JPH0577412B2 - - 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 for measuring 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, conventionally, corneal refractive power was measured using a corneal topography 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 measured. 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 the Problems] The purpose of the present invention is to eliminate the drawbacks of the conventional art, and to make it possible to easily measure, for example, axial length and corneal shape with one device. The purpose of the present invention is to provide an ophthalmological measuring device.

In an ophthalmological measurement device that includes a probe that can be displaced in the axial direction and can come into contact with the eye to be examined, and that measures predetermined information of the eye to be examined using the probe, at least a part of the probe is formed of a transparent member. and a means for projecting an index onto the cornea of the eye to be examined, and a means for projecting a corneal reflection image of the index onto an optical position detector via the light-transmitting member to detect index image position information. be done.

〔Example〕

FIG. 1 shows a first embodiment of the present invention, where 1 is a ring-shaped light source, 2 is a ring-shaped index, 3 is a light reflecting member, 4 is a light splitting member, 5 is an imaging lens, 6 is an aperture, and 7 is a light beam. a position detector, 8 a transparent member (for example, acrylic, optical glass, etc.) through which ultrasonic waves can pass; 9 an ultrasonic transducer; 10 an acoustic matching layer; 11 an acoustic absorber; 12
is a light source, and 13 is a fixation target.

Here, the imaging lens 5 has a rear focal point at the position of the aperture 6 and is a telecentric optical system, so even if the working distance to the subject's eye deviates somewhat from the original distance, the accuracy of corneal shape measurement will be affected. It's difficult. Although the index projection system projects the ring-shaped index 2 directly onto the subject's eye, a ring-shaped cylindrical lens (not shown) whose back focus is at the position of the ring-shaped index 2 is placed between the subject's eye and the ring-shaped index 2. When provided, since the index is projected from infinity, changes in the working distance due to the imaging lens 5 and dust do not affect corneal shape measurement.

To describe the corneal shape measurement system in the above configuration, a ring-shaped light source 1 illuminates a ring-shaped index 2, and the ring-shaped index 2 is projected onto the cornea Ec of the eye to be examined to form a corneal reflection image 2' which is a virtual image.

The principal beam from the corneal reflection image 2' exits approximately parallel to the measurement optical axis X, passes through the light reflection member 3 and the light splitting member 4, and forms an image on an optical position detector 7 such as a two-dimensional detection element. The ring-shaped index 2 is a perfectly circular toric index; however, if the radius of corneal curvature is small, the corneal reflection image will be a small perfect circular toric image, 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, talking about the ultrasonic measurement system, the light source 12 is turned on, the fixation target 13 is illuminated, and the fixation target 13 is illuminated.
The ultrasonic contactor consisting of the transparent member 8 and the ultrasonic transducer 9 is moved in the X-axis direction while the subject is staring at the object, and the surface V of the transparent member 8 is aligned with the cornea Ec of the eye to be measured.
so that it is in contact with

Ultrasonic pulses emitted from the ultrasonic transducer 9 are transmitted to the eye to be examined via the acoustic matching layer 10 and the transparent member 8, and the echoes from the eye to be examined are transmitted through the transparent member 8 and the acoustic matching layer 10 to ultrasonic vibrations. The child 9 receives the ultrasonic echo signal and calculates the axial length and the like from the time measurement of the ultrasonic echo signal.

FIGS. 2 to 6 each show a different embodiment.

In the embodiment shown in FIG. 2, a corneal reflection image 2' of the ring-shaped index 2 passes through a transparent member 8, passes around an ultrasonic transducer 9, and is focused on an optical position detector 7 by an imaging lens 5.

In the embodiment shown in FIG. 3, the vibrator 9 is provided in a ring shape around the X-axis, and the central opening of the vibrator 9,
The ring-shaped index 2 is projected onto the cornea Ec through the light-transmitting member 8, and the reflected corneal image 2' is transmitted to the optical position detector 7 by the imaging lens 5 through the light-transmitting member 8 and the light splitting members 4, 4'. imaged.

In the embodiment shown in FIG. 4, a corneal reflection image 2' of the ring-shaped index 2 passes through light-transmitting members 8, 8' and is imaged on an optical position detector 7 by an imaging lens 5, while an ultrasound transducer 9 The ultrasonic pulses are transmitted and received via the ultrasonic reflecting surface 14.

In the embodiment shown in FIG. 5, the surface of the ultrasonic probe consisting of a transparent member and an ultrasonic transducer that contacts the cornea is provided on a circular plane V' centered on the X-axis and on its circumference. A ring-shaped light source 1, which is composed of a surface L that functions as a ring-shaped light deflection means and is incorporated in a light-transmitting member, illuminates a ring-shaped index 2, and the light is deflected by the surface L to form an image on the cornea Ec. , the corneal reflection image 2' is the light-transmitting member 8, the light-reflecting member 3, and the light-splitting member 4.
After that, an image is formed on the optical position detector 7 by the imaging lens 5.

In the embodiment shown in FIG. 6, a ring-shaped index 16 is projected onto the cornea Ec through a transparent member 8'' that functions as a lens, and the reflected corneal image 2'' is transmitted through the transparent member 8'' to an optical position detector. 7.

In the above example, the ultrasound medium part was considered to be translucent in areas other than the area through which the corneal shape measuring light beam passes, but the area other than the area through which the corneal shape measuring light beam passes may be constructed with a light-blocking member. It is clear that even if the member is a light-transmitting member, the end face may be coated with black color to provide light-shielding properties.

[Effects] 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 to 6 are diagrams showing embodiments of the present invention. In the figures, 2 and 16 are ring-shaped indicators, 4 and 4' are light splitting members, 5 is an imaging lens, 6 is an aperture, and 7 is a light beam. position detector; 8, 8', 8'' are transparent members; 9 is an ultrasonic transducer; 10 is an acoustic matching layer; 11 is an acoustic absorber;
14 is an ultrasonic reflecting surface.

Claims (1)

[Scope of Claims] 1. In an ophthalmological measuring device that includes a probe that can be displaced in the 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, at least a part of the probe a means for projecting an index onto the cornea of the eye to be examined; and a means for projecting a corneal reflection image of the index onto an optical position detector via the transparent member to detect index image position information. An ophthalmological measuring device characterized by having means. 2. The ophthalmologic measuring device according to claim 1, wherein the predetermined information is ocular axis 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 a fixation target is presented to the eye to be examined via the probe. 4. The ophthalmological measuring device according to claim 1, wherein a part of the probe is provided with a light reflecting section. 5. The ophthalmological measuring device according to claim 1, wherein the probe is ring-shaped and the index is projected onto the eye to be examined from a central opening of the probe. 6. The ophthalmological measuring device according to claim 1, wherein a portion of the probe is provided with an ultrasonic reflecting surface. 7. The ophthalmological measuring device according to claim 1, wherein the index is provided inside the probe, and an end surface of the probe on the eye side to be examined is a light deflection surface. 8. The ophthalmological measuring device according to claim 1, wherein the probe is lens-shaped.