JP4609697B2 - Eye refractive power measuring device - Google Patents

Description

  The present invention relates to an eye refractive power measuring apparatus that measures the eye refractive power of an eye to be examined.

The eye refractive power measurement apparatus has a fixation target optical system that moves a fixation target to be fixed to the eye to be examined in the optical axis direction of the eye to be examined, and is suitable from a state in which the fixation target is imaged on the fundus of the eye to be examined. The distance refractive power is objectively measured in a state in which the subject's eye is clouded by moving far away by an appropriate diopter (see Patent Document 1). Since this fixation target optical system can measure the refractive power of the near vision and far vision eyes, the apparent size (viewing angle) of the fixation target image can be set regardless of the fixation target presentation distance. The configuration is almost constant.
Japanese Patent Laid-Open No. 10-127581

  However, in the eye refractive power measuring apparatus provided with the fixation target optical system as described above, the refractive power and the adjustment power in a state where the fixation target is moved from a distant position to a near position and the vicinity thereof is shown or When objectively confirming, for example, even if the fixation target is presented at a position corresponding to 30 cm, the apparent size (viewing angle) of the fixation target does not change. I can't feel that the target is approaching. For this reason, there has been a problem that accuracy is insufficient when measuring and confirming refractive power and adjustment power in near vision.

  In view of the above problems, an object of the present invention is to provide an eye refractive power measuring apparatus that can more accurately measure and confirm refractive power and accommodation power during near vision.

(1) In an eye refractive power measuring apparatus that objectively measures the refractive power of an eye to be examined,
A fixation target optical system for presenting a fixation target to the eye to be examined through an objective lens system having the anterior eye portion of the eye to be examined as its front focal position;
A variable distance means for changing the distance of the fixation target for the eye;
When the fixation target is moved from the distant vision presentation distance to the near vision presentation distance by the distance variable means, the size variable means for increasing the apparent size of the fixation target as the fixation target approaches the near distance. When,
It is characterized by providing.
(2) In the eye refractive power measurement device according to (1), when the fixation target is moved to the near vision presentation distance by the distance varying means, the refractive power of the subject's eye for near use is objectively changed. It is provided with a near power measuring means for measuring.
(3) In the eye refractive power measurement device according to any one of (1) to (2) , the fixation target optical system is provided with an astigmatism correction optical system that corrects an astigmatism state of an eye to be examined. Control means for driving and controlling the astigmatism correcting optical system based on astigmatism refractive power data of the eye to be examined obtained in advance when the distance for near vision is presented is provided.

  According to the present invention, it is possible to more accurately confirm and measure the refractive power and the adjusting power during near vision.

  A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic external view of an eye refractive power measuring apparatus. 1 is a base, and 2 is a face fixing unit for fixing the face of the eye to be examined. Reference numeral 3 denotes a main body, and 4 denotes a measuring unit in which an optical system, which will be described later, is housed. The main body 3 slides back and forth on the horizontal plane of the base 1 by operation of the joystick 5, and a rotation knob of the joystick 5 By rotating 5a, the measuring unit 4 moves up and down with respect to the main body 3. A measurement start switch is provided on the top of the joystick 5. Reference numeral 7 denotes a TV monitor that displays an anterior segment image and various information of the eye to be examined. Reference numeral 8 denotes a switch unit, on which a measurement mode changeover switch and the like are arranged.

  FIG. 2 is a schematic configuration diagram of the optical system. Reference numeral 11 denotes two measurement light sources having wavelengths in the infrared region, which are arranged so as to be rotatable about the optical axis. Reference numeral 12 denotes a condenser lens. Reference numeral 13 denotes a measurement target plate having a measurement index (spot opening) and movable so as to be arranged at a position conjugate with the fundus of the eye E to be examined. 14 is a projection lens, and 15a and 15b are beam splitters. Reference numeral 17 is an objective lens, 31 is a beam splitter, 16 is a mirror, 18 and 19 are relay lenses, 20 is a strip-shaped corneal reflection removing mask arranged at a position conjugate with the cornea of the eye E, and 21 is a target plate 13. The moving lens 22 is an imaging lens. Reference numeral 23 denotes a measurement light-receiving element, and the measurement light-receiving element 23 rotates around the optical axis in synchronization with the measurement light source 11 and the corneal reflection removal mask 20.

  Reference numeral 30 denotes a fixation target presenting optical system. The fixation target presenting optical system 30 includes beam splitters 15a and 15b, an objective lens 17, a beam splitter 31, a first relay lens 32 that can move on the optical axis, a second relay lens 33, and a fixation target display unit 34. . The vicinity of the anterior eye portion of the eye to be examined at the time of measurement is at the front focal position of the objective lens 17. Although the objective lens 17 is shown as a single lens, the objective lens system may be configured by a combination of a plurality of lenses. The fixation target display unit 34 includes an image display such as a liquid crystal monitor or a plasma monitor, and can freely change the type and size of the fixation target presented to the eye to be examined.

  FIG. 3 shows an example of a fixation target presented on the fixation target display unit 34, and a fixation target 34a as a fixation target is displayed at the center of the masked circular presentation surface. In this example, a soccer ball is used as a design. The display surface of the fixation target display unit 34 is disposed so as to be positioned at the rear focal position of the second relay lens 33. The light flux from the fixation target 34a becomes a parallel light flux by the second relay lens 33, and a fixation target image 34a 'is formed by the first relay lens. The eye to be examined sees this fixation target image 34 a ′ through the objective lens 17. The first relay lens 32 moves on the optical axis to optically change the presentation position (presentation distance) of the fixation target image 34a ′. At the time of measuring the distance refractive power, the first relay lens 32 is moved to perform adjustment removal of the eye to be examined.

  Reference numeral 45 denotes an observation optical system, and the anterior eye image of the eye illuminated by an illumination light source (not shown) is reflected by the beam splitter 15 b and then captured by the CCD camera 48 via the objective lens 46 and the mirror 47.

  FIG. 4 is a schematic configuration diagram of a control system of the apparatus. The video signal from the CCD camera 48 is input to the image processing unit 51 and output to the TV monitor 7. A control unit 50 includes a fixation target display unit 34, a light receiving element 23, a switch unit 8, a measurement light source 11, a motor 56 for driving the measurement light source 11 and the light receiving element 23, a measurement target plate 13 and a lens 21. A motor 57 that moves, a motor 58 that moves the first relay lens 32, a potentiometer 60 that detects the movement position of the target plate 13, a memory 62, and the like are connected. The control unit 50 controls the fixation target display unit 34 to change the size of the fixation target 34a displayed on the display surface according to the presentation distance. Further, the control unit 50 calculates the eye refractive power and the like based on the detection signals from the light receiving element 23 and the potentiometer 60.

  The operation of the apparatus having the above configuration will be described below. First, the case where the normal distance power measurement mode is set by the switch of the switch unit 8 will be described. While observing the anterior segment image of the eye to be examined displayed on the monitor 7, the joystick 5 and the rotary knob 5a are operated to perform alignment. When the alignment is completed, the measurement start switch 6 is pressed to perform measurement. A fixation target 34a is presented to the eye to be examined by a fixation target presenting optical system.

  The measurement light emitted from the measurement light source 11 is condensed in the vicinity of the cornea of the eye E through the condenser lens 12, the target plate 13, the projection lens 14, and the beam splitters 15a and 15b, and then reaches the fundus. In the case of normal eyes, the target image reflected by the fundus is reflected by the beam splitter 15a, passes through the objective lens 17 and the beam splitter 31, and then is reflected again by the mirror 16, passes through the relay lenses 18 and 19 and the lens 21, and is connected. An image is formed on the light receiving element 23 by the image lens 22. If the eye to be examined has a refractive error, the motor 57 is driven based on the received signal of the fundus reflected light received by the light receiving element 23 to bring the target plate 13 together with the moving lens 21 to a position conjugate with the fundus of the eye E to be examined. To move.

  Next, after the first relay lens 32 is moved by driving the motor 58 to place the fixation target 34a and the fundus of the eye E in a conjugate position, an appropriate diopter component is further removed to remove the adjustment of the eye to be examined. The first relay lens 32 is moved so that only fog is applied. Next, the measurement light source 11, the corneal reflection removal mask 20, and the light receiving element 23 are rotated 180 degrees around the optical axis while the eye E is clouded. During the rotation, the target plate 13 and the moving lens 21 are moved by a signal from the light receiving element 23, and the potentiometer 60 detects the amount of movement to obtain the refractive power in each meridian direction. The control unit 50 obtains objective refractive power values of S (spherical refractive power), C (astigmatic power), and A (astigmatic axis angle) of the eye to be examined by performing predetermined processing on this refractive power. The objective refractive power values S, C, A in the cloud state are stored in the memory 62.

  In the above-mentioned distance refractive power measurement stage, the size of the fixation target 34a displayed on the fixation target display unit 34 is fixed without changing. The light flux from the fixation target 34a becomes a parallel light flux by the second relay lens 33, and a fixation target image 34a 'is formed by the first relay lens. The presentation distance of the fixation target 34 a (fixation target image 34 a ′) is changed by moving the first relay lens 32 in the optical axis direction, but the vicinity of the anterior eye portion of the eye to be examined is at the front focal position of the objective lens 17. Therefore, the apparent size (viewing angle) of the fixation target 34a does not change. For this reason, in the measurement of the refractive power for distance, the apparent size (viewing angle) of the fixation target 34a can be presented as substantially the same regardless of the diopter of the eye to be examined.

  Next, the case where the eye refractive power during near vision is measured will be described. After the above distance power measurement, when the near distance measurement mode (mode in which the fixation target is a near vision presentation distance) is set by the switch 8, the position of the S value obtained by the distance power measurement ( When astigmatism is present, the fixation target 34a (fixation target image 34a ') is moved in the near direction with reference to an equivalent spherical value obtained by adding half of the C value to the S value. For example, when the distance refractive power is −2.0D, the position where the fixation target 34a is moved closer to the distance of 2.0D from the position of 0D (diopter) becomes the reference position. Thereby, the eye to be examined is in a state of being corrected for distance. Next, in order to make the eye to be inspected to be near vision, the first relay lens 32 is moved to change the presentation position of the target from the distance position to the near position (for example, a position 35 cm from the eye to be examined). Move slowly to. The distance of the near-use position is set in advance by a near-use position setting switch arranged in the switch unit 8.

  At this time, the control unit 50 continuously increases the size of the fixation target 34 a displayed on the fixation target display unit 34 according to the presentation distance of the fixation target. 5A to 5D show examples in which the size of the fixation target 34a is changed according to the presentation distance, and the presentation distance from the eye to be examined is 5 m, 1 m, 50 cm, in order from FIG. This is an example when the distance is 35 cm. The presentation distance 5 m is a position moved 0.2 D from the reference position of the distance power, the presentation distance 1 m is 1.0 D, the presentation distance 50 cm is 2.0 D, and the presentation distance 35 cm is about 2 .8D, respectively, is a position moved from the reference position of the distance power to the near side. As shown in FIG. 5, as the fixation target 34a approaches the eye to be examined, the size of the fixation target 34a (the figure is an example of a soccer ball) increases. In addition, since it is necessary to be able to see the fixation target even when measuring the refractive power for distance, in the case of this soccer ball, at a distance of 5 m or more and at an infinite distance, it is almost the same size as when the presentation distance is 5 m. And

  Thus, as the fixation target 34a approaches, the apparent size (visual angle) of the fixation target 34a increases by increasing the size of the fixation target 34a. It can be easily recognized sensuously that 34a has approached near. As a result, the subject exercises adjustment power to fixate the fixation target that has come to the near position. The refractive power at this time can be accurately measured by rotating the measurement light source 11, the light receiving element 23, etc. in the same manner as described above, and obtaining the refractive power based on the output from the potentiometer 60. In addition, it becomes easier for the subject to confirm the ability to adjust his / her eyes. Then, it is possible to obtain the adjustment force based on the refractive power at the time of near use or to determine the addition power. The adjusting power is determined by the difference between the distance power and the near power. The addition at the target presentation distance of 35 cm is 35 cm = about 2.8 D, and is thus determined by the difference between the 2.8 D and the adjusting force. When the control force and the addition power are calculated by the control unit 50, the results are displayed on the monitor 7.

  In the measurement as described above, the amount of movement in the near and far, the speed of movement, the repetition of the near and far movement, and the like can be arbitrarily set. Further, in the case of a configuration in which the apparent size (viewing angle) of the fixation target is changed by continuously changing the size of the fixation target in the image display as described above, the fixation target is moved from a distant place to a near place. This is particularly advantageous in the measurement of the adjustment force that moves (or from near to far) and continuously measures the change in refractive power induced by the movement of the fixation target over time. The present invention can also be applied to the near point measurement for obtaining the near point of the eye to be examined.

  The change in the apparent size (viewing angle) of the fixation target according to the presenting distance may be a change that makes you feel that you are approaching the sensory distance, but it matches the actual change in viewing angle with respect to the presenting distance. If the display magnification is changed, the fixation target can be felt more naturally. FIG. 6 is a graph showing the calculation result of the ball diameter / target presentation distance and the actual viewing angle viewed by the eye when the soccer ball with a diameter of 22 cm approaches from 5 m to 35 cm, and the calculation result. It is shown. The viewing angle of the eye to be examined can be obtained from the diameter of the ball and the fixation target presentation distance. Based on this, if the size of the fixation target 34a is changed in accordance with the actual viewing angle in accordance with the presentation distance, it becomes easier to recognize the sense of distance when the object approaches the eye to be examined. At this time, if the image of the entire ball cannot be displayed on the fixation target display unit 34, as shown in FIG. 5D, an enlarged view of the ball corresponding to the actual viewing angle (a part of the enlarged ball is taken). Display).

  FIG. 7 is an example in which a fixation target image to be watched on the eye to be examined is a landscape target. A single road and a vehicle fixation target 34b are used to drive a car from a distance according to the target presentation distance. The structure is approaching. In this case, the car at infinity in FIG. 7 (a) looks very small, but as it approaches the position 1 m from the eye in FIG. 7 (b) and the position 35 cm from the eye in FIG. 7 (c). As the vehicle becomes larger, the viewing angle gradually increases, and it becomes easier to recognize that the fixation target 34b is approaching. Moreover, it is good also as a structure which a to-be-tested eye approaches a vehicle as a structure which expands a car and a road.

  When confirming the refractive power and the appearance at the near position, it may be switched to two types of fixation targets: far vision and near vision. For example, when the fixation target is set as the distance for far vision, as shown in FIG. 7 (a), the fixation target is designed to image far vision, and the fixation target is the distance for near vision. In this case, as shown in FIG. 7C, the display is switched to a fixation target having an image of near vision.

  Next, a description will be given of a function that allows the subject to experience a comparison of the appearance when the distance is viewed and the distance when the distance is corrected based on the distance refractive power measurement value. When the near switch disposed in the switch unit 8 is pressed, the first relay lens 32 moves, and the fixation target placed at the far position based on the measured value of the distance refractive power is, for example, 35 cm (far) The near-use distance is a distance moved to the near position by about 2.8D from the use position. The fixation target at the distance position is, for example, a fixation target having an image of distant vision shown in FIG. 7 (a), and the fixation target at the near position is the near fixation target shown in FIG. 7 (c). It is switched to the fixation target of the image that makes you imagine the perspective. Each time the comparison switch arranged in the switch unit 8 is pressed, the fixation target is alternately switched between the distance position and the near position, and the design of the fixation target is also as shown in FIG. 7 (c) and are alternately switched. Thereby, the subject can confirm the comparison of the appearance when the distance is viewed and the distance is viewed, and in the near vision, it is easy to recognize that the fixation target is close sensuously. When the fixation target at the near position appears to be out of focus, the adjustment power is insufficient, so that it is easy to appeal to the subject about the necessity of the addition.

  FIG. 8 is a diagram showing a second embodiment. The same reference numerals as those in FIG. 2 indicate members having the same functions, and the description thereof is omitted. The fixation optical system 30 of the second embodiment includes a disk 71 in which a plurality of fixation target plates 74 are arranged on the circumference instead of the fixation target display unit 34, and a drive unit (not shown) that rotates the disk 71. And an illumination light source 73 that illuminates the fixation target plate 74. In the disk 71, a fixation target plate 74 is switched and arranged on the optical axis of the fixation optical system 30. On the plurality of fixation target plates 74, the visual targets of the symbols corresponding to the visual target presentation distances as shown in FIGS. 5 and 7 are respectively drawn. In this example, the fixation target plate 74 is switched and arranged according to the presentation distance by rotation control of the disk 71, and the apparent size (viewing angle) of the visual target is changed by changing the size of the visual target stepwise. Change. In the distance power measurement mode, the distance fixation target in the fixation target plate 74 is arranged in the optical path. In the mode in which the fixation target is a near vision presentation distance, a fixation target plate 74 on which a fixation target having a size corresponding to the near presentation distance is drawn is switched and arranged.

  FIG. 9 is a diagram showing a third embodiment. The same reference numerals as those in FIG. 2 indicate members having the same functions, and the description thereof is omitted. In the third embodiment, by using a zoom lens for the fixation optical system 30, the apparent size (viewing angle) of the target to be presented is changed according to the presentation distance. Reference numeral 80 denotes a fixation target, 81 denotes an illumination light source, and 82 denotes a zoom lens optical system arranged instead of the first relay lens 32. The zoom lens optical system 82 includes a convex lens 82a and a concave lens 82b. By moving the concave lens 82b in the optical axis direction, the projection magnification of the visual target image 80 ′ of the fixation target plate 80 is variable. The imaging position of the visual target image 80 ′ can be changed by moving the convex lens 82a and the concave lens 82b integrally. In the distance power measurement, the projection magnification is kept constant. In the near measurement mode, the projection magnification is changed according to the presentation distance by moving the concave lens 82b. In this case, the apparent size (viewing angle) of the fixation target can be continuously changed as in the first embodiment.

  FIG. 10 is a diagram illustrating a fixation target presenting optical system according to the fourth embodiment. On the optical axis of the fixation target optical system, an objective lens 90, a diaphragm 91, a lens 92, and a fixation target display unit 93 are arranged in this order from the eye to be examined. The diaphragm 91 is conjugate with the vicinity of the anterior eye portion of the eye to be examined with respect to the objective lens 90, and is disposed at the front focal position of the lens 92. In this example, the optical system composed of the objective lens 90 and the lens 92 constitutes an objective lens system corresponding to the objective lens 17 of Example 1, and the vicinity of the anterior eye portion of the eye to be examined is located at the front focal position of the objective lens system. To do. In this example, the fixation target display unit 93 is moved in the optical axis direction to change the presentation distance. The fixation target display unit 93 is the same as the fixation target display unit 34 of the first embodiment, and changes the size of the fixation target by image display. The diaphragm 91 makes it easier to keep the size of the target luminous flux incident on the pupil of the eye to be examined more constant, and this is not necessarily required. In this example as well, in the mode in which the fixation target is a near vision presentation distance, the size of the fixation target displayed on the fixation target display unit 93 is changed according to the presentation distance.

  In addition, when the fixation target is presented to the subject's eye with strong astigmatism in the mode in which the fixation target is the near vision presentation distance, the subject may see the fixation target double. Therefore, it is difficult to realize whether or not a fixation target is presented in the vicinity. In this case, the subject cannot fully exercise the adjustment force, and cannot accurately measure the refractive power and adjustment force during near vision. Therefore, in the above embodiment, it is preferable to provide an astigmatism correction optical system for correcting the astigmatism state of the eye to be examined in the fixation target presenting optical system.

  FIG. 11 shows the fixation target presenting optical system of the first embodiment provided with an astigmatism correcting optical system and a driving mechanism for correcting the astigmatism state of the eye to be examined. The astigmatism correcting optical system and the driving mechanism described below can also be applied to the fixation target presenting optical systems described in the second to fourth embodiments. An astigmatism correcting optical system 37 has two negative cylindrical lenses 37a and 37b having the same focal length, and both can rotate independently of each other in the same direction or in the opposite direction around the optical axis. Reference numeral 38 denotes a driving mechanism that rotates the lens 37a and the lens 37b around the optical axis. The control unit 50 outputs a drive signal to the drive mechanism 38 in order to adjust the astigmatism correction optical system 37 so that the astigmatism state of the eye to be examined is corrected. When two cylindrical lenses are used, a spherical component is generated, so that the position of the fixation target 34a is corrected accordingly.

  In the apparatus having such a configuration, when measuring the eye refractive power at the near vision of the subject's eye having astigmatism, after the distance refractive power measurement, setting the near measurement mode with the switch 8 unit, The fixation target 34a (fixation target image 34a ') is moved in the near direction with reference to the position of the S value (refractive power in the weak principal meridian direction) obtained by the refractive power. Also, based on the astigmatic power of C (astigmatism power: refractive power in the strong main meridian direction−refractive power in the weak main meridian direction) and A (astigmatic axis angle) obtained in advance by measuring the refractive power for distance, etc. The astigmatism correction optical system 37 is driven and controlled by the control unit 50 so that the astigmatism state of the eye to be examined is corrected. Thereby, the astigmatism state of the eye to be examined is corrected.

  By providing the astigmatism correcting optical system 37, even for an eye to be inspected with strong astigmatism, the problem that the fixation target approaching near is doubled is solved, and the near is approached. Accordingly, it is possible to sufficiently fix the fixation target whose size increases according to the above. For this reason, the subject can easily perceive that the fixation target is approaching in the vicinity, and the adjustment force is applied to try to fixate the fixation target in the near position. Measurement is possible. Also, when the subject confirms how the target looks at the near-use position, if the fixation target appears to be blurred, the cause is not due to astigmatism of the eye, but the eye's ability to adjust You can see exactly that this is due to a shortage.

1 is a schematic external view of an eye refractive power measurement device. It is a schematic block diagram of the optical system of the apparatus of a 1st Example. It is a figure which shows the example of the fixation target shown by a fixation target display part. It is a schematic block diagram of the control system of an apparatus. It is a figure which shows the example which changed the size of the fixation target according to the presentation distance. When a soccer ball with a diameter of 22 cm approaches from 5 m to 35 cm, the calculation result of the ball diameter / target presentation distance and the actual viewing angle visually recognized by the eye to be examined are shown in the graph. is there. This is an example in which a design of a fixation target to be watched by an eye to be examined is a landscape target. It is a figure which shows 2nd Example. It is a figure which shows 3rd Example. It is a figure which shows the fixation target presentation optical system of 4th Example. The fixation target presenting optical system of the first embodiment is provided with an astigmatism correcting optical system and a driving mechanism for correcting the astigmatism state of the eye to be examined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 Switch part 17 Objective lens 30 Fixation target presentation optical system 32 1st relay lens 33 2nd relay lens 34 Fixation target display part 34a, 34b Fixation target 34a 'Fixation target image 37 Astigmatism correction optical system 38 Drive mechanism 50 Control unit 71 Disc 73 Illumination light source 74 Fixation target plate 80 Fixation target plate 80 'Target image 82 Zoom lens optical system

Claims (3)

In an eye refractive power measurement device that objectively measures the refractive power of the eye to be examined,
A fixation target optical system for presenting a fixation target to the eye to be examined through an objective lens system having the anterior eye portion of the eye to be examined as its front focal position;
A variable distance means for changing the distance of the fixation target for the eye;
When the fixation target is moved from the distant vision presentation distance to the near vision presentation distance by the distance variable means, the size variable means for increasing the apparent size of the fixation target as the fixation target approaches the near distance. When,
An eye refractive power measuring device comprising: 2. The eye refractive power measuring apparatus according to claim 1, wherein when the fixation target is moved to a near vision presentation distance by the distance varying means, a near power for objectively measuring the refractive power of the subject's eye for near use. An eye refractive power measuring device comprising: a refractive power measuring means for use. 3. The eye refractive power measuring apparatus according to claim 1, wherein the fixation target optical system is provided with an astigmatism correction optical system for correcting an astigmatism state of an eye to be examined, and the fixation target is presented as near vision. An eye refractive power measuring apparatus, comprising a control means for driving and controlling the astigmatism correcting optical system based on astigmatism refractive power data of the eye to be examined obtained in advance when the distance is set.