JPH0349445B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. OBJECTIVES OF THE INVENTION A-1. Field of Industrial Application The present invention relates to an objective type automatic eye refractometer having a fixation target projection system that causes a subject's eye to have a foggy vision.

A-2 Prior Art As a device for measuring the refractive power of the eye, there are many objective-type automatic devices because the measurement time is fast, the measurement does not require skill, and there is little difference in measurement between examiners. Refractive power measuring devices have been proposed, but the common method is to project a measurement target onto the fundus of the eye to be examined, detect the reflected light from the fundus of the eye to be examined with a light receiving element, and then measure the refractive power based on the results of the detected hairs. This method obtains refractive power information of the eye to be examined. These devices are provided with a fixation target for the purpose of stabilizing the subject's line of sight during measurement. However, when the subject looks at the fixation test in the device, an accommodative force acts on the subject's eye, so it is not possible to accurately measure refractive power in this state.
Therefore, with conventional devices, the refractive power is measured when the accommodative force is working at the beginning of the measurement, and then the fixation chart is set so that it is positioned only at an appropriate diopter, so that the subject's eye is placed in a foggy vision state. The adjustment power was removed. 1 of these
The process is controlled by a built-in microcomputer and is carried out automatically, so it is called an auto-fog (other methods are referred to here as manual methods).

However, there are some eyes to be examined that are not suitable for such an auto-fogging method. When the subject's eye has severe astigmatism, the amount of blur in the fixation target is large, making it impossible to stably gaze at the fixation target. Furthermore, an auto fogger for the eye of a child with a large accommodative ability does not produce a sufficient fogging effect.

In view of the drawbacks of the above-mentioned conventional devices, an object of the present invention is to
To provide an objective type automatic eye refractive power measurement device that allows even a person who cannot perform proper measurement using an autofog method to perform measurement in an appropriate foggy vision state.

B. Structure of the Invention B-1 Means for Solving Problems The gist of the present invention for achieving the above-mentioned object is to project a measuring index on the ophthalmoscope of the eye to be examined, and to measure the reflected light from the fundus of the eye to be examined. In an objective automatic refractive power measuring device that can detect with a light receiving element and obtain refractive power information of the eye to be examined, the refractive power measurement device uses a light receiving element to detect the refractive power of the eye to be examined. a fixation target projection system; a correction optical system including an astigmatism correction optical system arranged between the fixation target and the subject's eye and capable of adjusting the degree of refraction; a first mist applying means that changes the refractive power of the corrective optical system by an arbitrary amount and applies a mist to the eye to be examined; The present invention is characterized by having a fog changeover switch for selecting between the first fog applying means and the second fog applying means.

RO-2 Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 1 is an optical system layout diagram of one embodiment of the objective automatic eye refractive power measuring device according to the present invention.

1 is a measurement light source with a wavelength in the infrared region; 2;
3 is a condenser lens; 4 is a movable spot diaphragm (measurement target; hereinafter simply referred to as spot diaphragm) to be placed at a position conjugate to the fundus of the eye 8 to be examined; 5, 6;
is an objective lens, 7 and 9 are prisms, 10 is a mirror, 11 and 12 are relay lenses, and 13 is the eye to be examined 8
14 is a moving lens that moves together with the spot diaphragm 4, and 15 is an imaging lens.
Reference numeral 16 indicates a light receiving element for measurement, which is connected to the light source 1 for measurement.
It rotates around the optical axis in synchronization with the corneal reflection removal mask 13. A first relay lens 17 is movable on the optical axis, and the amount of movement thereof is proportional to the spherical refractive power of the eye to be examined. As is well known, when a cylindrical component is created using two cylindrical lenses, it is necessary to take the spherical effect into account and make corrections. 1
Reference numerals 8 and 19 are positive cylindrical lenses having the same focal length, and both are rotatable about the optical axis by the same amount in the same direction or in opposite directions. 20 is a second relay lens, 21 is a fixation target placed at the focal position of the second relay lens 20, 22 is a condensing lens,
23 is an illumination lamp.

Figures 2 and 3 show other embodiments of the fixation target optical system, and 18a and 19a in Figure 2 are positive cylindrical lenses with equal focal lengths, and the same direction is opposite. It is possible to rotate around the optical axis by the same amount. In FIG. 3, 18b is a positive cylindrical lens, which is movable on the optical axis.
Reference numeral 19b indicates a negative cylindrical lens, and the positive cylindrical lens 18b rotates around the optical axis together. Further, both of these cylindrical lenses and the first relay lens are movable together on the optical axis.
There are various other combinations, but there is no point in excluding them.

Figure 4 shows the first relay lens 1 in the fixation target optical system.
7 and the cylindrical lenses 18 and 19. Reference numeral 24 denotes a dial provided on the side of the body (not shown), which generates a pulse signal by rotating a rotary encoder. 25 is a pulse counter, 26 is a microcomputer that controls all operations related to objective and subjective measurements, 27 is a display, 28 is a pulse motor driver, 29 is a cylindrical lens, 18, 1
9 is a pulse motor for rotating around the optical axis to change the cylindrical refractive power and the axis angle; 30 is a D/A converter for converting digital signals into analog signals;
31 is a DC motor for moving the first relay lens 17 along the optical axis and changing the spherical refractive power; 32
is an A/D converter.

With the above configuration, the light energy emitted from the light source 1 passes through the condensing lenses 2 and 3, the spot diaphragm 4, and the objective lens 5, and reaches the fundus of the eye where the light is condensed on the cornea of the eye 8 to be examined. On the other hand, the lighting lamp 23
The light passes through the condenser lens 22 and projects a fixation target onto the fundus of the eye to be examined, causing the eye 8 to be examined to fixate. The light reflected from the fundus of the eye is reflected by a mirror 10, passes through relay lenses 11 and 12, and is focused on a light receiving element by an imaging lens. The light energy incident on the light receiving element 16 is supplied to the microcomputer 26 as a digital signal. When the measurement button (not shown) is pressed after the alignment for the eye 8 to be examined is completed, the microcomputer 26 moves the spot diaphragm 4 and the moving lens 14 until the position of the spot diaphragm 4 is conjugate with the fundus of the eye 8 to be examined. . At the same time, the fixation target 21 is imaged on the fundus of the eye 8 to be examined, and then the first relay lens 17 is moved so that fog is automatically applied by an appropriate diopter. Thereafter, the measurement light source 1, the corneal reflection removal mask 13, and the measurement light receiving element 16 are rotated by 180° around the optical axis. During rotation, the spot diaphragm 4 and the movable lens 14 are moved by signals from the light receiving element, and the refractive power value for each path can be determined from the amount of movement.

As described above, automatic fogging is applied unless the fogging switch (not shown) is pressed. This is because there are only a few people who cannot be measured by autofog, and there is no special meaning beyond that. Press the fog switch to switch to manual fog. In this case, the fixation target may be used as is, or it may be switched to a trial sight chart.

In this state, for example, if the subject cannot sufficiently see the fixation target or, for example, cannot see the Landolt ring corresponding to normal visual acuity of 1.0, the corrective optical system is moved by the following manual operation. The basics of this procedure are the same as for measuring subjective refractive power. That is, when measuring the spherical refractive power, when the spherical refractive power measurement switch is pressed and the dial 24 is rotated, a pulse signal is inputted to the microcomputer 26 by the counter 25 and sent to the DC motor via the D/A converter 30. 31 is activated to move the first relay lens on the optical axis. When measuring the cylindrical power, press the cylindrical power measuring switch, and when measuring the axial angle, press the axial angle measuring switch and rotate the dial 24. The microcomputer 26 starts the pulse motor 29. The cylindrical lenses 18 and 19 are rotated independently. For example, the dial 24 is
One pulse is generated by a rotation of 2°, and the spherical and cylindrical refractive powers are set to correspond to 0.25D, and the axial angle is set to correspond to 1°. As the dial 24 is rotated, the refractive power value is displayed on the display 27. The same applies to the embodiment shown in FIG. In the embodiment shown in FIG. 3, the first relay lens 17 and cylindrical lenses 18b and 19b are integrally moved by the DC motor 31 to set the spherical refractive power, and the cylindrical lens 18b is moved to set the cylindrical refractive power. do. Further, the cylindrical lenses 18b and 19b are moved integrally by the pulse motor 29.

However, since the problem here is how much fog should be applied to achieve accurate objective measurement, the above operating procedure will be greatly simplified. Once the approximate refractive power of the subject has been obtained in this manner, the examiner applies fog for an appropriate amount and time depending on the characteristics of the eye to be examined, and then presses the measurement button to take the measurement. It is also possible to conduct a more precise subjective test first, apply appropriate fogging based on the results, perform objective measurements, and confirm the results of the subjective test.

In normal cases where a detailed subjective test is not performed first, after the objective measurement, the switch for switching to subjective measurement (not shown) is pressed to switch to the subjective refractive power measurement, and the microcomputer 26 controls the objective measurement first. 1st relay lens 1 to the obtained value position
7 moves and the cylindrical lenses 18 and 19 rotate, the subjective measurement of the subject's eye 8 is performed in the same manner as described above, with the corrected refractive power obtained in the objective measurement as the initial value.

C. Effects of the Invention As is clear from the above explanation, according to the present invention, the refractive power of the fixation target projection system can be changed manually in a continuous or stepwise manner. By applying an appropriate amount of mist to remove the accommodative power of the subject's eye, it is possible to accurately measure refractive power even for people who are unable to adapt to the test.

[Brief explanation of drawings]

FIG. 1 is an optical system layout diagram of an eye refractometer according to the present invention, FIGS. 2 and 3 are optical system layout diagrams showing other embodiments of each fixation target system, and FIG. 4 is a block diagram. It is a diagram. 1...Light source for measurement, 4...Spot aperture, 5,
6... Objective lens, 8... Eye to be examined, 13... Corneal reflection removal mask, 14... Moving lens, 16...
Light receiving element, 17...first relay lens, 18,1
9...Cylindrical lens, 21...Optotype

Claims (1)

[Scope of Claims] 1. An objective automatic system capable of projecting a measuring index onto the eye to be examined, detecting reflected light from the fundus of the eye with a light receiving element, and obtaining refractive power information of the eye to be examined. In an eye refractive power measuring device, a fixation target projection system for causing the eye to be examined to fixate is placed at a position where the optical path of the measurement optical system is branched, and a fixation target projection system is placed between the fixation target and the eye to be examined. a corrective optical system including an astigmatism correcting optical system capable of adjusting the refractive power; and a first mist applying means for applying a mist to the subject's eye by changing the correcting optical system by a predetermined amount and time based on preliminary measurement values. , a second fog applying means that changes the refractive power of the corrective optical system by an arbitrary amount and applies a fog to the eye to be examined, and a fog changeover switch that selects between the first fog applying means and the second fog applying means. An objective automatic eye refractive power measuring device characterized by the following.