JP5200518B2 - Intraocular substance measurement device - Google Patents

Description

  The present invention relates to an intraocular substance measuring apparatus, and more particularly, to an intraocular substance measuring apparatus that measures the concentration of a substance contained in a specific part of a subject's eyeball.

Conventionally, a measuring instrument for measuring the concentration of a substance in an eye is known (for example, Patent Document 1). In this measuring instrument, the concentration of a substance in the eye is determined by irradiating the eye with a measurement light beam and a reference light beam and detecting light reflected from the fundus.
JP-T-2004-537356

  However, since the technique described in Patent Document 1 does not consider that the optical path length in the region that can contain the substance to be measured in the eyeball changes when the line-of-sight direction of the eyeball is tilted, There is a problem that the concentration cannot be measured accurately.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an intraocular substance measuring apparatus capable of accurately measuring the concentration of a substance to be measured in the eyeball.

In order to achieve the above object, an intraocular substance measuring device according to the present invention is reflected by the retina through a specific part that can contain the substance to be measured in the eyeball of the subject, and is based on the substance. Receiving first light having a wavelength including a specific wavelength at which light absorption characteristics appear, detecting the amount of received light, transmitting through the specific part and reflected by the retina, and having a wavelength not including the specific wavelength Based on the light receiving means that receives the second light and detects the amount of received light, the specifying means that specifies the line-of-sight direction of the eyeball of the person to be measured, and the specific part based on the line-of-sight direction specified by the specifying means An optical path length estimating means for estimating the optical path length of the first light, a received light amount of the first light detected by the light receiving means, a received light amount of the detected second light, and the optical path The optical path estimated by the length estimation means Based on, and is configured and a concentration calculation means for calculating the concentration of said substance in said specific site.

According to intraocular substance measuring apparatus in accordance with the present invention, it is reflected in transmission to the retina specific possible sites containing substance to be measured in the eyeball of the subject and the particular appearing absorption characteristics of light by material First light having a wavelength including the wavelength is received by the light receiving means, and the amount of received light is detected. Further, the second light having a wavelength that passes through the specific part and is reflected by the retina and does not include the specific wavelength is received by the light receiving unit, and the amount of received light is detected.

  Further, the eye direction of the eyeball of the measurement subject is specified by the specifying unit, and the optical path length of the first light at the specific site is estimated by the optical path length estimation unit based on the line of sight direction specified by the specifying unit. To do.

  Based on the received light amount of the first light detected by the light receiving unit, the received light amount of the second light detected by the concentration calculating unit, and the optical path length estimated by the optical path length estimating unit, Calculate the concentration of the substance.

  In this way, taking into account the optical path length of light of a wavelength including the wavelength at which light absorption characteristics appear at a specific part that can contain the substance to be measured, light reception through the specific part and reflected by the retina By calculating the concentration of the substance in a specific part of the eyeball based on the amount, the concentration of the substance to be measured in the eyeball can be accurately measured.

The intraocular substance measurement device according to the present invention is configured so that the first light source that irradiates the first light and the retina is transmitted through the specific part so that the retina is irradiated through the specific part. And a second light source for irradiating the second light .

The first light source and the second light source according to the present invention emit light having the same wavelength as the second light so as to pass through a specific part and irradiate the retina from two different positions. The reflected light of the light from one position is received and the amount of received light is detected, and the specifying means specifies the line-of-sight direction based on the received light amount of the reflected light from the two positions detected by the light receiving means. can do. As a result, the line-of-sight direction can be specified based on the amount of light received so as to be transmitted through the specific part from two positions and irradiated on the retina. In addition, the specifying unit can specify the line-of-sight direction by comparing the amounts of light reflected from the two positions detected by the light receiving unit.

The first light source that emits light from the above two positions emits light of a specific wavelength to the retina of the eyeball, and the concentration calculating means outputs the second light from one of the two positions detected by the light receiving means. Based on the received light amount of the light having the same wavelength as the light, the received light amount of the specific wavelength light detected, and the optical path length estimated by the optical path length estimation means, the concentration of the substance in the specific part can be calculated. Accordingly, since light emitted from the same single position is used for specifying the line-of-sight direction and measuring the substance concentration, a simple configuration can be achieved.

The concentration calculation means according to the invention that emits light of the same wavelength from the above two positions has a ratio of the amount of received light of the reflected light of the same wavelength as the second light from the two positions detected by the light receiving means. If it is not within the predetermined range, the concentration of the substance to be measured in the specific part can be prevented from being calculated. Thus, erroneous measurement can be prevented when the eyeball is not in a condition that allows concentration measurement.

The first light source can emit light by switching between the first light and the second light by current modulation.

The intraocular substance measuring device according to the present invention further includes a light source that emits light having a wavelength including the wavelength of the first light and the wavelength of the second light so that the retina is irradiated through the specific site. , the light receiving means comprises a second filter for transmitting light of a wavelength of the first filter and second light transmitting light of a specific wavelength, receive light of a specific wavelength transmitted through the first filter, the received light amount , And the second light transmitted through the second filter can be received to detect the amount of received light.

  Said 2nd light can be made into the light of the wavelength which does not show the light absorption characteristic by the substance of a measuring object. Thus, the concentration of the substance can be accurately measured using light having a wavelength at which the light absorption characteristic of the substance to be measured appears and light having a wavelength at which the light absorption characteristic does not appear.

  As described above, according to the intraocular substance measuring device of the present invention, in consideration of the optical path length of light having a wavelength including the wavelength at which light absorption characteristics appear, in a specific part that can contain the substance to be measured, It is possible to accurately measure the concentration of the substance to be measured in the eyeball by calculating the concentration of the substance in the specific part of the eyeball based on the amount of light received through the specific part and reflected by the retina. The effect of being able to be obtained is obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, a case where the present invention is applied to an intraocular substance measuring apparatus that measures the ethanol concentration in the eyeball of the measurement subject will be described as an example.

  As shown in FIG. 1, the intraocular substance measurement device 10 according to the first exemplary embodiment has light of a wavelength λ1 that does not show the light absorption characteristic of ethanol and light of ethanol on the eyeball of the measurement subject. The first light source 12 that emits light having a wavelength λ2 that changes the current λ2 by switching by current modulation, and the first light that receives the reflected light of the irradiation light emitted from the first light source 12 and detects the amount of received light A half mirror 16 that allows the irradiation light from the detector 14 and the first light source 12 to pass therethrough, reflects the reflected light reflected in the eyeball, and guides it to the first light detector 14, and the eyeball of the measurement subject The second light source 18 that emits light having a wavelength λ1 that does not exhibit the light absorption characteristic of ethanol, and the second light that receives the reflected light of the irradiation light emitted from the second light source 18 and detects the amount of received light Irradiation light from the detector 20 and the second light source 18 While controlling the light emission by the first light source 12 and the second light source 18, the half mirror 22 that reflects and reflects the reflected light reflected in the eyeball to the second light detector 20, and the first light detector 14 and a computer 24 that measures the ethanol concentration in the eyeball based on the detection results of the second photodetector 20. The computer 24 is connected to each of the first light source 12, the first light detector 14, the second light source 18, and the second light detector 20.

  The 1st light source 12 and the 2nd light source 18 are arrange | positioned in the position which becomes symmetrical with respect to the visual axis when the gaze direction of an eyeball is facing the front. The first light source 12 and the second light source 18 emit light so that the aqueous humor that can contain ethanol in the eyeball of the measurement subject is transmitted and reflected by the fundus of the retina.

  Here, when a white light source (wavelength of 400 nm to 1700 nm) is irradiated onto the pig's eyeball and an experiment is performed in which a part of the light reflected from the fundus is detected by an optical spectrum analyzer, the result shown in FIG. 2 is obtained. It is done. From this experimental result, it can be seen that the wavelength range that can be used for the measurement based on the amount of received reflected light is 1400 nm or less, and that the strongest reflected light can be obtained when light having a wavelength near 800 nm is used.

  Therefore, in the present embodiment, the first light source 12 and the second light source 18 may use light having a wavelength range of 1400 nm or less, for example, as light having a wavelength λ1 that does not exhibit light absorption characteristics by ethanol. It is preferable to use light having a wavelength near 800 nm. In addition, it is desirable to use light having a wavelength near zero absorption of light by ethanol, which will be described later, for example, light having a wavelength of 890 nm.

  Further, when an experiment for measuring a difference (absorbance difference spectrum) between an absorption spectrum of an aqueous solution having an ethanol concentration of 1000 mg / dL and an absorption spectrum of pure water, an experimental result as shown in FIG. 3 is obtained. From this experimental result, it can be seen that light absorption characteristics by ethanol appear at wavelengths near 906 nm and 1185 nm. Therefore, in the present embodiment, the first light source 12 may use light having a wavelength of 906 nm, for example, as light having a wavelength λ2 at which the light absorption characteristic by ethanol appears.

  The computer 24 includes a CPU, a ROM that stores a program for a density measurement processing routine, which will be described later, a RAM that stores data, an HDD, and a bus that connects them. When the computer 24 is described with function blocks divided for each function realizing means determined based on hardware and software, the light emission of each of the first light source 12 and the second light source 18 is controlled as shown in FIG. Receiving light of the wavelength λ1 detected by the first light detector 14, the received light amount of the light of wavelength λ2, and the received light of the wavelength λ1 detected by the second photodetector 20. Based on the received light amount acquisition unit 32 that acquires the amount of light, the received light amount of the light of wavelength λ1 by the first photodetector 14, and the received light amount of the light of wavelength λ1 by the second photodetector 20, the eyeball of the measurement subject A line-of-sight direction specifying unit 34 that specifies the line-of-sight direction, and a table storage unit 36 that stores a relationship between the line-of-sight direction and the optical path length of the light of wavelength λ2 from the first light source 12 in the aqueous humor of the eyeball. And gaze direction identification 34, the optical path length estimation unit 38 that estimates the optical path length of the light of the wavelength λ2 from the first light source 12 in the aqueous humor of the eyeball, and the estimated optical path length, Based on the amount of light received at the wavelength λ1 and the amount of light received at the wavelength λ2 by the first photodetector 14, a concentration calculator 40 that calculates the ethanol concentration in the aqueous humor of the eyeball and a display And a display unit 42 for displaying the ethanol concentration.

  Next, a method for specifying the gaze direction of the measurement subject will be described. First, it is known that the human eye shows a reflexive reflection characteristic. As shown in FIG. 5, the recursive reflection characteristic is a characteristic in which light reflected from the fundus of the retina returns on the same optical path as the irradiation light when light is irradiated from the light source toward the eyeball. The amount of reflected light depends on the angle of incidence with respect to the visual axis of the eye, and it is known that the amount of reflected light decreases as the angle of incidence with respect to the visual axis increases (Watanabe et al., “Remote soccer using retina reflexes” ”Research on the detection method”, Journal of the Virtual Reality Society of Japan, Vol 9, No. 1, pp. 105-114, 2004).

  As shown in FIG. 1, when the first light source 12 and the second light source 18 are arranged at an equal distance from the eyeball and the eyeball is irradiated with light having the same wavelength λ1, the first photodetector 14 and the second light source Each of the photodetectors 20 detects a received light amount I as shown in FIG.

  In FIG. 6, φ is an angle in the direction of the visual axis (line-of-sight direction), and θ1 and θ2 are the angles of the first light source 12 and the second light source 18 in a state where the angle in the direction of the visual axis is 0 (front). It is an angle with respect to the visual axis of each optical path. When θ1 = θ2, if φ is 0, the outputs of the first photodetector 14 and the second photodetector 20 are substantially the same. When φ is inclined in the positive direction, the output of the first photodetector 14 is decreased and the output of the second photodetector 20 is increased. On the other hand, when φ is inclined in the negative direction, the first photodetector 14 is increased. Output increases, and the output of the second photodetector 20 decreases. That is, when the output ratio of the first photodetector 14 and the second photodetector 20 is taken, the output ratio is 1 when φ = 0, and if φ is tilted, is the output ratio greater than 1? Less than 1. Therefore, the direction of the visual axis (gaze direction) can be specified from the output ratio of the first photodetector 14 and the second photodetector 20.

  Therefore, in the present embodiment, as shown in FIG. 6 above, from the relationship between the line-of-sight direction and the amount of light received by the first photodetector 14 and the amount of light received by the second photodetector 20, the line-of-sight direction, The relationship between the amount of light received by the first photodetector 14 and the ratio of the amount of received light of the second photodetector 20 is obtained. Further, based on the ratio of the received light amount of the wavelength λ1 detected by the first photodetector 14 and the received light amount of the wavelength λ1 detected by the second photodetector 20 in the line-of-sight direction specifying unit 34, as described above. From the relationship between the line-of-sight direction obtained in step 1 and the ratio of the amounts of light received by the first photodetector 14 and the second photodetector 20, the line-of-sight direction of the measurement subject is specified.

  In addition, when the ratio between the amount of light received at the wavelength λ1 detected by the first photodetector 14 and the amount of received light at the wavelength λ1 detected by the second photodetector 20 exceeds a predetermined range, the target eyeball is measured. It can be determined that the condition is not possible (when the line-of-sight direction exceeds the measurable range or when the eyes are closed).

Next, a method for estimating the optical path length of the light of wavelength λ2 in the aqueous humor of the eyeball will be described. First, in the eyeball, as a specific part capable of containing ethanol as a substance to be measured, there is aqueous humor between the cornea and the lens. When light is transmitted through this aqueous humor, the absorbance of light by ethanol is expressed by the following equation (1) according to Lambert-Beer's law.
Log (I ₀ / I _t ) = nkL (1)

Here, I ₀ is the amount of light incident on the aqueous humor, I _t is the amount of light emitted from the aqueous humor, n represents the concentration of ethanol, L is the optical path length, k is the absorption coefficient for the wavelength of light. That is, when the concentration n is obtained from incident light and outgoing light, the value of the optical path length L must be known, but the optical path length in the aqueous humor varies depending on the incident angle of the light.

As shown in FIG. 7, when it is assumed that the radius of curvature of the cornea is constant in the light incident range, the light path length L ₀ in the aqueous humor along the visual axis (the direction of the line of sight) is the light having the incident angle θ. geometric conditions for different optical path lengths L _theta in aqueous humor is that R _r (the radius of curvature of the aqueous humor side) rear surface radius of curvature of the cornea is different from L _0. In general, the posterior radius of curvature of the cornea is 6.2 to 6.8 mm, and the optical path length (aqueous humor depth) in the aqueous humor along the visual axis is 2.4 to 4.2 mm. (Edited by Toshiharu Tadashi et al., “Optical Measurement Handbook”, Asakura Shoten, 1981). Here, when L ₀ = 3.00 mm, R _r = 6.00 mm, and θ = 30 deg, L _θ is 3.21 mm, which is 7% of the optical path length in the aqueous humor along the visual axis. This causes a change in the optical path length. That is, if this change is not taken into account, it can be said that an error occurs in the concentration measurement of the substance to be measured.

  In the present embodiment, the optical path length in the aqueous humor is obtained for each incident angle with respect to the viewing direction based on the relationship between the incident angle of light with respect to the viewing direction (visual axis) and the optical path length. An optical path length determination table in which the optical path length is stored corresponding to the incident angle with respect to the line-of-sight direction is stored in the table storage unit 36.

  Further, the optical path length estimation unit 38 acquires the optical path length in the aqueous humor corresponding to the incident angle with respect to the visual line direction specified by the visual line direction specifying unit 34 from the optical path length determination table, and uses the optical path length as an estimated value.

Next, a method for calculating the ethanol concentration in the aqueous humor will be described. As shown in FIG. 1 above, the first light source 12 is used to irradiate the eyeball with light having a wavelength λ1 (890 nm) that does not exhibit the light absorption characteristic of ethanol and light having a wavelength λ2 (906 nm) that exhibits the absorption characteristic. When the reflected light is detected by the first photodetector 14, the amount of received light _It1 detected by the first photodetector 14 with respect to the reflected light of the wavelength λ1 can be expressed by the following equation (2). .

Here, I ₀₁ is the amount of light output at the wavelength λ 1 by the first light source 12, and β is the efficiency in consideration of all the optical losses on the optical path, and is the loss in the half mirror 16 and the loss in the eyeball. (The loss due to ethanol is not included), and the value includes the influence of the coupling loss between the reflected light and the first photodetector 14.

Next, the amount of received light _It2 detected by the first photodetector 14 with respect to the reflected light of the wavelength λ2 can be expressed by the following equation (3).

Here, I ₀₂ is the output light amount of the wavelength λ2 from the first light source 12, and γ is the efficiency in consideration of all the light loss on the optical path, as in β, and is the loss in the half mirror 16, the eyeball It is a value including the effect of the loss in the light and the coupling loss between the reflected light and the photodetector. C is the efficiency considering the absorption of ethanol in the eye.

  When the ratio between the above formula (2) and the above formula (3) is obtained, the following formula (4) is obtained.

Here, since (I ₀₂ × γ) / (I ₀₁ × β) is a constant value, when α is set, the following equation (5) is obtained from the above equation (4).

Note that the alpha, in a state that does not contain ethanol in the eye (c = 1), can be determined by measuring the I _t1 and I _t2.

  C can be expressed by the following equation (6).

  Substituting the above equation (6) into the above equation (5) yields the following equation (7).

  Here, n is the ethanol concentration, k is the ethanol absorption coefficient, and L is the optical path length. When n is obtained from the above equation (7), the following equation (8) is obtained.

Therefore, in the present embodiment, the concentration calculator 40 estimates the estimated optical path length L, the amount of received light I _t1 of light having a wavelength λ1 by the first photodetector 14, the amount of received light I _t2 of light having a wavelength λ2, and the known The ethanol concentration n in the aqueous humor of the eyeball is calculated according to the above equation (8) based on the value of the absorption coefficient k of ethanol and the value α obtained in advance.

  Next, the operation of the intraocular substance measurement device 10 according to the first embodiment will be described. First, the first light source 12 and the second light source 18 are arranged at positions that are symmetric with respect to the visual axis of the eyeball in a state where the line-of-sight direction of the eyeball of the measurement subject is facing the front. Then, the computer 24 executes a concentration measurement processing routine shown in FIG.

First, in step 100, the first light source 12 emits light of wavelength λ1, and the second light source 18 emits light of wavelength λ1. Irradiation light from the first light source 12 passes through the aqueous humor of the eyeball, reflects off the fundus of the retina, passes through the aqueous humor again, and the reflected light goes out of the eyeball. Then, the received light amount _It1 of the reflected light is detected by the first photodetector 14. Further, the irradiation light from the second light source 18 transmits the irradiation light through the aqueous humor of the eyeball, reflects it at the fundus of the retina, passes through the aqueous humor again, and the reflected light goes out of the eyeball. Then, the second light detector 20 detects the amount of received light _It0 .

In step 102, the received light amount _It1 detected by the first photodetector 14 is acquired and stored in a memory (not shown). In step 106, the received light amount I detected by the second photodetector 20 is obtained. _t0 is acquired and stored in the memory.

In step 108, the ratio between the received light amount _It1 stored in step 102 and the received light amount _It0 stored in step 106 is calculated. In step 110, the received light amount calculated in step 108 is calculated. It is determined whether or not the ratio is within a predetermined range. For the predetermined range, experimentally or statistically, the ratio of the amount of light received when the light of wavelength λ1 is irradiated so as to be reflected by the fundus of the retina of the eyeball is obtained in advance, and the obtained ratio of the amount of received light is calculated. Based on this, a predetermined range may be set.

  If the received light amount ratio is outside the predetermined range in step 110, it is determined that the target eyeball is not in a measurable condition, and the concentration measurement routine is terminated without measuring the ethanol concentration. To do. On the other hand, if the ratio of the amount of received light is within the predetermined range, it is determined that the target eyeball is in a measurable condition, and the process proceeds to step 112.

  In step 112, the line-of-sight direction of the eyeball of the person to be measured is specified based on the ratio of the amount of received light calculated in step 108. In step 114, the first light source 12 with respect to the line-of-sight direction specified in step 112 is determined. Based on the incident angle and the optical path length determination table of the table storage unit 36, the optical path length in the aqueous humor of the light of wavelength λ2 from the first light source 12 is estimated.

In step 116, light having a wavelength λ2 is emitted from the first light source 12, and the irradiated light is transmitted through the aqueous humor of the eyeball and reflected by the fundus of the retina. The first photodetector 14 reflects the reflected light. The amount of received light _It2 is detected. In step 118, the received light amount _It2 detected by the first photodetector 14 is acquired and stored in the memory.

Next, in step 120, the received light amount I _t1 stored in step 102, the received light amount I _t2 stored in step 118, the optical path length L estimated in step 114, the value α measured in advance, and Using the known value k, the ethanol concentration n in the aqueous humor of the eyeball is calculated according to the above equation (8). In step 122, the ethanol concentration calculated in step 120 is displayed on the display unit 42, and the concentration measurement routine is terminated.

  As described above, according to the intraocular substance measurement device according to the first embodiment, in the aqueous humor that can contain ethanol to be measured, the optical path length of the light having the wavelength at which the light absorption characteristic appears is taken into consideration. Then, the ethanol concentration in the eyeball can be accurately measured by calculating the ethanol concentration in the aqueous humor of the eyeball based on the amount of light received through the aqueous humor and reflected by the retina.

  Also, if it is determined that the ratio of the amounts of light received detected by the two photodetectors is outside the predetermined range, it is determined that the eyeball is not in a condition where the concentration can be measured, the concentration measurement is stopped, and an error occurs. Measurement can be prevented.

  Further, the identification of the direction of the line of sight and the measurement of the ethanol concentration can be performed together.

  Moreover, since the light absorbance of ethanol in the aqueous humor is proportional to the optical path length in the aqueous humor, the measurement error due to the variation in the line-of-sight direction can be reduced by estimating the optical path length.

  Further, by using a single semiconductor laser that switches the wavelength by current modulation as the light source that generates the wavelengths λ1 and λ2, it is possible to reduce the size and cost of the measurement system.

  In addition, in order to measure the ethanol concentration using the amount of light received from the first light source, in order to allow both light of wavelengths λ1 and λ2 from the first light source to pass through the same optical path, You only need to measure once at the beginning.

  In the above embodiment, the case where the first light source and the second light source are arranged at positions symmetrical to the visual axis in a state where the visual axis of the eye faces the front direction has been described as an example. The first light source and the second light source may be arranged at two different positions that are not symmetric with respect to the visual axis. In this case, the relationship between the line-of-sight direction and the amount of light received by the first photodetector and the amount of light received by the second photodetector is obtained, and the line-of-sight direction, the amount of light received by the first photodetector, The line-of-sight direction may be specified based on the relationship with the ratio of the amount of light received by the two photodetectors.

  Next, a second embodiment will be described. In addition, since the structure of the intraocular substance measuring device which concerns on 2nd Embodiment is the structure similar to 1st Embodiment, it attaches | subjects the same code | symbol and abbreviate | omits description.

  The second embodiment is different from the first embodiment in that misrepresentation using a mirror and erroneous measurement due to reflection of glasses or the like are prevented.

  When the measurement subject uses a mirror or when the measurement subject wears glasses or the like, an erroneous measurement may occur as described below.

  As shown in FIG. 9, when the first light source 12 and the second light source 18 irradiate light of the same wavelength λ1 toward the eyeball and specify the line-of-sight direction of the eyeball, a mirror is specified in front of the eyeball. When placed at an angle, the light emitted from the second light source 18 (see irradiation light 1 in FIG. 9) is reflected by a mirror, and the reflected light (see reflected light 1 in FIG. 9) is reflected by the first photodetector 14. Detected. Conversely, the light emitted from the first light source 12 (see irradiation light 2 in FIG. 9) is reflected by a mirror, and the reflected light (see reflected light 2 in FIG. 9) is detected by the second photodetector 20. . At this time, if the amount of received light detected by the first photodetector 14 and the amount of received light detected by the second photodetector 20 are equal to or greater than a certain level, the eyeball to be measured is in a condition that allows measurement. There is a possibility of being judged.

  In the intraocular substance measurement device according to the second embodiment, light emission by the first light source 12 and the second light source 18 is performed in a time-divided manner as described below. First, light is emitted only by the second light source 18 and the amount of received light is detected by the second photodetector 20. Next, the light emission by the second light source 18 is stopped, the light emission by only the first light source 12 is performed, and the received light amount is detected by the first photodetector 14.

  In this way, when the light emission by the first light source 12 and the second light source 18 is temporally divided, the retroreflection of the retina is used, and if there is no misrepresentation, the first photodetector 14 and the second photodetector. Each of 20 detects an amount of light received above a certain level. On the other hand, when there is a misrepresentation, the amount of received light detected by each of the first photodetector 14 and the second photodetector 20 becomes below a certain level. Therefore, when the amount of received light detected by each of the first photodetector 14 and the second photodetector 20 is below a certain level, it can be determined that the target eyeball is not in a measurable condition. . As a result, misrepresentation using a mirror and erroneous measurement due to reflection of glasses or the like can be prevented.

  Note that other operations of the intraocular substance measuring apparatus are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, a third embodiment will be described. In addition, since the structure of the intraocular substance measuring device which concerns on 3rd Embodiment is the structure similar to 1st Embodiment, it attaches | subjects the same code | symbol and abbreviate | omits description.

  In the third embodiment, in the process of measuring the ethanol concentration in the eyeball, false measurement using a mirror and reflection due to reflection of glasses, etc. are prevented. Is different.

  According to the intraocular substance measurement device according to the third embodiment, as shown in FIG. 10, the first light source 12 emits light of wavelengths λ1 and λ2, and the ethanol concentration in the eyeball is measured. In the case of misrepresentation by a mirror or the like, since the reflected light is not detected by the first photodetector 14, the amount of received light detected by the first photodetector 14 becomes a certain level or less. Therefore, when the received light amount of the wavelength λ1 or the received light amount of the wavelength λ2 detected by the first photodetector 14 is below a certain level, it is determined that the target eyeball is not in a measurable condition. can do. As a result, false measurement using a mirror and erroneous measurement due to reflection of glasses or the like can be prevented.

  Note that other operations of the intraocular substance measuring apparatus are the same as those in the first embodiment, and thus description thereof is omitted.

  Next, a fourth embodiment will be described. In addition, about the part which becomes the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The fourth embodiment is different from the first embodiment in that a filter is provided in the photodetector and the amount of light received with a predetermined wavelength is detected.

  As shown in FIG. 11, the intraocular substance measurement device 410 according to the fourth embodiment has a wavelength λ1 at which the light absorption characteristic due to ethanol does not appear with respect to the eyeball of the measurement subject, and the light absorption due to ethanol. The first light source 412 that emits light in a wavelength region including the wavelength λ2 where the characteristic appears and the reflected light of the irradiation light emitted from the first light source 412 receive each of the light of wavelength λ1 and the light of wavelength λ2. The first photodetector 414 that detects the amount of received light, the half mirror 16, and the first eye that emits light in a wavelength region including the wavelength λ1 at which the absorption characteristic of light by ethanol does not appear on the eyeball of the measurement subject. Of the reflected light of the irradiation light emitted from the two light sources 418 and the second light source 418, the second light detector 420 that receives light of wavelength λ1 and detects the amount of received light, the half mirror 22, and the first By the light source 412 and the second light source 418 A computer that controls light emission and switches the wavelength of light detected by the first photodetector 414, and measures the ethanol concentration in the eyeball based on the detection results of the first photodetector 414 and the second photodetector 420. 424.

  The first photodetector 414 includes a filter group 414A including a first filter that transmits light of wavelength λ1 and a second filter that transmits light of wavelength λ2, and is arranged in front of the light receiving surface according to control by the computer 424. Switch the filter to be set. When the first filter is set in front of the light receiving surface, the first photodetector 414 receives the light having the wavelength λ1 that has passed through the first filter, detects the amount of received light, and detects the second light in front of the light receiving surface. When the filter is set, the light of wavelength λ2 that has passed through the second filter is received and the amount of received light is detected.

  The second photodetector 420 includes a filter 420A that transmits light of wavelength λ1 in front of the light receiving surface, and receives the light of wavelength λ1 that has passed through the filter 420A to detect the amount of light received.

  When the computer 424 executes the concentration measurement processing routine, first, a filter that transmits light having the wavelength λ1 is set in front of the light receiving surface of the first photodetector 414. Then, light is emitted by the first light source 412, the irradiation light is transmitted through the aqueous humor of the eyeball, reflected by the fundus of the retina, and the reflected light having the wavelength λ 1 transmitted through the filter by the first photodetector 414. The amount of received light is detected. In addition, light is emitted by the second light source 418, the irradiated light is transmitted through the aqueous humor of the eyeball, reflected by the fundus of the retina, and reflected by the wavelength λ1 transmitted by the second photodetector 420 through the filter 420A. The amount of received light is detected.

  Then, based on the ratio of the detected amount of received light, the line-of-sight direction of the eyeball of the measurement subject is specified, and based on the incident angle of light from the first light source 412 with respect to the specified line-of-sight direction and the optical path length determination table. Then, the optical path length in the aqueous humor of the light of wavelength λ2 from the first light source 412 is estimated.

  Next, a filter that transmits light of wavelength λ2 is set in front of the light receiving surface of the first photodetector 414, light is emitted by the first light source 412, and irradiation light is transmitted through the aqueous humor of the eyeball. The amount of light reflected by the fundus of the retina is detected by the first photodetector 414 and the reflected light having the wavelength λ2 that has passed through the filter is detected. Then, the ethanol concentration in the aqueous humor of the eyeball is calculated based on each detected amount of received light and the estimated optical path length.

  Next, a fifth embodiment will be described. In addition, about the part which becomes the structure similar to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The fifth embodiment is different from the first embodiment in that light having a wavelength at which light absorption characteristics due to ethanol appear and light having a wavelength at which light absorption characteristics do not appear are emitted by different light sources. Yes.

  As shown in FIG. 12, the intraocular substance measurement device 510 according to the fifth embodiment emits light having a wavelength λ1 that does not show the light absorption characteristic of ethanol to the eyeball of the measurement subject. The light source 512, the first photodetector 14, the half mirror 16, the second light source 18, the second photodetector 20, the half mirror 22, and the light of the wavelength λ2 at which the light absorption characteristic by ethanol appears. The third light source 522, the third light detector 524 that receives the reflected light of the irradiation light emitted from the third light source 522, detects the amount of received light, and passes the irradiation light from the first light source 522. The first mirror 526 controls the light emission of the first light source 512, the second light source 18, and the third light source 522 while reflecting the reflected light reflected in the eyeball and guiding the reflected light to the third photodetector 524. Photodetector 14, second photodetection And a computer 524 for measuring the ethanol concentration in the eyeball based on the detection results of the detector 20 and the third photodetector 524.

  In the computer 524, an optical path length determination table storing optical path lengths obtained in advance based on the relationship between the incident angle of light from the third light source 522 with respect to the line-of-sight direction and the optical path length of light from the third light source 522, It is stored in the table storage unit 36. In addition, the optical path length estimation unit 38 acquires the optical path length corresponding to the incident angle with respect to the identified line-of-sight direction from the optical path length determination table, and uses it as the estimated value of the optical path length from the third light source 522.

  Other configurations of the intraocular substance measurement device 510 are the same as those in the first embodiment, and thus description thereof is omitted. Since the operation is the same as that of the first embodiment, the description thereof is omitted.

  In the first to fifth embodiments described above, an example in which the optical path length is estimated using the optical path length determination table storing the relationship between the incident angle with respect to the line-of-sight direction and the optical path length is taken as an example. Although described above, the present invention is not limited to this. A relational expression indicating the relationship between the incident angle with respect to the line-of-sight direction and the optical path length is obtained, and the optical path length corresponding to the incident angle with respect to the line-of-sight direction is estimated according to this relational expression. You may make it do.

  Further, the case where the first light having a wavelength at which the light absorption characteristic due to ethanol appears and the second light having a wavelength at which the absorption characteristic does not appear is emitted to the eyeball as an example, but the present invention is not limited thereto. The wavelength of the first light may be a wavelength including the wavelength at which the absorption characteristic appears, and the wavelength of the second light is not the wavelength at which the absorption characteristic included in the first light is included. It is good. In addition, the second light may include a wavelength at which the absorption characteristic appears as long as the second light does not include the wavelength at which the absorption characteristic included in the first light appears. In this case, the ethanol concentration may be calculated according to an equation derived in consideration of the light absorption coefficient for the first light and the light absorption coefficient for the second light.

  Moreover, although the case where the measurement target substance is ethanol has been described as an example, the present invention is not limited to this. For example, glucose is a measurement target substance, and the concentration of glucose contained in a specific part in the eyeball is measured. You may do it.

  Moreover, although the case where the line-of-sight direction of the eyeball was specified using the received light amount of the first photodetector and the received light amount of the second photodetector has been described as an example, the present invention is not limited to this, and the eyeball is determined by the camera. May be specified, and the line-of-sight direction of the eyeball may be specified by performing image recognition processing on the captured image.

  In addition, the case where the part that can contain ethanol is aqueous humor in the eyeball has been described as an example, but the present invention is not limited to this, and the part that can contain ethanol and exists on the visual axis. I just need it. For example, the portion that can contain ethanol may be a crystalline body or a vitreous body.

It is the schematic which showed the structure of the intraocular substance measuring device which concerns on the 1st Embodiment of this invention. It is a graph which shows the light reception amount of the reflected light according to the wavelength of the light to irradiate. It is a graph which shows the magnitude | size of the light absorbency according to the wavelength of the light to irradiate. It is the schematic which showed the structure of the computer of the intraocular substance measuring device which concerns on the 1st Embodiment of this invention. It is an image figure which shows the reflexive reflection characteristic of an eyeball. It is a graph which shows the relationship between the output of a 1st photodetector, the output of a 2nd photodetector, and a gaze direction. In the aqueous humor of an eyeball, it is an image figure for demonstrating the optical path length in the aqueous humor of the light along a visual axis, and the optical path length in the aqueous humor of the light of incident angle (theta). It is a flowchart which shows the content of the density | concentration measurement process routine performed with the computer which concerns on the 1st Embodiment of this invention. It is an image figure which shows the case where the misrepresentation which puts a mirror in front of an eyeball is performed. It is an image figure which shows a mode that reflected light is not detected with a 1st photodetector, when the misrepresentation which puts a mirror in front of an eyeball is performed. It is the schematic which shows the structure of the intraocular substance measuring device which concerns on the 4th Embodiment of this invention. It is the schematic which shows the structure of the intraocular substance measuring device which concerns on the 5th Embodiment of this invention.

Explanation of symbols

10, 410, 510 Intraocular substance measuring device 12, 412, 512 First light source 14, 414 First light detector 16, 22, 526 Half mirror 18, 418 Second light source 20, 420 Second light detector 24, 424 524 Computer 30 Light source control unit 34 Line-of-sight direction specification unit 36 Table storage unit 38 Optical path length estimation unit 40 Density calculation unit 414A Filter group 420A Filter 522 Third light source 524 Third photodetector

Claims (8)

Receives first light having a wavelength including a specific wavelength that passes through a specific part of the eyeball of the measurement subject that can contain the substance to be measured and is reflected by the retina and appears to absorb light by the substance. A light receiving means for detecting the amount of received light, receiving second light having a wavelength that passes through the specific part and is reflected by the retina and does not include the specific wavelength,
A specifying means for specifying a line-of-sight direction of the eyeball of the measurement subject;
An optical path length estimating means for estimating an optical path length of the first light in the specific part based on the line-of-sight direction specified by the specifying means;
Based on the received light amount of the first light detected by the light receiving unit, the received light amount of the second light, and the optical path length estimated by the optical path length estimating unit, Concentration calculating means for calculating the concentration of the substance of
Intraocular substance measuring device including: A first light source that irradiates the first light so as to pass through the specific part and irradiate the retina ;
The intraocular substance measurement device according to claim 1, further comprising a second light source that irradiates the second light so as to pass through the specific part and irradiate the retina . The first light source and the second light source emit light having the same wavelength as the second light so as to be transmitted to the retina from two different positions.
The light receiving means receives the reflected light of the light from the two positions and detects the amount of light received,
The intraocular substance measurement apparatus according to claim 2, wherein the specifying unit specifies the line-of-sight direction based on a received light amount of the reflected light from the two positions detected by the light receiving unit. The first light source emits the light of the specific wavelength with respect to the retina before Symbol eyeball,
The concentration calculation unit is configured to receive an amount of received light having the same wavelength as the second light from any one of the two positions detected by the light receiving unit, an amount of received light of the detected specific wavelength , The intraocular substance measurement device according to claim 3, wherein the concentration of the substance in the specific part is calculated based on the optical path length estimated by the optical path length estimation means. When the ratio of the amount of reflected light of light having the same wavelength as the second light from the two positions detected by the light receiving means is not within a predetermined range, the concentration calculating means The intraocular substance measuring device according to claim 3 or 4, wherein the concentration of the substance to be measured is not calculated. The intraocular substance measuring device according to claim 2, wherein the first light source emits light by switching between the first light and the second light by current modulation. A light source that emits light having a wavelength including the wavelength of the first light and the wavelength of the second light so as to be transmitted to the retina through the specific site;
It said light receiving means, wherein a second filter for transmitting light of a wavelength of the first filter and the second light transmitting light of a specific wavelength, said first filter receiving light transmitted through said specific wavelength The intraocular substance measurement device according to claim 1, wherein the received light amount is detected and the second light transmitted through the second filter is received to detect the received light amount.   The intraocular substance measuring device according to any one of claims 1 to 7, wherein the second light is light having a wavelength at which light absorption characteristics of the substance to be measured do not appear.

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