JPH04269937A - Ophthalmologic apparatus - Google Patents

Abstract

PURPOSE:To enable accurate alignment detection with a simple operation regardless of personal difference in the shape of an eye to be inspected in an ophthalmologic apparatus which perform the alignment detection for determining whether the eye to be inspected and the ophthalmologic apparatus is in a specified positional relationship. CONSTITUTION:This apparatus is provided with a first alignment detecting optical system (a) which projects a parallel luminous flux to a cornea 19 of an eye 18 to be inspected and forms a false image by the reflected light thereof on a photodetecting surface of a photodetector 8 to perform an aignment detection roughly and a second alignment detecting optical system (b) which makes an index for alignment detection project to the cornea 19 of the eye 18 to be inspected, and the reflection image of the index is received with a photodetector 15 to perform a strict alignment detection. The combination of both the optical systems enables accurate alignment detection with a simple operation.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an ophthalmological device, and in particular to an ophthalmological device such as an intraocular pressure measuring device, which requires high precision in the alignment of the eye to be examined and the ophthalmic device, that is, in setting a predetermined positional relationship between the two. This relates to the required ophthalmological equipment.

0002

[Prior Art] Inocular pressure measuring devices are known that measure intraocular pressure by injecting fluid onto the corneal surface and measuring the time until corneal applanation or the pressure signal when the corneal deformation detection signal reaches its maximum. (Patent Application Hei 1-192331, Patent Publication No. 1983
-58577). This device blows airflow generated at a predetermined pressure onto the center of the cornea of the eye being examined.
Intraocular pressure is calculated from the time it takes for the cornea to deform into a flat surface or from the pressure signal when the corneal deformation detection signal reaches its maximum. Whether or not the cornea has been applanated is determined by the maximum amount of light received by a light receiving element that receives light from a light source such as an LED through a lens.

In this case, if the intraocular pressure measuring device and the eye to be examined are not in an accurate predetermined positional relationship, the measurement error will increase.
An alignment detection optical system for detecting whether or not the above-mentioned positional relationship exists is provided, and is incorporated into the apparatus in a predetermined positional relationship with the measurement optical system.

In the conventional configuration, this alignment detection optical system projects a parallel light beam onto the corneal surface of the eye to be examined, receives the reflected light, forms a virtual image of the reflected light, and detects whether the alignment is successful or not. A method that projects an alignment detection index (a small focused spot light) onto the vertex of the corneal surface of the eye being examined, and detects whether the alignment is successful or not by receiving the reflected image. Either one is adopted.

[0005]

[Problems to be Solved by the Invention] However, in the above-mentioned method of projecting a parallel light beam onto the subject's eye, since a virtual image is used, the premise is that the shape of the cornea of the subject's eye, which reflects the irradiated light, must be adjusted to a certain level. The radius of curvature of the cornea must be determined using a model eye, and usually the radius of curvature of the cornea is between 7.5 mm and 7.8 mm.
was based on one value. However, the radius of curvature of the cornea of the actual eye to be examined does not necessarily have the same shape as the model eye due to individual differences among the examinees. This has the disadvantage of causing a decrease in alignment detection accuracy.

On the other hand, in the method of projecting an alignment detection index onto the corneal vertex of the eye to be examined, there is no decrease in alignment detection accuracy due to differences in the shape of the eye to be examined. However, if the position of the eye to be examined deviates from the predetermined alignment position, the position of the reflected image by the cornea will move significantly, and the field of view of the observation optical system of the operator (examiner) who performs the alignment detection operation will change. It may come off. For this reason, the target image often becomes invisible, especially at the beginning of the alignment operation, making it difficult to operate.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional drawbacks in an ophthalmologic apparatus that performs this type of alignment detection, and to enable accurate alignment with simple operations.

[0008]

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, in an ophthalmological apparatus that performs alignment detection as described above, a first beam of light is projected onto the corneal surface of the eye to be examined. a first alignment detection optical system comprising a projection optical system, a first light receiving optical system for receiving the reflected light of the parallel light beam by the cornea and detecting alignment by forming a virtual image by the reflected light; A second alignment detection system consisting of a second projection optical system that projects an alignment detection index onto the corneal surface of the optometrist, and a second light reception optical system that detects alignment by receiving a reflected image of the index. A configuration was adopted in which an optical system was provided and alignment detection was performed using both the first and second alignment detection optical systems.

[0009]

[Operation] According to this configuration, the first alignment detection optical system performs rough detection, and then the second alignment detection optical system performs rough detection.
By performing precise detection using the alignment detection optical system, alignment detection can be performed accurately with a simple operation.

0010

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows the configuration of an alignment detection 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 detection optical systems shown in FIGS. 1(a) and 1(b). In reality, the configurations (a) and (b) are integrally constructed by sharing the objective lens 1 and the relay lens 2, but each configuration is shown separately here for ease of understanding. . Actually (b)
The pinhole plate 16 and light source 17 are placed behind the half mirror 3 in (a), and the lens 13, pinhole plate 14, and light receiving element 15 in (b) are placed behind the half mirror 5 in (a). Ru.

First, the configuration (a) will be explained. In (a), a parallel light beam is projected onto the surface of the cornea 19 of the eye 18 by a light source 12 such as an LED, a pinhole plate 4 with a pinhole formed therein, a half mirror 3, a relay lens 2, and an objective lens 1. One projection optical system is constructed.

[0012] Also, the objective lens 1, half mirrors 5, 6,
Taking lens 7, light receiving element 8 such as CCD, lens 9
, alignment chart 10, and this chart 10
A first light-receiving optical system receives the reflected light from the cornea 19 of the parallel light beam by a light source 11 such as an LED for projecting the light, forms a virtual image by the reflected light, and detects whether the alignment is successful or not. configured. A first alignment detection optical system is constituted by this first light receiving optical system and the first projection optical system.

Next, the configuration of (b) will be explained. 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 place an index for alignment detection (a small focused spot light) on the vertex of the surface of the cornea 19 of the eye 18 to be examined. A second projection optical system for projecting is configured.

[0014] Also, 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 is configured to receive the reflected image of the index and detect whether the alignment is successful or not. A second alignment detection optical system is constituted by this second light receiving optical system and the second projection optical system.

Next, the alignment detection operation with the above configuration will be explained. In this embodiment, when performing alignment, rough alignment detection is first 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, the eye 1 of a patient whose face is fixed by a chin rest and a forehead rest (not shown) of the ophthalmological apparatus is examined.
Light sources 12 and 17 with objective lens 1 directly facing 8
and 11 are lit. In the configuration of (a), after the light from the light source 12 passes through the pinhole of the pinhole plate 4,
A relay lens 2 forms a pinhole image on the back focal plane of the objective lens 1. Therefore, the projection light beam exits to the front side of the objective lens 1, becomes a parallel light beam, and is irradiated onto the cornea 19 of the eye 18 to be examined.

Next, the parallel light beam reflected by the cornea 19 is reflected as if it were emitted from a position indicated by the reference numeral 20 within 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 corneal vertex 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, d
x=r/2 dy=(r/2)×tanθ.

After this reflected light flux passes through the objective lens 1,
It is reflected by the half mirror 5 and the mirror 6, and is imaged by the taking lens 7 on the light receiving surface of the light receiving element 8, so that a virtual image at position 20 is formed. On the light receiving surface of the light receiving element 8,
Alignment chart 10 illuminated by light source 11
Since the image is projected in advance through the lens 9 and the taking lens 7, rough alignment can be completed by positioning the virtual image at a predetermined position in the chart image.

Next, detection is performed using the configuration (b). 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 aligning the position of the pinhole with the rear focal point of the relay lens 2, the light beam emerging from the front side of the relay lens 2 becomes a parallel light beam, enters the objective lens 1, and exits from the front side of the objective lens 1. The reflected light forms an image at the front focal point 21 of the objective lens 1.

When the eye 18 to be examined is positioned at a predetermined alignment position, it is assumed that the vertex of the cornea 19 coincides with the position 21, and at that time, the reflected light from the cornea 19 passes through the objective lens 1 and then is focused into a pinhole by the lens 13. A reflected image of the index is formed at the position of the pinhole in the plate 14, and the light is received by the light receiving element 15 to detect accurate alignment.

As described above, according to this embodiment, first (a
Rough alignment detection is performed using the configuration (b), and then strict alignment detection is performed using the configuration (b). First, the detection performed using configuration (a) is roughly performed, so as explained in the conventional example, there is no problem with the decrease in detection accuracy due to individual differences in the corneal shape of the subject's eye, and the accuracy is determined by the following (b). High accuracy is guaranteed by the detection performed by the configuration. Furthermore, since rough alignment has been achieved beforehand when performing detection with the configuration (b), there is no operational problem as described in the conventional example, and alignment detection can be performed with a simple operation.

As described above, according to this embodiment, by using two types of alignment detection optical systems, alignment detection can be performed with high precision with simple operations, regardless of individual differences in the shape of the eye to be examined, and alignment can be performed easily. Ru.

Note that in the above configuration, the light source 12 in (a) and the light source 12 in (b)
It is preferable that the wavelengths of the light emitted from the light sources 17 of the two types are different from each other. In this way, even if the light sources 12 and 17 are turned on at the same time, problems caused by light interference in the two detection optical systems can be avoided. In addition, the light source 1 serves as half mirrors 3 and 5.
The light source 12,
The intensity of the light emitted by No. 17 does not need to be increased so much. In addition, if the half mirror 6 is configured to reflect light of the wavelength of the light source 12 well and transmit light of other wavelengths well, the appearance of the anterior segment of the eye 18 can be seen by 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 clear from the above description, according to the present invention, in the ophthalmological apparatus that performs alignment detection as described above, the first projection optical system projects a parallel light beam onto the corneal surface of the eye to be examined. and a first alignment detection optical system for detecting alignment by receiving the reflected light from the cornea of the parallel light flux and forming a virtual image by the reflected light, and a cornea of the eye to be examined. A second alignment detection optical system includes a second projection optical system that projects an alignment detection index onto a surface, and a second light reception optical system that detects alignment by receiving a reflected image of the index. Since a configuration is adopted in which alignment detection is performed using both the first and second alignment detection optical systems, alignment detection is first roughly performed by the first alignment detection optical system, and then by the second alignment detection optical system. By strictly performing alignment detection using an optical system, an excellent effect can be obtained in that alignment detection can be performed accurately with a simple operation, regardless of individual differences in the shape of the eye to be examined.

[Brief explanation of the drawing]

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

[Explanation of symbols]

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

Claims (2)

[Claims] 1. In an ophthalmological apparatus that performs alignment detection to determine whether or not an eye to be examined and the ophthalmological apparatus are in a predetermined positional relationship, a first projection optical system that projects a parallel light beam onto the corneal surface of the eye to be examined; a first alignment detection optical system comprising a first light receiving optical system for detecting alignment by receiving reflected light from the cornea of the parallel light beam and forming a virtual image by the reflected light; a second projection optical system for projecting an alignment detection index; and a second projection optical system for detecting alignment by receiving a reflected image of the index.
1. An ophthalmological apparatus characterized in that a second alignment detection optical system comprising a light receiving optical system is provided, and alignment detection is performed using both the first and second alignment detection optical systems. 2. The first and second projection optical systems project light onto the subject's eye with different wavelengths.
The ophthalmological device described in .