JPS5829447A - Apparatus for monitoring gaze of eye to be inspected in ophthalmic machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a viewing direction monitoring device for use in ophthalmological instruments.

In ophthalmic instruments such as fundus cameras and refractive power measurement devices,
It is necessary to perform measurements and photography in a state where the optical axis of the eye to be examined, that is, the direction of the line of sight, and the optical axis of the ophthalmological instrument are aligned, that is, with no deviation in the direction of the line of sight.

Particularly, regarding the perimeter of the IN equipment, any deviation in the visual field direction during measurement is a measurement error, and eliminating the deviation in the visual field direction is an essential condition.

Therefore, in ophthalmological instruments, a visual target is provided to fix the patient's line of sight to a single point on the ophthalmological instrument.

The subject is asked to watch this closely. However, even if the line of sight is once fixed on the fixation target, the direction of the OIl and fixed imaging line often deviates.

An a# direction monitoring device in the ophthalmological instrument is required.

As an example of a line-of-sight direction monitoring device in a conventional Oa class instrument, one is known that is configured so that the examiner observes the anterior end of the eye to be examined using a reference telescope.

However, for example, when using a visual field needle, the examiner must also record the visual field measurement results, which requires a great deal of effort on the part of the examiner and can lead to measurement errors.
Become.

Another example of a line-of-sight direction monitoring device in a conventional ophthalmological instrument is one that projects an infrared l11111 constant beam onto the cornea of the eye to be examined;
In the device that electrically detects the direction deviation of the reflected light of the infrared light measurement beam by the corneal surface, the infrared light measurement beam is projected toward the eye to be examined, and the light reflected from the fundus of the eye to be examined from the skeleton beam is utilized. A device is known that detects a deviation in the reference direction. However, these conventional devices have the disadvantage that they require an infrared beam projector, making them complicated and large-sized, making them difficult to incorporate into conventional ophthalmological instruments. especially.

If the above-mentioned line-of-sight direction monitoring device must be incorporated in a part corresponding to the center of the visual field, such as a visual field needle, if the device becomes complicated and large, it may be necessary to incorporate the visual field direction monitoring device into a part corresponding to the center of the visual field within the visual field measurement range. It has the fatal drawback of making many parts unmeasurable.

It is an object of the present invention to provide a line-of-sight direction monitoring device for an Illustrator instrument that eliminates these conventional drawbacks, and its structural features include: It has an imaging optical system, an aperture diaphragm disposed on a connecting surface of the imaging optical system, and a photodetector for detecting a scene that has passed through the aperture diaphragm, The aim is to monitor the line of sight of the eye to be examined using electrical signals. Therefore, the present invention can provide a visual line monitoring device with a simple structure and high precision without requiring a special measurement beam to be projected onto the eye to be examined for visual line monitoring.

Embodiments of the present invention will be described below based on the drawings.

@/The visual field needle line of sight monitoring device 2 of the embodiment is arranged behind the hemispherical dome 4 on which the visual field needle index is projected.

Objective lens 6, Barfun2 8, aperture diaphragm DIIIO.

Photodetector 12. It is composed of a signal processing system 14 and an eyepiece 16. 18 is the eye to be examined, and 2G is the examiner's limit. In a configuration of 0 or more, the inner surface of the hemispherical dome 4 is uniformly illuminated by the background light during visual field measurement, and the anterior segment of the eye 18 to be examined is illuminated by the hemispherical dome 4. Illuminated by diffused light from the inside.

The reflected light from the anterior segment of the subject's l1lsO passes through the gaze target aperture 22 of the hemispherical dome 4 and is focused by the objective lens 6.

The light is reflected by the bar 8, passes through the aperture plate 1°, and reaches the photodetector 12. The photodetector 12 converts the amount of incident light into an electrical signal and sends it to the signal processing system 14 . It was. Objective lens 6, half port 8. The eyepiece 16 constitutes a reference telescope, and the examiner uses the wrinkled reference telescope to perform visual inspection 1.
It is possible to visually observe 91111.
The above reference telescope is.

41, in the present invention, it is used for rounding to determine the reference line direction at the start of measurement of the eye 18 to be examined.

Next, the aperture diaphragm 30 on the aperture diaphragm plate 10 and the test object 1
The relationship with 1180 Maekumabe Ken I II' will be explained based on FIG. Anterior segment image of the subject's eye 18-Mori, -@$
! , consists of an iris image s3 and a sclera image 34, and has a reflectance of f
Pupil image S that is tO! The brightness increases in the order from iris Ken SS to sclera @314. Now, when the eye 18 to be examined is gazing at the gaze target provided in the opening 22 of the hemispherical dome 40,
As shown in FIG. 2(2), the subject 11
When the reference line of 1g deviates from the above gaze target, Fig. λ b)
, (as shown in J, the aperture diaphragm j530 and the anterior segment image 1g' of the subject's eye gradually shift from each other, and the aperture diaphragm 3
There are many parts of the iris image 331 and sclera image with high reflectivity on the top 0, and the amount of light passing through the aperture stop 30, that is, the photodetector 1.
2. The amount of light received increases. At this time, the relationship between the standard deviation angle α0 of the eye 1s to be examined and the output voltage V of the photodetector 12 is as shown in Figure 3.

Here, if the size of the aperture stop 6so and the pupil image 32 are the same, the curve shown by the broken line in FIG.
] If the pupil image 32 is larger, the solid line indicates 11!111.
11I. Therefore, it is desirable that the size of the aperture diaphragm 30 and the diameter 1132 be the same in terms of measurement accuracy and measurement range, and the size of the aperture diaphragm 30 is variable. The adjustment mechanism for the size of the aperture diaphragm 30 may be one that continuously changes the diameter of the aperture diaphragm 30 or a large number of aperture diaphragms 1 with an aperture diameter of 0Jll.
It is also possible to switch and insert 0.

Next, the photodetector 12 and the signal processing Il system 14 will be explained. In FIG. μ, the output of the photodetector 12 is input to a signal processing system 14. In FIG. The signal processing system 14 includes an amplifier 40
．． The signal from amplifier 40.

b Switch 42 for switching in either direction. Sample and hold circuit 44 that temporarily holds electrical signal values (voltage signals). a connodalator 46 for comparing the electrical signal (voltage signal) from .b with the electrical signal held in the sample and hold circuit 44; Warning generating device 48. Amplifier 40. Switch 42. f hold circuit 44. It is composed of a control circuit 460, a detection target time setting section 5, and a detection target time setting section 5.

The operation of the signal processing system 14 having the above configuration will be explained based on the flowchart shown in FIG. First, the detection target time setting unit 52 determines how many seconds or more a warning should be issued if the line of sight continues to shift.
Enter the information. If you set an extremely short time, a warning will be issued even if there is a shift in the line of sight between Hanno and Shun. On the other hand, if you set a long time, -Shun's gaze direction shift,
Alternatively, the photodetector 12 may be activated instantaneously by blinking of the subject's eye.
Does not issue a warning even if the amount of light incident on the device increases. moreover,
By using a special set time, it is possible to detect the eye blink itself, in addition to the line-of-sight direction shift.

Next, set the level of line-of-sight direction shift by turning the switch 42 to s.
Perform K connection. For example, to set a warning to be issued when the line of sight deviates by more than /0", the visual target of the perimeter is presented at the position lOo and the subject is asked to gaze at it. The electrical signals of the detector 12 are shown in Fig. 3 as ■,
The sample and hold circuit 44 holds the value of V, which is the value indicated by .

When the above settings are made, the switch 42 is connected after bK and visual field measurement is started. During visual field measurement, the photodetector 12
The output signal from the sample-and-hold circuit 44 is always compared by a comparator 46, and when the output voltage of the former becomes larger than the output voltage of the latter and the detection target time has elapsed, a warning generating device 48 is activated. The warning means of the warning generating device 48 is a visual one such as a tuning fork or a tuning fork such as a pude.

In this embodiment, by providing a sample hold circuit and setting a reference signal, detection errors due to individual differences in the eyes to be examined are eliminated, and highly accurate detection is always possible. Also,
By selecting this reference signal, it is possible to arbitrarily select a range in which no warning is issued.

That is, in the case of visual field measurement in the central area, the range in which no warning is issued is narrowed so that a warning is issued even for minute deviations in the direction of the line of sight, making highly accurate measurement possible. On the other hand, when a slight shift in the direction of the line of sight is allowed, such as when measuring the peripheral visual field, the measurement efficiency can be improved by widening the range in which no warning is issued.

The second embodiment of the present invention is the first embodiment in which a structure for removing stray light incident from the eyepiece lens 16 is added,
As shown in FIGS. 6 and 7, the same components as those in the first embodiment are simply given the same reference numerals and their explanations will be omitted.

As shown in FIG.
It is a disk in which transparent portions 64 and 64 are provided alternately, and is rotated by a motor 66. The reflector disk 60 is arranged so that the examiner does not feel the inside of the tree in his/her field of view, and the light detection 1i1
When the objective lens 6 is rotated at a frequency faster than the response speed of 2 and there is a reflector unit 62 in the optical path of the objective lens 6, only the reflected light from the anterior segment of the subject's eye enters the photodetector 12, and the transmitted light is When the portion 64 is present, the reflected light from the anterior segment of the subject's eye passes through the eyepiece 16 and reaches the examiner 20.

The third embodiment of the present invention, like the λth embodiment, has a structure for removing stray light incident from the eyepiece lens 16.
As shown in FIG. r, the same components as those in the first embodiment are simply given the same reference numerals and their explanations will be omitted. The movable reflector 70 can be inserted into and removed from the optical path of the objective lens 6, and when the photodetector 12 and signal processing system 14 are in operation, the movable reflector 70 is in the optical path of the objective lens 6 and the eyepiece Stray light incident from the lens 16 is completely blocked. On the other hand, when the examiner wishes to observe the line of sight, the movable reflector is moved to the position shown at 71, and a reference telescope is formed by the objective lens 6 and the eyepiece 16.

Although the above embodiment has been described with respect to a perimeter, similar functions can be obtained in other ophthalmological instruments by simply adding a simple mechanism. Furthermore, the visual line direction monitoring device of the present invention can be constructed as an enit and used by being attached to an existing ophthalmological instrument, and it has a very remarkable effect as a visual line direction monitoring device for an ophthalmological instrument.

As explained in detail above, the present invention focuses on differences in partial reflectance in the anterior segment of the human eye, and the anterior segment is illuminated with general illumination light without projecting any special measurement beam. The line-of-sight direction is detected using a very specific configuration in which an image is projected onto an aperture stop and a light detection unit is arranged to detect the amount of light transmitted through the aperture stop. It is possible to monitor whether or not it is inside.

is a diagram explaining the principle of the present invention, FIG. 3 is a graph showing the relationship between the deviation in the line of sight direction and the output signal of the photodetector, FIG. 5 is a circuit diagram of the signal processing system of the first embodiment, and FIG. The operation flowchart of the first embodiment, FIG. 6 is a principle diagram of the second embodiment, FIG. 7 is a plan view of the reflecting mirror disk of the second embodiment, and the second diagram is a principle diagram of the third embodiment. .

2... Test eye gaze direction monitoring device, 4... Hemispherical dome, 6... Objective lens, 8... Half mirror-110 fist... Aperture diaphragm, 12... Photodetector, 14... Signal processing system, 1600ii eye lens, 18
oI + eye to be examined, 20... examiner's eye

Claims (1)

[Claims] An imaging optical system for forming an image of a subject to be examined; an aperture diaphragm disposed on the imaging plane of the imaging optical system; and a photodetector for detecting the amount of light passing through the aperture diaphragm υ. A device for monitoring the line of sight direction of a subject's eye in an ophthalmological instrument, comprising: monitoring the line of sight direction of a station to be inspected using an electrical signal from the photodetector.