JPH03198831A - Ophthalmologic apparatus - Google Patents

Abstract

PURPOSE:To facilitate a state of positioning with an eye to be inspected while enabling accurate positioning by providing a ring-shaped photodetecting sensor circumferentially outside a circular photodetecting sensor to detect the state of positioning with the eye to be inspected based on outputs of both the sensors. CONSTITUTION:Cornea Ec of an eye E to be inspected is subjected to a fixed cornea deformation by blowing air from a nozzle 7. An intensity of air which caused the fixed cornea deformation is measured with a pressure sensor 6 within a current blowing means 5 to be converted to an eye pressure. A light source 1 serves concurrently for detecting the cornea deformation and for positioning. The cornea Ec is irradiated with a luminous flux from the light source 1 through a lens 2 and the light reflectogaed from the cornea is received with a lens 3 to form a light source image on a photoelectric sensor 4. The photoelectric sensor 4 is provided adjoining on a circular center part element 41 and a ring- shaped peripheral part element 42 surrounding it to obtain an output independently. When positioning is proper, a reflection image 10 from the cornea of the light source 1 becomes almost the same in shape as the center element 41. The position of the image 10 is deviated vertical to an optical axis or in a direction of the optical axis and thus, it involves the peripheral element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ophthalmologic apparatus that can detect the alignment state with an eye to be examined with a simple configuration.

[Prior art] If an ophthalmological device, such as a non-contact tonometer, is used to measure the eye to be examined in a state where the optical axis is not aligned perpendicularly or in the optical axis direction, the value will be different from the original value and the reliability of the measured value will be affected. Missing.

Therefore, it is necessary to perform alignment with the eye to be examined before measurement, and it has been considered to use completely independent sensors to detect alignment in the direction perpendicular to the optical axis and in the direction of the optical axis.

[Problems to be Solved by the Invention] However, in the conventional example described above, the structure becomes complicated because an independent sensor is provided.

An object of the present invention is to provide an ophthalmologic apparatus that solves the problems of the conventional technique described above.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a light source that irradiates the cornea of the eye to be examined, a light receiving optical system that receives light emitted from the light source and reflected by the cornea of the eye to be examined; In an ophthalmological apparatus including a light detection unit provided on a light receiving surface of a light receiving optical system, the light detection unit includes a circular light receiving sensor and a ring shaped light receiving sensor provided outside the circular light receiving sensor in a circumferential direction, When the alignment with the subject's eye is proper, the corneal reflection image of the light source in the photodetector has the same shape as the circular light receiving sensor or the ring-shaped light receiving sensor, and both the circular light receiving sensor and the ring-shaped light receiving sensor It is characterized by having means for detecting the state of alignment with the eye to be examined based on the output of the eye.

[Example] Fig. 1 shows a first example of the present invention applied to a non-contact tonometer. Air is blown from the nozzle 7 onto the cornea EC of the eye E to be examined to give a certain degree of corneal deformation.

The strength of the air at the time when a certain corneal deformation is achieved is measured by a pressure sensor 6 inside the airflow blowing means 5 and converted into intraocular pressure.

The light source 1 is used for both corneal deformation detection and position alignment. The light beam from the light source l illuminates the cornea EC via the lens 2, and the corneal reflected light is received by the lens 3, and a light source image is formed on the photoelectric sensor 4. The photoelectric sensor 4 is shown in Fig. 2 (
As shown in a), a circular center element 41 and a ring-shaped peripheral element 42 surrounding it are provided adjacent to each other, and outputs can be obtained independently. When the alignment is proper, the corneal reflection image 10 of the light source 1 has approximately the same shape as the central element 41, and the projected state thereof is shown in FIG. 2(b). Figure 2 (C)
indicates a state where the position is shifted in the direction perpendicular to the optical axis or in the direction of the optical axis, and the image 10 also covers peripheral elements. Here the second
Figure (d) shows a state in which the cornea is deformed and the light source image is blurred and enlarged by 10 degrees when the airflow is blown onto the cornea.

Now, FIG. 3 shows temporal changes in the output I of each of these elements. FIG. 3(a) shows the alignment, where I1 is the output of the center element 41 and I2 is the output of the peripheral element 42. If the positions are correct, only I1 will substantially appear and 12 will be zero. Figure 3(b) shows the change in airflow over time.
t, indicates the start of air blowing, and at t2, the light source image 10'
As shown in FIG. 2(d), if almost uniform light hits the blurring elements 41 and 42 and the areas of the elements 41 and 42 are the same, then the element 4
1.42 gives the same output. FIG. 3(C) shows the output difference ll-12 between the central element 41 and the peripheral element 42, at the moment when the value of I, -I, becomes half of the value of 11 at time t1. When the airflow is blown, the pressure inside the device is read by a pressure sensor 6, and the intraocular pressure is determined from this. Note that the difference is 1. -1.
Instead of contrast (II − I2 )/(II
+12) or only 11 may be used for deformation detection.

Next, FIG. 4 shows another embodiment, in which the air blowing means 12
A stream of air or the like is blown from the nozzle 11 through the tube 13. On the other hand, a light beam from a light source 15 provided on the optical axis is projected onto the center of corneal curvature of the eye to be examined via a half mirror 16 and lenses 17 and 18. The corneal reflected light returns along the same optical path and is reflected by the half mirror 16 to project a light source image onto the photoelectric sensor 14. Like the photoelectric sensor 4, the photoelectric sensor 14 is composed of a central element and a peripheral element, and detects corneal deformation and positional deviation.

Now, FIG. 5 shows a modification of the photoelectric sensor 4. In FIG.

In FIG. 5, the ring-shaped peripheral element adjacent to the center element 41 is divided into four parts 42a to 42d, and when there is a misalignment, it is possible to identify whether the direction of the misalignment is left, right, up, or down.

[Modification] Now, in the above description, the light source 1 is made into a circular shape having the same shape as the central element of the photoelectric sensor 4, but the same effect can be obtained even if it is made into a ring shape having the same shape as the peripheral part element.

[Effects of the Invention] As described above, according to the present invention, the state of alignment with the eye to be examined can be easily detected with a simple configuration. Moreover, accurate positioning can be performed regardless of differences in corneal reflectance.

[Brief explanation of drawings]

Fig. 1 is a diagram of the first embodiment of the present invention, Fig. 2 (a), (b), (c), and (d) respectively show the photoelectric sensor, the relationship between the photoelectric sensor and the light source image when alignment is proper, and Relationship between photoelectric sensor and light source image when alignment is incorrect,
A diagram showing the relationship between the photoelectric sensor and the light source image when the cornea is deformed by airflow. Figure 3 (a), (b), and (c) are the outputs at the time of positioning, respectively, and the outputs at the time of airflow blowing. A diagram showing a temporal change in the output difference between a central element and a peripheral element of a photoelectric sensor. Figure 4 is a diagram of a second embodiment of the present invention. Figure 5 is a diagram of a modified example of a photoelectric sensor. E is the eye to be examined, EC is the cornea, 1.15 is the light source, 4,1
4 is a photoelectric sensor, 5 and 12 are air flow blowing means, 6 is a pressure sensor, 7 and 11 are nozzles, 10 is a light source image, 41 is a central element, and 42 is a peripheral element. V (40 chants 2-Fig. 3)

Claims (2)

[Claims] (1) An ophthalmological device that includes a light source that illuminates the cornea of the eye to be examined, a light receiving optical system that receives light emitted from the light source and reflected by the cornea of the eye to be examined, and a light detection section provided on the light receiving surface of the light receiving optical system. In this, the light detecting section includes a circular light receiving sensor and a ring-shaped light receiving sensor provided outside the circular light receiving sensor in the circumferential direction, and when the alignment with the subject's eye is proper, the light detecting section has a circular light receiving sensor. A corneal reflection image of the light source has the same shape as the circular light receiving sensor or the ring-shaped light receiving sensor, and means for detecting an alignment state with the eye to be examined based on outputs of both the circular light receiving sensor and the ring-shaped light receiving sensor. An ophthalmological device characterized by having the following. (2) The ophthalmologic apparatus according to claim 1, wherein the ring-shaped light receiving sensor is a four-segment sensor.