JPS6377428A - Eye refraction power measuring apparatus - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an eye refractive power measurement device that measures eye refractive power by controlling an internal fixation target using a fog control method.

[Prior Art] This type of conventional device has a built-in fixation target for stabilizing the fixation of the subject's eye, but when the subject's eye looks into the fixed 1L target inside the instrument, This causes myopia, so to eliminate this problem, a fog control method is used to control and measure the fixation target.

This allows the fixation target to be moved to any position according to the refractive power of the subject's eye. The procedure of first moving the fixation target slightly to the far side to measure the eye refractive power, then moving the fixation target again and measuring is repeated.

However, measuring eye refractive power using such a cloud control method requires several seconds for one measurement, so it is difficult for children, the elderly, or subjects with nystagmus to gaze at the internal fixation target for this length of time. A drawback is that it is difficult to measure the eye refractive power of the examiner. In other words, for the examinee, it is difficult for the examiner to bear gazing at the internal fixation target even for a few seconds, and for the examiner, the examinee's eye moves, so the 7-line alignment of the instrument must be kept in place during this period. It takes a lot of effort to keep making adjustments. Furthermore, there is also the problem that measurement is difficult when targeting an eye that does not have an adjustment function, such as an aphakic eye.

[Object of the Invention] In order to improve such problems, the object of the present invention is to provide an eye refractive power measurement method that enables measurement in a short time by scratching and allows easy measurement of refractive power even in the subject's eye without an adjustment function. The goal is to provide equipment.

[Summary of the Invention] The gist of the present invention for achieving the above-mentioned object is to provide a fog control means for controlling fog of a fixation target, a position control means for setting the position of the fixation target, and a control means for controlling both of the abovementioned control means. This is an eye refractive power measurement device characterized by comprising a selection means for selecting.

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

In FIG. 1, 1 is an infrared light emitting diode, and the infrared light emitted from this diode 1 is transmitted through a condenser lens 2, a fundus projection chart 3, a relay lens 4, a circular diaphragm 5, a perforated mirror 6, a first Guicroic mirror 7,
The light passes through the second guichroic mirror 8 and the objective lens 9 to the eye E to be examined. As shown in FIG. 2, the projection chart 3 has slits 3a to 3C radially oriented in so-called three meridian directions at an angle of 1200 degrees to each other, and is movable along with the light emitting diode 1 in the optical axis direction. There is. 1st and 2nd groic mirror 7.8
has the characteristics of transmitting infrared light and reflecting visible light, and is arranged obliquely with respect to the optical axis.

On the other hand, the light reflected from the fundus Ef passes through the original optical path and is reflected around the perforated mirror 6, and along this reflected optical path passes through the diaphragm plate 10, the lens 11, the prism 121, and the reflecting mirror 13.
, a cylindrical lens 14, and a one-dimensional photoelectric conversion element 15 consisting of a COD are arranged in sequence. The aperture plate 10 has six openings 10a to 10f, as shown in FIG. It is supposed to be done. Further, as shown in FIG. 5, the cylindrical lens 14 is made up of three lenses 14a to 14c arranged in three meridian directions, and the photoelectric conversion element 15 is also made up of three elements 15a to 15c. 14a-14c and element 15
A to 15c correspond to each other one by one.

Visible light emitted from an illumination lamp 16 is incident on the first guichroic mirror 7, and the light from the illumination lamp 16 is directed to a fixation target 17 and a lens arranged along the optical axis of the illumination lamp 16. The light is incident through 18. Further, an observation optical system is arranged on the reflection side of the second guichroic mirror 8, and the reflected light from the guichroic mirror 8 is received by a TV relay lens 19 and a TV image pickup tube 20.

During measurement, a slit image of the projection chart 3 formed by infrared light from the light emitting diode 1 passes through the circular diaphragm 5 and the holes of the perforated mirror 6 through the relay lens 4, and then passes through the holes of the first and second gichroic mirrors 7. The image is formed on the primary imaging plane F located between .8 and 8. This image is transmitted through the objective lens 9 to the pupil E of the eye E.
It is projected from p and forms an image on the fundus Ef. on the other hand,
The light reflected from the fundus Ef is once imaged from the periphery of the pupil Ep onto the primary imaging plane F by the objective lens 9, and then reflected from the periphery of the perforated mirror 6, and then transferred to the diaphragm plate 10 and the lens 11.
, is separated and deflected by a prism 12 , and is imaged onto a photoelectric conversion element 15 via a cylindrical lens 14 .

In this case, the accommodation by the openings 10a to 10f of the diaphragm plate IO is separated by each element 12a to 12f of the prism 12. Further, the diaphragm plate 10 separates the incident light by focusing on the pupil Ep, and eliminates the influence of scattering within the eye E to be examined. The relationship between the photoelectric conversion elements 15 and the reflected images is that, as shown in FIG. The image is formed on 15c. The six openings of the aperture plate 10 are 10a, 10d, and 10.
b and 10e, and 10'c and lof form pairs, and each pair corresponds to three photoelectric conversion elements 15a to 15c. Therefore, reflected images Ra and Rd are formed on the element 15a, Rh and Re are formed on the element 15b, and Re and Rf are formed on the element 15c. On the other hand, the cylindrical lens 14 a -14
c is the opening 10a to 10f in the direction of having refractive power.
It has the role of forming an image on the photoelectric conversion elements 15a to 15c, reducing the image in the lateral direction, and increasing the amount of light.

Now, if the eye E to be examined is an emmetropic eye, the chart reflection image R projected by the infrared diode 1 and reflected by the fundus EF is re-imaged on the primary imaging plane F, separated by the diaphragm plate 10, and sent to the photoelectric conversion element. The image is formed at 15 predetermined positions. However, in a non-emmetropic eye, the fundus image is formed in front and behind the imaging plane F, so
The angle of the light beam incident on the aperture plate 10 changes and the prism 12
The deflection angle also changes, and the interval between the two reflected images R on the photoelectric conversion element 15 changes.

The signal of the photoelectric conversion element 15 becomes as shown in FIG.
By measuring the interval between the two peaks, the refractive power in the longitudinal direction of the photoelectric conversion element 15 can be measured. Further, the diopter of the eye E to be examined changes depending on the angle, and the refractive power Dθ in the θ direction can be expressed by the following formula: Dθ=AB□*5in2 (θ+θ.). Note that A is the spherical power Sp of the eye E to be examined.
The value related to h, Bo is the value related to astigmatic power cy+, θ0
is a value related to the astigmatic angle Ax.

Therefore, in order to obtain Sph, C71, and AI, it is sufficient to obtain the refractive powers in the three meridian directions. Therefore, as shown in FIG. 5, three photoelectric conversion elements 15a to 1
5c in a predetermined meridian direction and Sph, C! I, A
This is to calculate x.

FIG. 7 is a block diagram showing an embodiment of the electrical control system.

The output signals from the photoelectric conversion elements 15a to 15c are A/D
After being subjected to waveform processing and A/D conversion by the conversion circuit 21, it is taken into the RAM 23 via the data bus 22, and the microcomputer 24 operates according to the control program written in the ROM 25. Note that 26 is an interface circuit, and a display 29 displays measurement results based on signals from the measurement switch 27 and the selection switch 28.
, and controls a motor 30 that drives the illumination lamp 16 and the fixation target 17.

When performing general measurements, the selection switch 28 is set to the X position and the fixation target 1 illuminated by the illumination lamp 16 is placed on the subject.
7 and adjust the 7 alignment between the device and the eye E while watching the TV monitor connected to the TV image pickup tube 20.
Next, when the measurement switch 27 is pressed, the first measurement is performed at the position where the fixation target 17 is initially set, and the first refractive power is obtained. Therefore, the fixation target 17 is moved by the motor 30 to a position corresponding to the obtained refractive power. In this state, the fundus Ef of the eye E to be examined is in a substantially conjugate relationship with the fixation target 17, so that the eye E is in a clear vision state.

Then, in order to eliminate instrumental myopia, the fixation target 17 is moved in a direction slightly farther from that position and the measurement is repeated, and the measurement is continued while removing the accommodation force of the eye E. Check the area that has been removed, display the final measurement result on the display 29, and complete the measurement.

In addition, when measuring the subject's eye E, such as a child or the elderly, who cannot keep gazing at the open target 17 during foggy conditions, the selection switch 28 may be moved from the general measurement position, for example, indicated by X, to the position indicated by Y. Perform this by switching to the position.

In this way, the fixation target 17 is set at the normal viewing position, and when the measurement switch 27 is pressed, the measurement result is immediately displayed on the display 29 after one measurement. In this case, since the fixation target 17 does not move, the measurement is completed in a short time.

Further, when measuring an eye E without an accommodation function such as an aphakic eye, the selection switch 28 is set to the position indicated by Z. Therefore, if the measurement switch 27 is pressed to measure only once, and the fixation target 17 is moved to the position of the measured refractive power and placed almost conjugate with the eye E, the fixation target 17 becomes a stable state of clear vision. Therefore, the measurement is completed with the next measurement.

In this case, the fixation target 17 only needs to be moved once, making it possible to perform measurements in a short time.

[Effects of the Invention] As explained above, the eye refractive power measuring device according to the present invention has the following effects:
Since the selection means can control the presence or absence of positioning movements and the number of times, it is easy to measure eye refractive power even in subjects who cannot gaze at the fixation target for a certain period of time, such as children and the elderly, or patients with severe nystagmus or blinking. can be done. In addition, stable measurement can be performed in a short time even with an eye to be examined that does not have an accommodation function, such as an aphakic eye.

[Brief explanation of the drawing]

The drawings show an embodiment of the eye refractive power measuring device according to the present invention,
Figure 1 is a configuration diagram of the optical system, Figure 2 is a front view of the projection chart, Figure 3 is a front view of the aperture plate, Figure 4 is a front view of the prism, and Figure 5 is the fundus reflection image and photoelectric conversion. FIG. 6 is an output waveform diagram of the photoelectric conversion element, and FIG. 7 is a block circuit configuration diagram for electrical control. 1 is an infrared light emitting diode, 3 is a projection chart, 4 is a relay lens, 5 is a circular diaphragm, 6 is a perforated mirror, 7.
8 is a guichroic mirror, 9 is an objective lens, 10 is an aperture plate, 12 is a prism, 14 is a cylindrical lens,
15 is a photoelectric conversion element, 16 is an illumination lamp, 17 is a fixation target, 20 is a TV image pickup tube, 21 is an A/D conversion circuit, 24 is a microcomputer, 27 is a measurement switch, 28 is a selection switch, and 29 is a display device. , 30 is a motor. Patent applicant Canon Co., Ltd. Figure 7

Claims (1)

[Scope of Claims] 1. A cloud control device for controlling fog of the fixation target, a position control device for setting the position of the fixation target, and a selection device for selecting both of the control devices. Features of the eye refractive power measuring device. 2. The eye refractive power measuring device according to claim 1, wherein the position control means sets the fixation target at a normal viewing position and performs measurement. 3. The position control means sets the fixation target at a normal viewing position and measures it, moves the fixation target to a position corresponding to the eye refractive power obtained in the measurement, measures again, and ends the measurement. An eye refractive power measuring device according to claim 1, wherein the eye refractive power measuring device is configured to: