JP2614328B2 - Ophthalmic measurement device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ophthalmologic measuring apparatus, and particularly to an apparatus for measuring an eye refractive power and a corneal shape of a subject's eye.

[Prior Art] Conventionally, in an apparatus for measuring both the eye refractive power and the corneal shape, an index for measuring an eye refractive power and an index for measuring a corneal shape are separately provided.

As the corneal shape measurement index, a ring-shaped index that is continuously or discretely arranged on the same circumference around the optical axis is known.

[Problems to be Solved by the Invention] In the above-described conventional corneal shape measurement using a ring-shaped index, the corneal reflection image of the index generally has an elliptical shape. And the minor axis and the rotation angle were measured.

However, even if the cornea has irregular astigmatism in which the center of the ellipse deviates from the optical axis, it cannot be distinguished from the case of astigmatism in which the center of the ellipse is on the optical axis and has the same elliptical shape, and it is not possible to judge the irregular astigmatism of the cornea. . Also, in the case of irregular astigmatism, the corneal shape is forcibly calculated from the general elliptical shape, so that there is a problem that the reliability of the measurement is low.

An object of the present invention is to provide an apparatus which solves the above-mentioned problems of the conventional example.

Means for Solving the Problems In order to achieve the above object, according to the present invention, a first index substantially on the optical axis projected onto the fundus of the eye to be examined, and a position around the optical axis projected onto the cornea of the eye to be examined A second index, a first measuring means for receiving the fundus reflection image light of the first index to measure the eye refractive power of the eye to be inspected, and receiving the corneal reflection image light of the first index and the second index And a second measuring unit having a function of measuring a corneal shape of the eye to be examined based on a position of the corneal reflection image of the first index and three positions determined by the corneal reflection image of the second index. Features.

Embodiment FIG. 1 is a view showing an embodiment of the present invention. In the eye refractive power measurement, the light emitted from the light source 1 illuminates the eye refractive power measurement index 3 with the condenser lens 2. The light passes through the light splitting mirrors 7 and 8 and is projected through the objective lens 9 onto the fundus of the subject's eye. The reflected image of the eye refractive power measurement index 3 from the fundus passes through the light splitting mirrors 8 and 7 via the objective lens 9 and is reflected by the perforated mirror 6 to be reflected by the aperture mirror 10.
Relay lens 11 and prisms 12a to 12f through 10a to 10f
, And is reflected by the mirror 13 to form an image on the one-dimensional position detecting elements 15a to 15c such as one-dimensional CCD via the cylindrical lenses 14a to 14c. Note that the cylindrical lenses 14a to 14c have power in directions perpendicular to the detection directions of the one-dimensional position detecting elements 15a to 15c, respectively, and converge light in that direction on the corresponding one-dimensional position detecting element.

Here, the eye refractive power measurement index 3 has a shape as shown in FIG. 2, and its center 0 is arranged on the optical axis. The reflection image of the eye refractive power measurement index 3 from the fundus is shown by the openings 10a to 10f of the multi-hole aperture 10 (substantially conjugate with the pupil of the eye to be examined) shown in FIG.
Are separated into six pieces. Eye fundus to be examined and position detection element 15
Is conjugate, the six separated images are originally superimposed on the optical axis, but are made into six separated images due to the existence of the prisms 12a to 12f. Therefore, the eye refractive power is obtained from the distance between 3a 'and 3a "(hereinafter the same) appearing in the signals of the one-dimensional position detecting elements 15a to 15c.

On the other hand, the corneal shape measurement uses four indices 20a to 20d arranged as shown in FIG.
Light emitted from the indices 20a to 20d is reflected by the cornea, reflected by the light splitting mirror 8 via the objective lens 9, formed once by the relay lens 21, and reflected by the light splitting mirror 22 to form the field lens 23 and the mirror 24. The light is transmitted and reflected, passes through a stop 26 and a photosynthesis mirror 27 via a relay lens 25, and is imaged again on a two-dimensional image sensor 28. The diaphragm 26 is located at such a position that the magnification of the indicators 20a to 20d does not change even when the working distance between the apparatus and the eye to be examined changes, that is, the index 20 () in the eye to be examined when the working distance is appropriate and when it is inappropriate. A principal ray connecting the corneal reflection images (virtual images) of 20a to 20d) is arranged at a position intersecting the optical axis via the optical system. Here, the corneal reflection image of the eye refractive power measurement index 3 is also formed on the image sensor 28 via the optical system, and FIG. 6 shows the indexes 20a to 20d and the image sensor 28 of the eye refractive power measurement index 3. This is a representation of the appearance of the corneal reflection image above. Each reflection image is indicated by adding '.

Since the eye refractive power measurement index 3 is always emitted from the optical axis, if the corneal shape measurement indexes 20a to 20d are arranged symmetrically about the optical axis, the corneal reflection images 20a 'to 20d' The corneal reflection image 3 'is considered to be its geometric center. Generally, since the cornea has a toric surface, such a corneal reflection image for the subject has images 20a 'to 20d' arranged on an ellipse centered on image 3 '.

On the other hand, since an ellipse can be determined if three points are obtained with respect to a certain center, an ellipse can be determined by obtaining the position coordinates of three points among the images 20a 'to 20d' with the center of the image 3 'as the origin.

Here, the center of the image 3 'is defined as the origin, and each image 20a' is determined from the origin.
By comparing the distances of ~ 20d ', the presence or absence of irregular astigmatism can be detected. When determining the ellipse, for example, compare the ellipse obtained from the set of images 20a ', 20b', and 20c 'with the ellipse obtained from the images 20b', 20c ', and 20d'. If the shapes are not so different, the average value May be displayed, and if there is a large difference, an irregular astigmatism mark indicating a shape abnormality is displayed to inform the examiner that the shape is out of the toric surface. Note that even if the eyelids cover the image 20a ',
Obviously, it is possible to display the measured values using 0b ', 20c', 20d '. As a modified example, the index 20a
Even if 〜20d are not arranged symmetrically with respect to the optical axis, images 20a ′ to 2
The same is possible if the position of 0d 'is calibrated.

Incidentally, in FIG. 1, in addition to the above-described two measurement threads, the corneal shape measurement optical system is separated from the corneal shape measurement optical system by the light splitting mirror 22 and formed into an image by the field lens 30, the mirror 31, and the relay lens 32. The anterior ocular segment observation optical system combined with the optical system is shown. Further, a fixation target optical system for fixing the subject during corneal shape measurement and eye refractive power measurement is shown. Specifically, the fixation target optical system includes an illumination light source 43, a fixation movable in the optical axis direction. It comprises a target 42, a relay lens 41, light splitting mirrors 7, 8, and an objective lens 9.

[Modification] By the way, in FIG. 1, the center of the eye refractive power measurement index 3 is assumed to be on the optical axis, but even if the center is apparently off the optical axis, the indexes 20a to 20d are described above. As described above, there is no problem if calibration is performed using a spherical surface having a known curvature in advance.

That is, even in this case, in the present invention, it is considered that the center of the eye refractive power measurement index is substantially on the optical axis.

In the embodiment shown in FIG. 1, three one-dimensional position detecting elements are used for measuring the eye refractive power, but this may be a two-dimensional image pickup element.
Further, the image pickup device 28 may be shared by using a bypass light path. Further, the optical system may be moved to obtain the fundus conjugate position from the light amount balance.

The index 3 for measuring the refractive power of the eye and the index 20 for measuring the corneal shape were used.
(20a to 20d) are not limited to those described above, and may be, for example, both rings.

[Effects of the Invention] As described above, according to the present invention, irregular astigmatism of the cornea is obtained by obtaining the corneal shape from the corneal reflection image of the predetermined index for measuring the refractive power of the eye and the corneal reflection image of the index for measuring the corneal shape. It is possible to provide an ophthalmologic measuring apparatus having a more accurate corneal shape measuring function, which can determine the presence / absence of the corneal shape and without using a new center position measuring index.

[Brief description of the drawings]

FIG. 1 is a diagram of an embodiment of the present invention, FIG. 2 is a diagram of a specific example of an index for measuring the refractive power of an eye, FIG. 3 is an enlarged view of a diaphragm 10, and FIG. FIG. 5 is a view showing a reflected image, FIG. 5 is a view showing a specific example of a corneal shape measurement index, FIG. 6 is a view showing a corneal reflection image on an imaging means, and 3 is an eye refractive power measurement index (corneal shape measurement). 15a to 15c are one-dimensional optical position detection elements 20a to 20d are corneal shape measurement indices 28 are imaging elements 42 are fixation targets.

Claims (1)

(57) [Claims] 1. A first index projected substantially on the optical axis projected onto the fundus of the eye to be examined, a second index projected around the optical axis projected onto the cornea of the eye to be examined, and a fundus reflection image of the first index. First measuring means for receiving light and measuring the eye refractive power of the eye to be inspected;
The corneal reflection image light of the index and the second index is received, and the position of the corneal reflection image of the first index and the positions of three points determined by the corneal reflection image of the second index are used to form the corneal shape of the eye to be examined. An ophthalmologic measuring apparatus comprising a second measuring means having a function of measuring.