JPH119565A - Ophthalmorheometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a highly accurate measurement regardless of the size of the diameter of a blood vessel by matching a light receiving stop with the diameter of the blood vessel. SOLUTION: The diameter of a blood vessel is calculated by a blood vessel diameter measuring means 54 from a blood vessel image signal of a blood vessel as part to be measured from a one-dimensional CCD 45 and a system control part 52 outputs a drive signal to a measuring light irradiation range varying means 39 and drive means 38 and 50 within a light receiving stop varying means 51 referring to a table for determining the size of a measuring light stop 35 and a confocal stop 47 with respect to the diameter of the blood vessel based on the data of the size of the blood vessel calculated and the drive means 38 and 50 insert the measuring light stop 35 and the confocal stop 47 respectively with the optimum size thereof into an optical path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus blood flow meter for measuring a blood flow velocity in a blood vessel on a fundus.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for measuring the blood flow velocity of the fundus, as described in Japanese Patent Application Laid-Open No. 55-75670, a concave lens as a beam diameter conversion lens or a beam diameter conversion lens is provided in the optical path of a measurement light irradiation optical system. Devices for inserting a convex lens are known. In this case, the beam diameter is large when a concave lens is inserted, the beam diameter is small when a convex lens is inserted,
By configuring so as not to enter when none enters, the magnitude of the measurement light is changed in three stages to make the measurement range variable.

[0003]

However, in the above-described conventional example, only by changing the beam diameter of the measuring light,
Since the size of the light receiving aperture must be adjusted to the largest beam diameter, when the beam diameter is small, the scattered light from the tissue around the blood vessel enters the measuring light receiving optical system, and the measurement accuracy increases. The problem of lowering occurs.

On the other hand, when a light-receiving aperture is arranged at a position substantially conjugate to the fundus of the measuring light receiving optical system, and a measuring light aperture for defining the size of the measuring light on the fundus is arranged in the measuring light irradiation optical system, As shown in FIG. 8, there is no problem when the image U of the measurement light and the image S of the light reception stop on the fundus, which are narrowed by the measurement light stop, and the blood vessel diameter of the measurement site are almost the same, Since the size of the light-receiving aperture is fixed, for example, as shown in FIG. 9, when the blood vessel diameter of the measurement site is large, the measurement light may not be applied to the blood vessel center where the blood flow velocity is maximum.
Conversely, when the diameter of the blood vessel at the site to be measured is small as shown in FIG. 10, unnecessary reflected light from a site around the blood vessel enters the measuring light receiving optical system, and the measurement accuracy is deteriorated. There is a title.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a fundus blood flow meter capable of performing highly accurate measurement regardless of the size of a blood vessel diameter.

[0006]

A fundus blood flow meter according to the present invention for achieving the above object has a measuring light irradiation optical system for measuring a blood flow in a blood vessel of a fundus, and a scattered light from the blood vessel. In a fundus blood flow meter having a measurement light receiving optical system that receives light, and a light reception stop arranged at a substantially conjugate position of the fundus in the measurement light reception optical system, a light reception stop variable unit that changes the size of the light reception stop is provided. It is characterized by having been provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a configuration diagram of a fundus blood flow meter according to 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. For example, a field lens 4 with a band-pass filter that transmits only light of the wavelength of Yellow Castle, 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 8, which is a fixation target display element movable along the optical path, a relay lens 9, a light-shielding member 10 conjugate with the vicinity of the cornea of the eye E to be inspected, a perforated mirror 11, and a wavelength light of the yellow castle. Band-bass mirrors 12 that almost reflect other light beams are sequentially arranged.

The ring slit 5, the light shielding members 6, 1
Numeral 0 is for separating the fundus illumination light and the fundus observation light in the anterior segment of the eye E, and its shape does not matter as long as it forms a necessary light-shielding region.

A fundus observation optical system is provided behind the perforated mirror 11, and includes a focusing lens 13, a relay lens 14, and a scale plate 1 movable along an optical path.
5. An optical path switching mirror 16 and an eyepiece 17 which can be inserted into and removed from the optical path are sequentially arranged to reach an 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 a liquid crystal monitor 20. .

An image rotator 21 and a double-side polished galvanometric mirror 22 having a rotation axis perpendicular to the paper are disposed on the optical path in the reflection direction of the band bus mirror 12, and a lower reflection surface 22a of the galvanometric mirror 22 is provided. The second focus lens 23 is disposed in the reflection direction of the lens, and the lens 24 is disposed in the reflection direction of the upper reflection surface 22b.
A focus unit 25 movable along the optical path is provided. Note that the front focal plane of the lens 24 is
Has a conjugate relationship with the pupil Ep, and a galvanometric mirror 22 is arranged at the focal plane.

An optical path length compensating meniscus 26, a black spot plate 27 having a light-shielding portion in the optical path, and a concave mirror 28 are arranged behind the galvanometric mirror 22, and reflected by the lower reflective surface 22a of the galvanometric mirror 22. A relay optical system that guides a light beam that passes without being directed to the upper reflecting surface 22b of the galvanometric mirror 22 is configured. The meniscus 26 for correcting the optical path length is used to correct the position of the upper reflection surface 22b and the lower reflection surface 22a of the galvanometric mirror 22 in the vertical direction in the drawing caused by the mirror thickness. Rotator 21
It works only in the light path going to.

In the focus unit 25, a dichroic mirror 29 and a condenser lens 30 are arranged on the same optical path as the lens 24, and a shaping mask 31 and a mirror 32 are arranged on an optical path in the direction of reflection of the dichroic mirror 29. The focus unit 25 moves integrally in a direction indicated by an arrow.

On the optical path in the incident direction of the condenser lens 30,
Fixed mirror 33, optical path switching mirror 3 retractable from optical path
4 are arranged in parallel, and on the optical path in the incident direction of the optical path switching mirror 34, a measuring light stop 35 almost conjugate to the pupil Ep, a collimator lens 36, and a measuring laser diode 37 for emitting coherent red light, for example, are arranged. Have been. Measuring light stop 35 is driven by driving means 38 to form a measuring light irradiation range movable means 39.
As shown in FIG. 2, the disk has a plurality of apertures 35a, 35b, 35c of different sizes in a disk, and apertures of a selected size are inserted into the optical path.

Further, on the optical path in the incident direction of the mirror 32, a beam expander 40 composed of a cylindrical lens or the like, and a tracking light source 41 that emits, for example, green light different from other high-luminance light sources are arranged.

A second focusing lens 23, a dichroic mirror 42, a field lens 43, a magnifying lens 44, an image intensifier, which are movable along the optical path, are provided on the reflected optical path of the lower reflective surface 22a of the galvanometric mirror 22. The attached one-dimensional CCDs 45 are sequentially arranged to form a blood vessel detection system.

On the optical path in the direction of reflection of the dichroic mirror 42, an imaging lens 46, a confocal stop 47, and mirror pairs 48a and 48b substantially conjugate to the pupil Ep of the eye E to be examined are arranged. Photomultipliers 49a and 49b are arranged in the reflection direction of 48b, respectively, to form a light receiving optical system for measurement.

The confocal diaphragm 47 comprises a light-receiving diaphragm varying means 51 driven by a driving means 50. The confocal diaphragm 47 has a plurality of diaphragm holes 47a and 47 as shown in FIG.
b, 47c.
An aperture of a selected size is inserted into the optical path in the same manner as in (1). For convenience of illustration, all the optical paths are shown on the same plane, but the reflected optical paths of the mirror pairs 48a and 48b, the measuring optical path in the emission direction of the tracking light source 41, and the optical paths from the laser diode 37 to the mask 31 are respectively shown. It is perpendicular to the paper.

Further, a system control unit 52 for controlling the entire apparatus is provided.
Input means 53 operated by the examiner, photomultiplier 4
The outputs of the blood vessel diameter measuring means 54 are connected to the control circuit 55 for controlling the galvanometric mirror 22, the optical path switching mirror 34, and the driving means 38 for the measuring light stop 35. , Are connected to driving means 50 of the confocal aperture 47, respectively. The output of the one-dimensional CCD 45 is supplied to a galvanometric mirror control circuit 55 through a blood vessel position detection circuit 56.
It is connected to the.

FIG. 4 shows the arrangement of each light beam on the pupil Ep of the eye E to be examined. I denotes an area of the ring slit 5 illuminated by yellow illumination light, O denotes a fundus observation light beam and a perforated mirror 1.
1 is an image of an opening, V is a measurement / vessel received light beam, an image of an effective portion of the upper and lower reflection surfaces 22a and 22b of the galvanometric mirror 22, Da and Db are two measured light beams and an image of a mirror pair 48a and 48b, respectively. It is. Further, P2 and P2 'are incident positions of the measuring light, and indicate the positions of the measuring light selected by switching the optical path switching mirror 34, and a region M indicated by a chain line is a lower reflection surface 22a of the galvanometric mirror 22.
It is an image of.

The white light emitted from the observation light source 1 passes through the condenser lens 3 and only the yellow wavelength light is transmitted by the field lens 4 with the band-pass filter, passes through the ring slit 5, the light shielding member 6, and the relay lens 7, The transmissive liquid crystal plate 8 is illuminated from behind. The luminous flux from the transmissive liquid crystal plate 8 passes through the relay lens 9 and the light blocking member 10 and is reflected by the perforated mirror 11. Only the wavelength light in the yellow range passes through the band pass mirror 12, passes through the objective lens 2, Once formed as a fundus illumination light beam image I on the pupil Ep of the optometry E,
The fundus Ea is almost uniformly illuminated. At this time, a fixation target is displayed on the transmissive liquid crystal panel 8, and the subject's eye E
And is presented to the subject as a target image.

The light reflected from the fundus oculi Ea returns along the same optical path, is extracted from the pupil Ep as a light beam O for fundus oculi observation, and the opening at the center of the perforated mirror 11 and the focusing lens 1
3. Pass the relay lens 14 and the fundus image on the scale 15
After forming an image as Ea ′, the light reaches the optical path switching mirror 16. Here, when the optical path switching mirror 16 is retracted from the optical path, the fundus oculi image Ea 'can be observed by the examiner's eye e via the eyepiece 17, while the optical path switching mirror 1
When the lens 6 is inserted in the optical path, 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.

While observing the fundus image Ea ', the examiner performs alignment of the apparatus with the eyepiece 17 or the liquid crystal monitor 20. The measurement light emitted from the laser diode 37 is collimated by a collimator lens 36, shaped into a predetermined size by a measurement light stop 35, and when an optical path switching mirror 34 is inserted in the optical path, the optical path switching mirror 34 is fixed. When the light is reflected by the mirrors 33 and passes below the condenser lens 30, and 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.

On the other hand, the tracking light emitted from the tracking light source 41 has its beam diameter expanded by a beam expander 40 at different magnifications in the vertical and horizontal directions, is reflected by a mirror 32, is shaped into a desired shape by a mask 31, and is formed into a dichroic mirror. The light is reflected by 29 and is superimposed on the measurement light which is imaged in the form of a spot at a position conjugate with the center of the opening of the mask 31 by the condenser lens 30. The superimposed measurement light and tracking light pass through the lens 24 and are once reflected by the upper reflection surface 22b of the galvanometric mirror 22,
After passing through the black point plate 27, the light is reflected by the concave mirror 28, passes through the black point plate 27, the meniscus 26 for optical path length correction again, and returns to the galvanometric mirror 22.

Here, the galvanometric mirror 22 is arranged at a conjugate position of the pupil Ep of the eye E to be examined, and has a shape shown by a broken line M in FIG. The concave mirror 28, the black spot plate 27, and the meniscus plate 26 for optical path length correction are concentrically arranged on the optical axis, and cooperate to reduce the upper reflection surface 22b and the lower reflection surface 22a of the galvanometric mirror 22 by -1. The function of the relay optical system that forms an image is given. Therefore, by inserting and retracting the optical path switching mirror 34 into the optical path, the two light beams reflected at either of the positions P1 and P1 ′ shown in FIG. The light is returned to the positions P2 and P2 'located in the cutout portions of the galvanometric mirror 22, and goes to the image rotator 21 without being reflected by the galvanometric mirror 22. Then, both light beams deflected by the band-pass mirror 12 in the direction of the objective lens 2 via the image rotator 21 are emitted to the fundus oculi Ea of the eye E through the objective lens 2.

As described above, the measurement light and the tracking light are
When the light is reflected in the upper reflecting surface 22b of the galvanometric mirror 22 and returned again, the light is incident on the galvanometric mirror 22 in a state decentered from the optical axis of the objective lens 2, and as a result, as shown in FIG. Spot image
After the image is formed as P2 or P2 ', the fundus oculi Ea is illuminated in a point shape.

The scattered and reflected light from the fundus oculi Ea is reflected on the objective lens 2 again.
And is reflected by the band-pass mirror 12, passes through the image rotator 21, and passes through the galvanometric mirror 22.
Is reflected by the lower reflection surface 22a, passes through the focusing lens 23, and is separated from the measurement light and the tracking light by the dichroic mirror 42.

The tracking light is a dichroic mirror 4
2, the light passes through the field lens 43, and is imaged by the imaging lens 44 on the one-dimensional CCD 45 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 picked up by the one-dimensional CCD 45, data representing the moving amount of the blood vessel image is created in the blood vessel position detection circuit 56 and output to the galvanometric mirror control circuit 55. The control circuit 55 drives the galvanometric mirror 22 so as to compensate for this movement amount.

Further, the blood vessel image signal picked up by the one-dimensional CCD 45 is also output to the blood vessel diameter measuring means 54 to calculate the blood vessel diameter. The blood vessel diameter data is output to the system control unit 52, and the system control unit 52 refers to a table such as Table 1 that determines the size of the measurement light stop 35 and the confocal stop 47 with respect to the blood vessel diameter, and determines the size of each of them. The driving signal is output to the driving means 38, 50 such as a stepping motor.

Table 1 Measurement stop 35 Confocal stop 47 Small blood vessel diameter Small hole 35c Small hole 47a Medium blood hole Small hole 35b Small hole 47b Large blood vessel diameter Small hole 35a Small hole 47c

On the other hand, the measuring light is a dichroic mirror 42
Are reflected by the mirrors 48a and 48b through the opening of the confocal stop 47, and are received by the photomultipliers 49a and 49b, respectively. The light receiving signals of the photomultipliers 49a and 49b are output to the system control unit 52 and frequency-analyzed. At this time, because of the spectral characteristics of the band-pass mirror 12, the observation light source 1
The illuminating light does not reach the one-dimensional CCD 45 and the harmful flare light is hard to be mixed because the imaging range is set narrow. Therefore, only the blood vessel image by the tracking light is captured on the one-dimensional CCD 45. In addition, since blood hemoglobin and melanin on pigment epithelium have significantly different spectral reflectances in the green wavelength range, it is possible to capture a blood vessel image with good contrast by setting the tracking light to green light. .

Further, the fundus by the measuring light and the tracking light
A part of the scattered reflected light at Ea passes through the band-pass mirror 12 and is guided to the fundus observation optical system behind the perforated mirror 11, and the tracking light is placed on the scale plate 15 as shown in FIG.
The measurement light is formed as a spot image at the center of the indicator T as shown in FIG. These images are displayed on the eyepiece 17 or the liquid crystal monitor 2.
The image is observed together with the fundus image Ea ′ and the optotype image through 0. At this time, the spot image is observed superimposed on the center of the indicator T, and the indicator T can be moved one-dimensionally on the fundus oculi Ea by an operation member such as an operation rod of the input means 53.

At the time of measurement, the examiner first focuses the fundus image Ea '. When the focus knob of the input means 53 is operated, the transmission type liquid crystal plate 8,
The focusing lenses 13, 23 and the focus unit 25 move along the optical path in conjunction with each other. When the fundus image Ea 'is in focus, the transmissive liquid crystal plate 8, the scale plate 15, the one-dimensional CCD 45, and the confocal stop 47 are simultaneously conjugate with the fundus Ea.

At this time, the confocal stop 47 is for focusing on a desired blood vessel, and only reflects light reflected on a blood vessel at a specific depth to the photomultipliers 49a and 49.
By receiving light at b, it is possible to measure the blood flow velocity of a desired blood vessel.

That is, the fundus Ea to be measured in FIG.
When the position of the upper blood vessel is represented by the measurement site V1, and the position of the blood vessel in the choroid behind this blood vessel is represented by the measurement site V2, the light beam from the laser diode (not shown) enters the mirror 65 from below, and And irradiates the measurement site V1. The reflected light at the measurement site V1 is reflected by the mirror pair 48a, 48
The light passes through an aperture 66 having the same light receiving direction determining function as that of b, and is conjugated to the measurement site V1 by a lens 67.
8, the light is received by a photomultiplier (not shown). In this optical system, the reflected light at the measurement site V2 indicated by the dotted line forms an image by the lens 67 similarly to the light beam reflected at the measurement site V1 indicated by the solid line, but cannot pass through the small hole 68. No light is received by the photomultiplier.

After the focusing is completed, the examiner operates the input means 53 to move the target image, guide the line of sight of the eye E to change the observation area, and change the blood vessel to be measured to the scale plate. 15 moves to the predetermined position. And input means 5
The indicator T is rotated by operating the image rotator 21 with the operation rod 3 so that the indicator T is perpendicular to the traveling direction of the blood vessel to be measured.

At this time, since the fundus observation light does not pass through the image rotator 21, it is recognized that only the indicator T rotates. As a result, the pupil shown in FIG.
The image of each optical member on the Ep also rotates by the same angle in the same direction around the origin, and the straight line connecting the centers of the measured received light beams Da and Db and the centers of the spot images P1 and P1, that is, the x-axis Corresponds to the running direction of the blood vessel.

In this 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 T indicating the tracking light is the measurement blood vessel. , The fundus image Ea ′ indicated by the indicator T is enlarged and captured on the one-dimensional CCD 45 of the blood vessel detection system.

After the angle adjustment is completed, the input means 53
By operating the operating rod, the spot image superimposed on the tracking light is made to coincide with the measurement site, and the measurement site is selected. The one-dimensional CCD 45 outputs a blood vessel image signal of the blood vessel to be measured to the blood vessel diameter measuring means 54, and the blood vessel diameter is calculated. The calculated blood vessel diameter data is output to the system control unit 52,
The control unit 52 refers to the table in Table 1 that determines the correspondence between the measurement light stop 35 and the confocal stop 47 with respect to the blood vessel diameter, and refers to the measurement light irradiation range variable unit 39 and the driving unit 38 in the light reception stop variable unit 51, A drive signal is output to 50. Then, the driving means 38 and 50 respectively drive the measuring light stop 35 and the confocal stop 47 to select a stop hole.

That is, the variable apertures 35 and 47 shown in FIGS.
In the table of Table 1, for example, the aperture 35b is selected as the measurement light aperture 35, and the aperture 47 is selected as the confocal aperture 47.
If b is selected, as shown in FIG.
When the size of the image S of the confocal stop 47 and the size of the image U of the measuring light focused on the measuring light stop 35 are substantially the same as the blood vessel diameter, the sizes of the measuring light stop 35 and the confocal stop 47 do not change. .

On the other hand, when the blood vessel diameter is large as shown in FIG. 5B, the system control unit 52 determines that the size of the currently selected diaphragm is smaller than the blood vessel diameter calculated by the blood vessel diameter measuring means 54. It is determined that the measurement light stop 35 is inappropriate, and the measurement light stop 35 is changed to a smaller diameter 35a, and the confocal stop 47 is set to a larger diameter 4a.
7c, the drive signal is output to the drive means 38 and 50, respectively, resulting in B 'shown in FIG. Conversely, when the blood vessel diameter is small as in C shown in FIG. 5, the reverse of the above determination is made, the measurement light aperture 35 is changed to a larger aperture 35c, and the confocal aperture 47 is smaller. The diameter of the aperture 47a is changed to C 'shown in FIG. Thereafter, the input means 53 is operated again to input the start of tracking and the start of measurement, and the measurement is continued.

As described above, by providing the measuring light irradiation range changing means for changing the size of the measuring light in the measuring light irradiation optical system, the measurement accuracy can be improved without putting unnecessary light into the fundus of the eye E to be inspected. be able to. Further, the measurement is facilitated by calculating a blood vessel diameter from a blood vessel image signal obtained by imaging the blood vessel to be measured, and providing a control unit for controlling the size of the light-receiving aperture and the measurement light irradiation range in accordance with the blood vessel diameter.

In this embodiment, the size of the irradiation light of the irradiation optical system and the size of the light receiving area of the light receiving optical system are changed by using the stop. However, the size of the light beam is changed by inserting and removing the lens. You may make it. Also, the variable aperture 35,
47 is configured such that a disk having a plurality of apertures is rotated by a driving means to insert an aperture of a desired diameter into the optical path. May be switched.

Although the measuring light stop 35 is arranged almost at a conjugate position with the pupil Ep, it may be arranged almost at a conjugate position with the fundus oculi Ea.
Further, the measurement light stop 35 was used as a member constituting the measurement light irradiation range changing means in order to change the irradiation range on the fundus oculi Ea, but the lens group was inserted into and removed from the optical path to change the irradiation range optically. There is no problem.

In this embodiment, the blood vessel diameter measuring means 54 calculates the blood vessel diameter based on the blood vessel image signal picked up by the one-dimensional CCD 45, and the system control section 52 optimizes the measurement light stop 35 and confocal stop 47. Although the aperture hole is selected, a switching input means such as a switch is provided, and the examiner observes the blood vessel on the fundus oculi Ea and the spot size of the laser diode 27 as the measurement light, and the examiner It can also be configured to select itself.

Further, it is preferable that the measurement light stop 35 and the confocal stop 47 be changed at the same time, but the size of the stop hole of the measurement light stop 35 is made sufficiently large so that the confocal stop 47 is changed. The aperture may be used as a light receiving aperture, and only its size may be changed.

[0046]

As described above, in the fundus blood flow meter according to the present invention, the light receiving aperture is arranged at the fundus conjugate position in the measuring light receiving optical system, and the size of the light receiving aperture is changed to cover the fundus on the fundus. By receiving light from the measuring blood vessel, the diameter of the light receiving aperture can be increased in the case of a large blood vessel diameter to reliably measure the maximum blood flow velocity of the blood flow in the blood vessel. In the case of a small blood vessel diameter, the size of the light-receiving aperture can be reduced to prevent the influence of unnecessary reflected light from the peripheral portion, and the fundus blood flow velocity can be measured with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fundus blood flow meter according to an embodiment.

FIG. 2 is a front view of a measurement light stop.

FIG. 3 is a front view of a confocal stop.

FIG. 4 is an explanatory diagram of a light beam arrangement on a pupil Ep.

FIG. 5 is an explanatory diagram of beam diameter and size adjustment of a confocal stop.

FIG. 6 is an explanatory diagram of a confocal optical system.

FIG. 7 is an explanatory diagram of beam diameter and size adjustment of a confocal stop.

FIG. 8 is an explanatory diagram of a beam diameter and a light receiving aperture of a conventional example.

FIG. 9 is an explanatory diagram of a beam diameter and a light receiving aperture of a conventional example.

FIG. 10 is an explanatory diagram of a beam diameter and a light receiving aperture of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Observation light source 8 Transmission liquid crystal plate 19 CCD camera 20 Liquid crystal monitor 29, 42 Dichroic mirror 32 Galvanometric mirror 35 Measurement light stop 37 Laser diode 38, 50 Driving means 39 Measurement light irradiation range variable means 41 Tracking light source 45 One-dimensional CCD 47 confocal aperture 49a, 49b photomultiplier 51 variable light reception aperture 52 system control unit 53 input means 54 blood vessel diameter measurement means 55 galvanometric mirror control circuit 56 blood vessel position detection circuit

Claims (8)

[Claims] 1. A measuring light irradiation optical system for measuring a blood flow in a fundus blood vessel, a measuring light receiving optical system for receiving scattered light from the blood vessel, and a fundus substantially conjugate in the measuring light receiving optical system. A fundus blood flow meter having a light-receiving aperture disposed at a position,
A fundus blood flow meter, comprising a variable light-receiving diaphragm for changing the size of the light-receiving diaphragm. 2. The apparatus according to claim 1, further comprising a blood vessel diameter measuring means for measuring a blood vessel diameter of the blood vessel to be measured, and a control unit for receiving the output from the blood vessel diameter measuring means and controlling the light receiving aperture variable means. Fundus blood flow meter. 3. A confocal stop for limiting a light receiving area located at a position substantially conjugate with the fundus of the eye.
2. A fundus blood flow meter according to item 1. 4. The fundus blood flow meter according to claim 1, further comprising a measurement light irradiation range changing unit that changes the size of the measurement light emitted from the measurement light irradiation optical system on the fundus. 5. A blood vessel diameter measuring means for measuring a blood vessel diameter of a blood vessel to be measured, and a control unit for receiving said output from said blood vessel diameter measuring means and controlling said measuring light irradiation range variable means and said light receiving aperture variable means. The fundus blood flow meter according to claim 4, comprising: 6. The fundus blood flow meter according to claim 4, further comprising a switch input means for switching between the measurement light irradiation range changing means and the light receiving aperture changing means. 7. The fundus blood flow meter according to claim 4, wherein the measurement light irradiation range changing means is a variable measurement light stop. 8. The fundus blood flow meter according to claim 4, wherein the measurement light irradiation range changing means changes the irradiation range optically.