JPH0473039A - Ophthalmologic measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the observing of an image of an outer eye part during a measure ment by arranging a light adjusting means to adjust a quantity of light of the outer eye part image according to a maximum lightness and an arithmetic means which separates a target image from a combined image of the outer eye part image and the target image to perform an ophthalmological measurement. CONSTITUTION:Light sources 21a and 21b are turned ON to project an outer eye part image Ma onto an image sensor 15, after an alignment, a video signal thereof is taken into a memory 24 with a signal processing circuit 22 and the outer eye part image Ma is scanned with a microprocessor unit 25 to detect a maximum lightness. Here, when the maximum lightness of the outer eye part image is large, an opening area of a variable stop 18 is reduced with the unit 25 to turn ON a light source 1. As a result, a combined image of the outer eye part image Ma and a target image Mb low slightly in lightness is projected onto the image sensor 15 to be displayed on a TV monitor 23 while being taken into a memory 24 with a signal processing circuit 22. As the target image Mb is normally high noticeably in contract as compared with the outer eye part image Ma, a binary coding is performed with a specified factor of contrast as threshold thereby enabling complete separation of the target image Mb from the combined image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides an apparatus for measuring external ocular parts of an eye to be examined while displaying an image of the external part of the eye on a monitor, such as an eye refractive power measuring device or a corneal shape measuring device, for example.
The present invention relates to an ophthalmological measurement device that detects and measures a reflected light beam of a measurement target reflected at a measurement site of an eye to be examined.

[Prior Art] In a conventional ophthalmological measuring device, for example, an eye refractive power measuring device uses an observation optical system to capture an image of the external eye using an image sensor when aligning the eye to be examined, and displays the image on a root observation monitor. By switching the optical system using a wavelength division member such as a beam splitter, the reflected image of the optotype projected onto the fundus of the eye to be examined by the projection optical system is projected onto the image sensor by the light receiving optical system, and the image is determined based on the image formation position and shape. The eye refractive power of the eye to be examined is measured.

[Problems to be Solved by the Invention] However, the external eye image projected onto the image sensor is displayed as is on the genital root observation monitor, and the external eye image is switched to the optotype reflection image during measurement. There is a problem in that the examiner cannot observe the image of the external eye. Also,
Measurements are repeated multiple times to improve measurement accuracy, but since the external eye image and the target reflection image are displayed alternately at intervals of several frames at most, even if there is a slight misalignment, the measurement is repeated multiple times. The problem is that it is difficult for examiners to recognize. Also,
Measurements are also performed with the subject eye wearing a contact lens in an over-refraction state, but if the contact lens suddenly slides down the corneal surface, the fall cannot be detected, and the contact lens is not near the center of the contact lens. There is also a risk that a measurement value obtained when the end portion touches the cornea may be incorrectly adopted.

An object of the present invention is to provide an ophthalmological measuring device that can simultaneously project an external eye image and a target reflection image onto the same image sensor and observe the external eye image during measurement.

[Means for Solving the Problems] In order to achieve the above object, the ophthalmological measurement device according to the present invention includes an observation optical system that projects an image of the external eye of the eye to be examined onto an image sensor, and a predetermined image of the eye to be examined. a projection optical system that projects an optotype onto the site; a measurement optical system that projects the optotype image reflected at the predetermined site onto the image sensor; and the extraocular part image and the optotype image projected onto the image sensor. In an ophthalmological measuring device, the ophthalmological measuring device has a display means for outputting and displaying a maximum brightness of the external eye image, and a detection means for detecting the maximum brightness of the external eye image, and a light amount of the external eye image that enters the image sensor via the observation optical system. a light control means for adjusting the brightness according to the maximum brightness, and separating the optotype image from a composite image of the extraocular part image and the optotype image simultaneously projected onto the image sensor while being adjusted by the light control means. The invention is characterized in that it has a calculation means for performing ophthalmological measurements.

[Operation] The ophthalmological measurement device having the above-described configuration adjusts the amount of light incident on the image sensor through the observation optical system according to the maximum brightness of the image of the external eye on the image sensor, and Ophthalmological measurements are performed by separating the optotype image from the composite image of the image and the optotype image.

[Example code] The present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a configuration diagram of an embodiment in which the present invention is applied to an eye refractive power measuring device.
On the optical path 01 from the light source 1 consisting of D to the eye E,
A collimating lens 2, a fundus optotype 3 having an opening as shown in FIG. 2, a relay lens 4, a projection diaphragm 5, a perforated mirror 6, a relay lens 7, a total reflection mirror 8, a dichroic mirror 9, and an objective lens 10 are sequentially installed. are arranged in
The image of the fundus optotype 3 is projected onto the fundus Er of the eye E to be examined. Further, on the reflected optical path 02 of the perforated mirror 6, there is a measurement diaphragm 11 having at least three apertures approximately conjugate with the pupil of the subject flffE as shown in FIG.
, a relay lens 12, a prism 13 composed of a small prism corresponding to the numerical aperture of the measurement aperture 11, and a dichroic mirror 14 are arranged, and an image pickup device 15 is arranged in the direction of reflection of the dichroic mirror 14. A dichroic mirror 16, a relay lens 17, a variable aperture 18, a dichroic mirror 14, and an image sensor 15 are arranged on the optical path 03 behind the dichroic mirror 9, and in the direction of reflection of the dichroic mirror 16, a relay lens 19 and a fixation target light source are arranged. A fixation target unit 20 including a fixation target 20a and a fixation target 20b is arranged, and the eye to be examined E
Light sources 21a and 21b are arranged in front of the. The output of the image sensor 15 is connected to a video signal processing circuit 22, and the output of the video signal processing circuit 22 is connected to a television monitor 23, a frame memory 24, a microprocessor unit 25 containing a program, etc. The output of 25 is connected to the light source 1, the variable diaphragm 18, and the fixation target unit 20, and is used to control the lighting and light amount of the light source 1, adjust the aperture of the variable diaphragm 18, and fixation target unit 2.
0 position control etc. Note that the pupil E1 of the eye E to be examined and the projection aperture 5 are approximately conjugate, and the pupil E1 of the eye E to be examined is approximately conjugate.
The fundus Er is approximately conjugate with the fundus optotype 3 and the image sensor 15,
Further, the external eye portion of the eye E to be examined is arranged substantially conjugate with the light receiving surface of the image sensor 15.

During alignment, the light sources 21a and 21 for illuminating the external eye
b is turned on to illuminate the external eye part of the eye E to be examined, and the external eye part image is obtained using the objective lens 10, dichroic mirror 9.16, relay lens 17, variable aperture 18, and dichroic mirror 14.
The external eye image is projected onto the light receiving surface of the image sensor 15 via the signal processing circuit 22 and displayed on the television monitor 23 . At this time, the variable diaphragm 18 is opened to the maximum according to a command from the microprocessor unit 25, and the brightest external eye image Ma is displayed on the television monitor 23 as shown in FIG. Alignment is performed by observing the external eye image Ma.

On the other hand, when only the light source 1 is turned on, the light beam travels on the optical path 01, passes through the collimating lens 2, the fundus optotype 3, the relay lens 4, the projection diaphragm 5, the perforated mirror 6, and the relay lens 7, and then passes through the total reflection mirror. 18 and dichroic mirror 9
The light flux reflected by the fundus Er returns through the same optical path, and after being reflected by the perforated mirror 6, passes through the measurement aperture 11, the relay lens 12, and the prism 13. dichroic mirror 1
4 and is projected onto the image sensor 15 as optotype images Mb as shown in FIG. 24, and the eye refraction value can be measured based on the coordinate position of the optotype image Mb.

As a step before measuring the eye refraction value, first, the light source 21a
, 21b is turned on to display the external eye part image Ma on the image sensor 15.
is projected and alignment is performed, and after most of the alignment is completed, the video signal of the extraocular part image Ma for frames is taken into the frame memory 24 by the signal processing circuit 22. Since the image captured in the frame memory 24 is expressed in, for example, 8 bits and 256 gradations, the microprocessor unit 25 scans one frame of the external eye image Ma to detect the maximum brightness. . For example, if the maximum brightness of this external eye image is 240, this maximum brightness is 100.
Microprocessor unit 2
5 controls the aperture area of the variable diaphragm 18. In this way, when the aperture area of the variable aperture 18 is narrowed, the light source 1
When the light is turned on, a composite image of the external eye image Ma' and the target image Mb, which has a slightly lower brightness, is projected onto the surface of the image sensor 15, as shown in FIG. 6, and this composite image is processed by the signal processing circuit. 2
2, the image is displayed on the television monitor 23 and simultaneously taken into the frame memory 24.

Since the gradation of the optotype image Mb is usually much higher than that of the extraocular part image Ma', the optotype image Mb is completely separated from the composite image by binarizing it with a gradation of 150 as a threshold, for example. An ocular refraction value measurement can be performed. In this way, the extraocular part image Ma'' and the optotype image M are displayed on the television monitor 23.
If ``b'' and ``b'' can be displayed at the same time, the examiner can accurately grasp the alignment state at the time of measurement. Furthermore, disturbance light caused by unexpected illumination of the external eye part is also recognized as a bright spot in the external eye part image Ma, and the aperture of the variable diaphragm 18 is adjusted based on the light intensity of this bright spot, so that the aperture of the variable diaphragm 18 is adjusted. can prevent harmful light. Note that the gradation value used when changing the aperture of the variable diaphragm 18 and the gradation value used when binarizing are determined by a program stored in the microprocessor unit 25 in advance.

In eye refractive power measurement, simultaneity is used to remove accommodation of the eye E to be examined! 20b is blurred and the subject's eye E is made to gaze at it. The light beam from the fixation target light source 20a is transmitted to the fixation target 20b and the relay lens 19.
It is reflected by the dichroic mirror 16, passes through the dichroic mirror 9 and the objective lens 10, and reaches the eye E to be examined! 20b is presented, and the fixation target unit 20 is moved in a direction along the optical path according to a control signal from the microprocessor unit 25 to function. Therefore, in actual measurement, the microprocessor unit 25 calculates the eye refractive power of the eye E to be examined, moves the fixation target unit 20 based on this measurement value, removes the accommodative power of the eye E, and repeats the process. Measurements will be taken.

Furthermore, if the optotype image Mb is not bright enough due to variations in the reflected light flux of the fundus Er of the eye E to be examined, and it is not possible to accurately separate and recognize it from the external eye part image Ma', the microprocessor unit 25 adjusts the amount of light. It is also possible to increase the amount of light from the light source 1 to the extent that separation and recognition is possible.

Further, when the above-mentioned measurement is completed, the aperture of the variable diaphragm 18 is preferably opened to the maximum again to prepare for the next measurement. Note that the variable aperture 18 may be replaced by two polarizing plates, and the amount of light of the extraocular image Ma' can be adjusted by changing the rotation angle of the polarizing plates.

In addition, although the case where this invention was applied to the eye refractive power measurement was demonstrated in the Example, it is possible to apply similarly to the corneal shape measurement.

[Effects of the Invention] As explained above, the ophthalmological measuring device according to the present invention adjusts the light intensity of the luminous flux that enters the image sensor through the observation optical system according to the maximum brightness of the extraocular image on the image carrier. Since the eye refractive power is measured by separating the optotype image from the composite image of the extraocular part image and the optotype image on the image element, the extraocular part image is displayed on a TV monitor and the extraocular part image is measured. Measurements can be made without interrupting observation, and the examiner can always grasp the alignment status. Furthermore, in the case of wearing a contact lens, measurement can be performed while confirming the position of the contact lens on the cornea of the eye to be examined, so measurement can be easily performed at a desired contact lens site.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmological measuring device according to the present invention, and the first
2 is a front view of the projection diaphragm, 3 is a front view of the measurement diaphragm, 4 is an explanatory diagram of the display on the TV monitor, 5 is an explanatory diagram of the target image, FIG. 6 is an explanatory diagram of the composite image. 1 is a light source, 21 is a light source, 15 is an image pickup device, 18 is a variable aperture, 20 is a fixation target unit, 22 is a signal processing circuit, 23 is a television monitor, 24 is a frame memory, and 25 is a microprocessor unit. Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. An observation optical system that projects an image of the extraocular part of the eye to be examined onto an image sensor; and a projection optical system that projects an optotype onto a predetermined part of the eye to be examined;
Ophthalmological measurement comprising: a measurement optical system that projects the optotype image reflected at the predetermined site onto the imaging device; and a display unit that outputs and displays the extraocular part image and the optotype image projected onto the imaging device. In the apparatus, a detection means for detecting a maximum brightness of the extraocular image; a light control means for adjusting the amount of light of the extraocular image that enters the image sensor via the observation optical system according to the maximum brightness; and a calculation means for performing ophthalmological measurements by separating the optotype image from a composite image of the extraocular part image and the optotype image simultaneously projected onto the imaging device in a state adjusted by the light adjustment means. Features of the ophthalmological measuring device. 2. The ophthalmological measuring device according to claim 1, wherein the brightness of the optotype image is adjustable.