JP2003102687A - Ophthalmic refractive power measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for presenting the refractive power distribution of a human eye by the distribution of refractive power represented by each position on a cornea. SOLUTION: In an instrument for irradiating an eyeground with a specific pattern, guiding reflected light therefrom to a photodetective element by a photodetective optical system incorporated in the instrument and measuring the refractive power distribution of the human eye from a reflection pattern obtained on the element, two kinds of multiplex ring patterns where a specific pattern repeats transmission/shielding alternately as multiplex ring patterns form images on the cornea and on the eyeground. Due to the fact that the position of the pattern on the cornea and the position of the pattern on the eyeground correspond to each other, one to one, the ophthalmic refractive power measuring instrument presents a refractive power obtained from the eyeground pattern as a distribution on the cornea.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eye-refractive-power measuring device (commonly called "autoref") for objectively and automatically measuring the refractive power of the human eye in the field of ophthalmology / glasses.

[0002]

2. Description of the Related Art An autoref that measures the refractive power of the human eye by irradiating a specific light beam into the human eye, detecting the reflected light from the fundus of the subject, and performing calculation using the information of this reflected light. Have been implemented in various ways. For example, there are a device that uses continuous light and a device that uses intermittent light as incident light, and there is a difference even on the light receiving side that the reflected light from the fundus is received by a surface / received by a line / received by a point. The measurement target is also divided into those that measure the size of the image and those that measure the time difference between the moving images. A number of improvements have been made to make the measurement faster and more accurate, such as whether or not the image is formed on the light receiving surface.

However, the conventional autoreflector gives the refractive power information at a certain position of the cornea, that is, the spherical power, the cylindrical power and the axial angle thereof, which are typified by a fixed position of the cornea of the human eye. It was not possible to measure the refractive power distribution of the human eye represented by each corneal position over a wide range.

[0004]

DISCLOSURE OF THE INVENTION The present invention is to measure the refractive power of the human eye represented by the respective positions over a wide range of the cornea and provide information on the refractive power distribution on the cornea of the human eye. is there.

[0005]

[Means for Solving the Problems] A projection optical system for irradiating light for measurement into the human eye, a light receiving optical system for detecting reflected light from the fundus of the human eye, and a cornea of the human eye In the autoref that basically has the observation optical system, the fog optical system that the subject is always relaxed and does not cause the adjustment action during measurement, and the processing system that performs image processing of information to calculate the refractive power, An apparatus having the above-mentioned means is provided.

The projecting optical system has a measuring light source and a condensing optical section for condensing the light flux from the measuring light source and guiding it to the human eye. In this condensing optical unit, there are a diaphragm 1 for forming a specific pattern at a corneal position and a diaphragm 2 for forming a specific pattern at a fundus position, and the shapes of the specific patterns of the respective diaphragms 1 and 2. Has a multi-ring structure for measuring the cornea in a wide range, and in particular, the diaphragm 2 for forming a fundus image is placed at the focal position of the projection optical unit.

The light receiving optical system comprises an image forming optical section for collecting and forming an image of reflected light from the fundus of the eye, and a flat light receiving element for detecting a reflected image of the fundus of the eye. It has a matching movement mechanism that is connected to a motor so that it can receive light and moves in a certain direction. The light receiving optical system and the light projecting optical system are separated by a half mirror in order to more efficiently irradiate / receive light. The processing system calculates the refractive power distribution of the human eye by performing image analysis from the pattern shape selected by the light receiving element.

[0008]

The light emitted from the measuring light source passes through the diaphragms 1 and 2 of the projection optical system and forms a pattern of the diaphragm on the cornea and the fundus of the eye. At this time, the pattern on the cornea and the pattern on the fundus of the eye have a one-to-one correspondence. This is because of the optical axis symmetry of the measuring optical system and the human eye. That is, the refractive power information of the fundus is represented by the size of the pattern on the fundus and, at the same time, corresponds to the position on the cornea opposite to the pattern.

The pattern image reflected on the fundus and formed on the light receiving element has information on the refractive power of the subject, and the amount of displacement is analyzed by image processing of this information by an information processing device built in the apparatus or external. The refractive power represented by each specific position of the cornea is calculated. At this time, the light receiving element is connected to a motor in order to improve the recognition accuracy of the image, and can be moved by obtaining the maximum height of the pattern distribution.

[0010]

Embodiments of the ophthalmologic apparatus of the present invention will be described in detail below with reference to the drawings. The wide-range measurement method of the present example calculates the refractive power of light rays incident from the plurality of predetermined positions on the corneal surface, and by comprehensively evaluating these data, the refractive power on the cornea can be calculated. You can see the distribution.

FIG. 1 shows an embodiment of an optical system for an auto reflex incorporating the present invention. Reference numeral 1 is a projection optical system, 2 is a light receiving optical system, 3 is a fog optical system, and 4 is an observation optical system. The projection optical system 1 will be described with reference to FIG. Reference numeral 10 is a human eye (focal length f0), 12 is an objective lens (f1), 13 is a ring diaphragm 1, 14 is a projection lens (f2), 15 is a ring diaphragm 2, and 16 is a point light source. Here 1
The ring diaphragms 3 and 15 have a plurality of ring patterns as shown in FIG. The ring diaphragm 13 is located on the fundus of the human eye.
The ring diaphragm 15 is arranged to form an image on the cornea. As shown in FIG. 2, the radii h2i, h of each ring on the ring diaphragm
1i and the radii H1i and H2i of the image formation pattern for the human eye are connected by the following relational expression. Here, m1 indicates the image forming magnification of the objective lens 12 as seen from the human eye, and b indicates the length between the diaphragm and the light projecting lens. H1i = ((m1.f2 / (m1.f1-f2-b)). H1i ... (1) H2i = (f0 / f1) .h2i ... (2)

The length a from the aperture of the light source and the in-eye distance t of this image (image forming position P of the light source) are related to each other in the calculation of geometrical optics, although not described in detail here. The size of the fundus H2i can be changed by changing the distance t.

In FIG. 3, a light receiving optical system 2 is shown, 21 is an objective lens (f3), 22 is a corneal antireflection diaphragm, 23 is an image forming lens (f4), and 24 is a light receiving element. If the image forming height on the light receiving element 24 is Yi and the image forming magnification of the light receiving objective lens is m2, this Yi is connected to H2i by the following relational expression. Yi = f4 · H2i / m2 / (f0 + x). ． ． ． (3) Here, x is an amount depending on the refractive power D of the human eye, and x and D are related by the following equation. x = D · f0 · f0 / (1000−D · f0). ． ． ． (4)

In this way, the total refractive power of the human eye can be calculated by calculating each ring diameter on the light receiving element for each meridian. In practice, however, a plurality of simulated eyes whose values are known in advance are prepared. The numerical value of the pattern obtained by the light receiving element is registered for each of the simulated eyes, and the refractive power is calculated by comparing the actual pattern size with the registered pattern size. By doing so, it is possible to manufacture a device calibrated with a reference eye, irrespective of the manufacturing error and assembly adjustment error of the optical component.

The refractive power of a certain point on the ring calculated here becomes the value of the corneal position corresponding to the ring one by one, and by calculating the values of all the rings, the refractive power at the whole corneal position is calculated. It is equivalent to finding the distribution. That is, the refractive power H2i (Yi on the light receiving element) is made to correspond to the corresponding position H1i on the cornea.

The positional relationship between the present apparatus and the eye to be inspected is determined by the observation optical system 4 by the light receiving objective lens 21 and the observation imaging lens 42.
And is guided to the image pickup device 43 for observation. The image of this image sensor is displayed on another monitor (not shown) in the present invention, and a mark is attached to this monitor at a position corresponding to the corneal position. The positional relationship between the human eye and this device is confirmed.

In the fog optical system 3, the target target 34 is imaged on the fundus through the fog imaging lens 33 and the objective lens 21. The optotype 34 moves in accordance with the refractive power of the eye to be inspected.
The distance is moved by an amount corresponding to the movement of 4 and is set to a distance far in advance by a refractive power of 2 to 3D so that the subject does not stare. This function allows the subject to relax and fixate his eyes during the measurement without staring at the target.

[0018]

INDUSTRIAL APPLICABILITY The present invention is used for measuring refractive power distribution in recent refractive surgery, and since the distribution can be shown by distribution on the cornea, cutting of the corneal surface by surgery is performed. It works well when performing surgery. Further, when measuring the visual acuity of the subject, various aberrations due to the influence of the refractive power distribution can be evaluated, and it can be effectively used to obtain better visual acuity.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing the structure of an ophthalmologic apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a projection optical system as an embodiment of the present invention.

FIG. 3 is a diagram showing a light receiving optical system as an embodiment of the present invention.

FIG. 4 is a diagram showing a ring pattern as an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 Projection optical system 2 Receiving optical system 3 Fog optical system 4 Observation optical system 10 Human eye 11 Half mirror 12 Objective lens 13 Ring diaphragm (fundus) 14 Projection relay lens 15 Ring diaphragm (cornea) 16 Measurement light source 21 Objective lens 22 Corneal reflection diaphragm 23 Light receiving imaging lens 24 Light receiving element 31 Half mirror 32 Corneal reflection diaphragm 33 Cloud fog imaging lens 34 Visual target 41 Reflecting mirror 42 Observation imaging lens 43 Imaging element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference)

Claims (4)

[Claims] 1. A refraction power distribution of a human eye and a passage point of a cornea from a reflection pattern image incident on a fundus of a subject and a cornea so as to form a specific pattern respectively. An eye-refractive-power measuring device having a light-receiving processing system for simultaneously obtaining and. 2. The eye refractive power measuring device according to claim 1, wherein the specific pattern to be irradiated is a slit diaphragm on a multiple ring that alternately repeats light transmission / light blocking. 3. The eye refractive power measuring device according to claim 1, wherein the element that receives the reflected image from the fundus is a two-dimensional element, and is movable according to the focus position of the reflected image. . 4. The eye according to claim 1, wherein the light projecting system and the light receiving processing system are separated by a half mirror, and the fundus diaphragm of the light projecting system is located at the focal position of the light projecting lens. Refractive power measuring device.