JP3056800B2 - Ophthalmic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmologic apparatus, and particularly to a high precision in alignment between an eye to be examined and an ophthalmic apparatus, that is, setting of a predetermined positional relationship between the two, as in an intraocular pressure measuring apparatus. It relates to the required ophthalmic device.

[0002]

2. Description of the Related Art There is known an intraocular pressure measuring apparatus which measures an intraocular pressure by injecting a fluid onto a corneal surface and measuring a time until a corneal applanation or a pressure signal when a corneal deformation detection signal is maximized. (Japanese Patent Application No. 1-192331, Japanese Patent Publication No. 63-58577). In this device, an airflow generated by a predetermined pressure is blown to the center of the cornea of the eye to be examined, and the intraocular pressure is calculated from the time until the cornea is deformed into a plane or the pressure signal when the corneal deformation detection signal is maximized. calculate. Whether or not the cornea has been applanated is determined by the fact that the amount of light received by a light receiving element that receives light from a light source such as an LED via a lens is maximized.

[0003] In this case, if the tonometry device and the eye to be examined are not exactly in a predetermined positional relationship, a measurement error becomes large.
An alignment detecting optical system for detecting whether or not the positional relationship is established is provided, and is incorporated in the apparatus in a predetermined positional relationship with the measuring optical system.

In a conventional configuration, as this alignment detecting optical system, a parallel light beam is projected on the cornea surface of the eye to be examined, the reflected light is received, and a virtual image is formed by the reflected light to detect the success or failure of the alignment. Either the system or the system that projects an alignment detection index (small condensed spot light) on the vertex of the corneal surface of the eye to be examined and detects the pass / fail of the alignment by receiving the reflected image. One is adopted.

[0005]

However, in the above-mentioned method of projecting a parallel light beam to the eye to be examined, since a virtual image is used, it is premised on that the shape of the cornea of the eye to be examined which reflects the irradiation light is fixed. The eye must be obtained from a model eye. Usually, the radius of curvature of the cornea is any one of 7.5 mm to 7.8 mm.
One value was used as a reference. However, the actual radius of curvature of the cornea of the eye to be inspected is not always the same as that of the model eye due to individual differences among examinees. This has the disadvantage that the alignment detection accuracy is reduced.

On the other hand, in the method of projecting the alignment detection index on the cornea vertex of the eye to be inspected, the alignment detection accuracy does not decrease due to the difference in the shape of the eye to be inspected. However, when the position of the eye to be examined deviates from a predetermined alignment position, the position of the image reflected by the cornea moves greatly, and the field of view of the observation optical system of the operator (examiner) performing an operation for performing alignment by detecting the alignment. May get out of the way. For this reason, the index image often becomes invisible especially at the beginning of the operation for performing the alignment, and there is a disadvantage that the operation is difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ophthalmologic apparatus for performing this type of alignment detection so that the above-mentioned conventional disadvantages can be solved and alignment can be accurately performed by a simple operation.

[0008]

According to the present invention, there is provided an ophthalmologic apparatus for performing alignment detection as described above, wherein a first light beam for projecting a parallel light beam onto a corneal surface of an eye to be examined is provided. A first alignment detecting optical system including a projection optical system, a first light receiving optical system for receiving light reflected by the cornea of the parallel light beam and forming a virtual image based on the reflected light to detect alignment; Second alignment detection including a second projection optical system for projecting an alignment detection target on the corneal surface of the optometry, and a second light receiving optical system for detecting alignment by receiving a reflected image of the target. An arrangement is provided in which an optical system is provided, and alignment detection is performed using both the first and second alignment detection optical systems.

[0009]

According to such a configuration, first, the first alignment detection optical system roughly performs detection, and then, the second alignment detection optical system.
Strict detection is performed by the alignment detection optical system described above, so that alignment detection can be accurately performed by a simple operation.

[0010]

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a configuration of an alignment detecting optical system provided in an ophthalmologic apparatus according to an embodiment of the present invention. The apparatus of this embodiment is provided with two alignment detecting optical systems shown in FIGS. 1A and 1B. Actually, the configurations of (a) and (b) are integrally formed by sharing the objective lens 1 and the relay lens 2, but here, the respective configurations are separately illustrated for easy understanding. . Actually (b)
The pinhole plate 16 and the light source 17 are disposed behind the half mirror 3 in FIG. 5A, and the lens 13, the pinhole plate 14 and the light receiving element 15 in FIG. 4B are disposed behind the half mirror 5 in FIG. You.

First, the configuration (a) will be described. 2A, a light source 12 such as an LED, a pinhole plate 4 having a pinhole, a half mirror 3, a relay lens 2, and an objective lens 1 project a parallel light beam onto the surface of the cornea 19 of the eye 18 to be inspected. One projection optical system is configured.

Also, an objective lens 1, half mirrors 5, 6,
Taking lens 7, light receiving element 8, such as CCD, lens 9, alignment chart 10, and chart 1
A first light receiving optical system for receiving light reflected by the cornea 19 of the parallel light flux by a light source 11 such as an LED for projecting 0, forming a virtual image based on the reflected light, and detecting whether alignment is successful or not. Is configured. The first light receiving optical system and the first projection optical system constitute a first alignment detecting optical system.

Next, the configuration (b) will be described. In (b), a light source 17 such as an LED, a pinhole plate 16, a relay lens 2, and an objective lens 1 are used to apply an alignment detection index (small condensed spot light) to a vertex on the surface of the cornea 19 of the subject's eye 18. A second projection optical system for projecting is configured.

The objective lens 1, the lens 13, the pinhole plate 14, and the light receiving element 15 such as a phototransistor.
Thus, a second light receiving optical system for receiving the reflected image of the index and detecting whether the alignment is successful or not is configured. The second light receiving optical system and the second projection optical system constitute a second alignment detecting optical system.

Next, the alignment detecting operation according to the above configuration will be described. In this embodiment, in performing alignment, first, rough alignment detection is performed by the first alignment detection optical system (a), and then strict alignment detection is performed by the second alignment detection optical system (b).

Specifically, first, a subject's eye 1 whose face is fixed by a chin rest (not shown) and a forehead rest of an ophthalmologic apparatus.
8 and the light sources 12 and 17
And 11 are lit. Then, in the configuration of (a), after the light of the light source 12 passes through the pinhole of the pinhole plate 4,
The relay lens 2 forms an image of a pinhole on the rear focal plane of the objective lens 1. For this reason, the projection light beam exits the front side of the objective lens 1 and becomes a parallel light beam, which is irradiated on the cornea 19 of the eye 18 to be inspected.

Next, the reflected light of the parallel light flux from the cornea 19 is reflected as if it were emitted from the position indicated by the reference numeral 20 in the eye 18 to be examined. The position 20 is determined by the radius r of the cornea and the angle θ of the parallel light beam. The distance between the vertex of the cornea and the position 20 is dx, and the distance between the optical axis of the optical system corresponding to the center line of the eye 18 and the position 20 is dy. Then, dx = r / 2 dy = (r / 2) × tan θ.

After this reflected light beam passes through the objective lens 1,
The light is reflected by the half mirror 5 and the mirror 6 and forms an image on the light receiving surface of the light receiving element 8 by the taking lens 7 to form a virtual image at the position 20. On the light receiving surface of the light receiving element 8,
Alignment chart 10 illuminated by light source 11
Is projected through the lens 9 and the taking lens 7 in advance, so that the rough alignment can be completed by performing an operation of positioning the position of the virtual image at a predetermined position in the chart image.

Next, detection is performed by the configuration shown in FIG. In the configuration of (b), the light emitted from the light source 17 enters the relay lens 2 after passing through the pinhole of the pinhole plate 16. By keeping the position of the pinhole coincident with the rear focal point of the relay lens 2, the light beam emitted to the front side of the relay lens 2 becomes a parallel light beam and enters the objective lens 1,
The light emitted to the front side of the objective lens 1 forms an image at the front focal position 21 of the objective lens 1.

When the subject's eye 18 is positioned at a predetermined alignment position, the apex of the cornea 19 is assumed to coincide with the position 21. At that time, the reflected light from the cornea 19 passes through the objective lens 1 and then becomes a pinhole by the lens 13. A reflection image of the index is formed at the position of the pinhole on the plate 14, and the light is received by the light receiving element 15 to detect the correct alignment.

As described above, according to the present embodiment, rough alignment detection is first performed by the configuration (a), and then strict alignment detection is performed by the configuration (b). First, since the detection performed by the configuration of (a) is performed roughly, the decrease in detection accuracy due to individual differences in the corneal shape of the subject's eye does not pose a problem, as described in the conventional example.
The accuracy is assured with high accuracy by the detection performed by the following configuration (b). In addition, since alignment is roughly performed in advance when performing detection with the configuration of (b),
There is no operational problem described in the conventional example, and alignment can be detected by a simple operation.

As described above, according to the present embodiment, by using the two types of alignment detection optical system, the alignment can be detected with high accuracy and the alignment can be performed with a simple operation regardless of the individual difference in the shape of the eye to be inspected. You.

In the above configuration, it is preferable that the light emission wavelengths of the light source 12 shown in FIG. 7A and the light source 17 shown in FIG. In this way, even if the light sources 12 and 17 are turned on at the same time, it is possible to avoid a problem caused by light interference in the two detection optical systems. Further, by selecting the half mirrors 3 and 5 that have characteristics of reflecting light of the wavelength of the light source 12 well and transmitting light of the wavelength of the light source 17 well,
The emission intensities of 2, 17 do not need to be so high. If the half mirror 6 reflects the light of the wavelength of the light source 12 well and transmits the light of the other wavelengths well, the state of the anterior segment of the subject's eye 18 becomes the objective lens 1, the half mirror 6, The light passing through the taking lens 7 can be observed by the light receiving element 8.

[0024]

As is apparent from the above description, according to the present invention, in the ophthalmic apparatus for performing the alignment detection as described above, the first projection optical system for projecting a parallel light beam onto the corneal surface of the eye to be examined. A first alignment detection optical system including a first light receiving optical system for receiving the reflected light of the parallel light beam from the cornea and forming a virtual image based on the reflected light to detect alignment; and a cornea of the eye to be inspected. A second projection optical system for projecting an index for alignment detection on the surface and a second alignment detection optical system including a second light receiving optical system for detecting alignment by receiving a reflected image of the index are provided. The first and second alignment detection optical systems employ a configuration in which alignment detection is performed using both the first and second alignment detection optical systems. Broadly performed, by following strictly carried out by the second alignment detection optical system, regardless of the individual difference of the subject's eye shape exactly excellent effect that allows the alignment detection obtained by a simple operation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a configuration of an alignment detection optical system of an ophthalmologic apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Relay lens 3, 5, 6 Half mirror 4, 14, 16 Pinhole plate 7 Taking lens 8, 15 Light receiving element 9, 13 Lens 10 Alignment chart 11, 12, 17 Light source (LED) 18 Eye to be examined 19 Cornea

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61B 3/10 A61B 3/16

Claims (2)

(57) [Claims] A first projection optical system for projecting a parallel light beam onto a corneal surface of an eye to be inspected, wherein the ophthalmic device performs alignment detection as to whether or not the eye to be inspected and the ophthalmologic apparatus have a predetermined positional relationship; A first alignment detection optical system including a first light receiving optical system for receiving alignment light reflected by the cornea of the parallel light flux and forming a virtual image based on the reflection light to detect alignment; There is provided a second projection optical system for projecting an index for alignment detection, and a second alignment detection optical system including a second light receiving optical system for detecting alignment by receiving a reflected image of the index. An ophthalmologic apparatus that performs alignment detection using both the first and second alignment detection optical systems. 2. The ophthalmologic apparatus according to claim 1, wherein the first and second projection optical systems have different wavelengths of light projected onto an eye to be inspected.