JP3636553B2 - Fundus examination device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fundus examination apparatus used when examining the fundus in an ophthalmic clinic or the like.
[0002]
[Prior art]
The fundus blood flow meter using the Doppler effect calculates the blood flow velocity (maximum velocity Vmax) at the fundus according to the following equation.
Vmax = {λ / (n · α)} · || Δfmax1 | − | Δfmax2 || / cosβ (1)
[0003]
Here, the maximum frequency shifts calculated from the received light signals received by the two light receivers are Δfmax1 and Δfmax2, the wavelength of the laser is λ, the refractive index of the measurement site is n, and the two light receiving optical axes in the eye are formed. The angle is α, and the angle between the plane formed by the two light receiving optical axes in the eye and the blood flow velocity vector is β.
[0004]
Thus, by measuring from two directions, the contribution of the incident direction of the measurement light is canceled out, and blood flow in an arbitrary part on the fundus can be measured. In addition, the true maximum blood flow velocity can be measured with β = 0 ° by matching the angle β formed by the plane formed by the two light receiving optical axes and the intersection of the fundus and the blood velocity vector. Can do.
[0005]
However, since the maximum value Δfmax of the Doppler shift in the above equation (1) is detected as an interference signal between the component shifted by the blood flow and the stationary blood vessel wall, the maximum frequency shift Δfmax obtained by frequency analysis is , | Δfmax |
[0006]
For this reason, when measuring blood flow in blood vessels of different parts on the fundus, there are cases where the signs of the maximum frequency shifts Δfmax1 and Δfmax2 are both positive, negative, and positive / negative. Therefore, depending on the region to be measured, there arises a problem that it becomes impossible to determine the maximum blood flow velocity Vmax by the equation (1).
[0007]
FIG. 5 shows an explanatory diagram of the arrangement of the luminous flux in the eye. The measurement light is incident from the center hi = 0 of the pupil Ep, and the scattered light is received from the predetermined parts hs1 and hs2 of the pupil Ep. The angle at which the parts hs1 and hs2 are viewed is the angle α formed by the light receiving optical axis.
[0008]
Here, when measuring the blood vessel Ev1 at the center of the fundus oculi Ea, the maximum frequency shift Δfmax1 obtained from the light reception signal from the direction of the part hs1 and the maximum frequency shift obtained from the light reception signal from the direction of the part hs2 Δfmax2 has a different sign. At this time, since the signal light is perpendicularly incident on the blood vessel Ev1, there is no frequency shift caused by the direction of the signal light, and the obtained frequency shift is only caused by the direction of observation.
[0009]
Here, considering the velocity vector ν1 of the blood flow in the blood vessel Ev1, the wave vector κs1 in the direction of the part hs1 and the wave vector κs2 in the direction of the part hs2, these exist in different directions with respect to the normal of the velocity vector ν1. The inner product has a different sign, and the frequency shift of the different sign has occurred.
[0010]
On the other hand, when measuring the blood vessel Ev2 at the peripheral site, the direction of the site hs1 and the direction of the site hs2 exist in the same direction with respect to the specularly reflected light κi ′ having a frequency shift of 0. A shift is happening.
[0011]
Conventionally, the blood flow velocity is not calculated in consideration of the sign of the maximum frequency shift Δfmax, but recently, in order to cope with this problem, incident light is switched from two directions continuously and incident. Thus, it is considered to detect code information of frequency shift by receiving light from two directions.
[0012]
[Problems to be solved by the invention]
However, in the above-described conventional example, when detecting the code information of the frequency shift, the measurement light is incident from one direction, and the reflected light from the fundus oculi Ea is received by the two light receivers to obtain the maximum blood flow velocity Vmax. Next, the measurement light is incident from different directions, and the reflected light from the fundus oculi Ea is similarly received by the two light receivers to obtain the maximum blood flow velocity Vmax '. Seeking the maximum blood flow velocity.
[0013]
At this time, when one path is measured, for example, if the light beam is lost due to the eyelashes of the subject, the alignment is misaligned, or blinking or poor fixation occurs, correct measurement is not performed in that path. Therefore, even when the remaining paths are correctly measured, both paths are determined to be measurement failures, and there is a problem that the measurement of the correctly measured paths is wasted.
[0014]
And since it measures about the path | pass of two directions again after realignment, the subject will be forced to fix for a long time, and the problem that measurement time also becomes long arises.
[0015]
The object of the present invention is to eliminate the above-mentioned problems, without wasting the measurement results of correctly measured paths, to shorten the measurement time, and at the same time to irradiate the subject with unnecessary laser light It is an object of the present invention to provide a fundus examination apparatus that does not require fixation and does not force fixation for a long time.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a fundus examination apparatus according to the present invention comprises a measurement light irradiating means for irradiating measurement light on the fundus, a light receiving means for receiving signal light from the fundus, and an output signal from the light receiving means. A fundus examination apparatus having a calculation unit that receives and calculates a measurement result, and receives a plurality of measurement results calculated by the calculation unit in response to an output from the light receiving means that has received signal light based on measurement light under a plurality of measurement conditions. A measurement result display means for displaying; Measurement data selection means for manually selecting whether or not the measurement result is acceptable, and when the measurement data selection means selects NO In the measurement condition of the measurement result By the arithmetic unit Perform re-measurement Re-measurement means; Possible by measurement data selection means Memorize the measurement results when is selected, From multiple memorized measurement results A blood flow velocity calculation unit for calculating a fundus blood flow velocity It is characterized by that.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail based on the embodiment shown in FIGS.
FIG. 1 shows a block diagram of a first embodiment applied to a fundus blood flow meter, on an illumination light path from an observation light source 1 made of a tungsten lamp or the like that emits white light to an objective lens 2 facing the eye E. Is a condenser lens 3, for example, a field lens 4 with a band-pass filter that transmits only yellow wavelength light, a ring slit 5 provided at a position substantially conjugate with the pupil Ep of the eye E, and the crystalline lens of the eye E A light shielding member 6 provided at a substantially conjugate position, a relay lens 7, a transmissive liquid crystal plate 8 which is a fixation target display element movable along the optical path, a relay lens 9, and the vicinity of the cornea of the eye E to be examined. The light shielding member 10, the perforated mirror 11, and the band pass mirror 12 that transmits yellow wavelength light and reflects most of the other light beams are sequentially arranged to constitute an illumination optical system.
[0018]
A fundus observing optical system is formed behind the perforated mirror 11, and includes a focusing lens 13, a relay lens 14, a scale plate 15 that can move along the optical path, an optical path switching mirror 16 that can be inserted into and removed from the optical path, and an eyepiece. 17 are sequentially arranged to reach the examiner's eye e. A television relay lens 18 and a CCD camera 19 are arranged on the optical path in the reflection direction when the optical path switching mirror 16 is inserted in the optical path, and the output of the CCD camera 19 is connected to the liquid crystal monitor 20. .
[0019]
On the optical path in the reflection direction of the bandpass mirror 12, an image rotator 21 and a galvanometric mirror 22 having a rotation axis perpendicular to the paper surface and polished on both sides are arranged. The lower reflection surface 22a of the galvanometric mirror 22 is arranged. A focus lens 23 movable along the optical path is arranged in the reflection direction, and a lens 24 and a focus unit 25 movable along the optical path are arranged in the reflection direction of the upper reflection surface 22b. The front focal plane of the lens 24 has a conjugate relationship with the pupil Ep of the eye E, and the galvanometric mirror 22 is disposed on the focal plane.
[0020]
Further, an optical path length compensating meniscus 26, a black spot plate 27 having a light blocking portion in the optical path, and a concave mirror 28 are sequentially arranged above the galvanometric mirror 22 by a lower reflecting surface 22a of the galvanometric mirror 22. A relay optical system that guides a light beam that passes without being reflected back to the upper reflection surface 22 b of the galvanometric mirror 22 is configured. The meniscus 26 for correcting the optical path length is for correcting the vertical displacement of the drawing caused by the mirror thickness of the positions of the upper reflection surface 22b and the lower reflection surface 22a of the galvanometric mirror 22. It acts only in the optical path toward the rotator 21.
[0021]
In the focus unit 25, a dichroic mirror 29 and a condenser lens 30 are sequentially arranged on the same optical path as the lens 24, and a mask 31 and a mirror 32 are disposed on the optical path in the reflection direction of the dichroic mirror 29. The focus unit 25 can be moved integrally in the direction indicated by the arrow.
[0022]
A fixed mirror 33 and an optical path switching mirror 34 that can be retracted from the optical path are arranged in parallel on the optical path in the incident direction of the lens 30, and a collimator lens 35 is disposed on the optical path in the incident direction of the optical path switching mirror 34. Laser diodes 36 for measurement that emit red light are arranged. Further, on the optical path in the incident direction of the mirror 32, a beam expander 37 made of a cylindrical lens or the like, and a tracking light source 38 that emits, for example, green light with high brightness different from other light sources are arranged.
[0023]
A focusing lens 23, a dichroic mirror 39, a field lens 40, a magnifying lens 41, and a one-dimensional CCD 42 with an image intensifier are sequentially arranged on the optical path in the reflection direction of the lower reflecting surface 22a of the galvanometric mirror 22. A blood vessel detection system is configured. Further, on the optical path in the reflection direction of the dichroic mirror 39, an imaging lens 43, a confocal stop 44, and mirror pairs 45a and 45b provided substantially conjugate with the pupil Ep of the eye E to be examined are arranged. Photomultipliers 46a and 46b are arranged in the reflection direction of 45b, respectively, and a light receiving optical system for measurement is configured. For the convenience of illustration, all the optical paths are shown on the same plane. However, the reflection optical paths of the mirror pairs 45a and 45b, the measurement optical path in the emission direction of the tracking light source 38, and the optical path from the laser diode 36 to the mask 31 are respectively shown. It is perpendicular to the page.
[0024]
Further, a system control unit 47 for controlling the entire apparatus is provided. The system control unit 47 is connected to input means 48 operated by the examiner and outputs of the photomultipliers 46a and 46b. The output of the control unit 47 is connected to a galvanometric mirror control circuit 49 that controls the galvanometric mirror 22 and an optical path switching mirror 34, respectively. Further, the output of the one-dimensional CCD 42 is connected to the galvanometric mirror control circuit 49 via the blood vessel position detection circuit 50, and the output of the system control unit 47 includes the measurement result display means 51, the measurement data selection means 52, The optical path switching input means 53 and the storage means 54 are connected. The output of the storage means 54 is connected to the calculation section 55, and the output of the calculation section 55 is connected to the system control section 47.
[0025]
FIG. 2 shows the arrangement of each light beam on the pupil Ep of the eye E, I is an image of the ring slit 5 in an area illuminated by yellow illumination light, O is a fundus observation light beam, and the aperture of the apertured mirror 11. An image, V is a measurement / blood vessel received light beam, an image of an effective portion of the upper and lower reflection surfaces 22b, 22a of the galvanometric mirror 22, and Da, Db are two measurement received light beams, which are images of the mirror pairs 45a, 45b, respectively. P2 and P2 ′ indicate the position of the measurement light selected by switching the optical path switching mirror 34 at the incident position of the measurement light, and a region M indicated by a chain line is an image of the lower reflection surface 22a of the galvanometric mirror 22. is there.
[0026]
At the time of measurement, white light emitted from the observation light source 1 passes through the condenser lens 3, and only yellow wavelength light is transmitted through the field lens 4 with a bandpass filter, and passes through the ring slit 5, the light shielding member 6, and the relay lens 7. The transmissive liquid crystal 8 is illuminated from behind. Further, this luminous flux is reflected by the perforated mirror 11 through the relay lens 9 and the light shielding member 10, and only the wavelength light in the yellow region is transmitted through the bandpass mirror 12, passes through the objective lens 2, and the pupil Ep of the eye E to be examined. After the image is once formed as a fundus illumination light beam image I above, the fundus Ea is illuminated almost uniformly.
[0027]
At this time, a fixation target is displayed on the transmissive liquid crystal plate 8, and is projected onto the fundus oculi Ea of the eye E by illumination light and presented to the eye E as a target image. The ring slit 5 and the light shielding members 6 and 10 are for separating the fundus illumination light and the fundus observation light in the anterior eye part of the eye E. It doesn't matter.
[0028]
Reflected light from the fundus oculi Ea is taken out from the pupil Ep as a fundus oculi observation light beam O, returns on the same optical path, passes through the aperture at the center of the perforated mirror 11, the focusing lens 13, and the relay lens 14, and reaches the scale plate 15. After forming the fundus image Ea, the light path switching mirror 16 is reached. Here, when the optical path switching mirror 16 is retracted from the optical path, the fundus image Ea ′ can be observed through the eyepiece 17 by the examiner's eye e, while the optical path switching mirror 16 is inserted in the optical path. At this time, the fundus image Ea ′ formed on the scale plate 15 is re-imaged on the CCD camera 19 by the television relay lens 18 and displayed on the liquid crystal monitor 20.
[0029]
The examiner aligns the apparatus with the eyepiece 17 or the liquid crystal monitor 20 while observing the fundus image Ea ′. At this time, it is preferable to adopt an appropriate observation method according to the purpose, and in the case of observation with the eyepiece lens 17, since the resolution and sensitivity are generally higher than those of the liquid crystal monitor 20 or the like, the fine fundus Ea is fine. It is suitable for diagnosis by reading changes. On the other hand, in the case of observation with the liquid crystal monitor 20, since the field of view is not restricted, the examiner's fatigue can be reduced, and further, by connecting the output of the CCD camera 19 to an external video tape recorder, a video printer or the like, Since it is possible to electronically record changes in the measurement site on the fundus oculi Ea, it is extremely effective clinically.
[0030]
Next, the measurement light emitted from the laser diode 36 is collimated by the collimator lens 35, and when the optical path switching mirror 34 is inserted in the optical path, it is reflected by the optical path switching mirror 34 and the fixed mirror 33, respectively. When the optical path switching mirror 34 is retracted from the optical path, it passes directly above the condenser lens 30 and passes through the dichroic mirror 29 together.
[0031]
On the other hand, the tracking light emitted from the tracking light source 38 is enlarged in beam diameter by the beam expander 37 at different magnifications in the vertical and horizontal directions, reflected by the mirror 32, and then shaped into a desired shape by the shaping mask 31 to be dichroic mirrored. The light is reflected by 29 and is superposed on the measurement light that is focused in a spot shape at a position conjugate with the center of the opening of the mask 31 by the condenser lens 30.
[0032]
The superimposed measurement light and tracking light pass through the lens 24, are once reflected by the upper reflecting surface 22 b of the galvanometric mirror 22, pass through the black spot plate 27, and then are reflected by the concave mirror 28, and again by the black spot plate 27, the optical path length correction. It passes through the meniscus 26 and is returned to the galvanometric mirror 22. Here, since the galvanometric mirror 22 is disposed at a position conjugate with the pupil Ep of the eye E, the image has a shape indicated by a broken line M in FIG. 2 on the pupil Ep of the eye E. Yes.
[0033]
The concave mirror 28, the black spot plate 27, and the optical path length correcting meniscus 26 are arranged concentrically on the optical path, and the upper reflective surface 22b and the lower reflective surface 22a of the galvanometric mirror 22 are imaged by -1 times. Since the function of the relay optical system is given, the light beam reflected at the positions P1 and P1 ′ in FIG. 2 on the back side of the image M of the galvanometric mirror 22 by insertion and retraction of the optical path switching mirror 34 into the optical path is Then, they are returned to the positions P2 and P2 'located at the notches of the galvanometric mirror 22, respectively, and are directed to the image rotator 21 without being reflected by the galvanometric mirror 22. Then, the light beam deflected in the direction of the objective lens 2 by the band pass mirror 12 through the image rotator 21 is irradiated to the fundus oculi Ea of the eye E to be examined through the objective lens 2.
[0034]
As described above, the measurement light and the tracking light are reflected in the upper reflection surface 22b of the galvanometric mirror 22 and enter the galvanometric mirror 22 while being decentered from the optical axis of the objective lens 2 when returned again. As shown in FIG. 5, after forming a spot image P2 or P2 ′ on the pupil Ep, the fundus oculi Ea is irradiated in the form of dots.
[0035]
The scattered reflected light from the fundus Ea is again collected by the objective lens 2, reflected by the bandpass mirror 12, passes through the image rotator 21, is reflected by the lower reflective surface 22 a of the galvanometric mirror 22, and passes through the focusing lens 23. In the dichroic mirror 39, the measurement light and the tracking light are separated.
[0036]
The tracking light passes through the dichroic mirror 39, and is formed on the one-dimensional CCD 42 by the field lens 40 and the imaging lens 41 as a blood vessel image enlarged from the fundus image Ea ′ obtained by the fundus observation optical system. Then, based on the blood vessel image Ev ′ picked up by the one-dimensional CCD 42, data representing the movement amount of the blood vessel image Ev ′ is created in the blood vessel position detection circuit 50 and output to the galvanometric mirror control circuit 49. The galvanometric mirror control circuit 49 drives the galvanometric mirror 22 so as to compensate for this movement amount.
[0037]
On the other hand, the measurement light is reflected by the dichroic mirror 39, passes through the openings of the lens 43 and the confocal stop 44, is reflected by the mirror pairs 45a and 45b, and is received by the photomultipliers 46a and 46b, respectively. The outputs of the photomultipliers 46a and 46b are respectively output to the system control unit 47, and the received light signal is subjected to frequency analysis in the same manner as in the conventional example to obtain the blood flow velocity of the fundus oculi Ea.
[0038]
At this time, due to the spectral characteristics of the band-pass mirror 12, the illumination light from the observation light source 1 does not reach the one-dimensional CCD 42, and the imaging range is set narrower. Therefore, only the blood vessel image Ev ′ by the tracking light is picked up by the one-dimensional CCD 42. In addition, blood hemoglobin and melanin on pigment epithelium differ greatly in the spectral reflectance in the green wavelength range, so the blood vessel image Ev 'can be captured with good contrast by making the tracking light green light. It becomes.
[0039]
Further, part of the scattered and reflected light on the fundus oculi Ea due to the measurement light and tracking light is transmitted through the bandpass mirror 12 and guided to the fundus observation optical system behind the perforated mirror 11, and the tracking light is incident on the scale plate 15. An image is formed as a bar-shaped indicator, and the measurement light is formed as a spot image at the center of the indicator. These images are observed together with the fundus oculi image Ea ′ and the target image via the eyepiece 17 or the liquid crystal monitor 20. At this time, a spot image (not shown) is observed superimposed on the center of the indicator, and the indicator can be moved one-dimensionally on the fundus oculi Ea by an operation member such as an operation rod of the input means 48.
[0040]
The examiner first focuses the fundus image Ea ′. When a focus knob (not shown) of the input unit 48 is adjusted, the transmission type liquid crystal plate 8, the focusing lenses 13 and 23, and the focus unit 25 are moved along the optical path by a driving unit (not shown). When the fundus image Ea ′ is in focus, the transmissive liquid crystal plate 8, the scale plate 15, the one-dimensional CCD 42, and the confocal stop 44 are simultaneously conjugated with the fundus Ea.
[0041]
After focusing is completed, the indicator is rotated by operating the image rotator 21 with an operating rod (not shown) of the input unit 48 so that the indicator is perpendicular to the traveling direction of the blood vessel Ev to be measured.
[0042]
At this time, since the fundus oculi observation light does not pass through the image rotator 21, it is recognized that only the indicator rotates, so that the image of each optical member on the pupil Ep shown in FIG. The straight line that rotates by the same angle and connects the centers of the measurement received light beams Da and Db and the center of the spot images P and P ′, that is, the x axis coincides with the traveling direction of the blood vessel Ev.
[0043]
This operation corresponds to β = 0 ° in the equation (1) for speed calculation described in the conventional example. By setting β = 0 °, the following (a) to (c) Benefits arise.
[0044]
(a) When β = 90 °, that is, cos β = 0 from equation (1), the absolute value of the maximum blood flow velocity Vmax cannot be obtained from only the maximum frequency shifts Δfmax1 and fmax2, but β = 0 By rotating the fundus oculi image E ′ so as to be at an angle, an incapable measurement position can be avoided.
[0045]
(b) Since it is not necessary to measure the angle β, the error factor is reduced and the operation is simplified.
[0046]
(c) As described in the conventional example, the blood flow velocity is obtained from the interference signal between the scattered reflected light from the blood vessel wall and the scattered reflected light in the blood, so that the fundus Ea moves in the x-axis direction during the measurement. Even if the blood vessel Ev is made substantially parallel to the x-axis direction, the measurement result is not affected.
[0047]
On the other hand, when the fundus oculi Ea moves in the y-axis direction orthogonal to the x-axis, the light flux from the measurement laser diode 36 deviates from the blood vessel Ev at the measurement site, and the measurement value becomes unstable. In this embodiment, the movement amount of the blood vessel Ev only needs to be detected in the y-axis direction. In this embodiment, the blood vessel detection system behind the dichroic mirror 39 and the galvanometric mirror 22 perform tracking only in this one direction.
[0048]
In order to measure the blood flow velocity accurately and quickly for all the blood vessels Ev by performing this tracking, the one-dimensional CCD 42 that detects the movement amount of the blood vessel image Ev ′ is perpendicular to the blood vessel Ev to be measured. Further, by setting β = 0 °, there is an advantage that it is not necessary to use a two-dimensional sensor.
[0049]
In this embodiment, when the elements of the one-dimensional CCD 42 are arranged in the longitudinal direction of the tracking light and the angle adjustment of the measurement site has been completed, the longitudinal direction of the indicator indicating the tracking light is the travel of the measurement blood vessel Ev. Since it is orthogonal to the direction, the fundus image Ea ′ indicated by the indicator is magnified and captured on the one-dimensional CCD 42 of the blood vessel detection system.
[0050]
After the angle adjustment is completed, the operation part of the input means 48 is operated to match the spot image superimposed on the tracking light with the measurement part and select the measurement part. After the measurement site is determined, the input unit 48 is operated again to input the start of tracking.
[0051]
When a tracking start command is input from the input means 48 to the galvanometric mirror control circuit 49 via the system control unit 47, the primary position of the blood vessel image Ev ′ is based on the light reception signal of the one-dimensional CCD 42 in the blood vessel position detection circuit 50. A movement amount from the original reference position is calculated. Then, the galvanometric mirror control circuit 49 drives the galvanometric mirror 22 based on the amount of movement, and the image receiving position of the blood vessel image Ev ′ on the one-dimensional CCD 42 is controlled to be constant.
[0052]
After confirming the start of tracking, the examiner presses a measurement switch (not shown) of the input means 48 to start measurement. The system controller 47 inserts the optical path switching mirror 34 into the optical path. First, light beams incident from the positions of the spot images P1 and P2 on the pupil Ep of the eye E are received by the photomultipliers 46a and 46b, and this received light signal is received. The maximum frequency shifts | Δfmax1 | and | Δfmax2 | are obtained by the system control unit 47. Here, in the measurement result display means 51, for example, changes in | Δfmax1 | and | Δfmax2 | with respect to the measurement time are shown. If the measurement is not performed correctly due to the deviation of the luminous flux, the measurement result display means. 51 is displayed as a waveform disturbance of | Δfmax1 | and | Δfmax2 |.
[0053]
If the examiner determines that the measurement is correctly performed, the measurement data selection unit 52 stores the measurement data in the storage unit 54. If the measurement is not performed correctly, the measurement data is canceled and the alignment or fixation state or the subject's condition is canceled. Readjust after adjusting the degree of opening of the heel, etc., and perform the measurement again.
[0054]
When the measurement is completed in the first pass, the optical path switching mirror 34 is retracted from the optical path by the optical path switching input means 53, and the light flux is incident from the position of the spot images P1 ′ and P2 ′ on the pupil Ep of the eye E to be measured. Do. The positions of the spot images P1 ′ and P2 ′ on the pupil Ep pass through the center of the other spot images P1 and P2 as shown in FIG. 2 and are parallel to the straight line connecting the centers of the measurement light receiving beams Da and Db. It is arranged with the center on top.
[0055]
Next, similarly to the measurement in the first pass, the system control unit 47 again takes in the signals from the two photomultipliers 46a and 46b, and calculates the maximum frequency shifts | Δfmax1 ′ | and | Δfmax2 ′ | The measurement result display means 51 displays a graph representing changes in | Δfmax1 ′ | and | Δfmax2 ′ | with respect to the measurement time.
[0056]
If the examiner determines that the measurement is correctly performed, the data is stored in the storage unit 54 by the measurement data selection unit 52, otherwise the data is canceled and the measurement is performed again.
[0057]
When the measurement is correctly performed in both paths, the calculation unit 55 obtains the code information from the measurement results such as | Δfmax1 |, | Δfmax2 |, | Δfmax1 ′ |, | Δfmax2 ′ | The detected result is output to the system control unit 47, and the maximum fundus blood flow velocity Vmax, Vmax ′ is calculated by the system control unit 47.
[0058]
By selecting the incident light as described above, the arithmetic unit 55 causes the region of the angle φi shown in FIG. 5 where the sign of the maximum frequency shift | Δfmax1 | and | Δfmax2 | is switched, and the maximum frequency shift | Δfmax1 ′ | The region where the sign of | Δfmax2 ′ | can be separated, and in the region where the sign is not switched, Vmax≈Vmax ′.
[0059]
Also, in the region where one sign of maximum speed Vmax or Vmax 'is switched, it is possible to create a relationship of (the side where no sign is switched)> (the side where the sign is switched). Is finally displayed as the true blood flow velocity.
[0060]
Conventionally, if the measurement of one path is not performed correctly, both paths must be remeasured. However, by providing the measurement result display means 51 and the measurement data selection means 52, the measurement is correctly performed. Since the measurement data of the performed path is not wasted and it is not necessary to measure the correctly measured path repeatedly, a large number of measurement sites can be measured.
[0061]
In the present embodiment, the maximum frequency shift amount with respect to the passage of time is given as the information displayed on the measurement result display means 51. However, when the quality of the measurement is known, light reception from the photomultipliers 46a and 46b with respect to the passage of time. A signal may be displayed, or a change in the maximum blood flow velocity over time may be displayed. Further, some information on the process of calculating the maximum blood flow velocity from the light reception signals from the photomultipliers 46a and 46b may be used.
[0062]
In addition, the measurement result is judged at the end of the measurement of each of the two paths, that is, the path when the optical path switching mirror 34 is inserted in the optical path and the path when the optical path switching mirror 34 is retracted from the optical path. However, in the case of a subject with a good fixation state, a measurement method selection means is provided so that the optical path switching mirror 34 automatically operates when measurement of one path is completed, so that both paths The measurement may be performed continuously, and the measurement result display unit 51 and the measurement data selection unit 52 may determine whether or not the measurement is possible after the measurement is completed.
[0063]
Note that the optical path switching input means 53 is not necessary if the optical path is automatically switched when the measurement data selection means 52 selects that the measurement is correct.
[0064]
FIG. 3 shows a configuration diagram of the second embodiment. In the first embodiment, incident light is incident from two directions, and | Δfmax1 | and | Δfmax2 |, | Δfmax1 ′ | and | Δfmax2 ′ | In this embodiment, the determination is made by changing the position on the light receiving side.
[0065]
The light beam from the measurement laser diode 36 is reflected at the position P1 in FIG. 2 on the back side of the image M of the galvanometric mirror 22 and returned to the position P2 located at the notch of the galvanometric mirror 22. And incident from one direction. Further, the mirror pairs 45a and 45b and the photomultipliers 46a and 46b are integrally formed as a unit, and can be moved vertically by the system control unit 47 with respect to the light receiving optical system of the measurement signal.
[0066]
FIG. 4 shows an arrangement diagram of each light beam on the pupil Ep of the eye E, I is an image of the ring slit 5 in an area illuminated by yellow illumination light, and O is a fundus observation light beam and an opening of the perforated mirror 11. , V is a measurement / blood vessel received light beam and is an image of an effective portion of the upper and lower reflection surfaces 22a and 22b of the galvanometric mirror 22, and Da and Db are two measurement light received light beams and are images of the mirror pairs 45a and 45b, respectively. P1 is an incident position of the measurement light, and a region M indicated by a chain line is an image of the lower reflection surface 22a of the galvanometric mirror 22. Dc represents a measurement light beam selected when the photomultipliers 46a and 46b are moved, and Da, Db, and Dc are arranged in a straight line at the opening of the perforated mirror 11.
[0067]
The operation procedure of the apparatus is the same as that of the first embodiment, but when the first measurement is correctly performed, the examiner uses the optical path switching input means 53 to make a mirror pair unitized as shown by the dotted line in the figure. 45a and 45b and the photomultipliers 46a and 46b are moved. In such a state, the photomultiplier 66a receives the light beam Db by the mirror 65a, and the photomultiplier 66b receives the light beam Dc by the mirror 65b.
[0068]
In this state, the second measurement is started, and when the measurement is correctly performed, the calculation unit 55 stores | Δfmax1 |, | Δfmax2 |, | Δfmax1 ′ |, | Δfmax2 ′ | The code information is detected from the measurement result, and the result is output to the system control unit 47. The system control unit 47 calculates the maximum blood flow velocity Vmax and Vmax ′.
[0069]
In the second measurement, only the light beam Dc may be measured, and the measurement result of the first light beam may be used for measuring the light beam Db. In addition, three photomultipliers are prepared. Thus, it is also possible to receive the measurement light so as to correspond to the respective light beams Da, Db, Dc.
[0070]
【The invention's effect】
As described above, in the fundus examination apparatus according to the present invention, when the absolute value of the fundus blood flow is calculated, the examiner can determine whether the measurement is good or not every two measurement data. Even when the measurement is bad, the measurement data of the correctly measured path is not wasted, the correct measurement value can be obtained, the burden on the subject can be reduced, and the measurement time can be reduced. It can be shortened.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a first embodiment.
FIG. 2 is an explanatory diagram of light beam arrangement on the pupil.
FIG. 3 is a configuration diagram of a second embodiment.
FIG. 4 is an explanatory diagram of a light beam arrangement on the pupil.
FIG. 5 is an explanatory diagram of arrangement of intraocular light beams.
[Explanation of symbols]
1 Light source for observation
8 Transmission type liquid crystal plate
12 Bandpass mirror
19 CCD camera
20 LCD monitor
21 Image Rotator
22 Galvanometric mirror
25 Focus unit
36 Laser diode
37 Beam Expander
38 Light source for tracking
42 One-dimensional CCD
46a, 46b Photomultiplier
47 System controller
48 Input means
49 Galvanometric mirror control circuit
50 Blood vessel position detection circuit
51 Measurement result display means
52 Measurement data selection means
53 Optical path switching input means
54 Memory means
55 Calculation unit

Claims (8)

In a fundus examination apparatus having measurement light irradiating means for irradiating measurement light on the fundus, light receiving means for receiving signal light from the fundus, and a calculation unit that receives the output signal from the light receiving means and calculates a measurement result A measurement result display means for receiving the output from the light receiving means that has received the signal light based on the measurement light under a plurality of measurement conditions and displaying a plurality of measurement results calculated by the calculation unit ; Measurement data selection means to be selected, re-measurement means for performing re-measurement by the calculation unit under the measurement condition of the measurement result when the measurement data selection means is selected, and selection is possible by the measurement data selection means And a blood flow velocity calculating unit that stores the measurement result and calculates a fundus blood flow velocity from the stored plurality of measurement results.   The fundus examination apparatus according to claim 1, wherein the plurality of measurement results are measured from different irradiation directions of measurement light to the fundus.   The fundus examination apparatus according to claim 1, wherein the plurality of measurement results are measured from different wavelengths of measurement light.   The fundus examination apparatus according to claim 1, wherein the plurality of measurement results are measured from different light receiving directions of the light receiving unit.   The fundus examination apparatus according to any one of claims 1 to 4, wherein selection of whether or not a measurement result is possible by the measurement data selection unit is performed after each measurement result is calculated.   The fundus examination apparatus according to any one of claims 1 to 4, wherein selection of whether or not a measurement result is possible by the measurement data selection unit is performed after calculation of all measurement results is completed.   The fundus examination apparatus according to claim 2, further comprising an optical path switching unit that switches an optical path in the irradiation direction or the light receiving direction. The said measurement light irradiation means irradiates a coherent measurement light to a fundus blood vessel, and calculates the blood flow velocity by the said blood flow velocity calculation part from said several measurement result. The fundus examination apparatus according to one claim.

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