JPH0542108A - Ophthalmic machine - Google Patents

Abstract

PURPOSE:To improve measurement accuracy or to shorten measurement time by extending or contracting either of the permissible error of the visual axis of an optical system for aligning the optical axis of a main optical system to the visual axis of the eye to be examined and the permissible range of the working distance of an optical system for setting the working distance from the cornea vertex of the eye to be examined up to the main optical system. CONSTITUTION:The optical system 17 for reflecting the ray of an LED 18 at the cornea vertex P of the eye 13 to be examined by a lens 20, a half mirror 15 and an objective lens 11, and introducing the reflected ray by imaging 12 to a camera 16 and a photodetector 23 is formed to align the optical axis O of the lens 11 and the visual axis O' of the eye 13 to be examined. Index projection optical systems 24, 25 for setting the distance W up to the cornea vertex P and the tip Q of a nozzle 11 are installed symmetrically with the optical axis O and alternately switch LEDs 26, 27. The ray reflected by the vertex P is made incident on the opposite optical systems 25, 24 and is introduced from reflection plates 40, 45 to a photodetector 41 to display the index image on a display section not shown in Fig. The measurement accuracy is improved if either of the alignment of the visual axis or the permissible range of the working distance is made strict. The measurement is speeded up if the permissible range is widened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an alignment optical system for aligning the optical axis of a main optical system with the visual axis of an eye to be inspected and for setting the distance from the corneal vertex of the eye to be inspected to the main optical system. The improvement of ophthalmic machines.

[0002]

2. Description of the Related Art Conventionally, an ophthalmologic machine provided with an alignment optical system for aligning an optical axis of a main optical system with a visual axis of an eye to be examined and for setting a distance from a corneal vertex of the eye to be examined to the main optical system. It has been known. For example, in a non-contact tonometer as an ophthalmologic machine, a pair of alignment optical systems are provided symmetrically to each other on both sides of the optical axis of the main optical system. The pair of alignment optical systems irradiate a parallel light beam toward the cornea, and a corneal mirror reflection of the parallel light beam forms a virtual image as a pair of alignment index images on the cornea.
The pair of alignment index images are displayed in an overlapping manner when the distance from the apex of the cornea to the tip of the main optical system, for example, the tip of the jet nozzle, is a normal working distance, and at the center of the cornea. The pair of index images i1 and i2 are displayed separately as shown in FIG. 6 when the distance from the apex of the cornea to the tip of the injection nozzle is not the normal working distance.
In addition, the midpoint (centroid position) of the pair of index images i1 and i2 is
When the optical axis of the main optical system deviates vertically and horizontally with respect to the visual axis of the eye to be inspected, the optical axis deviates from the visual axis. The figure 6
In FIG. 1, 1 is a pupil of the eye to be inspected, 2 is a permissible range of working distance showing an allowable range of working distance, 3 is a permissible range of visual axis showing a permissible range of matching relationship between the visual axis of the eye to be examined and the optical axis of the main optical system. 4 indicates the visual axis.

[0003]

As described above, in the conventional ophthalmologic machine, the alignment operation for aligning the visual axis of the eye to be examined with the optical axis of the optical system and the alignment operation for setting the distance from the apex of the cornea to the main optical system. The alignment accuracy required to set the distance from the apex of the cornea to the main optical system is the alignment accuracy that aligns the visual axis of the eye to be examined with the optical axis of the main optical system, because Although the allowable range is larger than that of the pair of index images i1,
The alignment operation is performed so that i2 exists. However, by adjusting the working distance, the pair of index images i1,
Performing an alignment operation so that i2 exists in the visual axis allowable range 3 having a stricter allowable range requires a considerable amount of skill and difficulty, and it is difficult to improve the measurement accuracy.

On the other hand, speeding up of measurement is required at the time of screening for mass screening, but there is a problem that it is difficult to speed up measurement with this conventional ophthalmic machine.

The present invention has been made in view of the above circumstances, and an object thereof is to improve the measurement accuracy when it is desired to improve the measurement accuracy, and to speed up the measurement when it is desired to speed up the measurement. An object of the present invention is to provide an ophthalmologic machine that can be realized.

[0006]

In order to solve the above-mentioned problems, an ophthalmologic machine according to the present invention comprises an alignment optical system for visual axis alignment for aligning the optical axis of a main optical system with the visual axis of an eye to be examined. Working distance setting alignment optical system for setting a working distance from a corneal apex of an eye to be examined to a main optical system, a visual axis allowable range of the main optical system with respect to the visual axis, and a working distance allowance of the main optical system with respect to the corneal apex And an allowable range changing means capable of changing at least one of the range and the range.

[0007]

[Operation] According to the ophthalmologic machine of the present invention, the alignment operation for aligning the optical axis of the main optical system with the visual axis of the eye to be examined and the alignment operation for setting the working distance from the corneal apex to the main optical system are performed. This is done using separate alignment optics. Here, when it is desired to improve the measurement accuracy, at least one of the visual axis allowable range and the working distance allowable range is set to a stricter one by the allowable range changing means. Also,
When it is desired to speed up the measurement, the permissible range changing means expands at least one of the visual axis permissible range and the working distance permissible range. In order to speed up this measurement, if either the visual axis allowable range or the working distance allowable range is expanded from the standard allowable range, the measurement accuracy can be maintained within the range that does not interfere with the measurement. It is possible to speed up the measurement while aiming.

[0008]

1 is an anterior ocular segment observation optical system as a main optical system for observing an anterior ocular segment image including an eye to be examined. The anterior segment observation optical system 10 has an objective lens 11 and an imaging lens 12. On the optical axis O of the objective lens 11, a jet nozzle 14 for jetting an air pulse toward the subject's eye 13 is provided. The light flux forming the anterior segment image is focused on the CCD camera 16 via the objective lens 11, the half mirror 15, the half mirror 22, and the imaging lens 12. The half mirror 15 constitutes a part of an alignment optical system 17 for aligning the visual axis 4 of the eye 5 to be examined with the optical axis O of the main optical system as shown in FIG. The alignment optical system 17 has an LED 18 as a light source, an opening 19 and a collimator lens 20. The LED 18 emits infrared light.

The collimator lens 20 collimates the infrared light of the LED 18 into a parallel light flux. The parallel light flux is reflected by the half mirror 15 toward the objective lens 11, passes through the inside of the injection nozzle 14, and is emitted toward the cornea 21 of the subject's eye 13. The parallel light flux is reflected by the cornea 21, and the reflected light flux is condensed by the objective lens 11. The reflected light flux is an imaging lens
12, led to the CCD camera 16 via the half mirror 22.
A part of the reflected light flux is reflected by the half mirror 22 and guided to the light receiving element 23, and the index image i3 for visual axis alignment alignment is formed on the CCD camera 16. The anterior ocular segment image and the index image i3 formed on the CCD camera 16 are input to a video signal processing circuit described later to be imaged. Its CCD camera 16
A reticle image forming the visual axis allowable range mark 3 is projected on the screen.

From the apex P of the cornea 21 to the tip Q of the injection nozzle 14.
An alignment optical system for setting the working distance W up to is provided separately from the alignment optical system 17. This alignment optical system has index projection optical systems 24 and 25. The index projection optical systems 24 and 25 are provided with an optical axis O of the objective lens 11.
Are arranged symmetrically. The index projection optical system 24 has an LED 26 as a light source. The index projection optical system 25 has an LED 27 as a light source. LED26 has, for example, a wavelength of 760n
Emits m infrared light. The infrared light emitted from the LED 26 is condensed by the condenser lens 28 and guided to the opening 29. The infrared light is focused on the center of the opening 29 and then guided to the dichroic mirror 30. The LED 27 emits infrared light having a wavelength of 860 nm, for example. The infrared light emitted from the LED 27 is condensed by the condenser lens 31 and guided to the opening 32. The infrared light is focused on the center of the opening 32 and then guided to the dichroic mirror 33. The dichroic mirror 30 reflects infrared light having a wavelength of 760 nm,
It has the property of transmitting infrared light with a wavelength of 860 nm. The dichroic mirror 33 reflects infrared light having a wavelength of 860 nm and has a wavelength of 760 nm.
It has a property of transmitting infrared light of nm. The infrared light having a wavelength of 760 nm reflected by the dichroic mirror 30 is guided to the objective lens 34. The infrared light with a wavelength of 860 nm reflected by the dichroic mirror 33 is guided to the objective lens 35. The objective lenses 34 and 35 face the cornea 21 of the subject's eye 13. The focal position of the objective lens 34 is at the center of the aperture 29. Objective lens
The focal position of 35 is in the center of the aperture 32. Objective lenses 34, 35
The infrared light guided to is converted into a parallel light flux by the objective lenses 34 and 35 and projected on the cornea 21. Objective lens 34
The parallel light flux projected by forms the index image i1 for working distance alignment based on the corneal mirror reflection. The parallel light beam projected by the objective lens 35 forms an index image i2 for working distance alignment based on corneal mirror reflection. The reflected light flux forming the index image i1 is guided to the objective lens 35 and is made a parallel light flux when the focal position of the objective lens 35 is at the formation position of the index image i1. Then, the parallel light flux is guided to the total reflection mirror 37 via the dichroic mirror 33 and the half mirror 36. Then, the direction is changed by the total reflection mirror 37, and the total reflection mirror is passed through the relay lens 38.
Guided to 39. The parallel light flux reflected by the total reflection mirror 39 is redirected by the total reflection mirror 40 and guided to the light receiving element 41.

The reflected light flux forming the index image i2 is guided to the objective lens 34, and becomes a parallel light flux when the focal position of the objective lens 34 is at the point of the index image i2. The reflected light flux converted into the parallel light flux by the objective lens 34 passes through the dichroic mirror 30 and is guided to the total reflection mirror 42.
Is guided to the relay lens 43 by. The parallel light flux that has passed through the relay lens 43 is redirected by the total reflection mirrors 44 and 45 to form an image on the light receiving element 41. The index images i1 and i2 are matched in the light receiving element 41 when the distance from the corneal apex P of the eye to be inspected to the tip Q of the nozzle is a normal working distance and the corneal apex P coincides with the optical axis O. The image is formed, and in other cases, the image is formed separately.

The LEDs 18, 26, 27 are driven by drive circuits 46, 47, 48 as shown in FIG. This drive circuit 46 ~
48 is controlled by a control calculation unit 52 having a function described later. The LEDs 26 and 27 are alternately turned on and off as shown in FIG. The output of the light receiving element 41 is input to the signal processing circuit 49, and the output of the light receiving element 23 is input to the signal processing circuit 50.

The signal processing circuit 49 has a pair of index images i1 and i2.
The center of gravity position of is detected. The signal processing circuit 50 detects the barycentric position of the index image i3. The detection result is stored in the storage circuit 51. The detection data stored in the storage circuit 51 is input to the control calculation circuit 52. The control calculation circuit 52 calculates the distance between the centers of gravity of the pair of index images i1 and i2. The calculation time is repeated during the period t as shown in FIG.

The control arithmetic circuit 52 is a video signal processing circuit 53.
To control. The calculation result of the position of the center of gravity is input to the comparison circuits 54 and 55. The comparison circuit 54 has a function of setting the allowable working distance range 2. The comparison circuit 54 has a function of setting the visual axis allowable range 3. The comparison circuit 54 includes an allowable range value setting circuit 56.
The allowable range value setting information of is input. The allowable range value setting information of the allowable range value setting circuit 57 is input to the comparison circuit 55. The allowable range values are changed by the switches 58 and 59, respectively. Here, the switches 58 and 59, together with the allowable range value setting circuits 56 and 57, allow change of at least one of the visual axis allowable range of the main optical system with respect to the visual axis and the working distance allowable range of the main optical system with respect to the corneal vertex. Functions as a range changing means. The outputs of the comparison circuits 54 and 55 are input to the AND circuit 60, and the output of the AND circuit 60 is the fluid discharge driving means.
It is entered in 61.

The output of the CCD camera 16 is input to the video signal processing circuit 53. The output of the video signal processing circuit 53 is display means.
Entered in 63. As shown in FIG. 5, the display means 63 displays the pupil 1, the working distance allowable range 2, and the visual axis allowable range 3 as the anterior segment image.

The examiner adjusts the optical axis O of the optical system with respect to the visual axis 4 so that the index image i3 falls within the visual axis allowable range 3.
On the other hand, the video signal processing circuit 53 displays the working distance W on the bar graph 64 based on the calculation result of the control calculation unit 52. The working distance W is adjusted so that the shaded area of the bar graph 64 falls within the working distance range 2. W'indicates that the working distance W is optimum.

The AND circuit 60 outputs a fluid discharge driving start signal to the fluid discharge driving means 61 when both the working distance W and the visual axis 4 are set within the allowable ranges 2 and 3. The fluid discharge driving means 61 automatically controls the ejection nozzle 16 to the cornea 21.
An air pulse is started to be emitted toward. It should be noted that the air pulse can be emitted by a manual switch.

LED 26, condenser lens 28, aperture 29,
The dichroic mirror 30 and the objective lens 34 are provided for the cornea 21 to optically detect the deformation of the cornea due to the ejection of the air pulse.
It functions as a detection light projection optical system that projects the corneal deformation detection light toward. The cornea 21 is applanated by the jet of air pulses.

The reflected light beam due to the deformation of the cornea passes through the objective lens 35 and the dichroic mirror 33 and the half mirror 36.
Is guided to the condenser lens 65 and is focused on the light receiving element 66 by the condenser lens 65. The objective lens 35, the dichroic mirror 33, the half mirror 36, the condenser lens 65, and the light receiving element 66 form a detection light receiving optical system that receives the reflection of the corneal deformation detection light by the cornea 21, and the light receiving element thereof when the deformation of the cornea 21 starts. The amount of light received by 57 increases. The intraocular pressure is measured according to a known procedure based on the increase in the amount of light received due to the deformation of the cornea 21.

Here, when the working distance allowable range 2 is widened or strictly set, the corresponding switch 58 is used.
To operate. On the other hand, when the visual axis allowable range 3 is widened or strictly set, the switch 59 corresponding thereto is operated.

In FIG. 5, reference numeral 2'denotes a case where the working distance allowable range 2 is widened with respect to the reference. In this way, if only the working distance permissible range 2 is widened, the alignment operation of the working distance permissible range 2 is speeded up correspondingly within the range that does not affect the measurement accuracy, and the measurement speed can be increased. On the contrary, in order to improve the measurement accuracy, the working distance allowable range 2 may be set strictly with respect to the reference.

The same applies to the visual axis allowable range.

Although the embodiments have been described above, the measurement accuracy can be further improved by synchronizing with the pulse wave of the subject.

[0024]

[Effect] Since the ophthalmologic machine according to the present invention is configured as described above, the measurement accuracy can be improved when the measurement accuracy is desired to be improved, and the measurement speed can be improved when the measurement speed is desired. There is an effect that can be achieved.

[Brief description of drawings]

FIG. 1 is a plan view of an optical system of an ophthalmologic machine according to the present invention.

FIG. 2 is a side view of the optical system shown in FIG.

FIG. 3 is a control block diagram of the ophthalmologic machine according to the present invention.

FIG. 4 is a timing chart of on / off control of an LED according to the present invention.

FIG. 5 is an explanatory diagram of an alignment display state according to the present invention.

FIG. 6 is an explanatory diagram of a conventional alignment display state.

[Explanation of symbols]

 4 optic axis 13 eye 17 alignment optical system 21 cornea 24, 25 index image projection optical system P corneal apex W working distance

Claims (1)

[Claims] 1. An alignment optical system for aligning an optical axis of a main optical system with an optical axis of an eye to be inspected, and a working distance setting for setting a working distance from a corneal apex of the eye to the main optical system. An alignment optical system, and a permissible range changing means capable of changing at least one of a visual axis permissible range of the main optical system with respect to the visual axis and a working distance permissible range of the main optical system with respect to the corneal apex. Ophthalmic machine to be.