JPH1132992A - Instrument for measuring adjustment of eyeball crystal lens focal point - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously measure the eyeball adjusting state of an examinee in real time without restraining the head part of the examinee by unnecessitating the following-up of an eyeball and miniaturizing an optical system part to the degree of being loadable to the head part of the examinee. SOLUTION: While illuminating the eye to be examined 2 of the examinee with near infrared rays by a astigmatic optical system 3, the eyeground reflected light image of the eye 2 is condensed by astigmatic characteristic to form an image on the image pickup device 17 of a video camera device 4 and a measuring instrument measures the aspect ratio of the eyeground reflected light image obtained by photographing processing to measure the adjusting response of the eye 2 based on this measuring result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the function of an eyeball, and more particularly, to an eyeball lens for objectively and continuously measuring the focus adjustment of an eyeball without interrupting the visual function of a subject. The present invention relates to a focus adjustment measuring device.

SUMMARY OF THE INVENTION The present invention relates to an apparatus for measuring the state of focus adjustment (hereinafter referred to as "adjustment") of an eyeball by using a photorefraction method. The reflected light from the fundus is imaged by a video camera device using an optical system having astigmatism, and the two aberration axis directions of the reflected light image and the ratio of each diameter (hereinafter referred to as “aspect ratio” for simplicity) Is automatically measured from the image to determine the refraction state of the subject's eye, so that focus adjustment can be measured in real time and continuously without disturbing the visual function of the subject.

[0003]

2. Description of the Related Art A conventional method capable of real-time measurement is disclosed in Hatada, "Continuation / Physiological Optics 8, Visual Inspection Method II 2. Refraction / Adjustment Measurement Method (2)" O plus E, No. 177, pp120- 126 (1989), two thin measuring light beams are made incident on the pupil of the subject's eye with one point fixed, and the light source and the light receiving element are optically captured by capturing the reflected light from the fundus. An apparatus called an optometer, which measures the adjustment state of the lens from a position conjugate to the lens, has been mainly used.

[0004] Further, as an apparatus which does not require fixation, there is Ta.
keda et.al. ゝ hree-Dimensional OptometerIII "Appl.Op
t., Vol. 32, No. 22, pp. 4155-4168 (1993), a device that tracks the movement of the subject's eye using a movable optical system has been developed, which is a large-diameter concave mirror. Since the optical system and the control device are combined with a galvanometer mirror (a mirror whose direction is changed by an electric signal), the size of the device becomes considerably large.

In a measuring method using photorefraction caused by astigmatism or the like, the size of the fundus reflected light image is measured manually after recording the image in a photograph or a frame memory. This method is described in Howland et.al. ＾ ptics
of photorefraction: orthogonal and isotropic method
s "JOSA Vol. 73, No. 12, pp 1701-1708 (1983), Howland et.
al., ccommodation in infants as measured by photo
refraction "Vision Research Vol.27, No.12, pp2141-21
52 (1987).

A photorefraction using a surface light source and the knife edge method is described in Fukuma et al., "Measurement of Eye Refractive Power by Surface Light Source / Knife Edge Method", Optics, Vol. 18, No. 10 (1989). When the subject's eye is illuminated with a surface light source (actually, a number of light emitting diodes are arranged) and the reflection of the measurement light from the fundus is photographed, the pupil is reflected brightly. At this time, if a knife edge is placed in the photographing lens, A gradient occurs in the brightness of the pupil. Since this depends on the thickness of the light beam passing through the knife edge, that is, the accommodation state of the subject's eye, the accommodation state can be measured by measuring the brightness gradient.

[0007]

However, in the optometer system capable of real-time measurement, the scale of the apparatus is relatively large, and a thin measuring light beam must always enter the pupil of the eye. Then, the subject's eye had to be fixed by gazing at the fixation target, or the movement of the subject's eye had to be tracked using a large-scale movable optical system.

On the other hand, in the conventional astigmatism photorefraction method, since the astigmatism image is recorded in a photograph or a frame memory and then manually measured, it cannot be continuously measured in real time.

In the knife-edge method, since a surface light source is used, the size and power consumption of the light source have to be increased to some extent.

In view of the above circumstances, the present invention eliminates the need for tracking the eyeball and reduces the size of the optical system to such a degree that the optical system can be mounted on the subject's head. An object of the present invention is to provide an eyeball lens focus adjustment measurement device capable of continuously measuring the eyeball accommodation state of a subject without restriction in real time.

According to a second aspect of the present invention, an eyeball lens focus adjustment measuring device capable of measuring an eyeball accommodation state of a subject without restricting the subject's head while showing an index or the like in front of the subject to the subject. It is intended to provide.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, an eye lens lens focus adjustment measuring apparatus according to the present invention converges a fundus reflected light image of a test eye with astigmatic characteristics. An astigmatism optical system, a fundus image photographing device that converts a fundus reflection light image condensed by the astigmatism optical system into a video signal, and image processing of a video signal obtained by the fundus image photographing device. A focus measuring device for determining an aspect ratio of the fundus reflection light image and for determining an adjustment state of the subject's eye based on the aspect ratio.

In the above configuration, in the astigmatism optical system, the fundus reflection light image of the subject's eye is condensed with astigmatism characteristics. The collected fundus reflected light image is converted into a video signal by a fundus image photographing device. In the focus measurement device, the video signal obtained by the fundus image photographing device is subjected to image processing by the focus measurement device, and the aspect ratio of the fundus reflection light image is obtained,
Based on the aspect ratio, the accommodation state of the subject's eye is determined. This eliminates the need for tracking the eyeballs, makes it possible to reduce the size of the optical system to the extent that it can be mounted on the subject's head, and allows the subject's eyeball accommodation state to be real-time without restraining the subject's head. Can be measured continuously.

Here, in the present specification, the "aspect ratio of the fundus reflection light image" refers to the ratio of the diameters of the fundus reflection light image to be examined in the two aberration axis directions.

According to a second aspect of the present invention, in the eye-lens focus adjusting and measuring apparatus according to the first aspect, the astigmatism optical system transmits a visible light from the front of the subject by a dichroic mirror. While guiding to the subject's eye, the invisible light from the invisible light source was reflected and guided to the subject's subject's eye, and was reflected at the fundus of the subject's subject's eye while showing the subject a forward light image. A fundus reflection light image of invisible light is guided to the fundus image photographing apparatus.

In the above configuration, the visible light from the front of the subject is transmitted by the dichroic mirror provided in the astigmatism optical system, and the visible light from the invisible light source is guided to the subject's eye while being guided to the subject's eye. The reflected light is guided to the subject's eye, and the fundus reflected light image of the invisible light reflected by the fundus of the subject's test eye is guided to the fundus image photographing device while showing the subject a light image in front. Thus, the subject's eye adjustment state is measured without restricting the subject's head while showing the subject etc. in front of the subject.

[0017]

FIG. 1 is a block diagram showing an embodiment of an eye lens lens focus adjustment measuring apparatus according to the present invention.

The eye lens lens focus adjustment measuring device 1 shown in FIG. 1 generates near-infrared light and guides it to the subject's eye 2 (see FIG. 2). An astigmatism optical system 3 that captures light and condenses it with astigmatism characteristics, and converts a near-infrared light image of the test eye 2 condensed by the astigmatism optical system 3 into an electric signal (video signal) A video camera device 4 for conversion; and a measuring device 5 for performing image processing on a video signal output from the video camera device 4 and measuring an adjustment response of the subject's eye 2. The fundus reflection light image of the test subject's eye 2 is astigmatism characteristics,
While forming an image on the image sensor 17 (see FIG. 2) of the video camera device 4, the measuring device 5 was used to measure the aspect ratio of the fundus reflection light image obtained by the photographing process. The regulatory response of 2 is measured.

The astigmatism optical system 3, as shown in FIG.
A near-infrared light source 6 for generating near-infrared light, a collimator lens 7 for condensing near-infrared light emitted from the near-infrared light source 6 to be parallel light, and collimated by the collimator lens 7 A half mirror 8 that reflects a portion of the near-infrared light, a visible light cut filter 9 that transmits the near-infrared light reflected by the half mirror 8 and cuts visible light, and a visible light cut filter 9 While reflecting near-infrared light that has passed through, and transmitting visible light,
A dichroic mirror 10 that allows the near-infrared light (measuring light) reflected by the test eye 2 to be reflected again and enters the visible light cut filter 9, a visible light cut filter 9, and a half mirror 8. A half mirror 11 that reflects part of the near-infrared light (measurement light) that has passed through and transmits the rest, an imaging lens 12 that collects near-infrared light reflected by the half mirror 11, An imaging device 13 that converts near-infrared light condensed by the imaging lens 12 into an electric signal and generates a video signal for positioning an eyeball and observing an eyeball position, and an imaging lens 14 and a cylindrical lens 15 And a lens group 16 for converging near-infrared light transmitted through the half mirror 11 with astigmatism characteristics.

Then, the visible light from the front of the subject is transmitted by the dichroic mirror 10, and the near-infrared light from the near-infrared light source 6 is converted into parallel light by the collimator lens 7 while showing the subject an index ahead. Then, the light is reflected by the half mirror 8 and the dichroic mirror 10,
After being guided to the subject's eye 2 and refracted by the dichroic mirror 10 at the crystalline lens of the subject's eye 2 and reflected back by the fundus, the near-infrared light (measurement light) is again reflected, and then the visible light The measurement light is transmitted by the cut filter 9 and the half mirror 8. Furthermore, half mirror 1
1 reflects the measurement light, forms an image on the image sensor 13 by the imaging lens 12, and observes the eyeball position based on the video signal output from the image sensor 13 to position the eye 2 to be examined. And so on. Also,
In parallel with this operation, the measurement light transmitted through the half mirror 11 is condensed by the lens group 16 with astigmatism characteristics, and is imaged on the image sensor 17 of the video camera device 4.

The video camera device 4 is disposed at a position that is optically conjugate with the near-infrared light source 6, and the astigmatism optical system 3
An imaging element 17 that converts the condensed measurement light into an electric signal (video signal) with astigmatic characteristics by the lens group 16 of the optical system 3 is provided. Then, the collected measurement light is converted into an electric signal, and the obtained video signal is supplied to the measuring device 5.

As shown in FIG. 3, the measuring device 5 includes an A / D conversion circuit 18 for converting an analog signal format video signal output from the image pickup device 17 of the video camera device 4 into a digital signal format image data. , This A / D conversion circuit 18
Memory circuit 19 for storing the image data output from the memory in units of frames, and the frame memory circuit 19
Image processing is performed on the image data stored in the
An image measurement circuit 20 for determining an aspect ratio of a fundus reflection light image of the fundus;
A computer that executes processing for controlling the A / D conversion circuit 18 and the image measurement circuit 20 and processing for calculating the adjustment state of the subject's eye 2 based on the aspect ratio of the fundus reflection light image obtained by the image measurement circuit 20 And A / D conversion of the analog signal format video signal output from the video camera device 4 into digital signal format image data, image processing of the image data, and reflection of fundus reflected light. The aspect ratio of the image is determined, and the accommodation state of the subject's eye 2 is calculated.

In this case, the lens group 1 of the astigmatism optical system 3
The measurement light condensed by 6 forms an image at different positions in the refraction direction and the transmission direction by the cylindrical lens 15 constituting the lens group 16, and astigmatism occurs. From this,
When the subject's eye 2 is in focus at a distance, as shown in FIG. 4, the fundus reflection light image is formed on the image sensor 17 in an elliptical shape that is long in the horizontal direction. FIG. 5 shows when the subject's eye 2 is focused in the middle, for example, when the eye 2 is focused on 1.5 m, which is an adjustment state (focal length) corresponding to the most frequently used viewing distance. As described above, the fundus reflection light image is formed on the image sensor 17 in a substantially circular shape. further,
As shown in FIG. 6, when the subject is focused on the vicinity of the subject's eye 2, the fundus reflection light image is formed on the image sensor 17 in an elliptical shape that is long in the vertical direction. Whether the fundus reflected light image on the image sensor 17 is formed into a perfect circle when the focal length of the subject eye is determined is a degree of freedom in design, but as described above, depending on the purpose of the experiment, Considering that it is advantageous to make a perfect circle when in the adjustment state corresponding to the most frequently used viewing distance,
In this embodiment, the length is 1.5 m.

Then, based on the calibration curve registered in advance, the aspect ratio of the fundus reflection light image formed on the image pickup device 17 is corrected, thereby compensating for the optical characteristics unique to the eye lens for each subject. Then, the state of accommodation of the eye lens is determined.
That is, the data in the frame memory circuit 19 is read out, and the vertical and horizontal counters in the image measuring circuit 20 are driven. In the vertical direction, the number of scanning lines where data is present is detected. By detecting the maximum value of the number of data, the diameter (fillet diameter) in each direction is obtained. Although it is possible to obtain the focal length from the obtained aspect ratio by geometrical optics, the optical characteristics of the eyeball are not actually in accordance with the optical theory. Is done by asking for

As described above, in this embodiment, the astigmatic optical system 3 forms an image of the fundus reflection light of the subject's eye 2 on the image sensor 17 of the video camera device 4 with astigmatic characteristics. Meanwhile, the measuring device 5 is used to measure the aspect ratio of the fundus reflection light image obtained in the photographing process, and based on the measurement result, the accommodation response of the subject's eye 2 is measured. (Claim 1)
Effect).

First, instead of accurately inputting a thin measuring light beam to the subject's pupil, a collimated
Since it is only necessary to irradiate the test eye 2 with parallel light having a certain thickness, measurement light can be incident from the pupil even if there is some eye movement, and thus a device that tracks the eye is used. Without this, the accommodation response of the test eye 2 can be measured.

Also, since the fundus reflection light image of the test eye 2 can be formed on the image pickup device 17 of the video camera device 4 using the small-scale astigmatism optical system 3, the detector portion is used. The size and weight can be reduced, and the focus adjustment function of the subject's eye 2 can be measured by attaching to the subject's head without restraining the subject.

FIG. 2 shows only a device for one eye, but since the device itself is small, by installing two adjacent devices, the focus adjustment function of both eyes can be measured. can do.

Further, since an ordinary image can be taken of the subject's eye 2 by the imaging device 13 provided in the astigmatism optical system 3, eye movement, pupil reaction, etc. can be measured simultaneously. .

Further, in the above-described embodiment, the dichroic mirror 10 is provided in the astigmatism optical system 3, and while the light image from the front of the subject is guided to the subject's eye 2, the fundus reflection light of the subject's eye 2 Since the image is formed on the image sensor 17 of the video camera device 4, the eye condition of the subject can be adjusted without restricting the subject's head while showing the subject etc. in front of the subject. It can be measured (effect of claim 2).

[0031]

As described above, according to the present invention, according to the first aspect of the present invention, the tracking of the eyeball is not required, and the optical system is reduced in size to the extent that it can be mounted on the subject's head. The eye condition of the subject can be continuously measured in real time without restraining the head of the subject.

According to the second aspect, the subject's eye adjustment state can be measured without restricting the subject's head while showing the subject etc. in front of the subject.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an eye lens lens focus adjustment measuring apparatus according to the present invention.

FIG. 2 is a configuration diagram illustrating a detailed configuration example of the astigmatism optical system illustrated in FIG. 1;

FIG. 3 is a block diagram showing a detailed circuit configuration example of the measuring device shown in FIG.

FIG. 4 is a schematic diagram showing a measurement operation example of the eye lens lens focus adjustment measuring device shown in FIG. 1;

FIG. 5 is a schematic diagram showing a measurement operation example of the eye lens lens focus adjustment measuring device shown in FIG. 1;

FIG. 6 is a schematic diagram showing a measurement operation example of the eye lens lens focus adjustment measuring device shown in FIG. 1;

[Description of Signs] 1 Eye Lens Lens Focus Adjustment Measuring Device 2 Eye to be Tested 3 Astigmatism Optical System 4 Video Camera Device (Fundus Image Shooting Device) 5 Measuring Device (Focus Measuring Device) 6 Near Infrared Light Source 7 Collimator Lens 8, 11 Half Mirror 9 Visible light cut filter 10 Dichroic mirror 13 Image sensor 12, 14 Imaging lens 15 Cylindrical lens 16 Lens group 17 Image sensor 18 A / D conversion circuit 19 Frame memory circuit 20 Image measurement circuit 21 Computer

Claims (2)

[Claims] 1. An astigmatism optical system for converging a fundus reflection light image of a test eye with astigmatism characteristics, and converting a fundus reflection light image condensed by the astigmatism optical system into a video signal. A fundus image photographing device, and image processing of a video signal obtained by the fundus image photographing device to determine an aspect ratio of the fundus reflected light image,
A focus measuring device for obtaining an accommodation state of the subject's eye based on the aspect ratio. 2. The eye lens lens focus adjustment measuring device according to claim 1, wherein the astigmatism optical system transmits visible light from the front of the subject by a dichroic mirror and guides the visible light to the subject's eye. While reflecting the invisible light from the invisible light source, by guiding to the subject's eye,
An eyeball lens focus adjustment measuring device, wherein a fundus reflected light image of invisible light reflected by the fundus of the subject's eye is guided to the fundus image photographing device while showing a light image in front of the subject.