JP3221725B2 - Eye measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved eye measuring apparatus for measuring an intraocular dimension of a subject eye from a first measuring object surface to a second measuring object surface by observing interference fringes. About.

[0002]

2. Description of the Related Art Conventionally, an axial length, an anterior chamber depth, as a distance from a first measurement target surface to a second measurement target surface of an eye to be examined,
The eye measurement device that measures the thickness of the lens, etc. There is known a device which captures and measures an echogram obtained.

However, this conventional eye measuring apparatus has a measurement accuracy of about ± 0.2 mm.
The IOL (Intraocula) is calculated using the axial length obtained as a result of the measurement.
In order to determine the power of r lens), there is a problem that the measurement accuracy is insufficient. Further, in the conventional eye measuring apparatus using ultrasonic waves, since the probe must be brought into contact with the eye to be measured at the time of measurement, there is also a trouble that precautionary measures such as infection must be taken.

Therefore, a light beam having a short coherent length is projected on the eye to be examined, and the reflected light beam from the first measurement object surface and the reflection light beam from the second measurement object surface of the eye to be examined interfere with each other. In addition, an eye measurement apparatus for measuring an intraocular dimension from a first measurement target surface to a second measurement target surface has been developed.

[0005]

However, in this type of eye measuring apparatus of this type, since fixation of the eye to be inspected is not stable, interference fringes fluctuate, and it is difficult to perform measurement quickly.

In addition, a slight shift in diopter adjustment with respect to the eye to be examined reduces the amount of reflected light from the fundus of the eye to be examined, making it difficult to obtain interference fringes, speeding measurement of intraocular dimensions, and measuring accuracy. There is a problem that it is difficult to improve the quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a measuring apparatus for an eye to be examined which can speed up the measurement of the intraocular dimensions of the eye to be examined and further improve the measuring accuracy.

[0008]

Means for Solving the Problems The invention according to claim 1
In order to solve the above problem, coherent length
A projection optical system equipped with a measurement light source that projects a short light beam
Observation of interference fringes obtained by projecting light to the eye to be examined
The second measurement from the first measurement target surface of the subject's eye.
In the eye measurement device that measures the intraocular dimensions up to the target surface
In the light projecting optical system, a test object is provided separately from the measurement light source.
A diopter adjusting light source for adjusting the diopter of the eye;
In the optical optics, the luminous flux from the diopter adjusting light source and the measuring light
A diopter adjustment lens is placed at the position where the light beam from the source passes
The light emission amount of the diopter adjusting light source is equal to the light emission amount of the measuring light source.
The amount is set to be larger than the amount. Claim
Item 2. The invention according to Item 2, wherein the measurement light source and the diopter adjustment
Light quantity control means for controlling the light quantity with the light source is provided
It is characterized by the following.

[0009]

[0010]

[0011]

[For work] According to the examined eye measuring apparatus according to claim 1,
Since the diopter adjustment light source is specially provided and the light emission amount thereof can be set to be larger than the light emission amount of the measurement light source, a sufficient amount of reflected light from the fundus to adjust the diopter can be obtained.

[0012]

【Example】

[0013]

FIG. 1 shows a first embodiment of a living eye measuring apparatus according to the present invention.
It is an optical diagram showing an example. The eye measurement apparatus according to the first embodiment corresponds to claim 1 of the present invention.

In FIG. 1, reference numeral 100 denotes a corneal distance measuring system;
01 is an interference light projecting optical system, 102 is a ring-shaped light source projection unit that irradiates a cornea with a light beam, and 104 is an objective lens. The corneal distance measurement system 100 has a first optical path 105 and a second optical path 106. The first optical path 105 is roughly composed of a two-dimensional image sensor 107, an imaging lens 108, a half mirror 109, an aperture 110, a lens 111, a total reflection mirror 112, a lens 113, a half mirror 114, a dichroic mirror 115, and an objective lens 104. I have. The second optical path 106 generally includes a total reflection mirror 116, a lens 117, total reflection mirrors 118 and 119, and a stop 124.

The ring-shaped light source projection unit 102 includes a ring-shaped light source and a pattern plate (not shown), and here projects illumination light having parallel meridional sectional rays to the eye to be examined. I have. This illumination light is applied to the subject's eye 103
When irradiated toward the eye 103, a ring-shaped virtual image 121 is formed on the cornea 120 of the eye 103 to be inspected. Here, the wavelength of the illumination light of the ring-shaped light source projection unit 102 is 900 nm to 1000 nm. The dichroic mirror 115 transmits the illumination light, and reflects a wavelength of near-infrared light described later.

The light reflected by the cornea 120 is reflected by the objective lens 104,
The light is guided to a half mirror 114 via a dichroic mirror 115, and is branched into a first optical path 105 and a second optical path 106. First
The reflected light guided to the optical path is once formed as a ring-shaped aerial image 122 based on a lens 113, and further passes through a total reflection mirror 112, a lens 111, a diaphragm 110, a half mirror 109, and an imaging lens 108. An image is formed on the two-dimensional image sensor 107. The reflected light guided to the second optical path 106 is reflected by a total reflection mirror 119.
Is reflected by the objective lens 104 and is once reflected in the aerial image 123.
And a total reflection mirror 118, a lens 117, a half mirror 116, an aperture 124, a half mirror 109, and an imaging lens 108
Is imaged on the two-dimensional image sensor 107 via.

The stop 110 is relayed by a lens 111 and a lens 113 near the rear focal position of the objective lens 104, and the first optical system 100 is substantially telecentric on the object side. 125
Is a conjugate image of the stop 110. The aperture 124 is a lens 117
Is relayed in front of the subject's eye 103, where a conjugate image (real image) 126 is formed at a position 25 mm to 50 mm in front of the subject's eye.

The position of the apex of the cornea can be obtained based on a ring-shaped image formed on the two-dimensional light receiving element 107. For details, refer to Japanese Patent Application No. 2-145107 (Title of Invention: Intraocular Length). Measuring device: filing date May 31, 1990).

The interference light projecting optical system 101 includes a laser diode 130, a lens 131, and a pinhole 13 as a measurement light source.
2, beam splitter 133, lens 134, focusing lens 135,
Total reflection mirror 136, lens 137, total reflection mirror 138, 139,
140, a model eye unit member 141, a total reflection mirror 142, a pinhole 143, a lens 144, and a photosensor 145 having a point aperture. The laser diode 130 has a low coherent length, and the coherent length is, for example, 0.05 mm to
It is about 0.1 mm. Its wavelength is near infrared and has an antiglare effect. The laser light emitted from the laser diode 130 is focused on the pinhole 132 by the lens 131. The pinhole 132 plays a role as a secondary point light source. Note that an LED having a narrow spectrum width may be used as a light source instead of a laser diode. 162 is described later.
Half-mirror constituting a part of the diopter adjusting optical system 157
It is ra.

The laser light that has passed through the pinhole 132 is
The beam splitter 133 splits the beam toward the lens 134 and the beam toward the lens 137. The lens 134 is
Lens 135, total reflection mirror 136, dichroic mirror 11
5, together with the measurement optical path 130 '. Lens 137
Together with the total reflection mirrors 138, 139, 140 and the model eye unit member 141, a reference optical path 140 'is formed.

The lenses 134 and 137 play a role of collimating the laser light passing through the pinhole 132. Lens 13
The laser beam collimated by 4 is
By 35, a spot is formed at the focal position 146 of the lens 135. This focal position 146 is different from the fundus 147
And conjugate. The laser beam forming a spot at the focal position 146 is guided to the eye 103 via the total reflection mirror 136, the dichroic mirror 115, and the objective lens 104, and forms a spot on the fundus 147. The eye 103 can fixate the spot image.

The pinhole 143 is provided at the focal position of the lens 134, and the pinhole 143 is conjugate with the fundus 147.
The lens 135 has a function of collimating the fundus reflection light, and the collimated fundus reflection light is relayed by the lens 134 to the pinhole 143 via the beam splitter 133 and the total reflection mirror 142. The pinhole 143 is conjugate to the pinhole 132 and the reflection surface of the beam splitter 133. The laser beam collimated by the lens 137 is guided to the model eye unit member 141 by mirrors 138, 139, and 140. The model eye unit member 141 is movable so that the optical path length of the reference optical path and the optical path length of the measurement optical path are the same. This model eye unit member 141 is roughly composed of a lens 148, a reflection mirror 149, and a movable member 150. The model eye unit member 141 is used to eliminate the deflection of the reflected light beam due to the blur caused by the movement thereof, and may be a simple movable mirror in principle.

The fundus reflection light and the reference light form a pinhole 143.
The light flux that has passed through the pinhole 143 is converged on the photosensor 145 by the lens 144. By moving the model eye unit member 141, when the optical path difference between the reference optical path and the measurement optical path becomes about the coherent length of the laser diode 130, an interference waveform is obtained, and this interference waveform changes every time the optical path length changes by one wavelength. Changes sinusoidally, which
The distance from the device optical system to the fundus is measured, and the axial length is determined based on the position from the device optical system to the apex of the cornea and the position from the device optical system to the fundus. The details are also described in Japanese Patent Application No. 2-145107 (Title of Invention: Intraocular Length Measuring Device: Filing Date: May 31, 1990), and the description is omitted.

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

The diopter adjusting optical system 157 includes a diopter adjusting light source 1.
58, a lens 159, a total reflection mirror 160, a pinhole 161, half mirrors 162 and 163, and total reflection mirrors 164 and 165.
Half mirror 162 has pinhole 132 and beam splitter 13
It is arranged between 3 and. Pinhole 161 is pinhole
It is conjugate with respect to 132 and the half mirror 162, and serves as a secondary point light source.

The amount of light emitted from the diopter adjusting light source 158 is larger than the amount of light emitted from the laser diode 130. Diopter adjustment light source 158
The light flux emitted from the lens 159 is guided to the pinhole 161 via the lens 159 and the total reflection mirror 160, and the pinhole 161
Is collected. The light beam passing through the pinhole 161 is reflected by the half mirror 162 and guided to the beam splitter 133. The light beam is split by the beam splitter 133 into a light beam guided to the measurement light path 130 'and a light beam guided to the reference light path 140'. The light beam guided to the measurement light path 130 ′ is converted into a parallel light beam by the lens 134. The parallel light flux passes through a half mirror 163, a focusing lens 135, a total reflection mirror 136, a dichroic mirror 115, and an objective lens 104, and
It is projected on the fundus 147 of 103.

The reflected light from the fundus 147 passes through the objective lens 104,
The light is guided to the half mirror 163 via the dichroic mirror 115, the total reflection mirror 136, and the focusing lens 135. The reflected light guided to the half mirror 163
And the total reflection mirrors 164 and 165 and the lens 151
The light is guided to the two-dimensional image sensor 107 via the half mirror 116, the aperture 124, and the half mirror 109, and is imaged on the two-dimensional image sensor 107. In order for the spot image formed on the two-dimensional image sensor 107 to be clear
The diopter adjustment is performed by moving the focusing lens 135 for diopter adjustment.

At the time of diopter adjustment, of the reflected light from the fundus 147, the light flux that has passed through the half mirror 163 passes through the lens 134, the beam splitter 133, and the total reflection mirror 142, and enters the pinhole 143. The light is guided and focused on the pinhole 143. The light beam passing through the pinhole 143 is converged on the photo sensor 145 by the lens 144. Therefore, it is also possible to adjust the diopter by moving the focusing lens 135 so that the amount of light incident on the photosensor 145 is maximized. Incidentally, only when diopter adjustment, the half mirror 162 and 163 and inserted detachably in configuration with respect to the optical path of the interference optical system 101, in this first embodiment, only the interference optical system 101 when the diopter It is inserted into the optical path. The light emission amount of the laser diode 130 and the light emission amount of the diopter adjusting light source 158 are increased or decreased by a light amount control circuit (not shown). Also,
The laser diode 130 emits light after diopter adjustment.

Here, the wavelength of the diopter adjusting light source 158 is set to be more visible than the laser diode 130, which is a measuring light source, and the half mirror 156 reflects the light from the diopter adjusting light source 158, and By substituting a dichroic mirror that transmits light from the light source, the light amount of each light source can be used efficiently.

[0036]

FIG . 2 shows a second embodiment of the eye measuring apparatus according to the present invention .
It is an optical diagram of an example . In FIG. 2 , the first embodiment
The same components as in the example are denoted by the same reference numerals. In this embodiment, a polarization beam splitter 166 is provided instead of the half mirror 163. Further, a １ ／ wavelength plate 167 is provided between the subject's eye 103 and the objective lens 104, and a 波長 wavelength plate 168 is provided in front of the model eye unit member 141. The deflection beam splitter 166 is inserted into the measurement optical path 130 'only during diopter adjustment. The deflection beam splitter 166 transmits only the linearly polarized light component of the light beam from the diopter adjusting light source 158. This polarization beam splitter
The light flux transmitted through the objective lens 104 is transmitted in the same manner as in the first embodiment.
It is led to. The luminous flux that has passed through the objective lens 104 is advanced by a quarter wavelength (the phase is π / 2) when passing through the quarter-wave plate 167, and is converted into circularly polarized light. The circularly polarized light beam is projected onto the fundus 147, reflected by the fundus 147, and guided again to the quarter-wave plate 167. The reflected light of the circularly polarized light is further reduced in wavelength by 1/4 by the quarter wavelength plate 167.
Four wavelengths (the phase is π / 2) are advanced, and a total of 波長 wavelengths with respect to the wavelength of the original light flux (90
Then, the light beam is guided to the polarization beam splitter 166 along the original optical path. The polarization beam splitter 166 converts the fundus reflection light beam having a linear polarization characteristic orthogonal to the polarization direction of the original light beam by 90 degrees to the total reflection mirror 164.
Reflects toward. The fundus reflected light beam is formed on the two-dimensional image sensor 107 as in the third embodiment, and the focusing lens 135 is adjusted based on the spot image formed on the two-dimensional image sensor 107.

Since the quarter-wave plate 168 is also arranged in the reference light path, the light beam in the reference light path and the light beam in the measurement light path can interfere without any trouble.

[0038]

Third Embodiment FIGS. 3 and 4 are optical diagrams showing a third embodiment of the eye measuring apparatus according to the present invention.

In FIG . 3, reference numeral 20 denotes a semiconductor laser;
Denotes a collimating lens, and 22 and 23 denote beam splitters. As the semiconductor laser 20, a laser having a short coherent length is used as in the first to fourth embodiments. The laser light emitted from the semiconductor laser is collimated by a collimating lens 21.
Is converted into a parallel light beam. The parallel light flux is split by the reflection surface 24 of the beam splitter 22 into a parallel light flux P1 guided to the beam splitter 23 and a parallel light flux P2 guided to the optical path length changing member 25. The optical path length changing member 25 is
6 and 27, and has a function of changing the optical path length of the parallel light flux P2 by moving in the direction of the arrow. When the optical path length changing member 25 is moved by ΔL / 2 in the direction of the arrow, the optical path length of the parallel light flux P2 changes by the shift amount ΔL.

The beam splitter 23 has a reflection / transmission surface 28. A focusing lens 29 for adjusting diopter is provided between the beam splitters 23 and 22. The focusing lens 29 guides the parallel light flux P1 that has passed through the beam splitter 22 to the reflection / transmission surface 28 of the beam splitter 23 as a convergent light flux P1 '. In addition, beam splitter 23
, The parallel light flux P2 from the optical path length changing member 25 is guided. The parallel light flux P2 becomes a parallel light flux P2 'reflected on the reflection / transmission surface 28, and the parallel light flux P2' and the convergent light flux P1 '.
Is guided to the objective lens 56 via the beam splitter 55. With this objective lens 56, when the eye to be examined is an emmetropic eye, the convergent light beam P1 'becomes a parallel light beam P1 ", and the parallel light beam P1".
2 ′ becomes a convergent light beam P2 ″ and is guided to the living eye 31. The convergent light beam P2 ″ becomes a light beam heading toward the corneal curvature center 40. The apparatus main body is aligned with the living eye 31, and the two-dimensional image sensor 34 is used for observing the anterior segment. The infrared light emitted from the infrared LED 32 is a condenser lens
The light passes through 36, the pinhole 37, and the relay lens 49, is reflected by the half mirror 33, and is guided to the beam splitter 55.
The beam splitter 55 transmits the semiconductor laser light,
Other light is reflected.

The infrared light is reflected by the cornea 38, which is the first measurement target surface of the living eye 31, and passes through the objective lens 56 again.
The light is reflected by the beam splitter 55, passes through the half mirror 33, passes through the imaging lens 35, and is guided to the two-dimensional image sensor 34. The two-dimensional image sensor 34 is connected to a TV monitor 44. The alignment of the optical system with respect to the living eye 31 is performed by observing the reflected luminescent spot of the infrared reflected light beam projected on the TV monitor 44, and in the vertical and horizontal directions within a plane orthogonal to the optical axis direction of the optical system. By moving the optical system, the alignment of the optical axis O1 of the optical system with respect to the corneal vertex P is performed.

When the alignment distance of the optical system with respect to the living eye 31 in the optical axis direction is set so that the convergent light beam P2 ″ is incident toward the corneal curvature center 40 of the cornea 38 of the living eye 31 as shown in FIG. Thus, the convergent light beam P2 "is reflected by the cornea 38, and the reflected light beam P3 is reflected on the original optical path.
On the other hand, the parallel light flux P1 ″ guided to the living eye 31 is guided as a convergent light flux by the cornea 38 and the crystalline lens 41 to the fundus 42, which is the second measurement target surface.

The details of the measurement of intraocular dimensions according to the third embodiment are described in Japanese Patent Application No. 2-213999 (Title of Invention:
The description is omitted here because it is described in the living eye size measuring device: application date August 13, 1990).

Each of the reflected light beams P3 and P4 passes through the original optical path and is guided to the beam splitter 22. In the beam splitter 22, the two reflected light beams P3 and P4 are plane waves whose wavefront shapes are substantially flat. The reflected light flux P4 is reflected by the reflecting surface 24 of the beam splitter 22, passes through the imaging lens 46, forms an image on the confocal stop 47, and forms a collimating lens.
The light is guided by the 48 to the two-dimensional image sensor 43 as a parallel light beam. The two-dimensional image sensor 43 is connected to a TV monitor 44.

Incidentally, the contrast of the interference fringes projected on the TV monitor 44 is significantly reduced when the light amount of the reflected light beam P4 from the fundus 42 and the light amount of the reflected light beam P3 from the cornea 38 are significantly different. This is because the contrast of the interference fringes is best when the amounts of light beams that interfere with each other are equal. Therefore, in this optical system, a beam splitter is used to adjust the reflectance of the reflecting surface 24 of the beam splitter 22 so that the light amount of the reflected light beam P3 from the cornea 38 and the light amount of the reflected light beam P4 from the fundus 42 are substantially equal. The laser beam is designed so that the reflected light amount of the laser light reflected by the beam splitter 22 is smaller than the transmitted light amount of the laser light passing through the laser beam. However, since there is an individual difference in the living eye 31, the light amount of the reflected light beam P4 from the fundus may change depending on the individual difference.

Therefore, in this embodiment, a variable density filter 45 is provided between the beam splitter 22 and the focusing lens 29. When the contrast of the interference fringes is low, the density variable filter 45 is rotated to adjust the light amount of the reflected light beam P4 from the fundus 42 and the light amount of the reflected light beam P3 from the cornea 38 so as to be substantially the same. To obtain a good interference fringe. When the depth of the anterior chamber and the thickness of the crystalline lens are measured, a high-refractive-power optical path length changing member 50 is inserted between the beam splitter 22 and the focusing lens 29, and the parallel light flux P1 and the parallel light flux P2 are measured. The measurement is performed while shortening the optical path length difference between.

The beam splitter 22 and the collimating lens 21
Between them, a half mirror 60 is provided. The half mirror 60 constitutes a part of the diopter adjusting optical system 61. The diopter adjusting optical system 61 includes a diopter adjusting light source 62, a lens 63, a total reflection mirror 64, and a shutter 65. The half mirror 60 can be inserted into and removed from the optical path between the collimator lens 21 and the beam splitter 22, and is inserted into this optical path only when diopter is adjusted, so that semiconductor laser light is effectively used. The shutter 65 is provided in the optical path between the beam splitter 22 and the optical path length changing member 25 so as to be insertable and detachable, and is inserted into this optical path only at the time of diopter adjustment.

The luminous flux emitted from the diopter adjusting light source 62 is
The light is converted into a parallel light beam by the lens 63, reflected by the total reflection mirror 64, and guided to the half mirror 60.
And is guided to the beam splitter 22. The parallel light beam is split by the reflecting surface 24 of the beam splitter 22, but the light beam reflected by the reflecting surface 24 is
Is shielded from light. The light beam that has passed through the reflecting surface 24 is projected onto the fundus 42 along the same optical path as the light beam emitted from the semiconductor laser 20. The light beam reflected by the fundus 42 follows the original optical path in the same manner as the reflected light beam P4, and the beam splitter 22
And is reflected by its reflecting surface 24 to form an imaging lens.
The light passes through 46, forms an image on a confocal stop 47, is converted into a parallel light beam by a collimating lens 48a, and is further formed on a two-dimensional image sensor 43 by an imaging lens 48b. Imaging lens
48b is a collimating lens 48a and a two-dimensional image sensor 43
Are provided so as to be able to be inserted into and removed from the optical path between them, and are inserted into this optical path during diopter adjustment, and are retracted from this optical path during measurement. Therefore, the diopter is adjusted by moving the focusing lens 29 so that the reflected spot image from the fundus 42 formed on the two-dimensional image sensor 43 becomes clear.

The details of the measurement of intraocular dimensions according to the fifth embodiment are described in Japanese Patent Application No. 213999/1990 (Title of Invention:
The description is omitted here because it is described in the living eye size measuring device: application date August 13, 1990).

[0050]

The eye measuring apparatus according to the present invention is configured as described above, so that the measurement of the intraocular dimension of the eye to be inspected can be speeded up and the measurement accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is an optical diagram showing a first embodiment of an eye-to-be-measured measuring apparatus.

FIG. 2 is an optical diagram showing a second embodiment of the eye-to-be-measured measuring apparatus.

FIG. 3 is an optical diagram showing a third embodiment of the eye-to-be-measured measuring apparatus;

FIG. 4 is an enlarged view showing a reflection state of the light beam shown in FIG . 3;
You.

[Explanation of symbols]

130: laser diode (light source for measurement) 151: light source for fixation target 152: light source for diopter adjustment 61, 158 ... optical system 29, 135 for diopter adjustment 135: focusing lens for diopter adjustment

Claims (2)

(57) [Claims] A light source having a measuring light source for projecting a light beam having a short coherent length to the eye to be inspected, and observing interference fringes obtained by projecting light to the eye to be inspected.
In an eye measurement apparatus for measuring an intraocular dimension from a first measurement target surface to a second measurement target surface of an eye to be inspected, in the light projection optical system, separately from the measurement light source, an eye of the eye to be inspected is provided.
Diopter adjusting light source for adjusting diopter, and the projection light
The light flux from the diopter adjustment light source and the measurement light source
A diopter adjustment lens is placed at a position where these light beams pass,
An eye measurement device for an eye to be examined, wherein the light emission amount of the diopter adjustment light source is set to be larger than the light emission amount of the measurement light source. 2. A light amount control means for controlling light amounts of the measurement light source and the diopter adjustment light source is provided.
2. The eye measurement apparatus according to claim 1.