JPH0928671A - Blood sugar measuring device using natural fluorescence from the cornea - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable non-invasive blood sugar measuring making use of natural fluorescence from the eyeball. SOLUTION: An optical system 2 concentrates an excitation light with its wavelength selected from the visible to near infrared range upon the cornea, and the natural fluorescence emitted by the cornea under excitation light irradiation is detected. An arithmetic operation unit 4, which keeps in storage the relationship between the blood sugar fluctuation and the fluctuation in natural fluorescence from the cornea, outputs a blood sugar fluctuation on the basis of the deviation of the natural fluorescence detected by the optical system 2 from the stored value of natural fluorescence.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a device for non-invasively measuring blood glucose level.

[0002]

2. Description of the Related Art Since the measurement of blood glucose level is an important index for diagnosing the condition of diabetes and post-morbid management, various measuring methods have been developed. At present, the enzyme method is mainly used, but various methods such as the o-toluidine-boric acid (o-TB) method have been carried out. However, each method requires blood sampling each time, causing pain to the patient and laborious examination.

The inventor of the present invention irradiates the eye with excitation light of a selected wavelength in the visible to near-infrared region, and measures natural fluorescence from the glass body and the crystalline lens to measure the diabetic patient and the normal person. It reported that there was a significant difference between the two (Inai, 38 (10):
1059-1064, (1984)). The fluorescence from the eyeball is generally measured after intravenous injection of fluorescein-Na, but the natural fluorescence is the fluorescence measured without intravenous injection of fluorescein-Na.

[0004]

However, so far no knowledge has been obtained regarding the correlation between natural fluorescence from various places on the eyeball and blood glucose level. An object of the present invention is to enable blood glucose level to be measured non-invasively using natural fluorescence from the eyeball.

[0005]

The present inventor has found that, out of the natural fluorescence from the eyeball, the fluctuation value of the corneal natural fluorescence correlates with the fluctuation value of the blood glucose level, and has reached the present invention.
That is, according to the present invention, as shown in FIG. 1, an optical system that collects excitation light of a selected wavelength in the visible to near-infrared region on the cornea and detects natural fluorescence from the cornea due to the excitation light. 2, and a calculation unit 4 that holds the relationship between the blood glucose fluctuation value and the corneal natural fluorescence fluctuation value, and outputs the blood sugar fluctuation value based on the fluctuation value of the corneal natural fluorescence detection value by the optical system 2. It is a device that enables non-invasive measurement of blood glucose level.

[0006] For 16 patients with proliferative diabetic retinopathy (PDR) in non-insulin-dependent diabetes mellitus, the spontaneous corneal fluorescence value and the blood glucose level by blood sampling were measured twice at different times on the same day, and are shown in FIG. The relationship between blood glucose fluctuation and corneal natural fluorescence fluctuation was obtained. The correlation coefficient r =
The result of 0.648, p <0.01 (p is a risk rate) is shown.
It shows a significant positive correlation. The correlation as shown in FIG. 2 is stored in the calculation unit 4. On the other hand, as shown in FIG. 3, no significant correlation was observed between the blood glucose fluctuation value and the lens natural fluorescence fluctuation value measured at the same time.

[0007] Since it is not the absolute value of the blood glucose level that is obtained from the corneal natural fluorescence, but the absolute value, it is necessary to obtain the absolute value by measuring the blood glucose level of each patient by conventional blood sampling and the corneal natural fluorescence at that time. The detected value is measured and stored as a reference value, and the corneal natural fluorescence fluctuation value is calculated as the difference between the subsequent corneal natural fluorescence detection value and the reference value, and the corresponding blood glucose fluctuation value is calculated, and the blood glucose fluctuation value is calculated. The absolute blood glucose level at each time point can be obtained by comparing with the value reference value.

[0008]

EXAMPLE An example of an optical system for measuring a natural corneal fluorescence value will be described with reference to FIGS. FIG. 4 shows an optical system for irradiating the cornea with excitation light having a selected wavelength in the visible to near-infrared region and detecting natural fluorescence from the cornea due to the excitation light. In order to detect fluorescence from the cornea selectively, the anterior ocular segment fluorescence measurement adapter shown in FIG. 5 is attached to the optical system of FIG. 4, and the optical system of FIG. The fluorescence can be measured.

A fixed lens 12 and a scanning lens 14 are arranged along the optical axis 10, and the scanning lens 14 of the optical axis 10 is arranged.
The eyeball 16 which is the subject is arranged on the extension line on the side such that its eye axis coincides with the optical axis 10. An adapter 20 shown in FIG. 4 is arranged between the lens 18 and the eyeball 16 provided on the optical axis 10.

A tungsten lamp is provided as the excitation light source 22 in order to irradiate the eyeball 16 with the excitation light.
The excitation light 28 that is narrowed down at the predetermined wavelength is reflected by the mirror 30 through the filter 24 that extracts the predetermined wavelength light as the excitation light from the continuous-wave light from 2 and the slit 26 that makes the excitation light a light flux of a small system. Incident on the lenses 12, 14. The excitation light 28 condensed by the lenses 12 and 14 is adapted to be condensed from the lens 18 through the adapter 20 to a position of a predetermined depth of the eyeball. By moving the scanning lens 14 along the optical axis, the depth position where the excitation light 28 is focused moves along the eye axis. Here, in particular, the excitation light 28 is focused on the cornea.

In order to detect the fluorescence generated from the eyeball 16 by the irradiation of the excitation light, the detector slit 32 and the barrier filter 34 are provided on the extension line of the fixed lens 12 side on the optical axis 16.
After that, a photomultiplier tube (PMT) 36 is arranged.
An eye-axis fixing target light source 38 that emits light for a target is provided on the optical axis 10 so that the eye axis of the patient's eyeball 16 coincides with the optical axis 10, and the light passes through the slit 40 to form a beam. And enters the optical axis 10 by the beam splitter 41.

In order for the operator to confirm the position of the patient's eye, a patient alignment port 46 is arranged on the optical axis orthogonal to the optical axis 10 via a split screen 42 and a lens 44. A mirror 48 is detachably attached to the intersection of the optical axis of the optical axis 10 and the optical axis 10. The patient's eye 16 can be seen through the patient alignment port 46 when the mirror 48 is positioned across the optical axis 10.

Further, in order to correct the detected value by the intensity of the light source, a calibration glass surface 50 assembled integrally with the mirror 48 is provided, and the mirror 48 is provided with the optical axis 1.
When the glass surface 50 is arranged at a position crossing 0, the glass surface 50 is also arranged on the optical axis 10, and the excitation light from the light source 22 is reflected by the glass surface 50 and enters the detector 36, and the light source intensity is detected. It has become so.

[0014]

According to the present invention, the relationship between the blood glucose level by the blood sampling method and the natural corneal fluorescence value is measured once for each patient, and thereafter the blood glucose level is non-invasive only by measuring the natural corneal fluorescence value. Can be found at. Therefore, it becomes possible to easily perform the disease state determination and monitoring of the diabetic patient in a short time.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the present invention.

FIG. 2 is a diagram showing a correlation between a blood glucose fluctuation value and a corneal natural fluorescence fluctuation value in the present invention.

FIG. 3 is a diagram showing a correlation between a blood glucose fluctuation value and a lens natural fluorescence fluctuation value as a comparative example.

FIG. 4 is a schematic configuration diagram showing an optical system used in an example.

FIG. 5 is a schematic configuration diagram showing an adapter in the optical system of the same example.

[Explanation of symbols]

 2 Optical system 4 Calculation unit

Claims (1)

[Claims] 1. An optical system for concentrating excitation light of a selected wavelength in the visible to near-infrared region on the cornea and detecting natural fluorescence from the cornea due to the excitation light, blood glucose fluctuation value and corneal naturalness. A non-invasive blood glucose level, which holds a relationship with a fluorescence variation value, and an arithmetic unit which outputs a blood glucose variation value based on the variation value of the corneal natural fluorescence detection value by the optical system. measuring device.