JP2004016764A - Eye refraction power measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely calculate and display distribution of refraction power through a wide range of a cornea even to a human eye having a high refraction force value. <P>SOLUTION: An instrument irradiates the cornea and the eye ground with a specific pattern, receives reflected light from the eye ground to a moving plane element and calculates and displays distribution of refraction power on the cornea of the human eye. In the instrument, in order to perform precise measurement also to the human eye having the high refraction power value, a plurality of projection optical systems are set in advance and better data is selected and defined from among measured values from the respective projecting optical systems. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
The present invention relates to an eye-refractive-power measuring device that automatically measures the refractive power of a human eye in a wide range in the field of ophthalmology / eyeglasses. This effectively works when performing a cutting operation on the corneal surface in refractive surgery. Also, knowing the refractive power distribution on the cornea as well as the operation is used for evaluating the visual acuity of the human eye.
[0002]
[Prior art]
A refraction power measuring device that irradiates a specific light beam into the human eye, detects reflected light from the fundus of the subject, performs an operation using information of the reflected light, and measures the refracting power of the human eye. Various methods have been implemented. Recently, in addition to the conventional device that provides typical refractive power information from the measurement of refractive power at a specific position of the cornea, a device that measures and displays the distribution of refractive power over a wide area on the cornea has been developed. Are provided.
[0003]
As one method, there is a method disclosed in Japanese Patent Application No. 2001-338607. This is an apparatus which has a light projecting means of a pattern which forms an image on a cornea and a fundus of a human eye, respectively, receives light while moving a reflection pattern from the fundus, and measures a wide range of refractive power of the human eye. However, when the human eye has a high refractive power, the reflection pattern from the fundus is blurred, and there is a disadvantage that the measurement cannot be performed with high accuracy. As a result, the measurable range is limited.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide refractive power distribution information with high accuracy even at a high refractive power, which has not been conventionally possible, when measuring the refractive power distribution of the human eye represented at each position over a wide range of the cornea.
[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 light reflected from the fundus of the human eye, an observation optical system for viewing the cornea of the human eye, and a subject The present invention provides a fogging optical system for always relaxing and not performing an adjusting action at the time of measurement, and an apparatus having the following means in an autoref basically including a processing system for processing information to calculate refractive power.
[0006]
The light projecting optical system has a measuring light source and a light collecting optical unit that collects a light beam from the light source and guides the light beam to the human eye. A stop 1 for imaging a specific pattern at a corneal position and a stop 2 for imaging a specific pattern at a fundus position are included in the condensing optical unit. Has a multi-ring structure for measuring the cornea in a wide range, and in particular, the diaphragm 2 for fundus imaging is located at the focal position of the light projecting optical unit. Two or more light projecting optical systems are juxtaposed, and can be selected according to the refractive power of the human eye. The light projecting optical system may be connected to a motor or the like, and may be movable according to the refractive power of the eye to be examined.
[0007]
The light-receiving optical system includes an imaging optical unit that collects and forms an image of reflected light from the fundus, and a flat light-receiving element that detects a fundus-reflected image. The flat light-receiving element unit can receive a pattern from the fundus best. Is connected to a motor 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 perform irradiation / light reception more efficiently. 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]
[Action]
Light emitted from the measurement light source passes through the apertures 1 and 2 of the projection optical system, and forms an aperture pattern on the cornea and the fundus. At this time, the pattern on the cornea and the pattern on the fundus are in one-to-one correspondence. This is due to the optical axis symmetry of the measurement optical system and the human eye. In other words, the refractive power information of the fundus oculi is represented by the size of the pattern on the fundus, and at the same time, corresponds to the opposing position on the cornea. However, when the refracting power of the human eye is large, the pattern image on the fundus becomes blurred, which makes it difficult to determine the image formed by the light receiving element. For this purpose, a plurality of light projecting optical systems corresponding to the refractive power set in advance at appropriate stages are prepared, and several types of reference model eyes are measured and stored in each of them. In actual measurement, for example, three data, Dx1, Dx2, and Dx3, are obtained by a light projecting system divided into three levels of refractive power, D1, D2, and D3. Which of the three data is to be selected is determined by 1) selecting according to the contrast of each of the light and dark ring images, and 2) when two or more data having no difference in contrast are obtained, the average thereof is used as measurement data. I do.
[0009]
The pattern image reflected on the fundus and formed on the light receiving element has the refractive power information of the subject, and this is image-processed by an internal or external information processing device, and the amount of displacement is analyzed by analyzing the amount of displacement. It calculates the refractive power represented by a specific position. At this time, the light receiving element is connected to a motor and moves to find the maximum height of the energy distribution of the pattern image in order to further increase the image recognition accuracy. This is automatically repeated by the number of the set projection optical systems.
[0010]
【Example】
Hereinafter, embodiments of the ophthalmologic apparatus of the present invention will be described in detail with reference to the drawings. The wide-area measurement method of the present embodiment calculates the refractive power of light rays incident from the positions at a plurality of predetermined positions on the corneal surface for each number of light projecting systems, and comprehensively evaluates these data. The distribution of the refractive power on the cornea can be understood.
[0011]
FIG. 1 shows an embodiment. Numerals 1 and 1 ′ are set for measuring the refractive power of “+” and measuring the refractive power of “−”, respectively, by the light projecting optical system, and can be selected by the mirror 17. Reference numeral 2 denotes a light receiving optical system, 3 denotes a fog optical system, and 4 denotes an observation optical system. The light projecting optical system will be described with reference to FIG. Reference numeral 10 denotes a human eye (focal length f0), 12 denotes an objective lens (f1), 13 denotes a ring stop 1, 14 denotes a light projecting lens (f2), 15 denotes a ring stop 2, and 16 denotes a point light source. Here, the ring diaphragms 13 and 15 have a plurality of ring patterns as shown in FIG. The ring diaphragm 13 is arranged to form an image on the fundus of the human eye, and the ring diaphragm 15 is arranged to form an image on the cornea. As shown in FIG. 2, the radii h2i and h1i of each ring on the ring stop and the radii H1i and H2i of the imaging pattern with human eyes are connected by the following relational expression. Here, m1 is the imaging magnification of the objective lens 12 viewed from the human eye, b is the length between the stop and the light projecting lens, and c is the length between the light projecting lens and the stop.
H1i = ((m1 · f2 / (m1 · f1-f2-b)) · h1i
H2i = (f0 / f1) · h2i
[0012]
Note that the length a of the light source from the stop and the distance t before the eye of the image (the imaging position P of the light source) are associated with each other by a calculation of geometrical optics, though not described in detail here. The size of the fundus oculi H2i can be changed depending on how the distance t is set. This is used to create two types of projection optical systems. In other words, the size of the fundus pattern image is changed by dividing the refractive power into “+” and “−”.
[0013]
FIG. 3 shows a light receiving optical system, 21 denotes an objective lens (f3), 22 denotes an anti-corneal reflection stop, 23 denotes an imaging lens (f4), and 24 denotes a light receiving element. Assuming that 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, Yi is connected to H2i by the following relational expression.
Yi = f4 · H2i / m2 / (f0 + x)
Here, x is an amount that depends on the refractive power D of the human eye, and x and D are related as follows.
x = D · f0 · f0 / (1000−D · f0)
[0014]
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, and the simulation is performed. The number of patterns obtained by the light receiving element for each eye is registered for the number of set projection optical systems (two in this embodiment), and the actual pattern size is compared with the registered pattern size. To calculate the refractive power. In this way, a device calibrated with the reference simulation eye can be manufactured irrespective of manufacturing errors and assembly adjustment errors of optical components.
[0015]
The calculated refractive power at a certain point on the ring is a value of the corneal position corresponding to the ring on a one-to-one basis, and the refractive power distribution at the entire corneal position is obtained by calculating the values of all the rings. It is equivalent to that. That is, the refractive power H2i (Yi on the light receiving element) is made to correspond to the corresponding position H1i on the cornea.
[0016]
The positional relationship between the apparatus and the subject's eye is guided by the observation optical system 4 to the observation imaging element 43 via the light receiving objective lens 21 and the observation imaging lens 42. The image of the image pickup device is transferred to another monitor (not shown) in the present invention, and a mark is placed on the monitor at a position corresponding to the corneal position, and the corneal image is adjusted to this position. The positional relationship between the human eye and this device is confirmed.
[0017]
In the fog optical system 3, 34 target indices are formed 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 examined. This amount moves by an amount corresponding to the movement of the light receiving element 24, and is set in advance by 2 to 3D so that the subject does not stare. The distance is set as far as the refractive power of. With this function, the subject can relax and fixate without staring at the target during the measurement.
[0018]
Although the above is one data acquisition, in the present invention, the setting of the projection optical system is changed, and this routine is repeated one more time, and the data obtained the second time is compared with the first data. Data with low contrast is deleted. If neither of them is deleted, the average of the two obtained data is used as the measurement data.
【The invention's effect】
The present invention sets in advance a plurality of light projecting optical systems divided according to the target refractive power, and by measuring the human eye with each, without blurring the pattern image even in the subject's eye with high refractive power Can be measured. For this reason, in recent refractive surgery, it is used without regard to the magnitude of the refractive power of the subject, and its distribution can be shown by the distribution on the cornea. It works effectively when performing surgery. In addition, when measuring the visual acuity of the subject, various aberrations due to the influence of the refractive power distribution can be evaluated, and can be effectively used to obtain better visual acuity.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a structure of an ophthalmologic apparatus as one embodiment of the present invention.
FIG. 2 is a diagram showing a light projecting optical system as one embodiment of the present invention.
FIG. 3 is a diagram showing a light receiving optical system as one embodiment of the present invention.
FIG. 4 is a diagram showing a ring pattern as one embodiment of the present invention.
Reference Signs List 1 optical axis of projection optical system 2 optical axis of light receiving optical system 3 optical axis of fog optical system 4 optical axis of observation optical system 10 human eye 11 half mirror 12 objective lens 13 ring diaphragm (fundus)
14 Emitter relay lens 15 Ring diaphragm (cornea)
Reference Signs List 16 Measurement light source 17 Mirror 21 Objective lens 22 Cornea reflection stop 23 Light reception imaging lens 24 Light reception element 31 Half mirror 32 Corneal reflection stop 33 Cloud fog imaging lens 34 Target 41 Reflection mirror 42 Observation imaging lens 43 Image pickup element

Claims (2)

It has a plurality of light projecting optical systems that enter a specific pattern on the fundus and cornea of the person to be measured, respectively. An eye-refractive-power measuring device comprising a light-receiving processing system for simultaneously obtaining a refractive power distribution of an eye and a passing point of a cornea. 2. 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 in accordance with the focus position of the reflected image.

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