JPH0577413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ophthalmological measuring device, for example, an ophthalmological measuring device that measures the lengths of various parts of an eye to be examined, such as lens thickness, vitreous body length, and axial length.

[Conventional technology]

Conventionally, spectacle lenses or contact lenses have been used to correct refractive power after cataract surgery, but in recent years, intraocular lenses have been inserted into the position of the removed crystalline lens. In order to select an appropriate intraocular lens for patients with aphakic eyes, it is necessary to know the corneal refractive power and the axial length (the length from the cornea to the retina).

However, in the past, corneal refractive power was measured using a corneal profile measuring device, and axial length was measured using a separate ultrasonic measuring device, and after performing separate measurement operations with each measuring device, the intraocular lens was There was the inconvenience of having to calculate the refractive power. Furthermore, when measuring the axial length of the eye, there is an inconvenience in that it is difficult to align the ultrasonic probe with respect to the eye to be examined.

[Problems to be solved by the invention and means for solving them]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ophthalmological measuring device that overcomes the drawbacks of the conventional art and can easily measure, for example, the axial length of the eye and the shape of the cornea using a single device.

An ophthalmological measurement device that includes a probe that can be displaced in an axial direction and can come into contact with the eye to be examined, and that measures predetermined information about the eye to be examined using the probe, the eye being equipped with a central axis that is coaxial with the axis of the probe. This is achieved by having means for projecting an index onto the cornea, and means for projecting a corneal reflected image of the index onto an optical position detector via a lens to detect index image position information.

〔Example〕

FIG. 1 shows a first embodiment of the present invention, where 1 is a ring-shaped light source and 2 is a ring-shaped index.
It is projected onto Ec and forms a corneal reflection image 2' which is a virtual image by corneal reflection.

This corneal reflection image 2' is re-imaged by an objective lens 3 whose optical axis is the central axis of the ring-shaped index 2, and an index image is formed on an optical position detector 7 via an aperture 4. Note that the light from the corneal reflection image passes through the outer periphery of the ultrasound conducting member 5 and the ultrasound transducer 6.

The ring-shaped index 2 is a perfectly circular annular index,
If the corneal radius of curvature is small, the corneal reflection image will be a perfect circular torus image with a small diameter, and if there is corneal astigmatism, the corneal reflection image will be an ellipse.

The corneal reflection image on the optical position detector 7 is generally an ellipse, and by detecting the position coordinates of at least five points, a to e can be identified by solving the elliptic equation: ax ² +bxy+cy ² +dx+ey+1=0. ,
From this, the corneal shape is calculated. This calculation is performed by various known calculation means such as a microcomputer.

Note that the optical position detector 7 is not limited to the illustrated position, but may be located at a position conjugate thereto.

Now, let's talk about the ultrasonic measurement system using an ultrasonic probe composed of a transducer and a medium part. Place member 5 on the cornea.
The ultrasonic transducer 6 on the front side of the objective lens 3 is activated by contacting Ec, and the axial length of the eye is calculated by measuring the time of transmitting and receiving ultrasonic echoes. Here, the central axis of the ultrasonic transducer 6 is coaxial with the central axis of the ring-shaped index 2, and is also coaxial with the optical axis of the objective lens 3 in this embodiment.

Next, FIG. 2 shows a different embodiment of the present invention.

11 is a ring-shaped light source, 12 is a ring-shaped index, 1
3 is an objective lens. Here, the objective lens 13 has a rear focal point at the position of the aperture 14 and is a telecentric optical system, so that even if the working distance to the eye to be examined deviates somewhat from the original distance, the accuracy of corneal shape measurement is unlikely to be affected. are doing.

Note that although the index projection system projects the ring-shaped index 12 directly onto the subject's eye, a ring-shaped cylindrical lens (not shown) whose rear focal point is located at the position of the ring-shaped index 12 is inserted between the subject's eye and the ring-shaped index 12. Since the index is projected from infinity when it is provided in , changes in the working distance in combination with the objective lens 13 do not affect corneal shape measurement.

In this embodiment, the ultrasonic conductive member 15 and the ultrasonic vibrator 16 that constitute the ultrasonic measurement system are cylindrical. In the case of corneal shape measurement, the light from the corneal reflection image 12' is transmitted to the ultrasonic conducting member 1 which is a medium part.
5 and the hollow part of the ultrasonic transducer 16, and reaches the optical position detector 17 via the objective lens 13 and the aperture 14.

Here, the central axis of the ultrasonic transducer 16 is coaxial with the central axis of the ring-shaped index 12 and also with the optical axis of the objective lens 13.

Note that in the two embodiments described above, the ultrasonic transducer was provided in front of the objective lens, that is, on the side of the eye to be examined.
A hole may be provided in the center of the objective lens and the ultrasonic transducer may be internalized in this hole. Furthermore, the ultrasonic transducer inside this hole may be integrated with the objective lens.

Note that in the two embodiments described above, the central axis of the ultrasonic transducer, the central axis of the ring-shaped index, and the optical axis of the objective lens are all coaxial, but the central axis of the ultrasonic transducer and the ring-shaped Even if the central axis of the index is coaxial and the optical axis of the objective lens is parallel and decentered with respect to the axis, corneal shape measurement can be performed.

〔effect〕

As described above, according to the present invention, it is possible to easily measure, for example, the axial length of the eye and to measure the corneal shape with one device.

[Brief explanation of the drawing]

1 and 2 are views of different embodiments of the present invention. In the figures, 1 and 11 are ring-shaped light sources, 2 and 12 are ring-shaped indicators, 3 and 13 are objective lenses, 4 and 14 are apertures, and 5. , 15 are ultrasonic transducers, 6 and 16 are ultrasonic conducting members, and 7 and 17 are optical position detectors.

Claims (1)

[Scope of Claims] 1. In an ophthalmological measuring device that includes a probe that can be displaced in an axial direction and can come into contact with the eye to be examined, and that measures predetermined information about the eye to be examined using the probe, the probe is coaxial with the axis of the probe. and a means for projecting a corneal reflection image of the index onto an optical position detector via a lens to detect index image position information. An ophthalmological measuring device. 2. The ophthalmologic measuring device according to claim 1, wherein the predetermined information is axial length information, and the index is an index provided on the same circumference for corneal shape measurement. 3. The ophthalmological measuring device according to claim 1, wherein the axis of the probe is coaxial with the optical axis of the lens. 4. The ophthalmological measuring device according to claim 1, wherein the probe is provided on the eye side of the lens to be examined. 5. The ophthalmological measuring device according to claim 1, wherein the light flux of the corneal reflected image light of the index that reaches the optical position detector passes around the probe. 6. The ophthalmological measuring device according to claim 1, wherein the probe has a cylindrical shape, and a light flux reaching the optical position detector as a corneal reflected image light of the index passes through a hollow part of the probe. .