JP2000107130A - Optometric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an accurate and easy measurement of the radius of curvature of a cornea containing the peripheral part thereof simultaneously with the measurement of refraction. SOLUTION: Luminous fluxes from a red visible LED light source 19 are reflected separately on individual inclined surfaces, travels inside repeating the total reflection thereof being guided by a light guide 17 and reflected on a vertical surface at the other end thereof to be returned into the light guide 17. At this point, parts of the luminous fluxes diffusely reflected by a reflected light diffusion part are emitted from the light guide 17 to irradiate a cornea C containing the peripheral part thereof being turned to roughly parallel luminous fluxes in the direction of the cross section. Luminous fluxes from an infrared LED light source 20 are made parallel by a lens 21 to be projected onto the cornea C of an eye E to be inspected and cornea reflected light of the light source 19 and the light source 20 is imaged on an image sensor 12 of an image pickup means 13 through a light split member 6, an objective lens 7, a mirror 8, a stop 9, a lens 10 and a light split member 11 passing through optical paths 02 and 03. The image obtained is analyzed by an arithmetic means to recognize the positions of the images of the light sources and used for the measurement of the shape of the cornea and a positioning signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optometric apparatus used for refraction measurement, corneal measurement, and the like in an ophthalmic hospital or an optician.

[0002]

2. Description of the Related Art Conventionally, in order to measure the peripheral portion of the cornea,
2. Description of the Related Art An optometry apparatus is known which includes a corneal measurement unit that illuminates a cornea with a number of ring infrared light sources and detects a reflection image of the cornea to measure a cornea, and a refraction measurement unit that performs refraction measurement using infrared light. An optometry apparatus that illuminates the cornea with a large number of ring-shaped diffused light sources, detects a reflected image of the cornea, and measures the cornea around the cornea is also known. An optometry apparatus provided with a camera is also known.

[0003]

However, in the conventional example described above, in an optometry apparatus using a large number of ring infrared light sources, when the ring image overlaps the iris, the contrast is reduced, and accurate measurement becomes difficult. Further, an optometry apparatus that illuminates the cornea with a diffused light beam has a problem that illumination efficiency is low, a large number of LEDs are required, and a light source unit becomes large when a ring-shaped fluorescent lamp is used. Furthermore, in an optometry apparatus that uses another light source for corneal shape measurement and alignment,
There is a problem that the configuration is complicated because two light sources are required.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide an optometric apparatus for accurately and simply measuring a corneal curvature radius including a peripheral portion of a cornea simultaneously with refraction measurement.

Another object of the present invention is to increase the illumination efficiency and the contrast of a ring image when projecting a large number of ring light beams onto the cornea to measure the cornea, thereby enabling accurate measurement with a simple light source unit. An optometry apparatus is provided.

It is still another object of the present invention to provide an optometric apparatus for simply measuring the central portion of the cornea including astigmatism with a simple configuration.

[0007]

According to the present invention, there is provided an optometry apparatus for projecting infrared light onto a fundus, detecting reflected light from the fundus, and measuring refraction of the eye. A first corneal measuring means for projecting infrared light onto the cornea and detecting reflected light from the cornea to measure a corneal shape, and projecting visible light onto the cornea from a position different from the infrared light to form a corneal shape. And a second corneal measuring means for measuring, wherein the corneal shape is measured by the first corneal measuring means at the time of measurement by the refraction measuring means.

The optometry apparatus according to the present invention includes a light guide having a circular cross section having a light diffusion portion on one side, and a light source for illuminating the inside of the light guide, wherein the light diffusion illuminated by the light source is provided. The corneal shape is measured by detecting a corneal reflection image by a light beam from the part.

The optometry apparatus according to the present invention further comprises a light source for measuring a corneal shape including a peripheral portion of the cornea, and a light source for positioning at the time of measuring a corneal shape different from the light source for measurement provided in at least three meridian directions. And a corneal reflection image of the alignment light source is detected to measure a curvature of a central portion of the cornea.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a configuration diagram of an optometry apparatus capable of measuring a cornea and a refraction according to an embodiment. On the optical path O1, an infrared LED light source 1 for refraction measurement, a lens 2, a central aperture stop 3 conjugate with the pupil, a perforated mirror 4, a lens 5, a light splitting member 6 for splitting corneal measurement light and refraction measurement light. Are sequentially arranged to reach the eye E to be examined. An objective lens 7 and a mirror 8 are disposed on an optical path O2 in the reflection direction of the light splitting member 6, and an aperture 9, a lens 10, and a lens 10 at the focal position of the objective lens 7 are disposed on the optical path O3 in the reflection direction of the mirror 8. A light splitting member 11 for splitting the corneal measurement light and the refraction measurement light, and an image pickup means 13 having an image pickup element 12 conjugate to the ocular fundus are sequentially arranged.
Further, on the optical path O4 in the reflection direction of the perforated mirror 4, there are arranged a peripheral six-hole stop 14 conjugate with the pupil, a separation prism 15 composed of six prisms, and a lens 16, and the light splitting member 1
1 has been reached.

As shown in FIG. 2, a plurality of ring-shaped light guides 17 having a circular cross section are arranged concentrically around the optical path O1. As shown in FIG. 3, each of the light guides 17 includes a notch 18 having an inclined surface 18a and a vertical surface 18b, and a reflective surface on the inside, and a reflected light diffusing portion 17a on the cornea C and the reflective side. Are formed. Behind the inclined surface 18a, red visible LED light sources 19 for measuring a corneal shape including a peripheral portion are arranged, respectively. The light guide 17 may be arranged such that both end portions thereof are slightly overlapped to form a continuous ring light source portion.

Further, an infrared LED light source 20 having a wavelength different from that of the infrared LED light source 1 is arranged together with a lens 21 in the gap between the light guides 17 in the oblique four meridian directions around the optical path O1. Is projected.

With such a configuration, the infrared LED light source 1
The light flux from the lens travels on the optical path O1, and the lens 2, the central opening of the diaphragm 3, the hole of the perforated mirror 4, the lens 5, the light splitting member 6
And is projected on the fundus of the eye E. The reflected light from the fundus returns along the optical path O1, is reflected by the perforated mirror 4, and
The light passes through the aperture stop 14, the separation prism 15, and the lens 16, is reflected by the light splitting member 11, and is
Are received as six light beams. The positions of these six light beams are calculated, and the refraction value including astigmatism is measured.

The luminous flux from the visible LED light source 19 is reflected on the inclined surface 18a and guided to the light guide 17, travels through the interior while repeating total reflection, is reflected on the vertical surface 18b at the other end, and returns to the light guide 17 again. Return inside. At this time, a part of the luminous flux diffused and reflected by the reflected light diffusion unit 17a is emitted from the light guide 17 as shown in FIG. Since this light beam becomes a light beam that is substantially parallel light in the cross-sectional direction, it is suitable in terms of measurement accuracy and efficiency, whereby the ring light source unit can be simply configured with a small number of LEDs.

The luminous flux from the infrared LED light source 20 is
The light is converted into parallel light by the lens 21 and projected onto the cornea C of the eye E, and is used for alignment of the eye E at the time of measuring the curvature of the central part of the cornea and measuring the corneal shape. Light source 19 and light source 20
The corneal reflected light passes through the optical paths O2 and O3, and is imaged by the imaging element 12 of the imaging means 13 via the light splitting member 6, the objective lens 7, the mirror 8, the aperture 9, the lens 10, and the light splitting member 11. The image is analyzed by the arithmetic means to recognize the position of the light source image, and is used for a corneal shape measurement and a positioning signal.

The light beam of the light source 20 can be projected from the space between the light guides 17 without interfering with the ring light beam.
Further, since this light beam is infrared light, it does not affect the optometry performed thereafter. The measurement of the curvature of the central portion of the cornea is continuously performed at the time of refraction measurement, and the light source 20 can measure corneal astigmatism if the light source 20 has three or more meridians. Further, the light source 20 is also used for alignment when measuring the corneal shape by the light source 19. In addition, since the light beam of the light source 20 is projected as parallel light and received by reflected light parallel to the optical path O1, the position does not change depending on the distance. On the other hand, the light beam of the light source 19 is not parallel light. , The image height depends on the distance.

FIG. 5 shows a light source image 2 received by the image sensor 12.
0 ′ and a ring image 17 ′ in the vicinity thereof are shown. When the distance to the subject's eye E is appropriate, the image 20 ′ has two ring images 1.
It is located in the middle of 7 '. When the distance is too short, it approaches the inner ring image 17', and when it is too far, it approaches the outer ring image 17 '. The distance between the two images 20 ′ on the line segment L connecting the two images 20 ′ in the oblique direction of the light source 20 and each ring image 17 ′
By calculating and analyzing the distance between the intersections, the distance error at the time of measurement can be corrected, so that the corneal shape can be accurately measured regardless of the distance. Each ring image 1
The height of each ring image 17 'is corrected using the ratio of the average distance between the intersections with the image 7' and the distance between the images 20 'as a correction coefficient. As described above, by using the light source 20 for both the alignment at the time of measuring the corneal shape and the curvature measurement of the center of the cornea, the corneal shape measurement and the curvature of the central portion of the cornea can be accurately measured with a simple configuration.

The light guide 17 may use a continuous spiral member instead of using a plurality of ring members. In that case, only one light source 19 is required,
Since a light source may not have enough light, a strobe light source may be used, and a light beam from the direction of the strobe tube axis may be guided into the light guide 17 by a reflecting member or a lens.

[0019]

As described above, the optometry apparatus according to the present invention measures the cornea by the second corneal measuring means at the time of measurement by the refraction measuring means, thereby accurately correcting the corneal shape including the peripheral part of the cornea with visible light. It can be measured, and the radius of curvature of the central cornea can be measured simultaneously with the refraction measurement.

The optometry apparatus according to the present invention projects a large number of rings onto the cornea by detecting a corneal reflection image due to a light beam from a light diffusing portion of a light guide illuminated by a light source and measuring a corneal shape. The illumination efficiency is improved when measuring the cornea, and accurate measurement can be performed by increasing the contrast of the ring image with a small number of light sources.

Further, the optometry apparatus according to the present invention detects the corneal reflection image of the alignment light source and measures the curvature of the central portion of the cornea, thereby allowing the alignment light source at the time of measuring the shape of the cornea to be positioned at the central portion of the cornea. Since it can also be used for curvature measurement,
The central part of the cornea including astigmatism can be easily measured with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a front view of a lighting unit.

FIG. 3 is a side view of a cutout portion of the lighting unit.

FIG. 4 is an explanatory diagram of light emitted from a light guide.

FIG. 5 is an explanatory diagram of a corneal reflection image of an imaging unit.

[Explanation of symbols]

 1, 20 Infrared LED light source 3, 9, 14 Aperture 4 Perforated mirror 6, 11 Light splitting member 13 Imaging means 15 Separating prism 17 Light guide 19 Visible LED light source

Claims (3)

[Claims] 1. A refraction measuring means for projecting infrared light to the fundus and detecting reflected light from the fundus to measure refraction of the eye, and a cornea for projecting infrared light to the cornea and detecting reflected light from the cornea. A first corneal measuring means for measuring a shape, and a second corneal measuring means for measuring a corneal shape by projecting visible light onto the cornea from a position different from the infrared light, and measuring by the refraction measuring means. An optometric apparatus wherein the corneal shape is sometimes measured by the first corneal measuring means. 2. A light guide having a circular cross section having a light diffusion portion on one side, and a light source for illuminating the inside of the light guide, and a corneal reflection image by a light beam from the light diffusion portion illuminated by the light source An optometry apparatus for detecting a corneal shape and detecting a corneal shape. 3. A light source for measuring a corneal shape including a peripheral part of the cornea, and a light source for positioning at the time of measuring a corneal shape different from the light source for measurement provided at least in three meridian directions, the light source for positioning being provided. An optometric apparatus characterized in that a corneal reflection image of the corneal is detected to measure a curvature of a central portion of the cornea.