JP4330399B2 - Eye adjustment function measuring device - Google Patents

Description

  The present invention relates to an eye accommodation function measuring apparatus that objectively measures the accommodation function of an eye to be examined.

In ophthalmology clinics, etc., an eye refractive power measuring device that objectively measures eye refractive power is generally used, and a subjective value test is performed based on the objective refractive power value obtained thereby. The prescription frequency is determined. However, subjects who have accommodation tension in their eyes tend to cause eyestrain such as headaches and stiff shoulders when looking close. For this reason, the method and apparatus which measure accommodation tension are proposed by the following nonpatent literature 1 and patent documents 1. In these methods and apparatuses, paying attention to the fact that there is a certain correlation between the degree of accommodation tension and the appearance frequency of the high-frequency component of accommodation fine movement, a fixation target (stimulus target) is set every 0.5D steps from a distance. The time-dependent change of the refractive power data when the fixation target is stopped at each of the eight positions is sampled for 20 seconds, and a predetermined high-frequency component of the time-dependent change of the sampled refractive power data is sampled. By determining the appearance frequency, the accommodation function of the eye to be examined is objectively measured. Further, in the measurement result of the accommodation tension, the fixation target position, the accommodation reaction amount (refractive power), and the frequency of appearance of the high frequency component of the accommodation fine movement are expressed by one graph. The appearance frequency of the high-frequency component of the adjustment fine movement is expressed by shading or color coding.
JP-A-2003-70740 Seiko Suzuki and two others, “Evaluation of Adjustment Function by High Frequency Components of Adjustment Tremor”, Visual Science, Japanese Society of Ophthalmology, September 2001, Vol. 22, No. 3, p. 93-97

  However, the prior art has a problem that errors occur in measurement and diagnosis. That is, the configuration in which the examiner supports the measurement unit main body and moves the measurement unit main body as in Patent Document 1 described above causes a burden on the examiner and causes a measurement error if the alignment state is not properly maintained. Become. When the subject's eye has astigmatism, fixation micromovements and misalignment caused by astigmatism occur, which causes measurement errors. In the above-described prior art, skill is required for decoding the measurement result, and the frequency of appearance of the high-frequency component of the adjustment fine movement is not a quantitative display.

  In view of the above prior art, it is an object of the present invention to provide an eye accommodation function measuring apparatus that can reduce measurement errors and diagnostic errors.

  In order to solve the above-mentioned problems, the present invention is characterized by having the following configuration.

(1) The fixation target presenting means capable of changing the position of the fixation target presented to the eye to be examined in the distance direction with respect to the eye to be examined, and the fixation target are sequentially moved by a predetermined diopter, and a power detection optical system for detecting a time variation in power within a predetermined time at a predetermined measurement interval at each moving position, time variation in power within a predetermined time fixation target in the stopped state at each moving position Detects the alignment state of the refractive power detection optical system with respect to the subject's eye in an eye accommodation function measuring device that obtains the appearance frequency of a high-frequency component indicating the fine movement of ciliary muscle based on and alignment detection means for, in detecting the temporal change of the refractive power at a predetermined measurement interval for each of the movement positions of the fixation target, the power detection optical to the movement of the eye as an alignment state has a predetermined proper state Automatic tracking means to track the system If, on the basis of the detection result of the alignment detection means, alignment state in each moving position of the fixation target excludes power detection result detected at a predetermined measurement interval while deviated from predetermined appropriate state, solid Calculating means for obtaining the appearance frequency of the high-frequency component of the adjustment fine movement at each movement position of the visual target .
(2) The eye accommodation function measuring device according to (1) further includes astigmatism detection means for obtaining an astigmatism state of the subject eye based on the detection result of the refractive power detection optical system, and obtains the accommodation function state of the subject eye. The refractive power data for this is a refractive power in the strong main meridian direction or the weak main meridian direction of astigmatism based on the detection result of the astigmatism detection means.
(3) In the eye accommodation function measuring apparatus according to (1), the calculation means further includes a judgment means for judging which of a plurality of ranks the appearance frequency of the adjustment fine movement high frequency component belongs to.

  According to the present invention, it is possible to reduce measurement errors and diagnostic errors when measuring the eye accommodation function state.

  The best mode of the present invention will be described below with reference to the drawings. FIG. 1 is an external view of an eye accommodation function measuring apparatus according to the present invention. The measuring device is provided with a base 1, a face support unit 2 attached to the base 1, a moving base 3 movably provided on the base 1, and a movable base 3, which will be described later. A measuring unit 4 that houses the optical system is provided. The measuring unit 4 is moved in the left and right direction (X direction), the up and down direction (Y direction), and the front and rear direction (Z direction) with respect to the eye E by an XYZ driving unit 6 provided on the moving table 3. The drive unit 6 includes a slide mechanism, a motor, and the like provided for each of the X, Y, and Z directions. The movable table 3 is moved in the X direction and the Z direction on the base 1 by the operation of the joystick 5, and is moved in the Y direction by the Y drive of the XYZ drive unit 6 by rotating the rotary knob 5a. The moving table 3 is provided with a monitor 7 for displaying various information such as an observation image of the eye E to be examined and a measurement result, a switch unit 8 on which a measurement mode switching switch, a switch for inputting a working distance, 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. The eye refractive power measurement optical system 10 is configured as described above. The corneal reflection removal mask 20 is provided with a light receiving element on which the corneal reflection light is incident, and the presence or absence of blinking of the eye to be examined is detected based on the output signal of the light receiving element.

  Reference numeral 30 denotes a fixation target presenting optical system. Reference numeral 32 denotes a first relay lens that can move on the optical axis, and the amount of movement is proportional to the spherical refractive power of the eye to be examined. Reference numerals 37a and 37b are positive cylindrical lenses having the same focal length, and both can rotate independently of each other in the same direction or in the opposite direction, and constitute an astigmatism correcting optical system. When an astigmatism (columnar surface) component is created by two cylindrical lenses, the spherical component generated along with the generation is corrected. Reference numeral 33 denotes a second relay lens, 34 denotes a fixation target (stimulation target) disposed at the focal position of the second relay lens 33, 35 denotes a condenser lens, and 36 denotes an illumination lamp. The fixation target 34 is, for example, a burst target on which a landscape chart or a radial line is drawn. The first relay lens 32 optically changes the presentation position (presentation distance) of the fixation target 34 by moving on the optical axis. At the time of measuring the eye refractive power, the first relay lens 32 is moved to perform adjustment removal of the eye to be examined. The change of the presentation position of the fixation target 34 may be a configuration in which the fixation target 34, the condenser lens 35, and the illumination lamp 36 are moved in the optical axis direction as a set.

  Reference numeral 40 denotes an XY index projection optical system that projects an alignment index in the XY direction from the visual axis direction onto the cornea. Reference numeral 41 denotes a point light source that emits infrared light. The light beam emitted from the point light source 41 is reflected by the beam splitter 42, then becomes a parallel light beam by the objective lens 17 via the beam splitter 31, is reflected by the beam splitter 15 a, and is reflected in front of the eye E along the measurement optical axis. Project an indicator from

  Reference numeral 80 denotes a Z index projection optical system that projects an alignment index in the Z direction onto the cornea. The Z index projection optical system 80 includes two sets of target projection optical systems 80a and 80b arranged symmetrically around the measurement optical axis L1 facing the eye E, and outside the target projection optical systems 80a and 80b. Are provided with two sets of target projection optical systems 80c and 80d arranged symmetrically about the optical axis L1. The target projection optical systems 80a and 80b are constituted by infrared point light sources 81a and 81b, and the respective projection optical axes are arranged so as to intersect at a predetermined angle with respect to the measurement optical axis L1. The target projection optical systems 80a and 80b project a target at a finite distance to the eye E to be examined. The target projection optical systems 80c and 80d are composed of infrared point light sources 81c and 81d and collimating lenses 82c and 82d, and the respective projection optical axes intersect at a predetermined angle with respect to the measurement optical axis L1. Is arranged. The target projection optical systems 80c and 80d project the target at infinity with respect to the eye E.

  Reference numeral 45 denotes an observation optical system. A to-be-examined eye image illuminated by an illumination light source (not shown) and the respective index images projected by the index projection optical systems 40 and 80 are reflected by the beam splitter 15b, and then passed through the objective lens 46 and the mirror 47 to obtain a CCD camera. 48 is imaged. The observation optical system 45 also serves as a detection optical system that detects an alignment index image projected on the eye E.

  FIG. 3 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 monitor 7. A control unit 50 includes an XYZ driving unit 6, a light receiving element 23, a switch unit 8, a motor 56 for driving the measurement light source 11 and the light receiving element 23, a motor 57 for moving the measurement target plate 13 and the lens 21, a first. A motor 58 that moves the relay lens 32, a potentiometer 60 that detects the moving position of the target plate 13, a motor 61a that rotates the cylindrical lens 37a, a motor 61b that rotates the cylindrical lens 37b, a memory 62, a sound generator 63, and the like are connected. Has been. The control unit 50 controls each of these components, calculates the eye refractive power based on detection signals from the light receiving element 23 and the potentiometer 60, and has a function of analyzing an adjustment state described later.

  The operation of the apparatus having the above configuration will be described below. First, the measurement of the refractive power for objective distance will be described. In this case, a normal distance refractive power measurement mode is selected as the measurement mode by the mode changeover switch 8a of the switch unit 8. After fixing the subject's face to the face support unit 2, the measurement optical system is aligned with the eye to be examined. Here, the case where the automatic alignment and automatic tracking modes are set will be described.

  The examiner operates the joystick 5 and the rotary knob 5a while observing the anterior segment image and the reticle N displayed on the monitor 7, and moves the moving table 3 and the measuring unit 4 in the XYZ directions to perform rough alignment. As shown in FIG. 3, when the alignment index image M1 by the XY index projection optical system 40 and the four alignment index images Ma to Md by the Z index projection optical system appear, automatic alignment and tracking are performed. . The index image M1 and the index images Ma to Md are detected and processed by the image processing unit 51. The control unit 50 determines the alignment state in the XY directions with respect to the appropriate position based on the detection result of the index image M1 located at the center of the alignment index images. Further, the control unit 50 determines the alignment state in the Z direction based on the detection results of the index images Ma to Md.

  The determination of the alignment state in the Z direction is based on the image interval between the infinity index images Mc and Md by the target projection optical systems 80c and 80d and the image interval between the finite index images Ma and Mb by the target projection optical systems 80a and 80b. This is done by comparison. In the projection of an infinite distance target, even if the working distance (Z direction) changes, the image interval (image height) hardly changes. On the other hand, in the projection of a finite distance target, the image interval (image height) changes as the working distance (Z direction) changes. By utilizing this characteristic, the alignment state in the Z direction can be determined (see Japanese Patent Laid-Open No. 6-46999).

  The control unit 50 drives and controls the XYZ driving unit 6 based on the determination result of the alignment state in each direction, and moves the measuring unit 4 in each direction. If the alignment state in each direction of XYZ falls within a predetermined allowable range, a trigger signal is automatically generated to perform measurement.

  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 34 and the fundus of the eye E in a conjugate position, a further appropriate diopter is used to remove the adjustment of the eye to be examined. The first relay lens 32 is moved so that only fog is applied. In a state where the eye E is clouded, 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. 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 controller 50 performs a predetermined process on the refractive power to obtain objective refractive power values of S (spherical refractive power), C (astigmatic power), and A (astigmatic axis angle) of the eye to be examined. The objective refractive power values S, C, A in the cloud state are stored in the memory 62.

  Next, the measurement of the adjustment tension for obtaining the adjustment function state will be described. The human eye is subjectively perceived to be in a static refractive state when staring at a stationary target, but it can be adjusted by observing objective refractive power over time. A sine wave-like vibration called fine movement is observed. It is considered that the high-frequency component of accommodation fine movement is caused by the vibration of the refractive power of the crystalline lens and indicates the activity state of the ciliary muscle. As the load on the ciliary muscle increases, the frequency of appearance of the high-frequency component of accommodation fine movement also increases. The degree of accommodation tension of the eye to be examined can be estimated by examining the appearance frequency (hereinafter referred to as HFC) of the accommodation fine movement high frequency component.

  Hereinafter, adjustment tension measurement will be described using the flowchart of FIG. For the adjustment tension measurement, a general inspection mode and a specific work distance inspection mode are prepared. Whether the measurement is performed in the general inspection mode or the specific work distance inspection mode is obtained by obtaining inquiry information for the subject and selecting the mode changeover switch 8a of the switch 8 (step 1-1).

<General inspection>
In the general inspection mode, a main measurement mode and a simple measurement mode are further provided. In this measurement mode, the position where the fixation target is presented is determined based on the position of the S value obtained by the distance power measurement in the unadjusted state (which can be regarded as the far point position of the eye to be examined). In each diopter step (in the following, every 0.5D step), it is sequentially changed to 8 points, and the temporal change in refractive power at a predetermined time T (for example, 20 seconds in the following) is sampled at each step, and the adjustment tension This is a mode for obtaining. The simple measurement mode is a mode in which the moving position of the fixation target necessary for adjustment evaluation is extracted with respect to this measurement mode, and the adjustment tension is simply calculated by reducing the number of measurement steps (moving points of the fixation target). .

  First, when the general inspection mode is selected, the distance measurement in the non-adjusted state is executed (step 2-1), and then the simple measurement mode is set first (step 2-2). ). In the simple measurement, the fixation target is moved to two locations of + 0.5D and −3.0D, for example, based on the S value of the distance measurement as the main fixation target position that gives an adjustment load to the eye to be examined. . The change in refractive power with time at time T is sampled at each fixation target position. The sampled change in refractive power with time is stored in the memory 62 in association with each moving position of the fixation target. Further, blink detection during sampling is performed based on the output signal of the light receiving element of the corneal reflection removal mask 20 placed at a conjugate position with the eye cornea to be examined. For data when blinking is detected, a check mark is added so that the data will not be used later in HFC calculation.

  In addition, the presentation position of the fixation target in the simple measurement mode can be arbitrarily set using the switches 8b and 8c of the switch unit 8. When the switch 8c is pressed, a screen for selecting a fixation target presentation position used in the simple measurement mode is displayed on the monitor 7, and the fixation target presentation position is selected on the screen by the switch 8b. By pressing the switch 8c again, the fixation target setting information is updated.

  The control unit 50 calculates the HFC based on the sampling refractive power stored in the memory 62. The calculation of HFC will be briefly described. First, the refractive power data checked by the blink detection of the eye to be examined is removed from the calculation target. Data loss and disturbance due to blinking are corrected with a cubic spline function. Next, frequency analysis is performed using fast Fourier transform (FFT) to obtain a power spectrum. The power spectrum is calculated for each section of time T (20 seconds). Each section is set to be shifted by a certain time (for example, 1 second) within the time T, and the time in each section is the same (for example, 8 seconds). The calculated power spectrum is converted into a common logarithm and analyzed. From this power spectrum, an average power spectrum (unit: dB) in a section of high frequency components of 1.0 to 2.3 Hz is obtained and evaluated as an appearance frequency (HFC) of the adjusted fine movement high frequency component.

  When the HFC is calculated, the measurement result of the adjustment tension is displayed on the monitor 7 (step 2-3). FIG. 5 is a display example of the measurement result of the adjustment tension measurement in the simple measurement mode. As the measurement result, the three elements of the fixation target (stimulus target) position, the adjustment response amount, and the HFC are graphically displayed as a three-dimensional graph using a color code map. The graph shows the adjustment response amount (refractive power D) on the vertical axis and the fixation target position on the horizontal axis. At each fixation target position, the change in the adjustment reaction amount corresponding to the elapsed time within the predetermined time T is represented by a bar graph. Has been. The HFC is color-coded in seven levels as an example. For example, when the HFC is less than 50, it is displayed in green, and when it is 70 or more, it is displayed in red, and the interval is displayed in gradation from green to yellow via yellow. An eye to be examined with less accommodation tension has a low HFC value in far vision and exhibits a green color in the color code map. On the other hand, the eye to be examined having a large amount of accommodation tension has a high HFC value as a whole, and the color code map shows a red color, indicating that the ciliary muscle is in tension.

  Next, it is determined whether or not the HFC in the simple measurement mode is higher than a predetermined value (step 2-4). The control unit 50 obtains the average of the HFCs within the time T for each of the + 0.5D and −3.0D fixation target positions, and determines the average value in seven stages of ranks 1 to 7. For example, when the HFC is rank 4 or higher (average HFC is 58 or higher), a message is displayed indicating that the eye to be examined shifts to the main measurement mode for performing detailed measurement because there is a suspicion of eye strain. (Step 2-5). Thereafter, the main measurement is performed (step 2-6). In this measurement, based on the position of the S value obtained in the distance refractive power measurement, the presenting position of the fixation target is sequentially changed to 8 positions every 0.5D step, and the refractive power at time T is changed at each step. The change over time is sampled. The temporal change of the sampled refractive power is stored in the memory 62 in association with each moving position of the fixation target, and after the HFC for each fixation target position is calculated as described above, the measurement result is displayed. (Step 2-7).

  FIG. 6 is a display example of the measurement result in this measurement mode. As in the case of the simple measurement, the three elements of the fixation target position, the adjustment reaction amount, and the HFC are graphically displayed as a three-dimensional graph using a color code map. Is done. As for the adjustment response amount, a change within the time T of each fixation target position is represented by a bar graph. In the HFC, the average value obtained for each section shifted by a fixed time (1 second) within the time T of each fixation target position is expressed in seven stages in the bar graph indicating the amount of control response. . By displaying the measurement result in such a three-dimensional graph, the examiner can objectively grasp the accommodation function state of the eye to be examined.

  However, since skill is required for decoding the three-dimensional graph, a rank display 101 indicating the degree of accommodation tension of the eye to be examined is calculated and displayed for each fixation target position. The value of the rank display 101 is determined by the control unit 50 calculating the average value of the HFC for each fixation target position and belonging to one of the seven ranks as in the above color classification. That is, one rank division is displayed for each fixation target position. In this example, the fixation target positions of 0.5D, 0.0D, -0.5D, and -1.0D are determined to be in rank "6", respectively. The fixation target positions of −1.5D, −2.0D, −2.5D, and −3.0D are determined to be in rank “7”, respectively. In the present embodiment, numerical values are used as the quantitative display of ranking, but they may be expressed by the number of star marks or the length of a bar graph. Note that this rank display 101 is also displayed in the measurement result in the simple measurement mode.

  In this measurement mode, in addition to the rank display 101 for each fixation target position, a rank display 102 for the measurement results of all fixation target positions is displayed as a comprehensive determination. As for the value of the rank display 102, the average value of HFC at all the fixation target positions is calculated, and it is determined according to which of the seven ranks it belongs. In this example, it is determined that it belongs to the rank “6”, indicating that the level of accommodation tension is high.

  Such a quantified rank display 101 or 102 improves the readability of measurement results, and can reduce errors in diagnosis such as case determination, treatment policy determination, lens prescription determination, and the like. In addition, the burden on the examiner is reduced.

  On the other hand, if the HFC is rank 3 or less (average HFC is less than 58) in step 2-4, a message indicating that the suspicion of eye strain is low is displayed (step 2-8), and the measurement is completed. The determination of whether the eye fatigue of the eye to be examined is high or low can be determined from the results of excerpting the main refractive power positions within the entire range without carrying out the full measurement. Significant shortening can be achieved. For this reason, the simple measurement mode can be used as screening.

  Note that the simple measurement mode and the main measurement mode can be individually selected by the mode selection switch 8a. If it is determined in step 2-8 that the HFC is rank 3 or lower and the measurement is to be performed after the measurement is completed, the actual measurement mode may be switched using the switch 8a.

<Specific work distance inspection>
A case where the specific working distance inspection mode is selected by the switch 8a will be described. This inspection mode is effective when inspecting a subject whose main working distance is the near working distance. First, when the subject's main and the working distance (for example, 30 cm) are set using the working distance input switch 8b of the switch unit 8 (step 3-1), the setting is made. The fixation target is moved to a position corresponding to the working distance. The set work distance is displayed in the work distance column 7a of the monitor 7. When the alignment with respect to the eye to be examined is performed and the alignment state is within an appropriate range, the adjustment tension is automatically measured (step 3-2). By causing the subject's eye to see the fixation target located at the working distance, an adjustment load is applied to the subject's eye. The change in refractive power with time at the predetermined time T is sampled in this adjusted load state, and the data is stored in the memory 62.

  When the HFC is obtained from the sampled refractive power change, the measurement result of the adjustment tension is displayed on the monitor 7 (step 3-3). The measurement result is displayed in the form of a color code map showing the amount of adjustment reaction and the HFC at the fixation target position moved to the specific working distance, as in FIGS. Then, it is determined whether or not the HFC obtained at the fixation target position of the main working distance of the subject is a high value (step 3-4). As for the determination criteria, the average value of HFC within the time T is determined in seven stages of ranks 1 to 7 as in the previous example. When the rank is 4 or higher (average HFC is 58 or higher), the HFC is considered to be high. If the HFC is rank 4 or higher, a message is displayed on the monitor 7 indicating that there is an eye strain tendency and that the prescription of the addition lens is urged (step 3-5). If the HFC is rank 3 or lower, a message that the suspicion of eye strain is low is displayed (step 3-6).

  In this way, whether or not the subject is forced to adjust tension at the main working distance, this specific working distance inspection mode can be performed without performing the full measurement of the entire range described in the previous general inspection mode. Can be evaluated by using Therefore, the inspection time can be greatly shortened, and the burden on the subject and the examiner can be reduced.

  By using the simple measurement mode and the specific working distance mode as described above, the inspection time can be shortened with respect to all the measurement modes. Further, an example of reducing the inspection time by another method is used in the flowchart of FIG. To explain.

  First, the fixation target is moved to a designated position (step 4-1), and adjustment tension measurement is executed at the fixation target position (step 4-2). During this measurement, the pupil size of the eye to be examined is detected (step 4-3). The detection of the pupil size is detected by the image processing unit 51 based on the video signal of the anterior segment image from the CCD camera 48. Next, it is determined whether or not the pupil size has changed significantly with respect to the initial distance measurement or the previous adjustment tension measurement (step 4-4). If the amount of change in the pupil size is small (for example, within a variation of 1.0 mm), then the difference ΔD between the converted refractive power at the fixation target position and the detected refractive power is a predetermined allowable range ( For example, it is determined whether it is within 1.5D (step 4-5). When ΔD exceeds the permissible range, it indicates that the adjustment force of the eye to be examined is not following even if the fixation target position is moved further closer (or the eye to be examined has failed to adjust) . In this case, it can be determined that the adjustment tension state is unlikely to change. Therefore, when ΔD exceeds the allowable range, the measurement result is displayed at this time and the measurement is finished (step 4-7). This eliminates unnecessary measurement and shortens the inspection time. If ΔD is within the allowable range, the fixation target is moved to the next position and measurement is continued depending on whether or not the fixation target movement is completed (step 4-6). In the case of the main measurement mode in the above example, there are eight fixation targets.

  Here, when the fixation target is moved in the vicinity, a pupil size change, that is, a miosis may occur in the eye to be examined. If a noticeable miosis is recognized in step 4-4, it is determined that the depth of focus has increased and a factor for improving the refractive power has occurred, so the determination condition for the end of measurement in step 4-5 is changed (step 4). 4-8). For example, the allowable range is expanded from 1.5D to 2.5D.

  In addition to the above, the determination of the tracking state of the adjustment force is in the negative direction with respect to the refractive power at the current step (current fixation target position) compared to the refractive power at the previous step (previous fixation target position). It is good also as a condition whether it exists in. Alternatively, both may be used.

  If the determination in step 4-5 indicates that ΔD exceeds the allowable range, the HFC is calculated as in the simple measurement mode of the previous example, and whether the measurement is completed based on the result of the HFC. You may attach the condition of no. That is, if the HFC is a high value (rank 4 or higher), the measurement is continued. If the HFC is a low value (rank 3 or lower), the measurement is terminated. This is because even when the adjustment force of the eye to be examined does not follow the movement of the fixation target, adjustment tension may appear as the fixation target moves in the near direction.

  In the adjustment tension as described above, the predetermined time T for sampling the change in refractive power with time is not limited to the illustrated 20 seconds, and may be changed according to the amount of data necessary to analyze the HFC. For example, when the target of the high frequency component of the adjustment fine movement is 0.5 Hz or more, if sampling is performed for about 10 seconds, data of 5 cycles or more can be obtained and can be sufficiently analyzed. By shortening the predetermined time T, the entire measurement time can be greatly shortened. The switching of the predetermined time T can be changed to T = 20 seconds and 10 seconds by pressing the switch 8c and calling the switching screen of the predetermined time T on the monitor 7, and is thus changed using the switch 8b. Of course, the number and range that can be changed may be increased.

  Further, if the detection interval of the change in refractive power with time can be changed, it can be matched with the analysis target of the high-frequency component of the adjustment fine movement. For example, when high frequency components up to 2.3 Hz are targeted, if sampling is performed at an interval of about 80 msec, detection is performed five times during one cycle of 2.3 Hz, so that analysis of HFC becomes possible. . When analyzing a higher frequency component, it is preferable to sample the refractive power at shorter intervals. In detecting the change in refractive power over time, this apparatus can measure the change in refractive power at each position where the fixation target is moved in one meridian direction, and can measure at intervals of 20 msec. When importance is attached to the measurement accuracy, the refractive power measurement interval is switched to 20 msec. If it is set to 20 msec, high frequency components up to 10 Hz can be detected. The measurement interval is switched by pressing the switch 8c to call the switching screen on the monitor 7, and then using the switch 8b to set a desired measurement cycle between 80 and 20 msec. However, if the measurement interval is shortened, the amount of data increases, and it takes time for data transfer and data processing. Therefore, when the overall measurement time is important, the interval may be changed to a larger interval.

  Here, the method of measuring the refractive power change in one meridian direction as described above is that when there is astigmatism in the eye to be examined, an error occurs in the detection of the refractive power in the fixed meridian direction due to eye fixation fine movement or rotation. This causes a measurement error. Therefore, a measurement method for reducing this measurement error will be described using the flowchart of FIG.

  First, after moving the fixation target to a designated position (step 5-1), the refractive power is measured in all directions (step 5-2). The presence or absence of astigmatism is determined by this measurement (step 5-3), and when there is astigmatism, the measurement meridian direction is set to the strong main meridian direction or the weak main meridian direction of astigmatism (step 5-4). When the refractive power is measured in the meridian direction deviated by 45 ° from the strong main meridian direction or the weak main meridian direction, the angular deviation due to fixation fine movement or eye rotation tends to greatly change the detection of the refractive power. On the other hand, if the measurement meridian direction is the strong main meridian direction or the weak main meridian direction of astigmatism, the influence on the refractive power detection is small, and the measurement error can be suppressed to a small value. The adjustment tension measurement for detecting the refractive power change at the time T in the set measurement meridian direction is executed (step 5-5) and repeated until the adjustment tension measurement at all fixation target positions is completed (step 5-6). .

  Astigmatism detection may use the result of the first refracting power test in the unadjusted state. However, since there is an eye to be examined in which the axis angle of astigmatism changes by changing the adjustment load, it is preferable to fixate. Every time the target position is moved, the refracting power is measured in all directions, and after adjusting the meridian direction, the adjustment tension is measured. When there is no astigmatism in the eye to be examined, the measurement meridian direction is set to the horizontal direction (0 ° direction) (step 5-7).

  In addition, when there is astigmatism at each position where the measurement result of the first distance measurement or the fixation target is moved, the cylindrical lenses 37a and 37b are rotated by the motors 61a and 61b, and the C value and the A value of the measurement result are obtained. Astigmatism power to be corrected is created. By correcting the astigmatism state of the eye to be examined, the eye to be examined can stably see the fixation target 34 regardless of the axis angle, and the influence of the astigmatism on the measurement result is reduced.

  When executing the adjustment tension measurement as described above, it is convenient to set the automatic tracking mode in addition to the automatic alignment mode. In particular, since the inspection time is as long as about 3 minutes in this measurement mode, it is advantageous to use the automatic tracking mode. In the automatic tracking mode, as in the distance refractive power measurement described above, the alignment index image M1 by the index projection optical system 40 and the four alignment index images Ma to Md by the Z index projection optical system are image processing units 51. And the alignment state is determined based on the detection result. Then, the measuring unit 4 is moved by controlling the XYZ driving unit 6 so that the alignment state in each direction falls within a predetermined allowable range (appropriate range), and the optical system of the measuring unit 4 is moved by the movement of the eye to be examined. Auto-tracking.

  If the eye to be examined moves during measurement for a predetermined time T during which the change in refractive power over time is detected, and the alignment state is out of the allowable range, the refractive power data sampled during that time is excluded from the HFC calculation target. In order to eliminate the data loss at the predetermined time T, the control unit 50 measures the time when the refractive power data is excluded, and measures until the total time when the alignment is in an appropriate state reaches the predetermined time T. It may be continued. By doing this, it is possible to obtain a measurement result with reduced measurement error by excluding refracting power data with low reliability. Further, blinking of the eye to be examined during measurement can also be detected from the detection results of the alignment index images M1, Ma to Md. If there is blinking in the eyes, the index images M1, Ma to Md are not detected as prescribed. In this case, it is detected that there is blinking. Even when blinking is detected, the sampled refractive power data is excluded from the calculation target of the HFC.

  When the fixation target is moved to the next designated position, a 5-second break is taken. At this time, the subject blinks and has his eyes rested, but the subject may remove his face from the face support unit 2 or move his eyes greatly. May be controlled to stop automatic tracking. By so doing, it is possible to reduce malfunctions caused by unnecessary movements of the measurement unit 4.

  Further, by the operation of the automatic tracking mechanism, the sound generator 63 intermittently has a continuous sound or a short period during the predetermined time T in which the alignment state is in an appropriate range and the change in refractive power with time is measured. A sound is generated to inform the examiner and the subject that the measurement is in progress. During the 5-second break when the fixation target is changed to the next position, the sound from the sound generator 63 is emitted or a sound different from that during measurement is emitted, and this is notified to the examiner and the subject. The If the alignment state is out of the proper range due to a large movement of the eye to be examined, or if the measurement of the change in refractive power over time is not performed normally, this can be known by sound. The examiner can perform the inspection smoothly.

It is an external view of the eye accommodation function measuring device concerning the present invention. It is a schematic block diagram of an optical system. It is a schematic block diagram of a control system. It is a flowchart figure explaining adjustment tension measurement. It is an example of a display of the measurement result in simple measurement mode. It is an example of a display of the measurement result in this measurement mode. It is a flowchart figure explaining another example for aiming at shortening of inspection time. It is a flowchart figure explaining the measuring method for reducing the measurement error when there is astigmatism in the eye to be examined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Measurement part 6 XYZ drive part 7 Monitor 8 Switch part 10 Eye refractive power measurement optical system 23 Light receiving element 30 Fixation target presentation optical system 40 XY index | projection optical system 48 CCD camera 50 Control part 51 Image processing part 62 Memory 63 Sound generation 80 Z index projection optical system

Claims (3)

The fixation target presenting means capable of changing the fixation position of the fixation target to be displayed on the eye to be examined in the distance direction, and the fixation target are sequentially moved by a predetermined diopter, and each movement position of the fixation target is detected. And a refractive power detection optical system that detects a change in refractive power over time within a predetermined time at a predetermined measurement interval, and based on a temporal change in refractive power within a predetermined time when the fixation target is stopped at each moving position. Alignment detection for detecting an alignment state of the refractive power detection optical system with respect to an eye to be examined in an eye accommodation function measuring device that obtains an appearance frequency of a high-frequency component indicating a fine movement of ciliary muscles and obtains an adjustment function state of the eye to be examined. tracking means, the time course of the refractive power at each moving position of the fixation target during detection at predetermined measurement intervals, the power detection optical system in the movement of the subject's eye so that the alignment state has a predetermined proper state Auto-tracking means to let you Based on the detection result of the alignment detection means, alignment state in each moving position of the fixation target excludes power detection result detected at a predetermined measurement interval while deviated from predetermined appropriate state, the fixation target An eye adjustment function measuring apparatus, comprising: an arithmetic means for obtaining an appearance frequency of a high-frequency component of adjustment fine movement at each movement position . The eye accommodation function measuring device according to claim 1 further comprises astigmatism detection means for obtaining an astigmatism state of the eye to be examined based on a detection result of the refractive power detection optical system, and a refraction for obtaining an accommodation function state of the eye to be examined. The eye accommodation function measuring apparatus according to claim 1, wherein the force data is a refractive power in a strong main meridian direction or a weak main meridian direction of astigmatism based on a detection result of the astigmatism detection unit. 2. The eye accommodation function measuring apparatus according to claim 1, wherein the computing means further comprises determination means for judging which of a plurality of ranks the appearance frequency of the accommodation fine movement high frequency component belongs to.

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