by means of verbal responses or the use of an analogue scale, the stimulating substance being constituted by C0 2 mixtures with air at concentrations ranging from 10% to 95%, or isotonic solutions of a weak acid adjusted to a pH between 3.5 and 7.0.
  • weak acid there may be mentioned acetic acid, citric acid and the like.
  • the applicant has been able to verify in anesthetized cats that when a stream of a gaseous mixture of air and C0 2 is applied at different concentrations on the surface of the cornea, it is produced from a C0 2 concentration of 30-50%, an excitation of the sensory nerve endings of the cornea, responsible for detecting harmful stimuli.
  • the electrical activity in said corneal nerve fibers is recorded, checking a discharge of nerve impulses therein, proportional to the change in pH and the concentration of C0 2 in the gas mixture. This response is immediate, reaches a maximum at the time of application and persists while maintaining the stimulus.
  • the present invention also relates to the corresponding device for performing the stesiometries.
  • the device which is represented in Figure
  • FIGURES Figure 1 It represents the device for performing stesiometries of the present invention.
  • the different references have the following meaning:
  • Figure 2 It is a graph that represents, for different concentrations of C0 2 , the discharge of the terminations in the cat's cornea and the magnitude of pain in humans using the VAS scale. Semi-logarithmic representation is included.
  • Figure 3 It is a graphic representation showing the measurement in humans, expressed as repeated mean in successive days, which shows the reproducibility of the method of the invention. Semi-logarithmic representation is also included.
  • EXAMPLE 1 In 5 healthy volunteers, under 10 years of age and without any ocular pathology, a graduation goggle with a 0.1 mm tipped silicone tube, located 5 mm from the surface, was placed in its center corneal This tube was connected to a system composed of two gas tanks containing respectively 98% C0 2 and air, which are joined in a gas mixer, which allows to obtain predetermined concentrations of C0 2 (10 to 90%).
  • the mixer outlet was connected to one of the upper arms of a V-tube, the other being connected to a second air tank.
  • An electronic valve system allowed air or a given mixture of C0 2 to be alternately expelled through the lower outlet of the Y-tube.
  • the gas exiting the latter (air or the mixture of C0 2 ) was passed through a humidifier and a regulator. pressure and finally connected with the silicone tube located in front of the cornea.
  • a pulse of 1 s duration with 98% C0 2 was applied to the cornea and the subject was asked to consider the sensation of pain evoked as maximum.
  • air was sent to the cornea, adjusting the output flow below the mechanical threshold thereof, so that the gas stream was not felt by the subject.
  • pulses of 1 s duration were applied with increasing concentrations of C0 2 and with 1 min of interval between pulses, asking the subject to indicate at what time he felt some feeling of irritation in the eye, and when it happened, it was indicating the intensity of the feeling on a scale of 1 to 10, in which 10 corresponded to the feeling of initial pain evoked by C0 2 to 98%.
  • a stream of C0 2 was applied to the corneal surface at varying concentrations, measuring the variation in the frequency of fiber discharge studied. It could be observed that there was a proportionality relationship between the firing frequency of the fibers and the concentration of C0 2 .
  • the temporal course of the response was analogous to that evoked by application of a 10 M acetic acid solution on the cornea, although the intensity of the response to the 10 mM acetic acid solution was approximately 70% lower than in the case of C0 2 .
  • the gas mixtures were humidified and conducted through a gas impermeable tube to a three-way solenoid valve controlled by a pulse generator.
  • One of the valve outlets was connected to a 0.5 mm diameter silicone tube and taken to a universal lens holder for graduation tests. The end of this tube was placed in the center of the lens holder by means of a stereoscopic vision lens, placing it perpendicularly to the center of the cornea and at a distance of 8-10 mm from the corneal surface.
  • the second valve outlet deflects the gas away from the eye. Gas flows continuously through this outlet except when the electronic valve momentarily changes the direction of flow to the surface of the cornea, for a pre-established period of time (0.1-10 s) ( Figure 1).
  • the gas jet pressure was adjusted by regulating the flow of the gas mixture with a pressure regulator.
  • a pressure regulator for the calibration of the gas jet pressure, the tube outlet connected in series to a pressure transducer (Statham P23XL) was placed perpendicularly to the saucer of a precision balance with the nozzle placed at a distance of 10 cm from the saucer.
  • the force exerted by gas flow increases were measured in mg with the balance and correlated with the corresponding voltage outputs given by the transducer.
  • the gas temperature was 242C. 3.
  • the mechanical threshold was determined using air pulses of 3 seconds duration at different pressures starting from 1.11 mg to 6.25 mg at intervals of 0.25 mg performing ascending and descending series. All pressure pulses were applied in duplicate with intervals between stimuli of 1 minute. Five minutes after the determination of the mechanical threshold, the chiosensitivity to C0 2 was explored. Mixtures of C0 2 contained in separate containers in 8 individuals were used. Pulses of 3 seconds duration and increasing concentrations (0, 35, 50, 65, 80 and 98.5%) were sequentially applied at the cornea at 1 minute intervals with the gas flow adjusted 0.5 mg below of the ecological threshold. After a period of time of 5 minutes the experiment was repeated but with mixtures of C0 2 concentration in decreasing order. In another group of 5 participants, series of stimulations were carried out using pulses of varying concentration of C0 2 (between 10% and 90% of C0 2 at 5% intervals) applied at random.
  • VAS Visual Analog Scale
  • VDS Verbal Description Scale
  • the participant could indicate the intensity of the sensation by adjusting with a potentiometer the number of diodes lit.
  • the LEDs were numbered and their color varied gradually from green to red.
  • the individual also indicated the sensation using descrip- verbal tores.
  • the corneal temperature was measured at the place where the gas stream affected by placing a microwave (Sensotek IT-23, 0.003 inches in diameter) on the corneal surface previously anesthetized with tetracaine.
  • the corneal surface temperature was measured with a digital thermometer (Sensotek BAT-12) throughout the experimental protocol, with no temperature variations exceeding O.l ⁇ C.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • Veterinary Medicine (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Medical Informatics (AREA)
  • Molecular Biology (AREA)
  • Physics & Mathematics (AREA)
  • Biophysics (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Ophthalmology & Optometry (AREA)
  • Hospice & Palliative Care (AREA)
  • Pain & Pain Management (AREA)
  • Psychiatry (AREA)
  • Pathology (AREA)
  • Eye Examination Apparatus (AREA)

Abstract

Le procédé consiste à: (a) appliquer sur la cornée ou la conjonctive de l'÷il, dont on veut déterminer la sensibilité, un courant gazeux contenant du CO2 et de l'air en concentrations variables, ou bien une solution isotonique acide; et (b) effectuer une esthésiométrie qualitative ou quantitative de l'irritation locale produite par l'application du produit irritant, cette esthésiométrie étant fondée sur la détermination du seuil et de l'intensité de la douleur, au moyen de réponses verbales ou de l'utilisation d'une échelle logique. Le dispositif comprend: une bouteille de CO2 (1); une bouteille d'air (2); un mélangeur de gaz (3); un indicateur (4) du flux de gaz; un indicateur (5) de la teneur en CO2 sous forme de pourcentage; un transducteur de pression (6); un oscilloscope (7); une soupape (8); un générateur d'impulsion (9); un support universel (10) de verres; le numéro (11) représentant la cornée de l'individu à examiner. Application à la mesure de la sensibilité cornéenne et conjonctivale de l'÷il.
PCT/ES1993/000091 1992-11-20 1993-11-19 Procede et dispositif permettant d'effectuer des esthesiometries WO1994012104A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU54666/94A AU5466694A (en) 1992-11-20 1993-11-19 Method and device for effecting aesthesiometries

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ESP9202351 1992-11-20
ES9202351 1992-11-20

Publications (1)

Publication Number Publication Date
WO1994012104A1 true WO1994012104A1 (fr) 1994-06-09

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PCT/ES1993/000091 WO1994012104A1 (fr) 1992-11-20 1993-11-19 Procede et dispositif permettant d'effectuer des esthesiometries

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AU (1) AU5466694A (fr)
WO (1) WO1994012104A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3583889A1 (fr) 2018-06-18 2019-12-25 Brill Engines, S.L. Esthésiomètre portatif
WO2021119093A1 (fr) * 2019-12-10 2021-06-17 The Trustees Of Indiana University Esthésiomètre pneumatique muni d'un conditionneur d'impulsions de gaz
ES2837548A1 (es) * 2019-12-31 2021-06-30 Univ Miguel Hernandez De Elche Umh Procedimiento y dispositivo para producir una secreción lagrimal refleja y un kit para la medición de la magnitud de flujo lagrimal generado

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1146041A1 (ru) * 1983-07-27 1985-03-23 Ставропольский государственный медицинский институт Альгезиметр
DD285019A5 (de) * 1989-06-26 1990-12-05 Bezirkskrankenhaus Potsdam,Dd Non-kontakt-aesthesiometer-tonometer
US5230347A (en) * 1992-03-03 1993-07-27 Neurocommunication Research Laboratories, Inc. Apparatus and method for measuring tactile sensation localized on the optic cornea

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1146041A1 (ru) * 1983-07-27 1985-03-23 Ставропольский государственный медицинский институт Альгезиметр
DD285019A5 (de) * 1989-06-26 1990-12-05 Bezirkskrankenhaus Potsdam,Dd Non-kontakt-aesthesiometer-tonometer
US5230347A (en) * 1992-03-03 1993-07-27 Neurocommunication Research Laboratories, Inc. Apparatus and method for measuring tactile sensation localized on the optic cornea

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
E. JALAVISTO ET AL.: "Ageing and Relation between Stimulus Intensity and Duration in Corneal Sensibility", ACTA PHYSIOLOGICA SCANDINAVICA, vol. 23, 1951, STOCKHOLM (SE), pages 224 - 233 *

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3583889A1 (fr) 2018-06-18 2019-12-25 Brill Engines, S.L. Esthésiomètre portatif
WO2019243646A1 (fr) 2018-06-18 2019-12-26 Brill Engines, S.L. Esthésiomètre à main
KR20210021060A (ko) * 2018-06-18 2021-02-24 브릴 엔진스 에스.엘. 휴대용 촉각측정계
JP2021528154A (ja) * 2018-06-18 2021-10-21 ブリル エンジンズ エセ エレ 携帯角膜知覚計
KR102455939B1 (ko) 2018-06-18 2022-10-17 브릴 엔진스 에스.엘. 휴대용 촉각측정계
AU2019291163B2 (en) * 2018-06-18 2024-03-21 Brill Engines, S.L. Handheld aesthesiometer
WO2021119093A1 (fr) * 2019-12-10 2021-06-17 The Trustees Of Indiana University Esthésiomètre pneumatique muni d'un conditionneur d'impulsions de gaz
ES2837548A1 (es) * 2019-12-31 2021-06-30 Univ Miguel Hernandez De Elche Umh Procedimiento y dispositivo para producir una secreción lagrimal refleja y un kit para la medición de la magnitud de flujo lagrimal generado
WO2021136820A1 (fr) 2019-12-31 2021-07-08 Universidad Miguel Hernández De Elche (Umh) Procédé et dispositif pour produire une sécrétion lacrymale réflexe et kit pour la mesure de l'amplitude du flux de larmes évoqué

Also Published As

Publication number Publication date
AU5466694A (en) 1994-06-22

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