JPH0212086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ophthalmological measuring device capable of detecting whether the received light output level of an optotype reflected image from a subject's eye is within a normal operating range. It is.

[Prior art] For example, a non-contact tonometer that uses air pulses blows air pulses onto the cornea from the axial direction of the device, and measures intraocular pressure based on the time it takes for the cornea to applanate. However, if the corneal apex and the horizontal ocular axis do not exactly match the axis of the device, accurate intraocular pressure cannot be measured. Therefore, in the non-contact tonometer known from, for example, Japanese Patent Publication No. 56-55772, a positioning optical system is provided to align the corneal apex with the axis. Then, the examiner determines the moment when the subject's corneal apex coincides with the axis using this positioning means, and
The air pulse circuit is turned on and air pulses are fired.

In the conventional apparatus shown in FIG. 4, 1 is an illumination lamp, and light from this illumination lamp 1 is transmitted to an alignment target 2 drawn on a diffuser plate, and a dichroic mirror 3 that transmits infrared and reflects visible light. , the center of corneal curvature Eb of the eye to be examined E through the total reflection mirror 4, the lens 5, and the objective lens 7 which is reflected by the half mirror 6 and has an orifice 7a for emitting an air pulse at its center. The light is now focused on Further, reference numeral 8 denotes an infrared light emitting diode arranged behind the dichroic mirror 4 and provided at a position conjugate with the optotype 2.

The optotype image directed toward the center of corneal curvature Eb is reflected on the surface of the cornea Ec, becomes parallel light by the objective lens 7, and then passes through the half mirror 6 and lens 9 to a dichroic mirror that reflects infrared light and transmits visible light. 10, and the image is formed on a transparent plate 11 on which an aiming circle is drawn. Incidentally, the infrared light is reflected by the dichroic mirror 10 and formed into an image on the infrared detection diode 12 located at a conjugate position with the transparent plate 11. The examiner can match the position and focus of the visible light target image on the aiming circle through the eyepiece 13 while moving the entire apparatus. 14 is an infrared light emitting diode that emits parallel light and projects external light obliquely onto the cornea Ec. When the vertex of the cornea Ec is applanated from a convex surface to a flat surface by an air pulse, the The emitted light passes through the lens 15 to the infrared detection diode 16
The arrangement is such that the light is most efficiently focused on the top.

When the examiner presses the measurement button when the alignment is completed, the light passes through the orifice 7a of the objective lens 7,
An air pulse with a known pressure-time relationship is fired toward the apex of the cornea Ec. Then, the intraocular pressure can be determined by measuring the time it takes for the apex of the cornea Ec to change from a convex surface to a flat surface using the output of the infrared detection diode 16. When the measurement button is pressed, if the image of the alignment optotype 2 is not correctly within the aiming circle of the transparent plate 11, an infrared detection diode 12 is installed at a conjugate position with the transparent plate 11 so that an air pulse is not emitted. The measurement button is configured to work only when an output of . However, if the optical system of the apparatus becomes dirty with dust, fingerprints, etc., the attenuation of the optotype light increases even if the alignment is performed accurately. Therefore, the initially set air pulse emission signal strength cannot be obtained, which is equivalent to misalignment, and the air pulse will not be emitted even if the measurement button is pressed. In addition, when the optical system is slightly dirty, there is a drawback that the air pulse is emitted sometimes or not, resulting in an unstable state due to the difference in the reflectance of the cornea Ec.

[Object of the Invention] The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples, and to provide an ophthalmological device that can detect a decrease in the light receiving output level due to dirt in the optical system or deterioration of the light emitting/receiving element before measuring the subject's eye. The purpose of this invention is to provide a measuring device.

[Summary of the invention] The gist of the present invention for achieving the above object is as follows:
An ophthalmological measuring device that projects a target light flux from a light emitting element onto the eye to be examined, receives its reflected image with a light receiving element, and includes an objective lens facing the eye to be examined in an optical path from the light emitting element to the light receiving element. a reflecting member that is removably disposed on the subject's eye side of the objective lens and has a constant reflectance; and a reflecting member that is emitted from the light emitting element, is reflected by the reflecting member without passing through the subject's eye, and is received by the light receiving element. It has a means for detecting with a light receiving output lens, and a calculating means for comparing and calculating the light receiving output level with a predetermined level, and the optical system including the objective lens is contaminated due to an abnormality in the light receiving output level, the light emitting element, the light receiving This is an ophthalmological measuring device characterized by being able to detect deterioration of an element.

[Embodiments of the Invention] The present invention will be described in detail based on embodiments illustrated in FIGS. 1 to 3.

FIG. 1 shows an embodiment of the present invention, in which an objective lens 7 is held in a lens barrel 20 placed on the eye E side of the optical system in FIG. A removable objective lens cap 21 is attached thereto, and a reflecting plate 22 is attached to the surface facing the objective lens 7. The lens cap 21 is butted against a step provided on the lens barrel 20 so that the distance between the objective lens 7 and the reflecting plate 22 is a predetermined distance, and the presence of the lens cap 21 is detected by a micro switch 23. It is becoming more and more like this.

Figure 2 shows the infrared detection diode 1 shown in Figure 4.
2 shows the output side in various states of T
1 is the output when the positioning optotype reflected light from the cornea Ec of the eye E is accurately imaged on the infrared detection diode 12, and T2 is the output of the infrared detection diode 12 due to dirt in the optical system. output level V2 at which it should be determined that the position is out of alignment.
If the output drops below this level, air pulses will not be emitted even if the image is accurately formed. T3 is the output when the lens cap 21 having the reflector 22 according to the present invention is attached, and is lower than the output level V3 at which the air pulse is emitted, and the air pulse is emitted with the lens cap 21 attached. There is no danger. T4 indicates the output level when the lens cap 21 is attached to the optical system in a dirty state, and the amount of attenuation from V1 to V2 is equal to the amount of attenuation from V3 to V4.

Therefore, the lens cap 21 is attached and the reflector 2
By making sure that the output of the infrared detection diode 12 due to the reflected light from Therefore, it is possible to prevent the phenomenon in which the output level of the infrared detection diode 12 becomes lower than V2 and the air pulse is not emitted. Furthermore, in addition to dirt on the optical system, the output level of the infrared detection diode 12 may decrease due to a decrease in the amount of light due to deterioration of the infrared detection diode 12, but this can be detected in the same way.

FIG. 3 shows a block circuit configuration diagram for comparison calculation, warning display, and measurement system stoppage. The output obtained by the infrared detection diode 12 is amplified by the amplifier 24 and becomes one input of the comparator 25. Comparator 25
Fixed or variable resistors 26, 27 are connected to the other input terminals of
A reference voltage set in advance is input to the comparator 25.
The two are compared in . Further, an analog switch 28 is inserted on this reference voltage side, and a micro switch 23 that detects that the lens cap 21 is attached to the lens barrel 20 collects on/off information of the switch 23 into a comparator. It is now being given to 25 people.

For example, if the signal from the infrared detection diode 12 is input to the positive input of the comparator 25 and the reference voltage is input to the negative input, the output of the comparator 25 will have a certain threshold level, and the reflected light will be at the reference voltage. Binarized information appears, such as positive if larger than , 0 if smaller. 29 and 30 are a warning display element and a measurement stop circuit, respectively; when the output of the comparator 25 is 0, the warning display element 29 warns the examiner that the objective lens 7 is dirty. The warning display element 29 may be a light emitting element such as an LED or a sound element such as a buzzer.

Also, if the examiner does not notice this warning,
If the measurement button is pressed as it is, the measurement stop circuit 30 prevents air pulses from being emitted to the subject. Thus, use of this warning system may result in double warnings being given to the examiner. In addition, 31 is a switch that cancels this warning system when the examiner recognizes the warning and returns to normal measurement after thoroughly cleaning the objective lens 7; however, this switch 31 does not cancel the warning system. Therefore, even if the microswitch 23 is turned off, normal measurement cannot be performed.

[Effects of the Invention] As explained above, the ophthalmological measuring device according to the present invention detects a decrease in the received light output level using, for example, a reflector provided on the lens cap, without depending on the reflectance of the eye to be examined, and It is possible to detect dirt on the lens or deterioration of the light emitting element or light receiving element.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a lens cap having a reflector plate showing an embodiment of the ophthalmological measuring device according to the present invention;
FIG. 2 is a characteristic diagram of the output level of the infrared detection diode, FIG. 3 is a block diagram of the warning system, and FIG. 4 is a diagram of the configuration of the non-contact tonometer. 1 is an illumination light source, 2 is an optotype plate, 8 and 14 are infrared light emitting diodes, 3 and 10 are dichroic mirrors, 6 is a half mirror, 7 is an objective lens, 7
a is an orifice, 11 is a transparent plate, 13 is an eyepiece, 12 and 16 are infrared detection diodes, 20 is a lens barrel, 21 is a lens cap, 22 is a reflector, 23
is a micro switch.

Claims (1)

[Claims] 1. Projecting a target light flux from a light emitting element onto the eye to be examined;
The reflected image is received by a light-receiving element, and in an ophthalmological measuring device, the optical path from the light-emitting element to the light-receiving element is provided with an objective lens facing the eye to be examined, which is arranged so as to be freely removable from the eye to be examined side of the objective lens. a reflecting member having a constant reflectance, a means for detecting a received light output level that is emitted from the light emitting element, reflected by the reflective member without passing through the eye to be examined, and received by the light receiving element; The ophthalmology clinic is characterized in that it has a calculation means for comparing and calculating with a predetermined level, and is capable of detecting dirt in the optical system including the objective lens or deterioration of the light emitting element and the light receiving element due to an abnormality in the received light output level. Measuring device for 2. The ophthalmological measuring device according to claim 1, further comprising a warning means that issues a warning when the result of the comparison calculation performed by the calculation means deviates from a set value. 3. The ophthalmological measurement device according to claim 2, further comprising means for issuing a warning by the warning means and for stopping the operation of the measurement system. 4. The ophthalmological measuring device according to claim 1, wherein the reflecting member is installed at a fixed position in front of the objective lens. 5. The method according to claim 4, further comprising means for detecting that the reflecting member is installed in a fixed position, and the calculating means is operated only when the reflecting member is installed in a fixed position. Ophthalmological measuring device. 6. The ophthalmological measuring device according to claim 1, wherein the reflective member is provided on the inner surface of the protective cover of the objective lens.