DE2623177A1 - Detector for light transmissivity of cornea - performs electronic conversion of extinction to transmission - Google Patents

Abstract

Detector for light transmissivity of cornea in the eye which can be located in a physiological position during measurement operated by measuring the extinction value, and electronically converting this to a transmission value. The conversion mode of a cornea which has just been measured is programmed to a mathematical relationship which corresponds to any fundamental rule of arithmetic and which can be determined in suitable series of tests. The degree of transmission may be indicated in percentage of available light. Pref. measurement takes place in the visible band of the spectrum, partic. at wavelengths 300, 350, 450, 500, 540, 575, 650, 750 and 850 nm and with mixed light. Additional measurements may be performed with UV and quasi-IR light.

Description

Patent description

to the patent application for the additional patent device for measurement the extinction and determination of the light permeability of the cornea on the eye ".

The basic patent is in the course of business of the German Patent Office under the file number P 24 23 105.8-35.

The invention relates to a device for measuring the extinction the cornea of the eye, with the result of the extinction measurement using a suitable transformation device of the transmission value (light transmittance) the cornea can be determined as a percentage of the light provided.

So far, there is no objective method in ophthalmological practice for measuring the light transmittance of the cornea in the living eye. The examiner limited to a subjective description of corneal opacity. In some ways but an objective determination of the corneal transmission would be appropriate. Ongoing operative controls of transplant results, Objectivation of the corneal part of a deterioration in vision are just two examples a variety of uses.

All the procedures described so far, which are mainly used in scientific Range to be applied, from the photomicrographic method to use of photoreceptors, require dissection of the cornea. So you are not suitable for carrying out a transmission measurement in vivo. So far there are none Method and no devices described with the help of which the light transmission the cornea can be determined in the living eye.

The object of the invention is, with the help of the described in the basic patent Device for measuring the extinction of the cornea on the eye an existing dependency between extinction and light transmission by means of a suitable transformation device and thus the transmission value of the cornea as a percentage of the offered To throw out light.

As part of a dissertation at the University Eye Clinic in Kiel it could be determined that in the cornea of the rabbit eye the light transmission is clearly dependent on the absorbance to be measured when incident light. In addition, it could be shown that the attenuation referred to as extinction of light of a defined light intensity 10 falling on the cornea by far predominantly is caused by scattering in the sense of a Raleigh scattering, a measurement the extinction can therefore be limited to a measurement of the scatter. The two other mechanisms that are also involved in the extinction of light, namely absorption and surface reflection play a role if the correct measurement method is chosen and wavelength play a quantitatively negligible role.

FIG. 1 shows the determined relationship between extinction and transmission using the example of a measurement with a wavelength of 450 nm.

Since apart from the dimensions, the morphology of the human Eye coincides with that of the rabbit eye and it can be assumed that the different Amino acid sequence of the biological materials involved in the structure of the corneas plays no role in the absorbance measurement, it is by far more certainty Probability to assume that those described on the rabbit cornea Dependency relationships can be transferred to human relationships.

Furthermore, an improvement of the device registered in the basic patent, here the measuring head C, registered for an additional patent. The invention relates to a new measuring head C, in which the emissor ends in form of Cylinder section are formed, the light-conducting fibers to the cylinder axis demonstrate. The receptor fibers are bundled in the direction of the axis of the eye, whereby the surface of the receptor fibers is at right angles to the axis of the eye.

With the measuring head registered in the basic patent, there is the possibility of that by reflection, absorption or scattering phenomena through behind the cornea lying structures the result can be influenced.

The object of the invention is through the described below Accurate arrangement of emissor and receptor fibers, by lying behind the cornea Structures to obtain unaffected results, using the measuring head described here at the same time, measurements are allowed when the cornea is only slightly or not at all clouded.

FIG. 2 shows the schematic structure of the new measuring head.

The light-conducting fibers of the emissors 1 are in the form of a cylinder section formed with the light-conducting fibers pointing to the cylinder axis. The cylinder axis corresponds to the axis of the eye and at the same time to the axis of the receptor fibers 2. The The height of the emissor cylinder is approximately equal to the distance from the base of the cornea to the vertex of the cornea; The number of emissor fibers 1 is fixed to the number of receptor fibers 2 Relationship. The surface of the receptor ends is at a right angle to the axis of the eye. The emissor cylinder is only in four places by the centering device described in the basic patent interrupted.

Claims (5)

Claims:! 1.) Device for determining the light intensity rate the cornea of the eye, which is in a physiological position during the measurement can, characterized in that the determined with the device of the basic patent Absorbance value into a transmission value with the help of electronic wiring is converted, here the conversion mode of one of the corneas that have just been measured mathematical dependency corresponding to any species, which in appropriate Test series is to be determined in each case, is programmed in a known manner, where the degree of transmission is displayed e.g. as a percentage of the light offered. 2. Device according to claim 1, characterized in that 4 the measurement in the visible range of the spectrum, especially at wavelengths 300 nm, 350 nm, 450 nm, 500 nm, 540 nm, 575 nm, 650 nm, 750 nm, 850 nm and with mixed light takes place. For scientific purposes, additional measurements are made in the ultraviolet range and pre-standard near infrared light? 3. Device according to claim 1, characterized in that the device in the basic unit A of the basic patent is integrated. 4. Measuring head for the device according to claim 1 or the device of the basic patent, characterized in that the emissor ends 1 in the form of a Cylinder section are formed, the light-conducting fibers to the cylinder axis show while the cylinder axis of the eyes and at the same time the receptor axis corresponds, the height of the emissor cylinder approximately equal to the distance from the corneal base is at the apex of the cornea, the receptor fibers 2 are bundled in the direction of the eye axis, where the surface of the receptor fibers are at right angles to the axis of the eye and the number of emissor fibers to the number of receptor fibers in a fixed ratio is between 1: 100 to 100: 1, preferably 1: 1 to 1: 5. 5. Apparatus according to claim 4, characterized in that the measuring head connected in a simple way, e.g. by plugging, to the measuring unit of the basic patent can be.