JP2000037351A - Eyeground examination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and precisely measure a blood stream velocity and a bloodstream quantity by precisely tracking and localizing a blood vessel. SOLUTION: The signal of a one-dimensional CCD is sample-held and amplified by a prescribed gain to make a waveform (a) and it is given noise removing processing by a low-pass filter, next (b). Consequently, a peak holding circuit add-processes only a blood vessel image-extracted signal (c) and an offset circuit deletes a background part which is not required for extracting a specific point (d). In addition, after differential processing (e), a zero cross comparing part extracts a zero cross point and a part for discriminating the number of blood vessels discriminates a blood vessel to be single and outputs a blood vessel localization signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus examination apparatus for examining blood vessels on the fundus in an ophthalmic clinic or the like.

[0002]

2. Description of the Related Art Conventionally, a fundus blood flow meter irradiates a blood vessel to be measured in the fundus of an eye to be examined with a laser beam having a wavelength of λ, receives the scattered reflected light by a photodetector, and scatters the blood from the blood flow in the blood vessel. This device detects an interference signal between a Doppler shift component that is reflected light and scattered reflected light from a stationary blood vessel wall, and analyzes the frequency to obtain a blood flow velocity.

The blood flow velocity is the maximum velocity calculated from the following equation.
It can be obtained from Vmax. Vmax = {λ / (n · α)} · || Δfmax1 | − | Δfmax2 || / cosβ (1)

Here, the maximum shift of the frequency calculated from the light reception signals received by the two light receivers is represented by Δfmax1 and Δfmax.
2. The refractive index of the measurement site is n, the angle between the two light receiving optical axes in the eye 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. .

[0005] As described above, by performing measurement from two directions, the contribution of the incident direction of the measurement light is cancelled, and the blood flow velocity at an arbitrary site on the fundus can be measured. Also, 2
By making the angle β between the intersection line between the plane formed by the two light receiving optical axes and the fundus and the velocity vector of the blood flow coincide, β =
At 0 °, the true maximum blood flow velocity can be measured.

In a fundus blood flow meter that measures the blood vessel shape and blood flow velocity of a specific portion of a fundus blood vessel using this laser beam, the measurement light beam accurately strikes the measurement portion within the measurement processing time. Although it is necessary, it is difficult to keep the measurement light beam accurately applied to the measurement site due to the fact that the subject's eye has slight fixation. Therefore, an apparatus having a tracking means for detecting the position of a blood vessel and moving the irradiation position of the measurement light beam on the measurement site in real time in response to fixation fine movement is disclosed in Japanese Patent Application Laid-Open No. 63-288133. It is disclosed in, for example, JP-A-6-503733.

[0007] In these ophthalmologic devices, light receiving means for receiving a reflected light beam from the fundus due to the tracking light beam is
Performs waveform processing of the blood vessel image signal using a one-dimensional CCD,
Tracking is performed by calculating the amount of deviation between the tracking reference position and the position signal of the blood vessel image, and employs a method of irradiating the tracking light and the measurement light onto the fundus through a pupil conjugate position mirror. Further, when there are a plurality of position signals of blood vessel images, there is a method of performing tracking control based on a blood vessel position signal closest to the tracking reference position.

[0008]

However, in the above-described conventional example, when a thick blood vessel having a high contrast is selected as a measurement object, specularly reflected light from the blood vessel wall is observed at the center of the blood vessel. The signal may be observed as if there are two blood vessels. In this case, since two or more blood vessel position signals are present, tracking control is performed based on the blood vessel position signal closest to the tracking reference position. And the tracking becomes unstable.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a fundus examination apparatus that performs accurate tracking and easily and accurately measures blood vessel information of the fundus.

[0010]

According to the present invention, there is provided a fundus examination apparatus for illuminating a region including a target fundus blood vessel, and an image obtained by imaging a blood vessel image of the region. An imaging unit that outputs a signal; a singularity calculating unit that calculates a plurality of local maximum points and local minimum points of the blood vessel image; a distance information or a local maximum point between the local maximum points and the local minimum points detected by the singularity calculating unit And blood vessel information calculating means for calculating blood vessel information using at least one of the amplitude information of the minimum point.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 shows a configuration diagram of a fundus blood flow meter according to an embodiment. An eye E to be examined is provided on an illumination optical path from an observation light source 1 such as a tungsten lamp that emits white light to an objective lens 2 facing the eye E. A transmissive liquid crystal plate 3, a relay lens 4, a perforated mirror 5, which is a fixation target display element which is optically conjugate with the fundus of the eye and is movable along the optical path; Are sequentially arranged. A fundus observation optical system is arranged behind the perforated mirror 5, and an imaging lens 7 and an eyepiece 8, which are movable along an optical path, are arranged.
It has reached examiner's eye e.

An image rotator 9 and a galvanometric mirror 11 having a rotation axis perpendicular to the paper surface and polished on both sides are disposed on the optical path in the reflection direction of the band-pass mirror 6, and a lower reflection surface of the galvanometric mirror 11 is provided. 11a
In the direction of reflection, a relay lens 12 that is movable along the optical path is disposed, and in the direction of reflection of the upper reflecting surface 11b, a lens 13 having a front focal plane conjugate with the pupil of the eye E to be examined,
A focus unit 14 movable along the optical path is provided. The galvanometric mirror 11 has a notch below the rotation axis, and is arranged on the front focal plane of the lens 13. Also, galvanometric mirror 11
Behind, a lens 15 and a concave mirror 16 are arranged, and a lower reflective surface 11a of the galvanometric mirror 11 is disposed.
A relay optical system that guides a light beam not passing through the notch but reflected by the notch to the upper reflection surface 11b of the galvanometric mirror 11 is configured.

In the focus unit 14, a dichroic mirror 17 is disposed on the same optical path as the lens 13, and a mask plate 18 having a rectangular diaphragm and a mirror 19 are disposed on an optical path in the reflection direction of the dichroic mirror 17. Have been. A lens 20 is arranged on the optical path in the transmission direction of the dichroic mirror 17, and the focus unit 14 can be moved integrally. Also,
A measurement light source 21 such as a laser diode that emits collimated coherent red light is provided on the optical path in the incident direction of the lens 20, and is different from other light sources on the optical path in the incident direction of the mirror 19. For example, a high-intensity tracking light source 22 that emits green helium neon laser light is disposed.

A relay lens 12, a dichroic mirror 23, a magnifying lens 24, an image intensifier 25, and a one-dimensional CCD 26 are provided on the optical path in the direction of reflection of the lower reflecting surface 11a of the galvanometric mirror 11 along the optical path. Are sequentially arranged to form a blood vessel detection system. In addition, photomultipliers 27 and 28 are arranged in the reflection direction of the dichroic mirror 23 to form a light receiving optical system for measurement. For convenience of illustration,
Although all optical paths are shown on the same plane, the reflection direction of the dichroic mirror 23 and the like are actually orthogonal to the paper.

A system control unit 29 for controlling the entire apparatus is provided. The system control unit 29 includes an image intensifier 25, a one-dimensional CCD 26, photomultipliers 27 and 28, and input means 30 operated by an examiner. Are connected to each other, and the output of the system control unit 29 is the transmission type liquid crystal panel 5 and the display means 3 for displaying the measurement result.
1. It is connected to a galvanometric mirror control circuit 32 that controls the galvanometric mirror 11.

The transmission type liquid crystal plate 3, the image forming lens 7, the relay lens 12, and the focus unit 14 are operated by operating a focusing knob (not shown) so that the transmission type liquid crystal plate 3, the examiner's eye e, the mask plate 18, and the image in. The light receiving surface of the tensifier 26 is moved in the optical axis direction in conjunction with each other so that the light receiving surface is always optically conjugate with the fundus oculi Ea of the eye E to be inspected.

FIG. 2 shows a block diagram of the system control unit 29. Outputs of the image intensifier 25 and the photomultipliers 27 and 28 are connected to a processing condition determination unit 42 via respective control circuits 40 and 41. The output of the input means 30 is
It is connected to the.

The output of the one-dimensional CCD 26 is connected to a low-pass filter circuit 45 via a sample-and-hold circuit 43 and an amplifier 44, and the output of the low-pass filter 45 is connected to an addition circuit 46 together with an output via a peak-hold circuit 47. . The output of the adding circuit 46 is connected to an offset circuit 48 for removing unnecessary signal levels and a differentiating circuit 49 in order, and the output of the differentiating circuit 49 is a zero-cross comparing circuit 50.
Each is connected to a differentiating circuit 51.

The output of the zero-cross comparison circuit 50 is connected to a blood vessel number discriminating section 52 and a blood vessel position calculating section 53, and the output of the blood vessel number discriminating section 52 is connected to the blood vessel position calculating section 53. The output forms a tracking control system and is connected to a galvanometric mirror control circuit 32. The output of the offset circuit 48 and the output of the differentiating circuit 51 are connected to the blood vessel number determining unit 52. Further, the output of the differentiating circuit 51 is connected to the blood vessel diameter calculating unit 54, and the output of the differentiating circuit 49 and the output of the blood vessel number determining unit 52 are connected to the blood vessel diameter calculating unit 54, respectively. The low-pass filter 47, the addition circuit 46, the peak hold circuit 47, the offset circuit 48, the differentiation circuits 49 and 51, and the zero-cross comparison circuit 50 constitute a singular point extraction unit 55.

With such a configuration, the white light emitted from the observation light source 1 illuminates the transmission type liquid crystal plate 3 from behind, passes through the relay lens 4, is reflected by the perforated mirror 5, and has a wavelength in the yellow range. Only the light passes through the band-pass mirror 6, passes through the objective lens 2, forms an image of a fundus illumination light beam once on the pupil Ep of the eye E, and then illuminates the fundus Ea substantially uniformly.
At this time, a fixation target (not shown) is displayed on the transmissive liquid crystal plate 3, and this fixation target is formed by the illumination light and the fundus of the eye E to be examined.
The image is projected on Ea and presented to the eye E as a target image.

The reflected light from the fundus Ea returns along the same optical path, is extracted as a fundus observation light beam from the pupil Ep, passes through the center opening of the perforated mirror 5, the image forming lens 7, and the eyepiece lens by the examiner's eye e. The eye fundus image Ea 'can be observed via.

The measuring light emitted from the measuring light source 21 is collimated, passes through the lens 20 and passes through the dichroic mirror 17.
Through. The tracking light emitted from the tracking light source 22 is reflected by the mirror 19 and is reflected by the mask plate 18.
After being shaped into a desired shape by, the light is reflected by the dichroic mirror 17 and superimposed on the measurement light. At this time, the measurement light is imaged by the lens 20 into a spot at a position conjugate with the center of the opening of the mask plate 18.

Further, the measuring light and the tracking light are transmitted through the lens 1
3, the light is reflected by the upper reflecting surface 11b of the galvanometric mirror 11, passes through the lens 15 once, is reflected by the concave mirror 10, passes through the lens 15 again, and returns to the direction of the galvanometric mirror 11. Here, the galvanometric mirror 11 is arranged at a conjugate position with the pupil of the eye to be examined, and the concave mirror 10 and the lens 15 are arranged concentrically on the optical axis. Since it has the function of a relay system that forms an image with
The light flux is returned to the notch of the galvanometric mirror 11 and goes to the image rotator 9 without being reflected by the galvanometric mirror 11. Then, both light beams deflected by the bandpass mirror 6 to the objective lens 2 via the image rotator 9 are irradiated to the fundus oculi Ea of the eye E through the objective lens 2.

As described above, when the measurement light and the tracking light are reflected in the upper reflecting surface 11b of the galvanometric mirror 11 and return to the optical path again, the measurement light and the tracking light are decentered from the optical axis of the objective lens 2 and are applied to the galvanometric mirror 11. After being incident and forming a spot image on the pupil Ep, the fundus oculi Ea is illuminated in a point shape.

The scattered reflected light from the fundus oculi Ea due to the measurement light and the tracking light is condensed again by the objective lens 2, most of the light flux is reflected by the bandpass mirror 6, passes through the image rotator 9, and passes through the galvanometric mirror 11. The measurement light and the tracking light are reflected by the lower reflection surface 11a, pass through the relay lens 12, and are separated by the dichroic mirror 23.

The tracking light is a dichroic mirror 2
3 is formed on the photocathode of the image intensifier 26 as a blood vessel image Ev 'which is larger than the fundus image Ea' by the fundus observation optical system by the magnifying lens 24, and is amplified on the one-dimensional CCD 26 after being amplified. Is imaged. Then, based on the blood vessel image Ev 'picked up by the one-dimensional CCD 26, data representing the moving amount of the blood vessel image Ev' is created in the system control unit 29, and the galvanometric mirror control circuit 3
The blood vessel image Ev 'and the movement amount are output to 2. Then, the galvanometric mirror control circuit 32 drives the galvanometric mirror 11 so as to compensate for this movement amount, so that tracking of the blood vessel in the measured portion is performed.

On the other hand, the measuring light is a dichroic mirror 23
And are received by the photomultipliers 27 and 28. The outputs of the photomultipliers 27 and 28 are output to the system control unit 29, and the received light signal is subjected to frequency analysis in the same manner as in the conventional example, and the blood flow velocity of the fundus oculi Ea is obtained.

Further, the fundus by measuring light and tracking light
The scattered reflected light from Ea is condensed by the objective lens 2, and a part of the light flux passing through the band-pass mirror 6 is
The light reaches the examiner's eye e by following the same optical path as the reflected and scattered light from the fundus oculi Ea, and can be observed by the examiner as the measurement light image and the tracking index image A together with the fundus oculi image Ea '.

When examining the blood vessels in the fundus, the examiner first operates the operating rod (not shown) to perform positioning so that the optical axis of the eye E and the optical axis of the objective lens 2 coincide.
Next, a focus knob (not shown) is operated while observing the fundus image Ea 'to focus on the fundus oculi Ea of the eye E to be examined. When the subject is in focus, the fixation target of the transmissive liquid crystal plate 3 and the fundus oculi Ea are optically conjugated and presented to the subject's eye E. When the subject fixates the fixation target image, the examiner examines the subject's eye. Fundus image E of E
a 'can be observed. The examiner operates the input means 30 so that the measurement site reaches approximately the center of the observation visual field, moves the fixation target, and guides the eye E to be inspected.

Next, the input means 30 is operated to irradiate the fundus Ea with the tracking light, and the rotator operation knob (not shown) is operated so that the tracking index image A is perpendicular to the blood vessel to be measured. The angle of the galvanometric mirror 11 is controlled so that the measurement light is emitted.

FIG. 3 shows a fundus image Ea 'observed at this time, FIG. 3 shows a case where a thin blood vessel is selected as a measurement object, FIGS. 4 and 5 show a case where a thick blood vessel is selected, and FIG. When one blood vessel is irradiated with tracking light,
FIG. 5 shows a case where two blood vessels are irradiated. The blood vessel Ev irradiated by the tracking light is a blood vessel image E
The image is formed on the photoelectric surface of the image intensifier 26 as v ′, amplified and then imaged on the one-dimensional CCD 26,
It is output as a blood vessel image signal.

FIG. 6 shows a flow of a tracking signal when a thin blood vessel having no regular reflection from the blood vessel wall at the center of the blood vessel as shown in FIG. 3 is selected as a measurement object. After determining the measurement site, the examiner operates the input means 30 again to input the start of tracking. After the output signal of the one-dimensional CCD 26 is sampled and held by the sample and hold circuit 43, it is input to the amplifier 44 and amplified with an appropriate gain.
The output signal waveform is as shown in FIG. This output signal is input to the low-pass filter 45, where noise removal processing for cutting unnecessary high-frequency components is performed, and a waveform as shown in FIG. 6B is output.

Further, in order to extract only the blood vessel image, the peak hold circuit 47 performs a peak hold process, and the output signals of the low-pass filter 45 and the peak hold circuit 47 are added by an adder circuit 46, as shown in FIG. The signal has a waveform as shown. The output signal of the adding circuit 46 is input to the offset circuit 48, and first, the amplitude of the signal is calculated. Based on the amplitude information of the signal, the level at which the unnecessary signal is deleted is determined, and the background portion unnecessary for extracting the singular point of the blood vessel portion is saturated and deleted using the offset circuit 48.
The signal has the waveform shown in (d).

In this embodiment, the offset amount is determined at a level of about 1/3 of the amplitude indicated by the broken line in FIG. 6C, and the offset is set so as to saturate and delete unnecessary background portions. It is. The offset level is fixed at 1/3 of the amplitude, but may be variable according to the amplitude of the signal. The output signal of the offset circuit 48 is differentiated by a differentiating circuit 49, and a waveform as shown in FIG. 6 (e) is output and input to the zero-cross comparator 50. Furthermore,
This signal extracts a zero cross point and is input to the blood vessel position calculating unit 53, where it is treated as a blood vessel position signal.

On the other hand, the output of the differentiating circuit 49 is
The output signal is input to the blood vessel number determining unit 52, and it is determined whether the zero-cross point extracted by the zero-cross comparing unit 50 by the code determination is calculated from the maximum point or the minimum point of the blood vessel image. In this case, since there is only one zero cross point, the number of blood vessels
Is determined to be one blood vessel, the blood vessel position calculating unit 53
And the blood vessel position calculating section 53 outputs a blood vessel position signal as shown in FIG.

Similarly, FIG. 7 shows the flow of tracking signal processing when one thick blood vessel as shown in FIG. 4 is irradiated with the tracking beam, and FIG. 8 shows two blood vessels as shown in FIG. 2 shows a flow of a tracking signal process when is irradiated with a tracking beam.

When a thin blood vessel is selected as the object to be measured as shown in FIG. 3, the blood vessel position calculating section 53 calculates the deviation of the blood vessel position signal closest to the tracking reference position as shown in FIG. The galvanometric mirror 11 is driven by the galvanometric mirror control circuit 32 based on the deviation X, and the image receiving position of the blood vessel image Ev 'on the one-dimensional CCD 26 is changed as shown in FIG. It is controlled to be on the tracking reference position. Since the spot-shaped measurement light beam is irradiated on the fundus oculi Ea while being superimposed on the central position corresponding to the one-dimensional reference position of the tracking light, the measurement blood vessel Ev can be accurately captured by the tracking system.

On the other hand, when a thick blood vessel having a strong contrast is selected as a measurement object as shown in FIG. 4, specular reflection of the blood vessel wall is observed at the center of the blood vessel, and the image signal is as if two blood vessels were present. May be observed as present. If the zero cross point is treated as a blood vessel position signal in such a case, three points A, B, and C are extracted as shown in FIG. FIGS. 10A, 10B, and 10C show a blood vessel image signal and a blood vessel position signal when the blood vessel image changes due to eye movements such as a fixation eye movement. When the blood vessel position calculation unit 53 calculates the deviation of the blood vessel position signal closest to the tracking reference position and performs tracking, in the case shown in FIG. Deviation X,
Since the magnitude relationship between Y and Z is Z <Y <X, control is performed such that the point C comes to the tracking reference position. Similarly, (b)
In the case shown in (1), the point B is tracked because Y <Z <X. In the case shown in (c), the point A is tracked because X <Z <Y. As a result, tracking is not stable when there is eye movement such as fine fixation.

As described above, when there are a plurality of blood vessel position signals, the output signal of the differentiating circuit 49 is further added to the differentiating circuit 5.
1, the blood vessel number discriminating unit 52 determines from the sign of the output signal of the differentiating circuit 51 synchronized with the zero-cross point output from the zero-cross comparing unit 50 that the zero-cross point is determined from either the maximum point or the minimum point of the blood vessel image. Determine if it was created. Next, the blood vessel number determination unit 52 extracts the three zero cross points of the minimum point, the maximum point, and the minimum point as one group, measures the distance between the zero cross points of the minimum points, and compares the distance with a predetermined width W1. As shown in FIG. 7 (e), the distance W between the zero cross points of the minimum points is the width.
If it is within W1, it is recognized as one blood vessel and output to the blood vessel position calculation unit 53.

Further, the blood vessel number discriminating section 52 calculates the level differences H and H 'between the two minimum points and the maximum points as shown in FIG. 7D with respect to the signal waveform input from the offset circuit 48. , The larger of the level differences H and H ′ is compared with the maximum amplitude F. In the present embodiment, it is set so that when H <F * 0.5, it is recognized as one blood vessel. Blood vessel number discriminator 52
Is determined to be one blood vessel from two parameters of the distance W between the zero cross point of the minimum point and the level difference H between the minimum point and the maximum point, and the blood vessel number information is sent to the blood vessel position calculation unit 53. Output.

As shown in FIG. 8E, if the distance T between the zero-cross points of the minimum points is equal to or greater than the width W1, the number-of-vessels determining unit 52 recognizes that the number of blood vessels is two. Next, the blood vessel number discriminating unit 52 calculates the level differences H and H 'between the two minimum points and the maximum points as shown in FIG. , H ′ is compared with the maximum amplitude F. In the present embodiment, when H <F * 0.5, the number of blood vessels determining unit 52 is set to recognize one blood vessel, so that it is determined to be two blood vessels.

Further, the number-of-vessels determining unit 52 determines two blood vessels based on the two parameters of the distance W between the zero-cross point of the minimum point and the level difference H between the minimum point and the maximum point.
The blood vessel number information is output to the blood vessel position calculating unit 53, and the blood vessel position calculating unit 53 uses only the minimum point as a blood vessel position signal.
A blood vessel position signal as shown in FIG. By performing tracking based on this blood vessel position signal,
Stable tracking performance can be obtained.

FIG. 11 shows a case where two blood vessels are adjacent to each other, a regular reflection of the blood vessel wall is observed at the center of each blood vessel, and the video signal is observed as if there are four blood vessels. I have. Also in this case, similarly, the blood vessel number discriminating unit 52
Determines from the sign of the output signal of the differentiating circuit 51 synchronized with the zero cross point of the output of the zero cross comparator 50 whether the zero cross point is generated from the maximum point or the minimum point of the blood vessel image waveform. Next, the blood vessel number determination unit 52 extracts three blood vessel position signals of the minimum point, the maximum point, and the minimum point as one group, and measures the distance T between the two groups. The distance T is compared with the predetermined width W1, and since T> W1, it is recognized as two or more blood vessels. As shown in FIG.
Since the level difference between the two minimum points and the maximum point is equal to the maximum amplitude F, it is determined that there are two or more blood vessels. Subsequently, the distance W between the zero crossing point of the minimum point of each group,
W ′ is measured and compared with a predetermined width W1, and W <W1, W ′ <W1
Therefore, each group is determined to be one blood vessel.

For the group on the right side of FIG.
The level differences H and H ′ between the two minimum points and the maximum points are calculated, and the larger one of the level differences H and H ′ is compared with the maximum amplitude F, and H> F
Since it is * 0.5, it is determined to be one blood vessel. Then, similar processing is performed on the left group, and the result is output to the blood vessel position calculation unit 53. Blood vessel number discriminator 52
Performs processing with the center maximum point as the center of the blood vessel, ignoring the zero cross points of the minimum points at both ends in the group, and outputs a blood vessel position signal as shown in FIG.

In the present embodiment, the predetermined width W1 and the level difference 0.5 between the two minimum points and the maximum point with respect to the amplitude are fixed values, but the examiner observes and measures the fundus image Ea '. The value of W1 may be input to the input means 30 and set manually according to the blood vessel.

Although the above description has been made based on the embodiment applied to the blood vessel tracking system of the fundus blood flow meter, the configuration and effect relating to the blood vessel identification have the same effect in the measurement of the blood vessel diameter. This is not a blood vessel position but information of a blood vessel diameter as information perpendicular to the running direction of the blood vessel. Therefore, the control flow is as follows.

The output signals of the low-pass filter 45, the differentiation circuit 49, the differentiation circuit 51, and the blood vessel number discriminating section 52 are inputted to the blood vessel diameter calculating section 54, where the original signal, the characteristic point of the blood vessel image, and the blood vessel The determination of the maximum point / minimum point of the feature points of the image is used as the information on the number of blood vessels, and the blood vessel diameter calculation unit 54 calculates the blood vessel diameter based on these pieces of information. .

The pass band is narrowed by setting the cutoff frequency of the low-pass filter 45 to a lower frequency side,
There is also a method of removing the specular reflection component of the blood vessel wall with the low-pass filter 45. There is a drawback that it is cut off by the low-pass filter 45. The present embodiment can solve this problem, and can calculate an accurate blood vessel position signal.

[0049]

As described above, the ophthalmologic examination apparatus according to the present invention uses at least one of the distance information between the plurality of maximum points and the minimum points detected by the singularity calculation means or the amplitude information of the maximum points and the minimum points. By calculating the blood vessel information using this method, even when a video signal in which two blood vessels are present due to the regular reflection of the blood vessel wall is observed, the location where two blood vessels are actually adjacent is measured. The case can be clearly distinguished from the case, and a blood vessel image signal at an optimal level can be obtained regardless of the contrast. As a result, accurate tracking and blood vessel position measurement can be performed, and the fundus blood flow velocity and the fundus blood flow can be easily obtained accurately.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a block diagram of a system control unit.

FIG. 3 is an explanatory diagram of an observation fundus image.

FIG. 4 is an explanatory diagram of an observation fundus image.

FIG. 5 is an explanatory diagram of an observation fundus image.

FIG. 6 is a graph of a tracking signal of a thin blood vessel.

FIG. 7 is a graph of a tracking signal of one thick blood vessel.

FIG. 8 is a graph showing tracking signals of two blood vessels.

FIG. 9 is a graph showing a deviation amount from a tracking reference position in the case of a thin blood vessel.

FIG. 10 is a graph showing a deviation amount from a tracking reference position in the case of a thick blood vessel.

FIG. 11 is a graph showing a deviation amount from a tracking reference position when two blood vessels are adjacent to each other.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Observation light source 3 Transmissive liquid crystal plate 6 Bandpass mirror 9 Image rotator 11 Galvanometric mirror 14 Focus unit 21 Measurement light source 22 Tracking light source 25 Image intensifier 26 One-dimensional CCD 27, 28 Photomultiplier 29 System control part Reference Signs List 30 input means 31 display unit 32 galvanometric mirror control circuit 42 processing condition determination unit 43 sample hold circuit 45 low pass filter 47 peak hold circuit 48 offset circuit 50 zero cross comparison unit 52 blood vessel number discriminating unit 53 blood vessel position calculation unit 54 blood vessel diameter calculation unit 55 Singularity calculation unit

Claims (3)

[Claims] An illumination unit configured to illuminate a region including a target fundus blood vessel, an imaging unit configured to capture a blood vessel image of the region and output a video signal, and a plurality of maximum points and minimum points of the blood vessel image. Singularity point calculating means for calculating, and blood vessel information calculation for calculating blood vessel information using at least one of distance information between a plurality of local maximum points and local minimum points or amplitude information of local maximum points and local minimum points detected by the specific point calculating means An ophthalmologic examination apparatus comprising: 2. The blood vessel information calculating means includes a blood vessel position calculating means for determining the number of blood vessels and calculating positional information of a blood vessel image from the information on the number of blood vessels and the output result of the singularity calculating means. A fundus examination apparatus according to claim 1. 3. The blood vessel information calculating means includes a blood vessel diameter calculating means for determining the number of blood vessels and calculating a blood vessel diameter from the blood vessel number information, the output result of the singular point calculating means and the blood vessel image. 2. The fundus examination apparatus according to 1.