JP2002253508A - Ophthalmoscopic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly measure eye refractivity distribution and rest astigmatism distribution. SOLUTION: A light source 5 of a cornea measurement projection system illuminates inner parts of a short cylinder optical member 3, a boundary surface 4 reflects light flux to a disc type optical member 1, and light flux of the light source 5 is partially transmitted to the short cylinder optical member 2. The light flux from the light source 5 advances on the inside of the optical members 1 and 2 while repeating reflection. It is applied to spots of diffusion parts 6 to be diffused and reflected to be outgoing on the side of a subject eye E to illuminate the subject eye E. In this case, the diffusion parts 6 become secondary light sources to generate a number of cornea reflection images 6' on the cornea C of the subject eye E. In measuring the form of the cornea, a turret 22 is rotated by a step motor 25, and a specific target 23 is selectively put into an optical path O2. Light flux from the target 23 becomes parallel light after it passes a lens 21. As the target 23, a view target or a center target is used. As the light sources 5 and 30 are lighted, an image as illustrated in a monitor 34 appears. For measuring, the images of the reflection images 6' are taken into an arithmetic part 33 as well as an image 30'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optometry apparatus used in an ophthalmic hospital or the like.

[0002]

2. Description of the Related Art Conventionally, there are known a technique for objectively measuring a refractive power distribution of an eye to be examined and an apparatus for measuring a refractive power distribution and a residual astigmatism distribution of a cornea.

[0003]

However, in the above-mentioned prior art, since the whole area of the pupil cannot be measured at the same time,
It is difficult to accurately measure the refractive power distribution and the residual astigmatism distribution due to the change or movement of accommodation of the eye.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide an optometric apparatus capable of accurately measuring a refractive power distribution and a residual astigmatism distribution in a pupil.

[0005]

According to the present invention, there is provided an optometry apparatus for projecting a light beam onto a fundus, detecting a reflected light of the light beam for each portion in a pupil, and measuring an objective eye refractive power distribution. An eye refractive power measurement unit that obtains, a landscape target and a center target, and obtains a refractive value of a pupil center part from a value measured by the eye refractive power measurement unit using the landscape target, The method is characterized in that a refractive power distribution in the pupil is obtained from a value measured by the eye refraction measuring unit using a target.

An optometry apparatus according to the present invention comprises a projection system for projecting a point light beam onto the fundus, a small aperture stop, a focus lens, an area array sensor, and a wavefront splitting member substantially conjugate to a pupil, and the small aperture stop. And a light receiving system for focusing the area array sensor so as to be conjugate to the fundus, wherein refraction measurement is performed by detecting the position of the fundus luminous flux of the area array sensor.

Further, the optometry apparatus according to the present invention comprises a refractive power distribution measuring unit for projecting a light beam on the fundus and detecting the reflected light to measure a refractive power distribution in the pupil, and an eye refraction measured at a far point. A correction operation unit for correcting the refractive power distribution using a value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail based on the illustrated embodiment. FIG. 1 is a configuration diagram of an optometry apparatus according to a first embodiment. An optical path O1 is a refraction measurement light receiving system, an optical path O2 is a refraction measurement projection system and a target system, and an optical path O3 is an anterior ocular segment imaging system and a cornea measurement. It is a light receiving system. Light rays emitted from the anterior segment of the eye E such as the pupil are indicated by light flux A, and light rays emitted from the fundus are indicated by light flux R.

A circular optical member 1 having a hole 1a at the center is disposed in front of the eye E to be examined, and short cylindrical optical members 2, 3 are disposed around the optical member 1. I have.
The optical members 2 and 3 are connected via an inclined joint surface 4,
At the rear end of the optical member 3, a number of light sources 5 including LEDs emitting red or infrared light are arranged. These optical members 1, 2, and 3 are made of a transparent acrylic material or the like, and a large number of diffusing portions 6 are formed on the surface of the optical members 1 and 2 opposite to the eye E on which a reflective film such as aluminum is deposited. It is provided in spot form. The diffusion portion 6 is a rough rubbing surface, and the other portions are mirror-finished.

A dichroic mirror 7, an objective lens 8, a light splitting member 9, a relay lens 10 for making the anterior segment light flux A parallel, and a focus unit 11 are arranged on an optical path O1 passing through the center of the hole 1a. I have. In the focus unit 11, a central small aperture stop 12 conjugate to the fundus, a lens 13 in which the stop 12 is located at the front focal point, and a wavefront splitting member substantially conjugate to a pupil located in the rear focal point of the lens 13 , And an area array sensor 15 composed of a CCD and located at the focal point of the lens array 14 are sequentially arranged. The lens array 1
Reference numeral 4 is arranged in a honeycomb shape without any gap so that the individual hexagonal lenses have a pitch of approximately 0.5 mm on the pupil.

The optical path O2 in the direction of reflection of the light splitting member 9
Above are a mirror 16, a ring stop 17 conjugated to the pupil, a lens 18 whose front focus is located at the ring stop 17, a focus lens 19 housed in the focus unit 11 and formed of a concave lens, and a filter that transmits visible light and transmits infrared light. A dichroic mirror 20, a lens 21, a plurality of targets 23 attached to a turret 22, and a lamp light source 24 are sequentially arranged.

The optotype 23 comprises a landscape optotype for measuring the objective refraction value at the center of the pupil, a central optotype for measuring the refractive power distribution, a stripe optotype of various pitches for measuring the subjective refraction, and the like. The stripe target is configured so that the meridian direction can be freely rotated so as to change the stripe direction. The lens 21 is arranged at a position where the target 23 is in focus, and a step motor 25 for rotating the turret 22 is connected to the turret 22.

The dichroic mirror 20 has a lens 26 and a refraction measuring light source 27 composed of an infrared LED in the reflection direction.
Are arranged conjugate with the ocular fundus.

On the optical path O3 in the direction of reflection of the dichroic mirror 7, a lens 28, a light splitting member 29 as a half mirror, and a light source 30 composed of an infrared LED are arranged. The infrared LED light source 30 used for this alignment and corneal measurement is near the focal point of the lens 31.
A lens 31 and a video camera 32 are arranged in the reflection direction of the light splitting member 29.

The output of the area array sensor 15 is calculated by the arithmetic unit 3
3, the output of the video camera 32 and the arithmetic unit 33
Is connected to the monitor 34.

A light source 5 of the corneal measurement projection system illuminates the inside of the short cylindrical optical member 3, and a boundary surface 4 reflects a light beam to the disk-shaped optical member 1 and partially transmits the light beam of the light source 5. The light passes through the short cylindrical optical member 2. The luminous flux from this light source 5 is
Reflection proceeds inside the optical members 1 and 2 repeatedly,
When the light hits the spot-shaped diffusing portion 6, the light is diffusely reflected and the subject's eye E
The light exits to the side to illuminate the eye E to be examined.

In this case, the diffuser 6 becomes a secondary light source,
A large number of corneal reflection images 6 'are generated on the cornea C of the eye E to be examined. The diffusing section 6 is arranged such that the reflection images 6 'are distributed at equal intervals with substantially the same size. In a standard corneal curved surface, three adjacent reflection images 6 'form an equilateral triangle. The short cylindrical optical member 3 has a function of increasing the distance from the light source 5 to the diffusion unit 6 to uniformly illuminate each diffusion unit 6.

An image picked up by the video camera 32 via the optical path O3 is displayed on a monitor 34. The monitor 34 displays an anterior segment image E 'of the eye E, a pupil image P', and a reflected image 3 of the light source 30.
A large number of corneal reflection images 6 ′ by the 0 ′ and the diffusion unit 6 are projected. The interval between the reflection images 6 ′ is approximately 0.5 mm on the cornea C.

For alignment, an anterior eye image E ′ is photographed by a video camera 32, and a corneal reflection image 30 ′ of the light source 30 is visually confirmed on a monitor 34, and a signal of the reflection image 30 ′ is calculated by an arithmetic unit 33. To analyze. The alignment is performed so that the corneal reflection image 30 'is conjugate with a predetermined position on the imaging surface of the video camera 32.

When measuring the corneal shape, the turret 22 is rotated by the stepping motor 25, and a specific target 23 is alternatively put in the optical path O2. The light beam from the target 23 becomes parallel light when transmitted through the lens 21. The visual target 23 uses a landscape visual target or a central visual target, and when the light sources 5 and 30 are turned on,
An image as shown on the monitor 34 is obtained. For the measurement, the image of the reflection image 6 ′ is taken into the calculation unit 33 together with the reflection image 30 ′.

FIG. 2 shows a part of an image on the monitor 34. The curvature and corneal astigmatism of each part of the cornea C are calculated using the corneal reflection image 6 'from each diffusion part 6. To determine these characteristics near the reflection image S1, the image S2 and the image S3, and the image S4 and the image S
5. Calculate each interval between the image S6 and the image S7. From them,
The same calculation as that of a general keratometer is performed to calculate a radius of curvature and a corneal equivalent refractive power for each meridian, and corneal astigmatism is obtained from a difference in each meridian direction. In this way, the radius of curvature, corneal equivalent refractive power, and corneal astigmatism are calculated for each corneal portion, and an equivalent refractive power distribution, corneal astigmatism distribution, and the like can be obtained.

Since the corneal reflection images 6 'are substantially equally spaced on the cornea C, they can be easily calculated at each position in the same manner.
The corneal equivalent refractive power is calculated by assuming a so-called equivalent refractive index smaller than the actual refractive index of the cornea C in consideration of the refractive power of the back surface of the cornea C. In addition, the corneal surface refractive power assuming the actual refractive index of the cornea is calculated.

Based on the distance from the reflection image 30 'to each of the corneal reflection images 6', the inclination angle of the cornea C at the reflection image 6 'can be calculated. Can be calculated. The corneal surface refractive power is calculated as the reciprocal of the distance from the corneal vertex to the point where the parallel light is refracted on the corneal surface and intersects the optical axis. The corneal surface refractive power is calculated for each reflection image 6 'to obtain a corneal surface refractive power distribution, which is used to determine the ablation amount at the time of refraction correction by laser light.

In order to measure the refractive power distribution in the pupil P, a central target 23 is used. Since the central optotype 23 is an optotype with sufficient brightness for central fixation, the subject's eye E is in a state of natural mydriasis, and a wide pupil P can be measured. In this measurement, the measurement light source 27 is turned on after the alignment.
The ring aperture 17 that is substantially conjugate to the pupil P has a ring outer diameter of 3 mm when projected onto the pupil P and an inner diameter of about 1 mm. The portion on the optical axis is shielded so that the reflection of the objective lens 8 and the cornea C can be easily removed.

First, the diopter of the eye E to be examined is obtained by preliminary measurement, and the position of the focus unit 11 on the optical axis is determined and driven. Since the spread of the fundus image at the time of focusing becomes a predetermined size on the area array sensor 15 regardless of the diopter of the eye E, the spread of the image in the horizontal direction H shown in FIG. Focusing is performed by detecting a position where the size becomes large.

A stop 12 having a small aperture on the optical path O1 provided in the focus unit 11 of the light receiving system is conjugate with the refraction measurement light source 27 of the projection system. However, the small aperture is larger than the light source 27 and has a function of mainly removing the scattered reflection from the anterior eye such as the iris and the cornea, and also shields the scattered reflection from the objective lens 8 and the like.

When focused, the aperture 12 is conjugate to the fundus. The signal of the area array sensor 15 that has turned on the light source 27 and received the fundus reflection light is taken into the arithmetic unit 33 as shown in FIG. A fundus reflection image 27 'from the light source 27 is formed for each lens array, and when the refractive power is uniform in the pupil P, each reflection image 27' has the same arrangement as the center of the lens array. That is, when the eye optical system has no aberration, the intervals are equal, and the three adjacent reflection images 27 'are located at the vertices of an equilateral triangle. This is the same arrangement as the corneal reflection image 6 ', and is also approximately 0.5 mm apart on the pupil P.

When external light is applied to the iris, the luminous flux is received outside the pupil P depending on the wavelength. In this case, the presence of the aperture 12 does not impede the measurement by reaching the pupil region of the sensor surface. However, if the operation is performed in a dark room or a cover that covers the face is used, the reflected light from the iris is not received. In addition, scattering of the cornea C by the measurement projection light beam is almost eliminated by the diaphragm 12.

Each position of the fundus reflection image 27 'of the light source 27 shown in FIG. 3 is calculated, and the refractive power and astigmatism of each part of the pupil are obtained.
The calculation method is almost the same as in the case of the cornea C, and in order to obtain those in the vicinity of one image, the refractive power in the three meridian directions of the six image points surrounding it is calculated, and the refractive value including astigmatism is calculated. . If this calculation is performed for each part of the pupil P, the objective refractive power distribution and the astigmatism distribution in the pupil P are obtained. After correcting an error due to adjustment or the like, if a difference is calculated for each portion corresponding to the corneal astigmatism distribution obtained from the corneal equivalent refractive power in the three meridian directions previously calculated in the measurement of the cornea C, the residual mainly due to the crystalline lens is obtained. The astigmatism distribution is obtained.

As with the conventional auto-refractometer,
In order to measure the refraction value including astigmatism at the center of the pupil P, a bright landscape target is selected as the target 23. Preliminary measurement is performed after the alignment to determine the position of the focus unit 11 and, at the same time, fog the cloud to guide the eye E to a distant point. This process is similar to a conventional auto-refractometer. At this time, the pupil P hardly mydriatic because the target 23 is bright. If the pupil P is smaller than the ring stop 17, the measurement light impinges on the iris, but is not mixed into the measured light-receiving image by the action of the stop 12.

The refraction value is calculated using a light source image of about 2 to 3 mm at the center of the pupil. The calculation method is the same as described above, and is averaged within the pupil region to obtain a refraction value including objective astigmatism. Since the refraction value measured in this way is measured with cloudy fog using a bright scenery target and adjustment has been removed, this value is used to correct the above-described refractive power distribution.
When the difference between the refractive power of the central part of the pupil P measured by the central optotype and the refractive power measured by the landscape optotype is used as a correction value and the value of each part of the refractive power distribution is corrected, no adjustment is included. An objective refractive power distribution is obtained.

To perform the subjective refraction measurement, a target 23 having a stripe pattern is used. The pitch of the stripe pattern is 1.2,
Four types of 0.8, 0.6, and 0.4 are provided, and the turret 22 is rotated to select and present an appropriate optotype 23 sequentially. The meridian direction of the fringes is rotated by a step motor (not shown), and presented along with the main meridian of the astigmatism angle of the objective refraction value measured earlier. This detailed process is described in another document, for example, JP-A-2000-83901.

As described above, the difference between the objective refracting power and the subjective refracting power can be corrected by determining the subjective refraction value including astigmatism and correcting the objective refraction distribution previously obtained using the subjective refraction value. . The difference between the refractive power at the center of the pupil of the objective refractive distribution and the refractive power obtained by subjective refraction measurement is used as a correction value, and the refractive power of each part of the objective refractive distribution is corrected to obtain a refractive distribution. From this and the corneal surface refractive power distribution etc. obtained earlier, the amount of refraction correction ablation by laser light is determined. Since this is based on the corrected refractive power distribution, a correct ablation amount can be calculated.

FIG. 4 shows a refraction measuring optical system according to the second embodiment. The corneal measurement system and the anterior ocular segment observation alignment system are the same as those in FIG. Members having the same functions as those in FIG. 1 are denoted by the same reference numerals. Contrary to the first embodiment, the optical path O1 is a projection system and the optical path O2 is a light receiving system. The lens arrangement of the projection system is the same as in the first embodiment. The configuration of the corneal measurement system is the same as that of FIG.
The diffusion unit 6 may be a multiplex ring centered on the optical path O1.

An objective lens 8, a light splitting member 9, a ring diaphragm 17, a lens 18, a focus lens 19, a dichroic mirror 20, a lens 21, an optotype 23, and a voltage variable unit 41 are provided on an optical path O1 in front of the eye E to be examined. The connected lamp light sources 24 are arranged. A mirror 16, a lens 42, a small aperture stop 43, a lens 44, a Fresnel lens 45, a lens 46, focus lenses 47 and 48, and an area array sensor 15 are arranged on the optical path O2 in the reflection direction of the light splitting member 9. ing.

The optotype 23 is a scenery optotype whose center is bright, and when illuminated darkly, only the center of the optotype 23 is visible, so that it substantially functions as a central optotype. The brightness is adjusted by changing the voltage applied to the lamp light source 24 by the voltage variable unit 41. When obtaining a refraction value including astigmatism at the center of the pupil, the voltage is increased and the lamp light source 24 is turned on brightly. When measuring the refractive power distribution, if the voltage is lowered and the lamp is lit darkly, the mydriasis will occur naturally due to the darkness, and a wide pupil range can be measured without applying the mydriatic.

The lenses 42, 44 and 46 of the light receiving system have the same focal length as the lens 18, and the lens 42 is
And the conjugate position. The spacing of each of the lenses 42, 44, 46 is twice the individual lens focal length. Fresnel lens 45 is located between lens 44 and lens 46,
It is substantially conjugate to the pupil P. The focus lens 47 has the same focal length as the lens 19, and a focus unit 49 is formed together with the small aperture stop 43. The small aperture stop 43 is conjugate to the area array sensor 15 regardless of the position of the focus unit 49, and Small aperture stop 12 of the embodiment
Has the same function as.

The focus lens 19, focus lens 47 and small aperture stop 43 are integrated as a focus unit 49 and move in the optical axis direction to focus the light source 27 and the area array sensor 15 conjugate with the fundus. In this optical system, the area array sensor 15 can also be fixed.

FIG. 5 shows a Fresnel lens 45 which is a wavefront dividing member, and each ring is formed of a conical prism whose angle is gradually changed. The light beam deflection angle of each conical prism is substantially proportional to the distance from the optical axis of the prism, and is a convex lens to provide a function as a field lens, and the pitch of the ring is about 0.5 mm above the pupil. The reflected light from the point image of the fundus is divided and deflected by the Fresnel lens 45, and becomes a concentric ring image of approximately equal intervals on the area array sensor 15. Since the size of the ring image on the area array sensor 15 becomes constant when focused, the focusing is performed by detecting the spread of the image as in the first embodiment.

The solid line R transmitted through the Fresnel lens 45 is
The light beam is assumed to be deflected by the Fresnel lens 45, and the dotted line R 'indicates the deflected light beam. The diopter, that is, the refracting power of the eye E is calculated from the position of the focus unit 49 and the radial distance from a predetermined position of the ring image by the ring stop 17.

In order to measure the refractive power distribution by making the target 23 dark and using it as the central target, the position of each ring image in each meridian direction is detected, and the refractive power of the corresponding pupil portion in the radial direction is calculated. . To measure the refraction value including astigmatism, the target 23
And guide the eye to be examined to the far point. Assuming that the ring image at the center of 2 to 3 mm is an ellipse, the spherical power is obtained at the position of the focus unit 49, the astigmatic power is obtained from the degree of the ellipse, and the astigmatic angle is obtained from the main meridian direction. The correction of the refractive power distribution measured by the dark target using the refractive power measured by the bright target 23 is the same as in the first embodiment.

A value obtained by separately measuring the measured value of the subjective refraction is input to the device, and the refractive power distribution is obtained by correcting the objective refractive power distribution in the same manner as in the first embodiment. FIG. 6 shows the input unit, and a numeric keypad 51 is attached to the apparatus. When a subjective refraction value input button (not shown) is pressed, a display as shown in FIG. 6 appears on the monitor 34 for observing the anterior segment.

Numerical values of the spherical power S, the astigmatic power C, and the astigmatic angle A are input using the ten keys 51. The left and right sides of the subject's eye E are automatically displayed as R or L by the device recognizing which eye the measurement optical system is located at. When the input key Enter is pressed after inputting the numerical value, the objective refractive power distribution is corrected and the refractive power distribution is calculated as described above.

[0044]

As described above, the optometry apparatus according to the present invention can accurately obtain the eye refractive power distribution in the pupil without adjusting the eyes.

The optometry apparatus according to the present invention can measure the refractive power distribution without being affected by the reflection and scattering of the anterior segment.

Further, the optometry apparatus according to the present invention can obtain a correct corrected refractive power distribution.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optometry apparatus according to a first embodiment.

FIG. 2 is an enlarged explanatory view of a reflection image for corneal measurement.

FIG. 3 is an explanatory diagram of a fundus reflection image on an area array sensor.

FIG. 4 is a configuration diagram of a refraction measuring optical system according to a second embodiment.

FIG. 5 is a front view of the Fresnel lens.

FIG. 6 is a configuration diagram of a subjective refraction value input unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disc-shaped optical member 2, 3 Short cylindrical optical member 5, 24, 27, 30 Joining surface light source 6 Diffusion part 7, 20 Dichroic mirror 8 Objective lens 9, 29 Light splitting member 11, 49 Focusing unit 14 Lens array 15 Area Array sensor 17 Ring aperture 22 Turret 23 Optotype 33 Calculation unit 34 Monitor 41 Voltage variable unit 45 Fresnel lens 51 Numeric keypad

Claims (4)

[Claims] 1. An eye refractive power measuring unit for projecting a light beam onto the fundus and detecting reflected light for each part in the pupil to obtain an objective eye refractive power distribution, and has a landscape visual target and a central visual target. Then, the refraction value of the central part of the pupil is determined from the value measured by the eye refraction power measurement unit using the landscape target, and the refraction in the pupil is determined from the value measured by the eye refraction measurement unit using the center target. An optometry apparatus for determining a force distribution. 2. A projection system for projecting a point light beam onto the fundus, a small aperture stop, a focus lens, an area array sensor, and a wavefront splitting member substantially conjugate to the pupil, and the small aperture stop and the area array sensor located on the fundus. An optometry apparatus comprising: a light receiving system that focuses so as to be conjugated; and detects a position of a fundus luminous flux of the area array sensor to perform refraction measurement. 3. The optometric apparatus according to claim 1, further comprising a corneal shape measuring unit that projects a target light beam onto the cornea, analyzes a reflected image thereof, and measures a shape of the cornea. 4. A refractive power distribution measuring unit that projects a light beam on the fundus, detects reflected light thereof, and measures a refractive power distribution in the pupil;
An optometric apparatus comprising: a correction operation unit that corrects the refractive power distribution using an eye refraction value measured at a distant point.