JPH0191832A - Ophthalmic measuring apparatus - Google Patents

Abstract

PURPOSE:To enhance operability and to simply perform not only automatic measurement but also the measurement of the shape of the cornea, by providing a positioning observation optical system and changing over the same between at the time of positioning and at the time of measurement. CONSTITUTION:The television signal from a image sensing element 16 is stored in an image memory 24 and operated to calculate the position coordinates of four cornea reflected images 12A-12D on the image sensing element 16. The radii of curvature and the axial angles thereof on both strong and weak diameter lines can be calculated from four position coordinates by operation. An examiner may indicate the start of the measurement by a measuring switch 35 or the alignment state of the apparatus and an eye E to be examined is automatically judged by the apparatus and automatic measurement can be also performed at the point of time when positioning is completed. When the shape of the cornea is calculated by this method, a light source 7 is allowed to light by the switch operation of the examiner or automatically to turn cornea measuring light sources 12a-12d OFF and an ultrasonic probe 8 is advanced on an optical axis L to measure the axial length of the eye and the refractivity of an intraocular lens is calculated to be displayed.

Description

Detailed Description of the Invention C. Industrial Field of Application] The present invention is a method of measuring the length of each part of the eye to be examined, such as lens thickness and axial length, by bringing a detection probe into direct contact with the cornea of the eye to be examined, for example, using ultrasonic waves. The present invention relates to an ophthalmological measuring device that performs measurements.

[Prior Art] Conventionally, methods for measuring the length of various parts of the eye to be examined, such as lens thickness, vitreous body length, and axial length using ultrasound, and applanation-type eye measurements have been used to make measurements by bringing a detection probe into contact with the cornea. Pressure measuring devices and the like are well known. Furthermore, for both of these, there are two types: one in which the examiner holds the measurement part in his/her hand and contacts the cornea, and the other in which the measurement part is placed on a sliding table and brought into contact after positioning with the eye to be examined.

[Problems to be Solved by the Invention] However, in the method of holding and touching the subject's eye, the pressure is not constant when it is brought into contact with the subject's eye, and the measured value is short when measuring the axial length. Sometimes. A known solution to this problem is to place the measuring device on a sliding table.

Both axial length measurement and intraocular pressure measurement do not have an observation system, and the drawback is that the examiner himself or herself visually aligns the eye to be examined and the detection probe. In particular, these measurements are often performed in a semi-dark room, making the operations more difficult.

[Object of the Invention] An object of the present invention is to provide an ophthalmological measurement device that can improve the difficulty of alignment of conventional devices and improves operability.

[Summary of the invention] The gist of the present invention is to achieve the above objects.

A projection optical system that projects an index onto the cornea of the eye to be examined; an imaging optical system that forms a corneal reflected image of the index onto an optical position detection element;
Display means for detecting and displaying a reference position corresponding to a predetermined position on the optical position detecting element and the imaging position of the corneal reflection image on the optical position detecting element; and the corneal reflection on the optical position detecting element. A first detection system for alignment, which has a calculation means and line-of-sight guide means for calculating the distance between the image and the reference position, and a second detection system that detects information about the eye to be examined by bringing a detection probe into contact with the cornea of the eye to be examined. a detection system, and a first state in which the first detection system is activated and a second state in which the second detection system is activated are switchable by switching the first and second detection systems. The ophthalmological measuring device is characterized in that the optical axis of the imaging optical system in the first state and the central axis of the detection probe in the second state substantially coincide with each other.

[Implementation/Example of the invention] The present invention will be explained in detail based on illustrated embodiments.

1 and 2 show a first embodiment of the present invention, in which FIG. 1 shows the first state in which positioning is performed by observing the corneal reflection image in the ocular axis measurement device, and FIG. A second state is shown in which the detection probe is brought into contact with the cornea Ec of the eye E to be examined to measure the axial length and the like.

In FIG. 1, an objective lens l is provided facing the cornea Ec of the eye E to be examined, and a total reflection mirror 2 is provided behind it along the optical path.
．． Half mirror 3, aperture 4, relay lens 5. A two-dimensional image sensor 6 such as a COD is arranged, and the objective lens 1, total reflection mirror 2, and half mirror 3 are integrally constructed.
It can be moved up and down. A light source 7 for positioning is provided behind the half mirror 3. Also,
Behind the total reflection mirror 2, an ultrasonic probe 8 is held via a probe holder 9 by a sliding guide member 10 so as to be slidable back and forth.

The light beam emitted from the light source 7 passes through the half mirror 3, is reflected to the left by the total reflection mirror 2, and is projected onto the eye E via the objective lens 1. This light beam is reflected by the cornea Ec to form a corneal reflection image 7A. This corneal reflected image 7A is transmitted and refracted by the objective lens 1, reflected by the total reflection mirror 2 and the half mirror 3, and formed into an image on the image pickup device 6 via the aperture 4 and the relay lens 5.

FIG. 3 shows a state in which the aforementioned optical system and the subject's eye E are aligned by moving a sliding table (not shown), and a reflected image 7A of the light source 7 is formed on the image sensor 6 on a television monitor such as a CRT. 1
This is what is shown in 1. Note that P is a reference position observed by projection by an optical system or by electrical processing of a signal output from the image sensor 6. As shown in FIG. 3, when the corneal reflection image 7A falls within the reference position P,
According to the examiner's instructions, the objective lens 1, total reflection mirror 2, and half mirror 3 are moved downward as shown in FIG. Moving forward in the direction E, the ultrasound probe 8 is brought into contact with the cornea Ec of the eye E to be examined. Thereby, the echoes of the ultrasonic pulses emitted from the ultrasonic probe 8 can be used to measure various parts of the eye, such as the axial length.

FIG. 4 shows a block circuit configuration for carrying out the above-described operation. Here, the output of the two-dimensional image sensor 6 is connected to an image signal processing circuit 21 and a mixer circuit 22, and the image signal processing circuit 21 is connected to an internal bus 23. Also,
An image memory 24 is connected to the internal bus 23 , an output of the image memory 24 is connected to a mixer circuit 22 , and an output of the mixer circuit 22 is connected to the television monitor 11 .

Further, the ultrasonic probe 8 is connected to the internal bus 23 via an ultrasonic transmitting/receiving circuit 26 and an ultrasonic signal processing circuit 27. Furthermore, microprocessor unit (MPU)
28, the outputs of read only memory (ROM) 29, random access memory (RAM) 30, and nonvolatile memory 31 are connected to internal bus 23, and the output of internal bus 23 is connected to interface 32, electric motor 33, and printer 34; A measurement switch 35 and a light source 7 are connected to the interface 32 .

The signal from the image element 6 is converted into a television signal by the image signal processing circuit 21 and stored in the image memory 24. The signal of the corneal reflection image 7A is extracted from the stored signal by signal processing, and the position coordinates on the image sensor 6 are calculated. on the other hand,
The positional coordinates of the reference position P are stored in the read-only memory 29 or the nonvolatile memory 31 in advance, and when the difference between the two positional coordinates becomes smaller than a predetermined value, it is determined that the alignment between the eye E and the apparatus is complete. The objective lens 1, the total reflection mirror 2, and the nof mirror 3 are lowered by the electric motor 33.
The probe holder 9 is advanced to bring the ultrasound probe 8 into contact with the cornea Ec of the eye E to be examined.

Alternatively, the display means may display that the switching is possible and wait for the examiner's input using the measurement switch 35.Furthermore, in order to prevent the device from moving during switching, the sliding By fixing the stand with a fixing means such as an electromagnetic lock, the ultrasonic probe 8 can be reliably moved to a desired position.

In addition, the ultrasound probe 8 has a known sliding mechanism (not shown) and is biased forward by a weak tension spring or the like, so that even if the probe 8 moves further after contacting the eye E, it will retreat. In addition, the ultrasonic signal processing circuit 27 shown in FIG. 4 constantly processes the ultrasound echo waveform to prevent the cornea Ec from being damaged or the axial length to be measured too short. If the electric motor 33 is stopped based on a change in the signal waveform when the sonic probe 8 comes into contact with it, the above-mentioned danger will be further reduced.

5(a), (b) and FIG. 6 show a second embodiment in which the present invention is applied to a device for calculating the refractive power of an intraocular lens by measuring corneal shape and measuring axial length. Figure 5 (a)
is a side view, and (b) is a front view. In addition, Figures 1 and 2
The same reference numerals as in the figures indicate the same members. For example, four light sources 12a to 12d for corneal shape measurement are arranged around the objective lens 1. First, when measuring the corneal shape, the alignment light source 7 is turned off, and as shown in FIG. , light source 12 on the TV monitor 11
Corneal reflection images 12A to 120 of a-12d and a reference position P for corneal shape measurement are displayed. With the circuit configuration shown in FIG. 4, the television signal from the image sensor 6 is stored in the image memory 24, and the position coordinates of the four corneal reflection images 12A to 120 on the image sensor 6 are calculated by the processing. From the position coordinates of these four points, the radius of curvature on the strong and weak radial line and its axis angle can be calculated by calculation. This measurement may be started by the examiner using the measurement switch 35, or from the position coordinates of each corneal reflection image 12A-120, the apparatus and the eye to be examined E
It is also possible for the device to automatically determine the 7-alignment state and automatically measure when alignment is completed.

When the corneal shape is calculated in this way, the light source 7 is turned on and the corneal measurement light sources 12a-12d are turned off by the examiner's switch operation or automatically, and the ultrasonic wave is applied along the optical axis according to the above-mentioned procedure. The probe 8 is advanced to measure the axial length of the eye, and the examiner's switch operation automatically calculates and displays the refractive power of the intraocular lens according to a known formula.

Moreover, even if the positioning light source 7 is not provided, if the corneal reflection image position information of the corneal shape measurement light sources 12a to 12d is used for positioning when measuring the ocular axial length, the positioning light source 7 can be used.
Alignment can be performed without having to hold the

FIG. 8 shows a state in which this second embodiment is placed on a known sliding mechanism and the eye E to be examined is being measured. Objective lens 1. The ultrasonic probe 8 and the like have the same configuration as in FIGS. 1 and 5, and include a fixation lamp 1 for guiding the line of sight of the eye E to be examined.
4 is provided in front of the eye E to be examined. A display television monitor 11 is directed toward the examiner, and a movable sliding table 15 on which the entire device is placed is provided in front of the examiner. A joystick 16 is provided for adjustment.

Normally, the eye E to be examined is considered to have a cataract, so in order to guide the line of sight, the fixation lamp 14 is fixed with the other eye, which is different from the eye E with weak visual acuity, and the position of the fixation lamp 14 is It is preferable to measure a predetermined site on the cornea Ec by moving the .

Furthermore, if the fixation lamp 14 is not effective, many sound sources may be placed in front of the subject's eye E without relying on light, and the subject may be forced to fixate the direction in which the sound is generated, or a stereo sound source such as headphones may be used. It is also conceivable to guide the line of sight using sound, such as having the user fixate their gaze in the direction of a virtually synthesized sound source.

[Effects of the Invention] As explained above, the ophthalmological measuring device according to the present invention has an observation optical system for alignment, and has a structure in which it is switched between alignment and measurement, thereby improving operability. Applications such as automatic measurement and corneal shape measurement can also be easily implemented.

[Brief explanation of the drawing]

The drawings show an embodiment of the ophthalmological measuring device according to the present invention, and the first embodiment
The figures are a configuration diagram of the positioning state according to the first embodiment, and a configuration diagram of the alignment state according to the first embodiment.
3 is a front view of the display means, FIG. 4 is a block circuit configuration diagram, and FIG. 5(a) is a configuration diagram of the alignment state according to the second embodiment. (b) is a layout diagram of the light source for corneal shape measurement, FIG.
The figure is a configuration diagram of a device placed on a sliding table. Symbol l is the objective lens, 2 is the total reflection mirror, and 3 is the half mirror.
14 is an aperture, 5 is a relay lens, 6 is an image sensor, 7 is a light source for positioning, 8 is an ultrasonic glove, 9 is a probe holder, IO is a sliding guide member, 11 is a television monitor, 12
a N12d is a light source for corneal shape measurement, 14 is a fixation lamp, 1
5 is a sliding table. Figure 2 Figure 3 Figure 4 Figure 5 CG) (b) Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. A projection optical system that projects an index onto the cornea of the eye to be examined; an imaging optical system that forms a corneal reflected image of the index onto an optical position detection element; and a predetermined area on the optical position detection element. A display means for detecting and displaying a reference position corresponding to the position of It consists of a first detection system for alignment, which has a calculation means for calculation and a line-of-sight guide means, and a second detection system that detects information about the eye to be examined by bringing a detection probe into contact with the cornea of the eye to be examined. A first state in which the first detection system is activated and a second state in which the second detection system is activated are the same as those in the first and second detection systems.
The detection system can be switched by replacing the detection system, and the optical axis of the imaging optical system in the first state and the central axis of the detection probe in the second state are made to substantially coincide. Ophthalmology measuring device. 2. The ophthalmological measuring device according to claim 1, wherein the first detection system has a calculation mechanism that calculates the imaging position of the corneal reflection image on the optical position detection element. 3. The ophthalmological measuring device according to claim 1, wherein the first detection system has an arithmetic function for calculating the corneal shape based on the position of the corneal reflection image of the index. 4. The device according to claim 1, wherein the first state and the second state are switched when the distance between the corneal reflection image and the reference position becomes within a preset distance. Ophthalmology measuring device. 5. Ophthalmological measurement according to claim 1, wherein if the distance between the corneal reflection image and the reference position is within a preset distance, the display means displays that switching is possible. Device. 6. The device according to claim 1, further comprising a mechanism for fixing a sliding table on which the first and second detection systems are mounted when switching between the first state and the second state. Ophthalmology measuring device. 7. The ophthalmological measuring device according to claim 2, further comprising a projection optical system for photographing an index other than the index, and measuring the shape of the cornea from the position of the corneal reflection image. 8. The ophthalmological measuring device according to claim 1, wherein the line of sight guide means is a movable fixation lamp that causes the other eye of the subject to fixate. 9. The ophthalmological measuring device according to claim 1, wherein the line-of-sight guiding means is a sound emitted from a certain direction. 10. The ophthalmological measuring device according to claim 1, wherein the line of sight guide means includes a plurality of sound sources arranged in different directions with respect to the subject. 11. The ophthalmological measuring device according to claim 10, wherein the line-of-sight guiding means is a stereo sound source.