JP3591952B2 - Fundus examination device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fundus examination apparatus for examining blood vessels on the fundus of a subject's eye.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various ophthalmologic examination apparatuses that irradiate measurement light to the fundus and receive reflected light from the fundus have been known. A laser scanning ophthalmoscope having a function of measuring the sensitivity or a function of inspecting the irregularities of the fundus is used. This device uses an optical deflector placed at the pupil conjugate position of the subject's eye to irradiate the laser light spot focused at the fundus conjugate position on the fundus while deflecting it at a predetermined rate, and reflects the reflected image from the fundus. The light is again passed through the optical deflector, the fundus is photographed with the light receiver arranged at the conjugate position of the fundus, and the fundus image is focused on while observing the fundus image on a monitor to make a diagnosis.
[0003]
Also, it is known that by measuring the blood flow rate and blood flow rate of blood flowing through the blood vessels of the fundus, important information for quantifying the progress of diabetes or the like and the effect of the treatment can be obtained. For example, a fundus blood flow meter using a laser Doppler method based on a fundus camera has been proposed.
[0004]
In this fundus blood flow meter, the maximum shift of the frequency calculated from the light reception signals received by the two light receivers is Δfmax1 and Δfmax2, the wavelength of the laser light is λ, the refractive index of the measurement site is n, and 2 in the eye. Assuming that the angle between the two light receiving optical axes is α and the angle between the plane formed by the two light receiving optical axes in the eye and the velocity vector of the blood flow is β, the maximum blood flow velocity Vmax can be obtained from the following equation. .
Vmax = {λ / (n · α)} · ｛|| Δfmax1 | − | Δfmax2 || / cosβ} (1)
[0005]
By performing the measurement from two directions in this way, the contribution of the incident direction of the measurement light is canceled, and the blood flow at an arbitrary site on the fundus can be measured, and the plane formed by the two light receiving optical axes can be measured. By matching the angle β between the line of intersection with the fundus and the blood flow velocity vector, β = 0 °, so that the true blood flow velocity can be measured.
[0006]
In order to measure the blood flow velocity in the fundus blood vessels, it is necessary to irradiate spot-shaped measurement light to the blood vessels. For this purpose, it is necessary to deflect the irradiation light with a deflector in accordance with the fixation fine movement. Therefore, in this fundus blood flow meter, a blood vessel image is captured by a one-dimensional image sensor arranged at a fundus conjugate position of the measurement optical system, a positional shift due to fixation fine movement is detected, and light at the pupil conjugate position is detected. By deflecting the irradiation light beam by the deflector, the measurement light surely irradiates the blood vessel.
[0007]
In the measurement of blood flow velocity, in order to receive only the reflected light from the desired blood vessel out of the reflected light from the fundus, a confocal stop is arranged in the measuring light receiving optical system to form a confocal optical system. Further, the diameter of the blood vessel is measured using the blood vessel image taken for detecting the positional deviation, and the blood flow is calculated using the blood vessel diameter.
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned conventional fundus blood flow meter, it is necessary that the detector and the imaging device of the measuring light receiving optical system that receive the reflected light from the fundus be arranged at the fundus conjugate position. For example, in the irradiation optical system for measurement, by providing a split prism at the fundus conjugate position in the optical path, the spot image of the measurement light can be observed while confirming the in-focus state with a monitor or a direct image mirror arranged in the observation optical system. Although it can be moved to the conjugate position, in a measuring light receiving optical system that receives only the amount of reflected light or a one-dimensional image, the examiner cannot judge the in-focus state only from the output signal.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a fundus examination apparatus which can solve the above-mentioned problems and can reliably arrange a light receiving surface of a measurement light receiving optical system at a fundus conjugate position.
[0010]
[Means for Solving the Problems]
To achieve the above purpose Book A fundus examination apparatus according to the present invention includes a light deflecting unit disposed at a position substantially conjugate to a pupil of an eye to be examined, an illumination optical system for illuminating the fundus, an observation optical system for observing the fundus, and an apparatus for examining blood vessels in the fundus. In a fundus examination apparatus having a measuring light irradiation optical system and a measuring light receiving optical system disposed behind the light deflecting means, the focusing means of the measuring light receiving optical system and the focusing means of the observation optical system are provided. An interlocking means for interlocking and moving in the optical axis direction is provided.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described in detail based on the illustrated embodiment.
FIG. 1 shows a configuration diagram of a fundus blood flow meter of an embodiment. A condenser lens 3 is provided on an illumination optical path from an observation light source 1 composed of a tungsten lamp or the like that emits white light to an objective lens 2 facing the eye E. A field lens 4 with a band-pass filter that transmits only light in the yellow range, a ring slit 5 substantially conjugate to the pupil Ep of the eye E, a light-shielding member 6 substantially conjugate to the crystalline lens of the eye E, a relay lens 7, A transmissive liquid crystal plate 9, a relay lens 10, and a light shielding member conjugate with the vicinity of the cornea of the eye E to be inspected, which are fixation target display elements movable along the optical path by first focusing drive means 8 comprising a rack and a pinion. 11, an apertured mirror 12, and a band-pass mirror 13 that transmits light in the yellow range and almost reflects other light beams are sequentially arranged to form an illumination optical system. The ring slit 5 and the light shielding members 6 and 11 are for separating the fundus illumination light and the fundus observation light in the anterior segment of the eye E to be inspected. No problem.
[0014]
An observation optical system is provided behind the perforated mirror 12, and includes a first focusing lens 14, a relay lens 15, a scale plate 16, which is movable along the optical path, and an optical path switching mirror 17 which can be inserted into and removed from the optical path. , Eyepieces 18 are sequentially arranged to reach the examiner's eye e. A television relay lens 19 and a CCD camera 20 are arranged on the optical path in the reflection direction of the optical path switching mirror 17, and the output of the CCD camera 20 is connected to a liquid crystal television monitor 21.
[0015]
An image rotator 22, a galvanometric mirror 23, polished on both upper and lower surfaces and having a rotation axis perpendicular to the paper surface and conjugate to the pupil Ep of the eye E to be examined, on one side of the optical path, , A black spot plate 25 having a light-shielding portion in the optical path, and a concave mirror 26 are sequentially arranged, and the light flux passing through the lower reflection surface 23a of the galvanometric mirror 23 without being reflected by the lower reflection surface 23a. A relay optical system is configured to cooperate and guide the galvanometric mirror 23 to the upper reflecting surface 23b. The meniscus plate 24 for compensating the optical path length is used to correct the vertical displacement of the lower reflecting surface 23a and the upper reflecting surface 23b caused by the mirror thickness of the galvanometric mirror 23. It works only on the light path going to.
[0016]
In the incident direction of the upper reflecting surface 23b of the galvanometric mirror 23, the front focal plane thereof is integrally movable along the optical path by a lens 27 conjugate with the pupil Ep of the eye E to be inspected and the second focusing driving means 28. In the focusing unit 29, a dichroic mirror 30 and a condensing lens 31 are arranged on the same optical path as the lens 27, and a mask 32 and a split lens are arranged on the optical path in the incident direction of the dichroic mirror 30. The prism 33 and the mirror 34 are arranged.
[0017]
A fixed mirror 35 and an optical path switching mirror 36 that can be retracted from the optical path are arranged in parallel on the optical path in the incident direction of the condenser lens 31, and a collimator lens 37 and a coherent lens are disposed on the optical path in the incident direction of the optical path switching mirror 36. A measuring laser diode 38 that emits red light is arranged. Further, on the optical path in the incident direction of the mirror 34, a beam expander 39 composed of a cylindrical lens or the like, and a high-luminance tracking light source 40 that emits green light different from other light sources are arranged.
[0018]
On the optical path in the reflection direction of the lower reflective surface 23a of the galvanometric mirror 23, a second focusing lens 41, a dichroic mirror 42, a field lens 43, a magnifying lens 44, and an image intensifier movable along the optical path. The one-dimensional CCDs 45 are sequentially arranged to form a blood vessel detection system.
[0019]
The first focusing lens 14 in the fundus oculi observation optical system and the second focusing lens 41 in the light receiving optical system for measurement are connected by an interlocking means 46, and a focusing knob (not shown) provided at a fulcrum of the interlocking means 46. Is moved, the first focusing lens 14 and the second focusing lens 41 are interlocked while maintaining the conjugate relationship. Further, the second focusing lens 41 is provided with a focus position detecting means 47 such as a potentiometer, a rotary encoder, or a combination of a slit and a photocoupler, so that the focus position is detected.
[0020]
On the optical path in the reflection direction of the dichroic mirror 42, an imaging lens 48, a confocal stop 49, and mirror pairs 50a and 50b substantially conjugate to the pupil Ep of the eye E to be examined are arranged. Photomultipliers 51a and 51b are arranged in the directions, respectively, and constitute a light receiving optical system for measurement including a blood vessel detection system. For convenience of illustration, all the optical paths are shown on the same plane, but the reflected optical paths of the mirror pair 50a, 50b, the optical path for measuring the emission direction of the tracking light source 40, and the optical path from the laser diode 38 to the dichroic mirror 30. Are orthogonal to the paper.
[0021]
Further, a system control unit 52 for controlling the entire apparatus is provided. The system control unit 52 receives outputs from an input unit 53 operated by the examiner, photomultipliers 51a and 51b, and a focus position detection unit 47, respectively. The output of the system control unit 52 is connected to a control circuit 54 for controlling the galvanometric mirror 23 and an optical path switching mirror 36. The output of the one-dimensional CCD 45 is connected to the control circuit 54 via a blood vessel position detection circuit 55.
[0022]
FIG. 2 shows the arrangement of each light beam on the pupil Ep of the eye E to be examined, an image I of the ring slit 5 in an area illuminated by yellow illumination light, an image O of an opening of the perforated mirror 12 with a fundus observation light beam, An image V of the effective portion of the upper and lower reflecting surfaces of the galvanometric mirror 23 with the light beam for measurement / blood vessel reception, the images Da and Db of the mirror pair 50a and 50b with the two light reception light beams, and the optical path switching mirror 36 at the incident position of the measurement light. The positions P2 and P2 'of the measurement light selected by switching, and the image of the lower reflection surface 23a of the galvanometric mirror 23 are indicated by a chain line region M.
[0023]
The white light emitted from the observation light source 1 passes through the condenser lens 3, only the yellow wavelength light is transmitted by the field lens 4, passes through the ring slit 5, the light shielding member 6, the relay lens 7, and behind the transmission type liquid crystal plate 9. And is reflected by the perforated mirror 12 through the relay lens 10 and the light blocking member 11, and only the wavelength light in the yellow range passes through the band-pass mirror 13, passes through the objective lens 2, and is on the pupil Ep of the eye E to be examined. After the image is once formed as the fundus illumination light flux image I, the fundus oculi Ea is almost uniformly illuminated. At this time, a fixation target is displayed on the transmissive liquid crystal plate 9, and the fixation target is projected on the fundus oculi Ea of the eye E by illumination light, and is presented to the eye E as a target image.
[0024]
The reflected light from the fundus oculi Ea returns along the same optical path, is taken out of the pupil Ep as the fundus oculi observation light flux O, passes through the central opening of the perforated mirror 12, the first focusing lens 14, the relay lens 15, and then to the scale plate 16. After being formed as a fundus image Ea ', the light reaches the optical path switching mirror 17. Here, when the optical path switching mirror 17 is retracted from the optical path, the fundus image Ea 'can be observed by the examiner's eye e through the eyepiece 18. On the other hand, when the optical path switching mirror 17 is inserted in the optical path, the fundus oculi image Ea ′ formed on the scale plate 16 is re-imaged on the CCD camera 20 by the television relay lens 19 and displayed on the liquid crystal television monitor 21. It is projected.
[0025]
The examiner aligns the apparatus with the eyepiece 18 or the liquid crystal television monitor 21 while observing the fundus image Ea '. At this time, it is preferable to employ an appropriate observation method according to the purpose. In the case of observation with the eyepiece 18, since the resolution and sensitivity are generally higher than those of the liquid crystal television monitor 21 or the like, the fundus Ea It is suitable for reading a small change for diagnosis. On the other hand, in the case of observation by the liquid crystal television monitor 21, since the field of view is not restricted, fatigue of the examiner can be reduced, and by connecting the output of the CCD camera 20 to an external video tape recorder, video printer, or the like, Since it is possible to electronically record the change of the measurement site on the fundus image Ea ', it is extremely effective clinically.
[0026]
The measurement light emitted from the laser diode 38 is collimated by the collimator lens 37, and when the optical path switching mirror 36 is inserted in the optical path, the measurement light is reflected by the optical path switching mirror 36 and the fixed mirror 35, respectively. When the light passes below and the optical path switching mirror 36 is retracted from the optical path, it passes directly above the condenser lens 31 and passes through the dichroic mirror 30.
[0027]
On the other hand, the tracking light emitted from the tracking light source 40 has a beam diameter expanded by a beam expander 39 at different magnifications in the vertical and horizontal directions, is reflected by a mirror 34, is split by a split prism 33, and has a desired shape by a shaping mask 32. The light is shaped into a shape, is reflected by the dichroic mirror 30, and is superimposed on the measurement light.
[0028]
At this time, the measurement light is imaged in the form of a spot at a position conjugate with the center of the opening of the mask 32 by the condenser lens 31, and the measurement light and the tracking light pass through the lens 27 together and pass through the galvanometric mirror 23. Is reflected once upward by the upper reflection surface 23b, passes through the black point plate 25, is reflected by the concave mirror 26, and is decentered from the optical axis, and passes through the black point plate 25 and the meniscus plate 24 for optical path length correction. Returned to 23.
[0029]
That is, by inserting and retracting the optical path switching mirror 36 into and out of the optical path, the measurement light and the tracking light reflected at the positions P1 and P1 'below the image M of the galvanometric mirror 23 as shown in FIG. Since it is returned to the position of P2, P2 'in the cutout portion of the galvanometric mirror 23, it is directed to the image rotator 22 without being reflected by the galvanometric mirror 23, passes through the image rotator 22, and is passed by the bandpass mirror 13 to the objective lens. 2 and are formed as spot images P2 and P2 'on the pupil Ep, and irradiate the fundus oculi Ea of the eye E in a point-like manner. In this way, various types of flare light can be effectively removed.
[0030]
The scattered reflected light from the fundus oculi Ea is collected again by the objective lens 2, reflected by the band-pass mirror 13, passes through the image rotator 22, is reflected by the lower reflective surface 23a of the galvanometric mirror 23, and is focused on the second focusing lens. The measurement light and the tracking light pass through 41 and are separated by a dichroic mirror 42.
[0031]
The tracking light is transmitted through the dichroic mirror 42 and is formed on the one-dimensional CCD 45 by the field lens 43 and the imaging lens 44 as a blood vessel image which is larger than the fundus image Ea ′ by the fundus observation optical system. Then, based on the blood vessel image captured by the one-dimensional CCD 45, data indicating the moving amount of the blood vessel image is created in the blood vessel position detection circuit 55 and output to the system control unit 52. The system control unit 52 The galvanometric mirror 23 is driven so as to compensate for this movement amount.
[0032]
On the other hand, the measurement light is reflected by the dichroic mirror 42, reflected by the mirror pair 50a, 50b through the lens 48 and the opening of the confocal stop 49, and received by the photomultipliers 51a, 51b, respectively. The signal is output to the unit 52 and subjected to frequency analysis.
[0033]
At this time, the illuminating light from the observation light source 1 does not reach the one-dimensional CCD 45 due to the spectral characteristics of the band-pass mirror 13, and furthermore, the harmful light because the imaging range of the CCD 45 is set narrow. It is difficult for flare light to be mixed in. As a result, the one-dimensional CCD 45 captures only a blood vessel image by tracking light. In addition, since blood hemoglobin and melanin on pigment epithelium have significantly different spectral reflectances in a green wavelength region, a blood vessel image can be captured with good contrast by setting tracking light to green light.
[0034]
The luminous flux received by the one-dimensional CCD 45 is a luminous flux extracted from the measured / blood vessel received luminous flux V on the pupil Ep of the subject's eye E, and the measured received luminous flux Da, Db is extracted from the luminous flux by the mirror pair 50a, 50b. Light is received by the photomultipliers 51a and 51b. The reason why the measurement / blood vessel received light beam V is larger than the fundus observation light beam O is that the one-dimensional CCD 45 has a larger imaging magnification of the fundus than the CCD camera 20 of the fundus observation optical system. This is because it is difficult to secure the illuminance of the image plane above. On the other hand, the influence of the flare light generated in the anterior segment of the eye E due to the increase in the light flux is not a problem because the blood vessel image receiving optical system has a smaller image receiving range.
[0035]
Further, the interval between the measurement light receiving beams Da and Db on the pupil Ep directly affects the resolution of the blood flow velocity measurement. However, by increasing the measurement / blood vessel receiving light beam V, the interval between the measurement light receiving beams Da and Db can be sufficiently increased. Can be secured. Further, the received light beams Da, Db, V and the fundus oculi observation light beam O are wavelength-separated and superimposed on the pupil Ep of the eye E to be examined, so that the S / N ratio of the measurement signal is maintained and the smaller pupil becomes smaller. Measurement can also be performed on a subject having a diameter.
[0036]
Part of the scattered reflected light on the fundus oculi Ea due to the measurement light and the tracking light passes through the band-pass mirror 13 and is guided to the fundus observation optical system behind the perforated mirror 12, and the tracking light is split on the scale plate 16. The measurement light is formed as a spot image at the center of the indicator. These images are observed together with the fundus image Ea ′ and the optotype image via the eyepiece 18 or the liquid crystal television monitor 21. At this time, a spot image is superimposed and observed at the center of the indicator, and the indicator can be moved one-dimensionally on the fundus oculi Ea by an operating member such as an operating rod of the input means 53.
[0037]
At the time of measurement, the examiner first focuses while observing the fundus image Ea 'displayed on the television monitor 21. Focusing is performed by operating a focusing knob attached to a fulcrum of the interlocking means 46 to maintain a conjugate relationship between the first focusing lens 14 in the fundus observation optical system and the second focusing lens 41 in the measurement light receiving optical system. Perform while interlocking. In this way, the measurement optical system, such as the blood vessel observation optical system or the Doppler signal detection optical system, which is difficult for the examiner to check the in-focus state, is quickly moved to the conjugate position of the fundus oculi Ea together with the fundus observation optical system. You can move.
[0038]
Further, a focus detection signal from a focus position detecting means 47 for detecting an image position provided on the second focusing lens 41 is input to the system control unit 52, and the system control unit 52 performs a refraction abnormal value or image formation. Converted to magnification information. This refraction abnormal value is mainly used for α in Expression (1) of the conventional example to calculate the true blood flow velocity, and the imaging magnification information is used for calculating the blood vessel diameter and the blood flow rate.
[0039]
Next, the fixation target displayed on the transmissive liquid crystal plate 9 in the fundus illumination optical system is projected on the television monitor 21, and the knob of the first focusing drive means 8 is moved while watching the target image. Focus is performed. Further, the measurement light irradiation optical system also performs focusing by moving the knob of the second focusing drive means 48 of the focusing unit 29 while watching the split image of the indicator displayed on the television monitor 21.
[0040]
FIG. 3 is an explanatory diagram showing an operation of the confocal stop 49 for focusing on a predetermined blood vessel. The position of the blood vessel on the fundus oculi Ea to be measured is represented by a measurement site S1, and the choroid behind the blood vessel is measured. The position of the blood vessel inside is indicated by the measurement site S2. The light beam from the measuring laser diode 38 enters the mirror 61 from below, is reflected in the left and right directions, and irradiates the measurement site S1. The reflected light at the measurement site S1 passes through the opening 62 having the same light receiving direction determining function as the mirror pair 50a, 50b, is conjugated to the measurement site S1 by the lens 63, and is not shown after passing through the small hole 64. The light is received by the photomultiplier. On the other hand, the reflected light at the measurement site S2 indicated by the dotted line is imaged by the lens 63 in the same manner as the light beam reflected at the measurement site S1 indicated by the solid line. No light is received by the pliers.
[0041]
Thus, the confocal stop 49 having the same function as the small hole 64 is provided, and only the reflected light from the blood vessel at a specific depth is received by the photomultipliers 51a and 51b, so that the blood of the desired blood vessel is obtained. The flow velocity can be measured. In an actual examination, the examiner sets the depth of a blood vessel to be measured while observing the in-focus state on the fundus image Ea ', and focuses the fundus image Ea'.
[0042]
After the focusing is completed in this manner, the examiner operates the input means 53 to move the target image, guide the line of sight of the eye E, change the observation area, and scale the blood vessel to be measured. The plate 16 moves to a predetermined position. Then, the indicator is rotated by operating the image rotator 22 with the operation rod of the input means 53 so that the indicator is perpendicular to the traveling direction of the blood vessel to be measured.
[0043]
At this time, since the fundus oculi observation light does not pass through the image rotator 22, it is recognized that only the indicator rotates. As a result, the image of each optical member on the pupil Ep shown in FIG. 2 also rotates by the same angle in the same direction around the origin, and the straight lines connecting the centers of the measured light beams Da and Db and the spot images P1 and P1 ' The X axis, which is a straight line connecting the centers of P2 and P2 ', coincides with the traveling direction of the blood vessel. In this way, only the irradiation optical system and the light receiving optical system of the measurement light act on the image rotator 22 and the galvanometric mirror 23 which is the light beam deflecting means, and the fundus observation optical system is made independent of these components. The observation field of view can always be the same as a normal fundus camera regardless of the selection of the measurement site.
[0044]
The above operation is equivalent to setting β = 0 ° in the equation (1) for speed calculation described in the conventional example, and by setting β = 0 °, the following (a) to (c) Benefits arise.
[0045]
(A) When β = 90 °, that is, cosβ = 0, from the equation (1), the absolute value of the maximum blood flow velocity Vmax cannot be obtained from only the maximum frequency shifts Δfmax1 and Δfmax2. By rotating the fundus oculi image Ea ′ so as to be 0 °, the unmeasurable position can be avoided.
[0046]
(B) Since there is no need to measure the angle β, error factors are reduced, and the operation is simplified.
[0047]
(C) As described in the conventional example, since 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, the fundus Ea moves in the X-axis direction during the measurement. However, if the blood vessel is made substantially parallel to the X-axis direction, the measurement result is not affected.
[0048]
On the other hand, when the fundus oculi Ea moves in the Y-axis direction orthogonal to the X-axis, the luminous flux from the measurement laser diode 40 deviates from the blood vessel at the measurement site and the measurement value becomes unstable. It is sufficient to detect the moving amount of the blood vessel only in the Y-axis direction. In this embodiment, tracking in this one direction is performed by the blood vessel detection system behind the dichroic mirror 42 and the galvanometric mirror 23.
[0049]
In order to accurately and quickly measure the blood flow velocity of all the tested blood vessels by performing this tracking, it is preferable to arrange the one-dimensional CCD 45 for detecting the moving amount of the blood vessel image perpendicular to the blood vessel to be measured. Further, by setting β = 0 °, there is an advantage that it is not necessary to use a two-dimensional sensor.
[0050]
In the present embodiment, the elements of the one-dimensional CCD 45 are arranged in the longitudinal direction of the tracking light, and when the angle adjustment of the measurement site has been completed, the longitudinal direction of the indicator indicating the tracking light is the traveling direction of the measurement blood vessel. Therefore, the fundus image Ea 'indicated by the indicator is enlarged and formed on the one-dimensional CCD 45 of the blood vessel detection system. However, it is difficult for the examiner to immediately determine the in-focus state from the output of the one-dimensional CCD 45 alone.
[0051]
After the angle adjustment is completed, the operation rod of the input means 53 is operated to match the spot image superimposed on the tracking light with the measurement site and select the measurement site. Then, after determining the measurement site, the input means 53 is operated again to input the start of tracking.
[0052]
When a tracking start command is input from the input unit 53 to the control circuit 54 via the system control unit 52, the blood vessel position detection circuit 55 uses the one-dimensional CCD 45 from the one-dimensional reference position based on the light receiving signal of the one-dimensional CCD 45. Is calculated. Then, the galvanometric mirror 23 is driven by the control circuit 54 based on the amount of movement, and is controlled so that the image receiving position of the blood vessel image on the one-dimensional CCD 45 becomes constant.
[0053]
After confirming the start of tracking, the examiner presses the measurement switch of the input means 53 to start measurement. The optical path switching mirror 36 is inserted into the optical path by the system control unit 52. First, light beams incident from the positions of the spot images P1 and P1 'on the pupil Ep of the eye E to be inspected are received by the photomultipliers 51a and 51b. Is taken into the system controller 52, and the maximum frequency shifts | Δfmax1 | and | Δfmax2 | are obtained as processing results of the output signals from the photomultipliers 51a and 51b, respectively. Then, α is calculated using the imaging magnification value input to the system control unit 52 from the focus position detection means 67 and calculated.
[0054]
At this time, the luminous flux is incident from the positions of the spot images P1 and P1 'and is provided at a position which is sufficiently displaced with respect to the measured light-receiving luminous fluxes Da and Db. In 1), cosβ = 1, and Vmax = {λ / (n · α)} · || Δfmax1 | − | Δfmax2 ||, but depending on the position of the blood vessel on the fundus oculi Ea, the true flow rate is Vmax = There are cases where {λ / (n · α)} · || Δfmax1 | + | Δfmax2 || In this embodiment, first, the maximum speed Vmax according to the equation (1) is calculated as a temporary measurement in this state, and then the optical path switching mirror 36 is retracted from the optical path by the system control unit 52, and the pupil Ep of the eye E to be examined The measurement is performed by irradiating a light beam from the positions of the spot images P2 and P2 '.
[0055]
As shown in FIG. 2, the positions of the spot images P2 and P2 'on the pupil Ep pass through the centers of the other spot images P1 and P1' and are parallel to the straight lines connecting the centers of the measured light beams Da and Db. Although it is arranged so as to have a center point on the upper side, particularly in this embodiment, the interval between the spot images P1, P1 ', P2, P2' is larger than the distance between the centers of the measurement light receiving beams Da, Db, and The straight lines connecting the midpoints of the straight lines are selected so as to be orthogonal to the straight lines connecting their centers.
[0056]
After switching the position of the incident light from the spot images P1 and P1 'to the spot images P2 and P2' thus selected, the system control unit 52 takes in the signals from the two photomultipliers 51a and 51b again and outputs the maximum frequency of each. The shift | Δfmax1 ′ | and | Δfmax2 ′ | are calculated, and the maximum speed Vmax is calculated according to the equation (1). If the maximum speed Vmax at this time is set to Vmax ′, the system control unit 52 compares the two maximum speeds Vmax and Vmax ′ to determine an appropriate incident direction of the light flux for obtaining the true maximum flow velocity. Then, based on this information, control is performed such that the optical path switching operation is performed in an appropriate state and the main measurement is performed. This measurement is continuously performed at appropriate time intervals by repeatedly calculating the maximum speed Vmax or Vmax ′.
[0057]
In addition, the blood vessel diameter calculated from the blood vessel detection system in the observation light receiving optical system is similarly corrected from the imaging magnification value of the system control unit 52 to calculate the correct blood vessel diameter. Then, the blood flow rate is determined from the blood vessel diameter and the blood flow velocity determined previously.
[0058]
As described above, it is difficult to confirm the focus state only by the output of the blood vessel detection system, but it is necessary to move the focusing means of the measurement optical system in conjunction with the focusing means of the fundus observation optical system. As a result, a quick and reliable focusing operation can be performed, the position of the test blood vessel can be reliably detected, the blood vessel diameter can be measured, and the Doppler signal from the fundus oculi Ea can be accurately received. .
[0059]
In the present invention, the light receiving optical system for measurement including the blood vessel detection system is moved only in conjunction with the fundus observation optical system, but the fixation target display element of the fundus illumination optical system, and the fundus observation optical system, If the moving lenses for focusing of the measuring light irradiation optical system and the measuring light receiving optical system are linked to each other while maintaining the conjugate relationship, the focusing operation can be completed by one operation, and the measuring light irradiation The split optical system in the optical system can be eliminated. Further, the focus of the measuring light receiving optical system may be linked with any one of the other.
[0060]
Furthermore, in this embodiment, the examiner focuses while watching the television monitor 21, but by switching the optical path switching mirror 17, the examiner directly focuses while observing the fundus oculi Ea of the eye E to be examined. May be performed.
[0061]
【The invention's effect】
As explained above Book A fundus examination apparatus according to the present invention is a focusing optical system for measuring optical systems, such as a blood vessel detecting system or a speed detecting system, in which it is difficult for an examiner to confirm a focused state from an output signal thereof. By providing interlocking means for interlocking the focusing means of the observation optical system observed by the examiner in the optical axis direction while maintaining the conjugate relationship, the light receiving surface of the measuring light receiving optical system is securely arranged at the fundus conjugate position. It is possible to prevent the light beam deflecting means for moving the measurement site from acting on the observation optical system, so that alignment and measurement operation of the device are simplified as in a normal ophthalmic device. And a more accurate fundus examination can be performed more effectively.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fundus blood flow meter.
FIG. 2 is an explanatory diagram of a light beam arrangement on a pupil.
FIG. 3 is an explanatory diagram of a confocal optical system.
[Explanation of symbols]
1 Light source for observation
20 CCD camera
21 LCD TV monitor
22 Image Rotator
23 Galvanometric mirror
24 Meniscus for optical path length correction
29 Focusing Unit
38 Laser Diode
40 Light source for tracking
45 One-dimensional CCD
46 Interlocking means
47 Focus position detection means
51a, 51b Photomultiplier
53 input means
55 Blood vessel position detection circuit

Claims (6)

Light deflecting means arranged at a position substantially conjugate to the pupil of the subject's eye, an illumination optical system for illuminating the fundus, an observation optical system for observing the fundus, and a measurement light irradiation optical system for examining blood vessels in the fundus; In a fundus examination apparatus having a light receiving optical system for measurement arranged behind the light deflecting means, an interlocking means for moving the focusing means of the light receiving optical system for measurement and the focusing means of the observation optical system in the optical axis direction. A fundus examination device characterized by comprising means. The fundus examination apparatus according to claim 1, wherein the light receiving optical system for measurement is a confocal optical system for the fundus of the eye to be inspected. The focus position detecting means is provided in at least one of four optical systems of the illumination optical system, the observation optical system, the measurement light irradiation optical system, and the measurement light receiving optical system. Fundus examination device. The fundus examination apparatus according to claim 3, further comprising: a control unit that receives an output signal from the in-focus position detection unit and calculates an imaging magnification or a refraction abnormal value of the subject. The fundus examination apparatus according to claim 1, wherein the interlocking unit interlocks the target display unit of the illumination optical system in an optical axis direction . The fundus examination apparatus according to claim 1, wherein the interlocking unit also interlocks the focusing unit of the measurement light irradiation optical system in the optical axis direction .

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