JPH10295644A - Eye grounds photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deviation from being generated in an alignment by connecting a pupil detecting means to a first light receiving means for receiving an irradiation light from a front eye part illuminating light source which is reflected in the front eye part of an eye to be examined and guiding an optical axis of an grounds photographing optical system to the substantially center of the pupil detected by the pupil detection means. SOLUTION: When an inspector operates a jaw mount, adjusts a monitor display part so that a front eye part of an eye to be examined is reflected thereon, and presses a photograph button, a front part illuminating light source 21 for the alignment and an operation distance detection light source 19 are lit and the device 1 is advanced (moving frontward in the Z direction) so that the pupil image of the E to be examined is reflected on the front eye part image reflected on an image pick-up screen of an alignment camera 22. Secondly, a machine frame 2 is moved in the X direction or the Y direction so as to coincide the optical pupil of the eye grounds photographing optical system 3 with the pupil center. When a light receiving element 18 of an operation distance detecting optical system 5 detects a slit light (operation distance detection index) from the operation distance detecting light source 21, the movement of the machine frame 2 is made to stop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fundus photographing apparatus. More specifically, the present invention relates to a fundus photographing apparatus capable of easily and accurately aligning the apparatus with an eye to be examined.

[0002]

2. Description of the Related Art When photographing a fundus, it is necessary to automatically or manually perform an alignment operation and a working distance adjusting operation for making the optical pupil of the fundus photographing device coincide with the pupil of the eye to be examined.

Conventionally, a fundus photographing apparatus disclosed in Japanese Patent Application Laid-Open No. 8-275921 is known as a fundus photographing apparatus for automatically performing such an alignment operation and a working distance adjustment operation.

In the alignment operation in this fundus photographing apparatus, first, the subject is fixed by fixing the subject's eye by staring a predetermined fixation lamp, and a parallel light (alignment index) is applied to the anterior eye of the subject's eye from the front. Light), and aligning the optical axis of the fundus imaging device with the vertex of the surface of the eye to be inspected (the point closest to the imaging device on the surface of the eye to be inspected) based on the Purkinje image as a corneal reflection image. You. Further, the working distance adjusting operation is performed by projecting the working distance detection index light obliquely to the vertex of the eye to be inspected and detecting the index light reflected by the cornea from diagonally forward in parallel with the alignment operation. . Thereafter, the auto-focus index light is projected onto the fundus of the subject's eye through the fundus imaging optical system, and the focus lens and the like are moved along the optical path to focus on the fundus reflection index light received by the imaging video camera. Then, at the same time that the focus is achieved, the strobe discharge tube emits light to illuminate the fundus, and the fundus image is photographed by the photographing video camera.

Although there are devices that perform the above operations manually, they require considerable skill, and there is no guarantee that alignment, focusing, and the like are performed accurately.

[0006]

When photographing the fundus,
Depending on the purpose of the examination and the location of the affected area, it may be necessary to take an image centered on an arbitrary part of the fundus. In such a case, although not disclosed in the above-mentioned publication, usually, the subject's eye is rotated to take an image by moving a fixation lamp or turning on one of a plurality of fixation lamps. That is, by rotating the subject's eye by a small angle, the intersection between the fundus and the optical axis of the fundus imaging optical system is changed.

However, according to the alignment operation in the prior art, as described above, the alignment index light projected on the anterior ocular segment is reflected at the apex, that is, the optical axis of the fundus photographing optical system is adjusted to the eye to be examined. The fundus photographing optical system is moved so as to cross the vertex. Therefore, as shown in FIG. 5A, when the fixation lamp S stared by the subject having the normal eye is aligned so as to be on the optical axis ua of the fundus imaging optical system, the fundus imaging optical system Since the optical axis ua substantially coincides with the pupil center PC of the eye E to be examined, there is no problem.

[0008] That is, when the fixation lamp is displaced in order to photograph a different part as a center, as shown in FIG. 5 (b), the vertex of the eye E to be rotated and displaced in accordance with the displacement of the fixation lamp S When the optical axis of the fundus imaging optical system coincides with the ER, the optical axis ua of the fundus imaging optical system may be set at a position deviated from the pupil center PC of the eye E to be examined. As a result, even if the working distance detection operation is completed, the optical pupil of the fundus imaging apparatus does not completely coincide with the pupil P of the eye to be inspected (dimension L in the figure).
Only comes off). As a result, a part of the illumination light is blocked by the iris, so-called vignetting occurs, and there is a problem that a clear fundus image cannot be obtained as a whole. Further, when the eye E is oblique or the like, the eye may be rotated more than the normal rotation angle of the eye for the same fixation lamp transition.
The above problem will be exacerbated.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a fundus illumination optical system;
Fundus photographing optical system, in a fundus photographing apparatus having a focusing optical system, from the light source for anterior segment illumination to illuminate the anterior segment of the eye to be examined and the light source for anterior segment illumination reflected by the anterior segment A first alignment optical system having first light receiving means for receiving illumination light, a pupil detecting means connected to the first light receiving means, and an optical axis of the fundus photographing optical system, the pupil detecting means And first guiding means for guiding the pupil to the substantial center of the pupil.

Due to such structural features, when aligning the fundus photographing apparatus, the optical axis of the fundus photographing optical system always coincides with the center of the pupil even if the subject's eye rotates and moves with the change of the fixation lamp. Let me do. Therefore, the optical pupil of the fundus photographing apparatus always coincides with the center of the pupil even in the working distance detection operation without causing an alignment error. As a result, it is possible to photograph an arbitrary part of the fundus under optimal conditions. Note that the match here does not only mean a perfect match between the optical pupil of the device and the center of the pupil, but also includes a case where the optical pupil of the device is near the center of the pupil.

The above-mentioned fundus photographing apparatus is further provided with an alignment index projecting optical system for irradiating the anterior segment of the subject's eye with parallel light from the front and an index beam from the alignment index projecting optical system reflected by the anterior segment. Also provided is a second alignment optical system having a second light receiving means for receiving light, so that the optical axis of the fundus photographing optical system is guided to the vertex of the eye to be inspected by the first guiding means based on the received reflected image. With this configuration, the corneal apex can be detected in addition to the center of the pupil of the subject's eye. Therefore, it is determined whether the subject's eye is facing a predetermined direction (for example, whether the subject is staring at the fixation lamp). understand,
This is preferable because information on the line of sight including the deviation between the axis of the eye to be examined and the line of sight, such as whether or not the subject is oblique, can be obtained.

Further, in the fundus photographing apparatus wherein the first light receiving means is configured to receive the reflected light of the anterior ocular segment along the optical axis of the fundus photographing optical system, The light source for anterior segment illumination, the light receiving means, and the pupil detecting means are integrally provided on the machine frame, and can be integrally moved for the alignment operation and the working distance detecting operation.

In the above fundus photographing apparatus, the pupil detecting means is configured to detect a center of gravity of a low lightness range corresponding to the pupil in the received anterior ocular segment reflected light, and the first guiding means detects the fundus photographing. In an optical system configured to move the optical system so that its optical axis coincides with the center of gravity, a target position for alignment in the eye to be inspected can be directly and easily detected, and the detection accuracy is high. Is preferred.

The working distance detecting optical system detects a working distance based on a working distance detecting index projecting optical system for projecting an index toward an eye to be inspected and a reflected light from the cornea of the working distance detecting index. Working distance detecting means for detecting the corneal reflection light of the working distance detection index, the working distance detecting means for guiding the fundus imaging optical system in the direction of the eye to be examined, the second guiding means. In the apparatus further provided, since the working distance can be detected in addition to the alignment operation, the optical pupil of the fundus imaging optical system can be easily matched with the center of the pupil of the eye to be inspected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fundus photographing apparatus according to the present invention will be described based on an embodiment shown in the accompanying drawings.

FIG. 1 is a schematic layout diagram showing an embodiment of the fundus photographing apparatus of the present invention, FIG. 2 is an explanatory view showing the function of pupil detecting means in the fundus photographing apparatus of FIG. 1, and FIG. FIG. 4 is a flowchart showing an example of the operation of the apparatus, and FIG. 4 is a schematic layout diagram showing an alignment optical system in another embodiment of the fundus imaging apparatus of the present invention.

The fundus photographing apparatus 1 shown in FIG. 1 has two directions perpendicular to each other (the X direction and the Y direction) and the direction in which the eye E approaches and retracts (referred to as the Z direction). ), A machine frame 2 movable by a Z-direction drive mechanism 2z, an X-direction drive mechanism 2x, and a Y-direction drive mechanism 2y is provided. Each of the driving machines 2z, 2x, 2y can be constituted by a servomotor or the like.

On the machine frame 2, there are provided various components constituting an alignment optical system 4 for aligning (aligning) an optical axis of a fundus photographing optical system 3 with a pupil center PC of the eye E to be examined. Various devices constituting the working distance detecting optical system 5 for setting the working distance by matching the optical pupil of the fundus photographing optical system 3 with the pupil center PC of the eye E in parallel with the operation, the fundus of the eye E Various devices constituting a focusing optical system 6 for matching the focus of a fundus imaging optical system 3 to be described later with the fundus G when photographing the G, a fundus illumination for illuminating the fundus G for photographing the fundus G Various devices constituting the optical system 7 and various devices constituting the fundus photographing optical system 3 for photographing the fundus G are provided.

A fundus illumination optical system 7 includes a photographing light source 8 for illuminating a photographing portion of the fundus, and a mirror 9 for illuminating light from the photographing light source 8 to reach the fundus G through the pupil P from the front of the eye E to be examined. , Half mirror 10, and objective lens 11
And the like, which is equivalent to the apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-275921. The photographing light source 8 is composed of a strobe discharge tube.

The fundus photographing optical system 3 includes the fundus photographing television camera 12 and the objective lens 11 and the focus lens 13 for making the illumination light reflected by the fundus G reach the light receiving surface of the fundus photographing television camera 12. This is equivalent to the apparatus disclosed in the above-mentioned JP-A-8-275921.

In order to photograph the fundus by the above-described fundus photographing optical system 3, it is necessary to perform a focusing operation for previously setting the focus of the fundus photographing optical system 3 to the fundus G.

The focusing optical system 6 for performing focusing includes a focusing index light source 14, a half mirror 15 for directing index light from the focusing index light source 14 to the fundus G, the half mirror 10, The objective lens 11 and the reflected light of the focusing index from the fundus G are transmitted to the fundus photographing television camera 12.
Including the focus lens 13 that leads to
This is equivalent to the apparatus disclosed in the above-mentioned JP-A-8-275921. The focusing index light reaches the fundus along the optical path T of the fundus illumination optical system 3 by the half mirror 15, and the reflected light of the focusing index is transmitted along the optical path U of the fundus imaging optical system 3 for a fundus photographing television camera. It reaches 12. The movable unit 1 on the unique optical path V of the focusing optical system 7 including the focus lens 13 and the focusing index light source 14
6 is moved along the optical paths U and V to focus.

The fundus photographing apparatus transmits illumination light to the fundus through the pupil P, and receives reflected light from the fundus through the pupil P to the light receiving surface of the television camera 12 for photographing the fundus. Prior to focus and fundus photography, alignment and working distance detection must be performed.

The working distance detecting optical system 5 for detecting the working distance includes a working distance detecting index projecting optical system 17 for projecting the working distance detecting index onto the eyeball from obliquely forward, and a cornea of the eye E to be examined. And a light receiving element 18 for detecting the working distance by receiving the working distance detection index reflected obliquely from the eye E to be inspected. This working distance detecting optical system 5 is equivalent to that in the apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-275921. The working distance detection index is projected by projecting infrared light from the working distance detection light source 19 onto the surface of the eye E through the slit 20. The optical pupil of the fundus photographing optical system 3 and the pupil center PC of the eye E coincide with each other when the reflected light of the slit light passing through the slit 20 on the corneal surface enters the light receiving point of the light receiving element 18. It is set in the fundus imaging apparatus 1 in advance. With this configuration, the machine casing 2 is advanced toward the subject's eye E, and the working distance detection index is changed to the light receiving element 1.
8, the advance of the machine frame 2 is stopped,
The working distance is set.

The working distance detecting operation is performed prior to an alignment operation described later. However, if a line sensor or an area sensor is used as the light receiving element 18, the operation distance detection operation can be performed in parallel with the alignment operation. In this case, the machine casing 2 moves forward in the eye E direction while shifting in the XY directions.

Further, if a line sensor or an area sensor is used, the degree of freedom of the working distance control is increased, and even if the eye E moves back and forth (Z direction) after the working distance has been adjusted, it is determined whether the eye E has moved back and forth. It is possible to detect, and the working distance can be corrected even during the focusing operation. In other words, when continuously observing the fundus using a not-shown observation fundus illumination light source, the corneal reflected light of the fundus illumination light can be removed by correcting the working distance in accordance with the movement of the subject's eye. . Similarly, if the machine frame 2 is moved in the X and Y directions based on the signal from the pupil detector 25 during the focusing operation, the movement of the subject's eye can be further followed. Can be excluded, and a clear fundus image can be taken.

The alignment optical system 4 for performing the alignment operation is different from the conventional alignment mechanism, and a light source 21 for illuminating the anterior segment of the eye E with infrared light, and an anterior segment. And an alignment camera 22 for receiving the infrared light reflected by the optical path through the optical path U of the fundus photographing optical system 3. As a result, of the infrared light reflected by the anterior segment, the reflected light along the optical path U of the fundus imaging optical system 3 through the objective lens 11 is removed from the optical path U of the fundus imaging optical system 3 by the optical path switching mirror 23. ,
The optical path is bent again by another mirror 24 and guided to the alignment camera 22. The optical path switching mirror 2
Numeral 3 enters the optical path U of the fundus photographing optical system 3 during alignment, but retreats from the optical path U of the fundus photographing optical system 3 during illumination and photographing of the fundus.

A pupil detector 25 is connected to the alignment camera 22. The pupil detector 25 detects the pupil center PC based on the received anterior segment reflected infrared light. That is, in the pupil detector 25, as shown in FIG.
The luminance level of the anterior ocular segment reflected light is calculated, and the geometric center of gravity of the low luminance (dark) range I is detected. 2A and 2B, a range P having a low luminance corresponds to the pupil P, and a range I having a relatively high luminance corresponds to the iris. The fundus photographing optical system 3 is located at the center of the detected pupil P.
The machine frame moves in the X direction and the Y direction so that the optical axes of the machine frames coincide with each other. 2A is a signal on a scanning line (dashed line in FIG. 2B) M of the video signal output from the alignment camera 22 shown in FIG. 2B.
The pupil center of gravity is obtained by performing binarization at a reference level indicated by a broken line N in (a).

As described above, the alignment operation by the fundus photographing apparatus 1 is performed by changing the optical axis of the fundus photographing optical system 3 to the eye E.
In this case, the optical pupil of the fundus imaging optical system 3 always coincides with the pupil center PC even in the working distance detection operation. Therefore, even if one of the plurality of fixation lamps 26 shown in FIG. 1 is turned on to fixate on the subject to photograph an arbitrary part of the fundus G of the eye E, the fundus imaging optics The optical axis and optical pupil of the system 3 are set to the pupil center P of the eye E to be examined.
C can be matched.

Although not shown, the plurality of fixation lights 26 include a fixation light group for the right eye and a fixation light group for the left eye. In addition, a plurality of fixation lamps may be provided instead of a plurality of movable fixation lamps, and an arbitrary part of the fundus of the subject's eye may be photographed by moving the fixation lamp to an arbitrary position. .

The operation of the fundus photographing apparatus 1 will be described with reference to the flowchart of FIG.

First, when the photographing button of the fundus photographing apparatus 1 is pressed, the anterior segment illumination light source 19 is turned on, and an image by the alignment optical system 4 is displayed on a monitor display unit (not shown). The examinee fixes the head on the jaw table, and looks at the fixation lamp 26 through the objective lens 11 according to the instruction of the examiner. At this time, the jaw base determines whether the eye to be inspected is the right eye or the left eye based on the positional relationship of the jaw base with respect to the objective lens 11, and determines a predetermined fixation lamp of the right eye or left eye fixation lamp group. Light. As a result, the subject's eye may rotate by a small angle. In addition to the fixation light for alignment and working distance detection, a fixation light for focusing and photographing corresponding to the fixation light is provided in the above-mentioned prior art (Japanese Unexamined Patent Application Publication No. 2
No. 75921).

Next, the examiner operates the jaw base to adjust the anterior eye of the subject's eye on the monitor display unit, and presses the photographing button again. The light source 21 for anterior segment illumination and the light source 19 for working distance detection are turned on by the second button pressing operation. Then, the apparatus 1 is moved forward (moves forward in the Z direction) so that the pupil image of the eye E is projected in the anterior segment image projected on the imaging screen of the alignment camera 22. Next, the machine frame 2 moves in the X direction or the Y direction so that the optical pupil of the fundus imaging optical system 3 matches the pupil center PC. In parallel with this alignment operation, that is, the machine frame 2 advances toward the subject's eye while following the pupil center PC, and the light receiving element 18 of the working distance detecting optical system 5
Detects the slit light (working distance detection index) from the working distance detecting light source 21, the movement of the machine casing 2 stops.

At the same time, the anterior segment illumination light source 21 and the working distance detecting light source 19 are turned off, the optical path switching mirror 24 is retracted from the fundus photographing optical path U, and the focusing index light source 14 is turned on. At the same time, the focus lens 13 and the movable portion 16 of the focusing optical system 6 move and scan on their own optical paths to detect the focus of the fundus image.

At the same time that the focus is detected, the focus index light source 14 is turned off, the flash discharge tube as the photographing light source 8 emits light, and the fundus image is photographed on the fundus photographing television camera 12. After the photographed fundus image is recorded in a frame memory (not shown) and displayed on the monitor display unit, the machine casing 2 returns to the initial position and is ready for the next photographing.

FIG. 4 shows an alignment optical system in another embodiment of the fundus apparatus of the present invention. The fundus photographing apparatus 31 includes a known alignment optical system (referred to as a second alignment optical system) 34 in addition to the alignment optical system (referred to as a first alignment optical system) 4 in the fundus photographing apparatus 1 described above. Thus, both alignment optical systems 4 and 34 can be used selectively or can be used together.

As shown in the figure, the second alignment optical system 34 includes an infrared light emitting diode 32 as a light source for an alignment index. The infrared light from the diode 32 is reflected by a mirror 33 and transmitted through a condenser lens 35. Thus, the light is made to follow the illumination light path W of the first alignment optical system 4. In that case, a half mirror 36 that transmits a part of the infrared light and reflects a part of the infrared light is installed instead of the mirror 24 in FIG. The infrared light is transmitted to the optical path switching mirror 2.
The light is reflected by 3 and passes through the objective lens 11 to be converted into parallel light, which is emitted to the anterior segment of the eye E to be examined.
The infrared light reflected by the cornea is received by the alignment camera 22 along the same optical path as the first alignment optical system 4. Then, in response to a signal from an image input / output control circuit 37 connected to the alignment camera 22, the XY direction position detection control circuit 38 causes the Purkinje image, which is the corneal reflection image, to be centered on the imaging screen (of the fundus imaging optical system 3). The machine frame 2 is moved in the X and Y directions so as to come to the position corresponding to the optical axis) to perform alignment.

With this configuration, alignment can be performed by either the first alignment optical system 4 or the second alignment optical system 34. Also, whether the eye to be examined is facing a predetermined direction (for example,
Whether the subject is staring at the fixation lamp 26)
Information on a line of sight including a shift between the eye axis of the subject's eye and the line of sight, such as whether or not the subject is oblique, is obtained.

The alignment optical system and the alignment method described above are used in the fundus photographing apparatus in this embodiment,
It is clear that the present invention can be applied to not only a device for performing automatic alignment but also other fundus photographing devices.

[0040]

According to the fundus photographing apparatus of the present invention, the alignment operation is always easily and accurately performed even if the subject's eye is rotated by a small angle with a fixation lamp, regardless of the photographing part of the fundus. That is, irrespective of the fixation direction of the eye to be inspected, the optical axis of the fundus imaging optical system is directly made to coincide with the center of the pupil of the eye to be inspected. Therefore, it is possible to photograph an arbitrary part of the fundus under optimal conditions. In addition, it is possible to always align the center of the pupil of the same fixation lamp with respect to the subject's eye such as a squint that rotates at a different angle from the general one.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram showing one embodiment of a fundus photographing apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a function of a pupil detection unit in the fundus imaging apparatus of FIG.

FIG. 3 is a flowchart showing an example of the operation of the fundus imaging apparatus of the present invention.

FIG. 4 is a schematic layout diagram showing an alignment optical system in another embodiment of the fundus imaging apparatus of the present invention.

FIG. 5 is an explanatory diagram showing an alignment function in a conventional fundus imaging apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fundus photographing apparatus, 2 ... Machine frame, 3 ... Fundus photographing optical system, 4 ... Alignment optical system, 5 ...
・ Working distance detection optical system, 6 ・ ・ ・ focusing optical system, 7 ・ ・
・ Fundus illumination optical system, 8 ・ ・ ・ Light source for photography, 11 ・ ・ ・
Objective lens, 12 ... TV camera for fundus photography, 1
DESCRIPTION OF SYMBOLS 3 ... Focus lens, 14 ... Focusing index light source, 16 ... Movable part, 17 ... Working distance detection target projection optical system, 18 ... Light receiving element, 19 ... Working distance detection 20 ... Slit, 21 ... Light source for anterior segment illumination, 22 ... Alignment camera, 2
4 ... optical path switching mirror 25 ... pupil detector 26 ... fixation lamp 31 ... fundus imaging device 3
2 ... infrared light emitting diode, 33 ... mirror,
34: second alignment optical system, 35: condenser lens, 36: half mirror, 37: image input / output control circuit, 38: XY direction position detection control circuit,
T: optical path of a fundus illumination optical system, U: optical path of a fundus photographing optical system, V: optical path of a focusing optical system, E: eye to be examined, ER: vertex G: fundus , I: iris, P: pupil, PC
... Center of pupil.

Claims (5)

[Claims] 1. A fundus illumination optical system, a fundus photographing optical system,
In a fundus imaging apparatus having a focusing optical system, an anterior segment illumination light source for illuminating an anterior segment of an eye to be examined and illumination light from the anterior segment illumination light source reflected by the anterior segment are received. A first alignment optical system having a first light receiving means for,
A pupil detecting unit connected to the first light receiving unit; and a first guiding unit for guiding an optical axis of the fundus imaging optical system to a substantial center of the pupil detected by the pupil detecting unit. A fundus photographing apparatus characterized by the above-mentioned. 2. An alignment target projection optical system for irradiating the anterior eye of the subject's eye with parallel light from the front, and a second for receiving the target light reflected by the anterior eye from the alignment target projection optical system. And a second alignment optical system having a light receiving means, wherein the optical axis of the fundus photographing optical system is guided to the vertex of the eye by the first guiding means based on the received reflected image. The fundus photographing apparatus according to claim 1. 3. The fundus imaging apparatus according to claim 1, wherein the first light receiving unit is configured to receive anterior ocular segment reflected light along an optical axis of the fundus imaging optical system. 4. The pupil detecting means is configured to detect a center of gravity of a low lightness range corresponding to the pupil in the received anterior ocular segment reflected light, and the first guiding means includes a fundus photographing optical system. The fundus imaging apparatus according to any one of claims 1 to 3, wherein the fundus imaging apparatus is configured to move the optical axis to coincide with the center of gravity. 5. A working distance detecting optical system, comprising: a working distance detecting index projecting optical system for projecting an index toward an eye to be inspected; and a working distance detecting index from the cornea. Working distance detecting means for detecting a working distance based on the reflected light, wherein the working distance detecting means detects the corneal reflected light of the working distance detection index by moving the fundus photographing optical system toward the eye to be inspected. The fundus photographing apparatus according to any one of claims 1 to 4, further comprising second guiding means for guiding to the eye.