JP3942429B2 - Contrast sensitivity measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a contrast sensitivity measuring apparatus suitable for use in a visual acuity test using a contrast chart. More specifically, the present invention relates to a contrast sensitivity measuring apparatus and a measuring method suitable for accurately determining the aberration of the eyeball of a subject, such as improvement of visual acuity by eyeglasses or contact lenses during laser eye surgery.
[0002]
[Prior art]
Recently, an ophthalmic operation in which the cornea or the like is deformed with a laser has been attempted, and in that case, it is important to accurately measure the aberration of the eye. Visual function tests are performed before and after corneal surgery and cataract surgery. Here, visual function tests include visual acuity measurement, low contrast visual acuity measurement (also referred to as contrast visual acuity measurement), and contrast sensitivity measurement (also referred to as contrast sensitivity measurement).
[0003]
Here, the general visual acuity test using the standard visual acuity chart tests visual acuity for a fine object with a high contrast ratio. Therefore, for example, in a cataract patient, the turbidity of the lens causes light scattering and decreases the contrast of the image on the fundus, but does not affect the deviation of the optical focal position of the image. As a result, the image on the fundus is blurred, but it may be read as text by an optometer who is a cataract patient. In addition, when spherical aberration is caused by optical distortion of the cornea and the crystalline lens, the image on the fundus is blurred, but it may be read as characters by the eye examiner.
[0004]
On the other hand, the contrast sensitivity indicating the ability to detect whether or not a specific object is present with the minimum contrast is important in showing the visual ability of the subject in daily life and social life. Therefore, in the measurement of contrast sensitivity, sinusoidal lattice fringes are used to examine a single spatial frequency characteristic. The sine wave lattice fringe is a fringe pattern whose density changes in a sine wave manner. Contrast sensitivity measures the minimum contrast required to recognize a stripe pattern at various finenesses (spatial frequencies).
[0005]
[Problems to be solved by the invention]
However, since the subject (patient) reads the visual acuity chart according to the instruction of the inspector, the contrast sensitivity has the following problems.
(1) Since inspection is performed using a single visual acuity chart, the subject often memorizes the visual acuity chart in repeated inspections. For example, when the left eye is inspected after the right eye, if the right eye is better, even if it is not visible with the left eye, it can be answered correctly by memory, and it is difficult to accurately measure the contrast sensitivity of the subject.
{Circle around (2)} Contrast sensitivity measurement takes about 10 minutes, for example, and a clinical laboratory technician or doctor must concentrate on the inspection work during that time. Therefore, there is a problem that the medical examination time and the examination time become long.
(3) For contrast sensitivity measurement, it is desirable that the diameter of the pupil area of the subject or the area of the pupil area be constant. However, since the diameter of the pupil area or the area of the pupil area changes depending on the degree of fatigue of the subject and differs from the theoretical diameter or / and area of the pupil area, contrast sensitivity measurement is not possible. Can't be accurate.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to provide a contrast sensitivity measuring apparatus and a measuring method that can accurately measure the contrast sensitivity of a subject and that requires a short examination time. To do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a contrast sensitivity measuring apparatus according to the present invention includes, for example, as shown in FIG. 1, a contrast target presentation unit 100 that displays a first and a second contrast target side by side, and a subject's subject. A pupil data measurement unit 200 that forms an anterior eye image and measures the diameter or / and area of the pupil area of the subject, and a contrast target presenting unit 100 displays the first and second contrast targets. A measurement timing formation unit 300 that forms the measurement timing of the pupil data measurement unit 200 based on the presentation timing is provided. Here, “the diameter or / and area of the pupil region” corresponds to pupil data, and specifically refers to one or both of the diameter and area of the pupil region.
[0008]
In the apparatus configured as described above, the contrast target presenting unit 100 presents the first and second contrast targets side by side, so that the first and second contrast targets including information effective for measurement are displayed. The contrast target can be selected freely. Therefore, the memory immediately before the placement of the contrast target of the subject is useless, and accurate contrast sensitivity can be measured based on the placement of the contrast target visually recognized by the subject. Since the pupil data measurement unit 200 measures one or both of the diameter and area of the pupil area of the subject, the diameter or / and area of the pupil area of the subject is made constant. In contrast, the contrast target presenting unit 100 can cope with this, and the degree of freedom of the measurement environment is increased. The measurement timing forming unit 300 automates the measurement and facilitates the operation for the laboratory technician or doctor.
[0009]
Preferably, one of the first and second contrast targets is a target with zero contrast, and the other is a target having contrast for measuring contrast sensitivity. In this case, the first and second contrast targets may have a brightness different from the brightness of the background portion or may be the same. The contrast target effective for measuring the contrast sensitivity is preferably one of the first and second contrast targets.
[0010]
In order to achieve the above object, a contrast sensitivity measuring apparatus according to the present invention includes, for example, as shown in FIG. 1, a contrast target presenting unit 100 that randomly presents a contrast target at one of at least two positions. A pupil data measurement unit 200 that forms an image of the anterior eye portion of the subject and measures the diameter or / and area of the pupil area of the subject, and a contrast target display unit 100 presents the contrast target. A measurement timing formation unit 300 that forms the measurement timing of the pupil data measurement unit 200 based on the timing is provided.
[0011]
Preferably, the contrast target presenting unit 100 includes a target brightness adjustment unit 125 that adjusts the brightness of the contrast target, and the diameter or / and area of the pupil area of the subject measured by the pupil data measurement unit 200. Visual target lightness control means 120 that inputs the lightness control signal to the visual lightness adjustment means 125 so that the diameter or / and area of the pupil region becomes a predetermined value. If comprised in this way, the brightness of a contrast visual target can be adjusted, the diameter or / and area of a pupil area | region of a subject can be made constant, and exact contrast sensitivity can be measured.
[0012]
Preferably, the contrast target presenting unit 100 inputs the background illumination adjusting means 145 for adjusting the background illumination of the contrast target, and the diameter or / and area of the pupil area of the subject measured by the pupil data measuring unit 200. And a background illumination control unit 140 that sends a background illumination control signal to the background illumination adjustment unit 145 so that the diameter or / and area of the pupil region becomes a predetermined value. If comprised in this way, the background illumination of a contrast visual target can be adjusted, the diameter or / and area of a pupil area | region of a subject can be made constant, and exact contrast sensitivity can be measured.
[0013]
Preferably, for example, as shown in FIG. 1, the contrast target presenting unit 100 is configured to maintain at least the brightness of the contrast target or the illuminance of the background illumination so as to keep the retinal illuminance of the subject at a substantially predetermined value. Lightness / illuminance adjusting means (120, 140) for adjusting one of them is provided. Even in environments with significantly different brightness, such as daytime and nighttime, maintaining the subject's retinal illuminance at a substantially predetermined value makes it possible to make the environment for measuring the contrast sensitivity constant and provide accurate contrast. Sensitivity can be measured.
[0014]
Preferably, the pupil data measurement unit 200 forms an image of the anterior eye segment 401 of the subject before and at the time of measuring the contrast sensitivity, and measures the diameter or / and area of the pupil area of the subject. It is configured. With this configuration, it is easy to deal with the contrast visual target presenting unit 100 side so as to make the diameter or / and area of the pupil area of the subject constant, for example, when the adjustment amount is excessive or too small If so, the amount to be adjusted next time can be easily determined.
[0015]
Preferably, the pupil data measurement unit 200 measures the diameter or / and area of the subject's pupil area measured at the timing when the contrast target is presented or when the subject responds. It is configured. For the response timing of the subject, for example, the timing at which the response from the subject response device 310 such as a mouse is received or the timing at which the verbal response of the subject is received is input by the laboratory technician.
[0016]
Preferably, for example, as shown in FIG. 1, the diameter or / and area of the pupil region of the subject measured by the anterior segment illumination unit 500 that illuminates the anterior segment and the pupil data measurement unit 200 are input. In addition, an anterior ocular segment illumination control unit 510 that transmits an illumination control signal to the anterior ocular segment illumination unit 500 is provided so that the diameter or / and area of the pupil region becomes a predetermined value. If comprised in this way, the anterior eye part illumination part 500 can be adjusted, the diameter or / and area of a pupil area | region of a subject can be made constant, and exact contrast sensitivity can be measured.
[0017]
Preferably, for example, as shown in FIG. 9, a luminance measurement unit 160 that measures the luminance of the presentation target of the contrast target presentation unit 100 and the luminance of the contrast target based on the luminance measured by the luminance measurement unit 160 And a luminance calibration unit 162 for calibrating. For example, the luminance calibration unit 162 may be configured to perform calibration by sending a calibration signal to the visual target brightness adjusting unit 125 of the contrast visual target presenting unit 100.
[0018]
Preferably, for example, as shown in FIG. 9, the retinal illuminance calculation means 550 for calculating the retinal illuminance of the subject eye from the diameter or / and area of the pupil region of the subject eye and the brightness of the contrast target, Retinal illuminance adjustment means 560 for outputting an adjustment signal so that the retinal illuminance of the eye to be examined becomes a substantially constant value, and is configured to perform contrast sensitivity measurement in a state where the retinal illuminance of the eye to be examined has a substantially constant value. ing. The retinal illuminance adjustment unit 560 outputs, for example, a contrast target brightness adjustment signal to the visual target brightness adjustment unit 125, and the background control brightness adjustment signal of the contrast target to the background illumination adjustment unit 145. Or an adjustment signal of the brightness of the anterior eye illumination unit 500 may be output to the anterior eye illumination control means 510.
[0019]
In order to achieve the above object, the contrast sensitivity measuring method according to the present invention presents two contrast targets side by side as shown in FIG. 1, for example, and at least one contrast target is useful for contrast sensitivity inspection. Present as a visual target; generate a measurement timing signal for measuring the diameter or / and area of the pupil area of the subject based on the timing of presenting the two contrast visual targets; Forming an image of the anterior segment of the examiner and measuring the diameter or / and area of the pupil area of the subject.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol or a similar code | symbol is attached | subjected to the mutually same or equivalent member, and the overlapping description is abbreviate | omitted. FIG. 1 is a block diagram for explaining the first and second embodiments of the present invention, in which an optical system and a control system are shown in the same drawing. In the figure, the contrast target presenting unit 100 includes a first illumination optical system 110, a test target display control unit 120, a second illumination optical system 130, and a pedestal target display control unit 140.
[0021]
The first illumination optical system 110 mainly forms a test target such as a contrast target, and includes a light source 111, a condenser lens 112, a target replacement rotating motor 113, a target plate 114, an ND filter 115, and a magnification correction lens. 116 and a diffusion plate 117. The condenser lens 112 turns the light emitted from the light source 111 into a parallel light flux. On the optotype plate 114, as a contrast optotype, a test target for contrast sensitivity suitable for measurement of spatial frequency characteristics such as Gabor stimulation is printed with various characters in a predetermined size. In the contrast sensitivity target, a striped pattern having a spatial frequency of 1.5, 3, 6, 12, 18 [cycles / deg] at a viewing distance of 3 m is drawn.
[0022]
An ND (Neutral Density) filter 115 is a filter that changes only the amount of light such as 60% transmission or 40% transmission, and does not perform polarization or the like. The magnification correction lens 116 has a focal length such as infinity (0 diopter) or 5 meters (0.2 diopter), and is adjusted to replace the magnification correction lens 116 to present a test target to the subject. is doing. The diffusion plate 117 diffuses the light emitted from the condenser lens 112 to make the light quantity distribution uniform.
[0023]
The test target display control unit 120 drives the target replacement rotating motor 113 to stop the target plate 114 at an appropriate position, and performs control so that an appropriate test target can be presented to the subject. . Further, the test target display control unit 120 also functions as a target brightness control unit that sends a brightness control signal to the target brightness adjustment unit 125, and the pupil area of the subject measured by the pupil data measurement unit 200. A diameter (pupil diameter) is input, and a control signal for adjusting the brightness of the contrast visual target so that the pupil diameter becomes a predetermined value is output. The target brightness adjustment unit 125 adjusts the brightness of the contrast target. For example, the power of the light source 111 is adjusted or the ND filter 115 that adjusts the light transmission amount is replaced. .
[0024]
The second illumination optical system 130 mainly forms a background such as a pedestal target, and includes a light source 131, a condenser lens 132, a target replacement rotating motor 133, a target plate 134, an ND filter 135, and a magnification correction lens 136. And a diffusion plate 137. The second illumination optical system 130 is composed of optical parts that are substantially the same as those of the first illumination optical system 110, but is different in that the target printed on the target plate 134 is the background. In the contrast sensitivity target, a test target with a predetermined spatial frequency and a predetermined contrast is printed, so the brightness of the background is adjusted so that the brightness is almost the same between different test targets. Printed accordingly. Here, the contrast is given as a difference between the transmittance of the pedestal target and the transmittance of the test target. Further, instead of 100% transmission, for example, white noise or filtered band-limited noise stimulation may be used for the pedestal target.
[0025]
The pedestal target display control unit 140 drives the target replacement rotating motor 133 to stop the target plate 134 at an appropriate position, and displays a pedestal target having a contrast or brightness corresponding to the test target. It is controlled so that it can be presented. Further, the pedestal target display control unit 140 also functions as a background illumination control unit, and inputs the pupil diameter of the subject measured by the pupil data measurement unit 200 so that the pupil diameter becomes a predetermined value. A background illumination control signal is sent to the background illumination adjusting means 145. The background illumination adjusting unit 145 adjusts the background illumination of the contrast target. For example, the power is adjusted to adjust the light amount of the light source 131 and the ND filter 135 that adjusts the light transmission amount is replaced.
[0026]
The test target (contrast target) sent from the first illumination optical system 110 and the pedestal target (background illumination) sent from the second illumination optical system 130 are superimposed on the same optical path by the mirror 151, and the first mirror Is reflected by the concave mirror 153 as the second mirror, reflected again by the spectral mirror 152, and sent to the anterior eye portion 401 of the subject. The mirror 151 may be, for example, a half mirror, and the ratio between the transmittance and the reflectance may be determined according to the amount of light required by the light sources 111 and 131. By appropriately determining the ratio between the transmittance and the reflectance of the mirror 151, the energy efficiency is increased as compared with the case where light is constantly attenuated by the ND filters 115 and 135.
[0027]
The pupil data measurement unit 200 includes a light receiving element 201, a light receiving camera lens system 202, and a pupil diameter measurement calculation unit 220. Since the optical system related to the visual target uses a visible wavelength, the pupil data measurement unit 200 may use near infrared light, or may use visible light having a wavelength different from that of the test visual target. As the light receiving element 201, for example, an element capable of receiving a planar image such as a charge-coupled device (CCD) is used. The light receiving camera lens system 202 adjusts the magnification so that a pupil image can be projected onto the light receiving element 201 at an optimum magnification. The pupil image included in the image of the anterior segment 401 of the subject received by the light receiving element 201 may be both eyes or one eye. The pupil diameter measurement calculation unit 220 performs image processing and image recognition on the image of the anterior segment 401 received by the light receiving element 201, and outputs the pupil diameter in real time.
[0028]
The central processing unit 300 as the measurement timing forming unit is based on the timing when the contrast visual target presenting unit 100 presents the contrast visual target to the anterior eye portion 401 of the subject or the timing when the subject responds. A timing signal for measuring the pupil diameter of the subject by the pupil data measuring unit 200 is generated. Further, the central processing unit 300 has a function of combining and processing the contrast and visual acuity information presented by the contrast visual target presenting unit 100 and the pupil diameter information of the subject by the pupil data measuring unit 200. The subject response device 310 inputs a response to the subject's contrast target, and for example, an I / O device such as a mouse is used. The output signal of the subject response device 310 is input to the central processing unit 300.
[0029]
The subject's eye 400 to be examined has an anterior eye portion 401 such as cornea and a crystalline lens 402 as is anatomically known. The anterior segment illumination unit 500 illuminates the anterior segment 401, and for example, a fluorescent lamp, a white light bulb, an LED, or the like is used. The anterior segment illumination control means 510 receives the pupil diameter of the subject measured by the pupil data measurement unit 200 and sends an illumination control signal to the anterior segment illumination unit 500 so that the pupil diameter becomes a predetermined value. Thus, for example, the current and voltage supplied to the anterior segment illumination unit 500 are controlled to control the brightness of the anterior segment illumination unit 500.
[0030]
2A and 2B are explanatory diagrams of contrast using a contrast sensitivity target. FIG. 2A is a plan view of Gabor stimulation projected on the anterior eye portion of the subject, and FIG. 2B is a plan view B of FIG. A contrast chart luminance profile in the -B direction is shown. The peak interval d of the luminance profile corresponds to the spatial frequency. When the contrast is 100%, the test target TM using Gabor stimulation is used. ₁₀₀ The brightness amplitude of the pedestal target PM ₁₀₀ The luminance of the minimum value of Gabor stimulation is about 0.08. On the other hand, when the contrast is 50%, the test target TM using Gabor stimulation ₅₀ The luminance amplitude of the test target TM ₁₀₀ Pedestal target PM because it is smaller ₅₀ The luminance of is the lowest value of Gabor stimulation is about 0.28.
[0031]
That is, in the Gabor stimulus plan view, the luminance amplitude of the test target differs according to the contrast, so the pedestal target having the transmittance according to the luminance amplitude of the Gabor stimulus is selected and the brightness of the target for contrast sensitivity is selected. Need to be equal. Therefore, the central processing unit 300 drives the target replacement rotating motors 113 and 133 to make the target plates 114 and 134 an appropriate combination. The brightness of the contrast sensitivity targets may be made equal by appropriately adjusting the light amounts of the light sources 111 and 131 or the transmittances of the ND filters 115 and 135 by the central processing unit 300.
[0032]
FIG. 3 is a flowchart for explaining the first embodiment of the present invention, in which the brightness of the test target is adjusted so that the pupil diameter of the subject becomes a predetermined value. When the measurement of contrast sensitivity is started (S100), the central processing unit 300 takes in measurement basic data (S102). The measurement basic data includes the subject's visual acuity information, pupil wavefront data, cataract, optic nerve damage information, and the spatial frequency of the contrast sensitivity target presented this time. Next, an image of the anterior eye 401 of the subject is formed by the pupil data measuring unit 200, and the pupil diameter of the subject is measured (S104). The pedestal target display control unit 140 adjusts the background illuminance according to the pupil diameter of the subject, and sets the test target presentation conditions (S106). Note that the test target display control unit 120 may adjust the brightness of the test target according to the pupil diameter of the subject to set the test target presentation condition. Then, an image of the anterior eye 401 of the subject is formed by the pupil data measuring unit 200, the pupil diameter of the subject is measured (S107), and the pupil diameter of the subject matches a predetermined value. Judgment is made (S108), and if they do not match, the process returns to S106. If the pupil diameter of the subject matches the predetermined value, the test target display control unit 120 presents a contrast sensitivity target as a test target (S110).
[0033]
For the presentation of the contrast sensitivity target, for example, the up / down method is used. The up / down method is a kind of psychological measurement method. The stimulus presentation is a forced selection method in which a contrast visual target and a contrast neglected target are presented once in one trial, and the subject answers the position where the Gabor stimulus is located. It is. In one presentation of the contrast sensitivity target, the background is first presented to the subject, then the Gabor stimulus is presented, and the subject's response is stored. Then, the central processing unit 300 presents Gabor stimulation to the subject until the end of the measurement. In addition, there are a limit method, an adjustment method, a constant method, PEST, QUEST, and the like as a presentation method that replaces the up / down method. An example of the target presentation is shown in FIG. FIG. 4A shows a target with a large contrast on the left side and a contrast neglected target on the right side. FIG. 4B shows a target with a large contrast on the right side and a contrast neglected target on the left side.
[0034]
Next, the subject responds to the presented contrast sensitivity target (S112). When the contrast sensitivity target is presented in the up-and-down method, because the stimulus presentation in the up-and-down method is a two alternative forced choice method (2 AFC method), Respond. The response of the subject may be a subject response device such as a mouse or may be a voice. The inspection engineer or the central processing unit 300 compares the test target presentation in the test target display control unit 120 with the subject's response to determine whether the subject's response is appropriate (S114). The central processing unit 300 stores the contrast sensitivity target presentation conditions, the appropriateness of response, the pupil diameter of the subject, and the like (S116). Then, the inspection engineer or the central processing unit 300 reaches the end criterion, for example, the switching from the correct answer to the incorrect answer and the switching from the incorrect answer to the correct answer as shown in FIG. If it is not completed, the test target presentation condition is changed (S120), and the process returns to S104.
[0035]
If the number of test target presentations has reached the end reference value, it is determined whether the test for the spatial frequency of the predetermined contrast sensitivity target has been completed (S122). Continue measuring spatial frequency. If the inspection for the predetermined spatial frequency is completed, the response data is processed (S124), and the measurement result is displayed (S126). Next, it is determined whether there is a spatial frequency of another contrast sensitivity target to be measured or a response history, and it is determined whether the measurement has been completed (S128). Continue measuring or re-inspect. If the measurement is completed, the contrast sensitivity measurement of the subject is completed. In addition, clinical presentation time of the contrast sensitivity target for one time is, for example, 1 to 3 seconds, and particularly preferably 2 seconds.
[0036]
FIG. 5 is a diagram showing an example of contrast change by the up-and-down method of FIG. 3, with the vertical axis representing contrast and the horizontal axis representing the number of stimulations. Starting with a contrast of 100% (assuming 1), every time the subject answers correctly, the contrast of the stimulus is decreased in steps of 0.1 in logarithmic steps. Increase contrast. For example, the measurement ends when an incorrect answer occurs five times in the upper and lower directions. The contrast threshold value of the subject in this case is, for example, an average value of 10 times of the contrast threshold value that is incorrect, for example, 0.06 (= 10 ^-1.2 ) The contrast sensitivity is the reciprocal of the contrast threshold obtained for the subject.
[0037]
In addition, the results obtained by the contrast measurement by the up-and-down method are rearranged into about five levels at the contrast level, and then the average value s of the contrast threshold value is obtained by probit analysis which is one of the statistical analysis methods. ₀ And the variance σ can be obtained.
[0038]
FIG. 6 is a diagram showing an example of a response history of a subject with respect to contrast sensitivity targets having different spatial frequencies, where (A) is 3 cpd ([cycles / deg]), (B) is 6 cpd, and (C) is 12 cpd. , (D) shows the case of an 18 cpd striped pattern. The response history of the subject with respect to each spatial frequency has a pattern generally similar to the contrast measurement of FIG.
[0039]
FIG. 7 is a diagram showing the relationship between contrast sensitivity and spatial frequency. A contrast threshold value for each spatial frequency is obtained from the response history of the subject with respect to different spatial frequencies. Therefore, the central processing unit 300 calculates the contrast sensitivity by taking the inverse of the contrast threshold. In general, the contrast sensitivity of a subject takes a maximum value at a spatial frequency of 3 to 6 cpd, and tends to gradually decrease when the spatial frequency increases to 10 cpd or more. Compared with the standard pattern for contrast sensitivity spatial frequency, if there are abnormal values at some of the spatial frequencies, there may be a pathological abnormality in the subject's pupil or optic nerve. Is suitable for ophthalmic examination.
[0040]
FIG. 8 is a flowchart for explaining the second embodiment of the present invention, in which the brightness of the anterior ocular segment illumination unit is adjusted so that the pupil diameter of the subject becomes a predetermined value. S200 to S204 correspond to S100 to S104 in FIG. In S206, the anterior ocular segment illumination control means 510 sends an illumination control signal according to the pupil diameter of the subject, and adjusts the illuminance of the anterior ocular segment 401 by the anterior ocular segment illumination unit 500. Then, the pupil data measurement unit 200 forms an image of the anterior eye portion of the subject, measures the pupil diameter of the subject (S207), and determines whether the pupil diameter of the subject matches a predetermined value. If it does not match, the process returns to S206. If the pupil diameter of the subject matches the predetermined value, the test target display control unit 120 presents a contrast sensitivity target as the test target (S210). Note that S210 to S230 correspond to S110 to S130 of FIG.
[0041]
FIG. 9 is a block diagram for explaining the third and fourth embodiments of the present invention, in which the optical system and the control system are shown in the same drawing. 9 that have the same functions as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. In the figure, the luminance measuring unit 160 measures the luminance of the target of the contrast target presenting unit 100, and uses, for example, a power meter in which an illuminance meter and a visibility filter are omitted. The numerical value measured by the illuminometer is cd (candela), and the luminance of the presentation target is [cd / m. ² ]. The installation location of the illuminometer is, for example, an optical path between the light receiving camera lens system 202 and the anterior eye portion 401. For example, when a CRT monitor or a liquid crystal display device is used as the display device for the contrast target, the luminance of the CRT monitor can be substantially measured by measuring the illuminance because the illuminance is almost proportional to the luminance. The luminance calibration unit 162 calibrates the luminance of the contrast target based on the luminance measured by the luminance measurement unit 160. The influence by the secular change of the contrast target presenting unit 100 is removed by the calibration by the luminance calibration unit 162.
[0042]
The retinal illuminance calculation means 550 includes the diameter or more preferably the area of the pupil area of the subject eye measured by the pupil data measuring unit 200 for the retinal illuminance of the subject eye, and the contrast target presented by the test target display control unit 120. The brightness is calculated from the brightness, especially the brightness. The area of the pupil area is A [mm ² ], The luminance of the target is L [cd / m ² ], The retinal illuminance T is determined by the following equation.
T = A / L (1)
Here, the unit of the retinal illuminance T is Troland (troland).
[0043]
The retinal illuminance adjustment unit 560 outputs an adjustment signal so that the retinal illuminance of the eye to be examined becomes a substantially constant value. The background illumination brightness adjustment signal of the contrast target is output to the background illumination adjustment unit 145, or the brightness adjustment signal of the anterior segment illumination unit 500 is output to the anterior segment illumination control unit 510. To do. This is because the contrast sensitivity changes depending on the retinal illuminance of the eye to be examined (for example, the contrast sensitivity changes between daytime and morning and evening), so it is desirable to make the retinal illuminance of the eye to be constant.
[0044]
FIG. 10 is a flowchart for explaining the third embodiment of the present invention, and illustrates a case where the brightness is adjusted so that the retinal illuminance of the subject becomes a predetermined value. S300 to S304 correspond to S100 to S104 in FIG. In S306, the retinal illuminance calculation means 550 calculates the retinal illuminance of the subject. Then, the retinal illuminance adjusting means 560 outputs an adjustment signal to the visual target brightness adjusting means 125, the background illumination adjusting means 145, or the anterior eye illumination control means 510 so that the retinal illuminance of the eye to be examined becomes a substantially constant value. Note that S310 to S330 correspond to S110 to S130 of FIG.
[0045]
FIG. 11 is a flow chart for explaining the fourth embodiment of the present invention. When the contrast sensitivity is measured with the brightness of the uniform contrast target, the pupil diameter of the subject is measured, and the predetermined pupil diameter is measured. The case of converting to contrast sensitivity is described. S400 to S404 correspond to S100 to S104 in FIG. In S406, the background illuminance and the test target are adjusted according to the pupil diameter of the subject. S410 to S422 respectively correspond to S110 to S122 of FIG.
[0046]
In the response data processing of S424, the pupil diameter of the subject when the contrast sensitivity is measured is converted into the contrast sensitivity when measured with the reference pupil diameter. Since the contrast sensitivity changes depending on the pupil diameter of the eye to be examined, it is desirable to make the pupil diameter of the eye to be constant. On the other hand, the response speed of the pupil diameter has a time constant of about several tens of seconds to several minutes. is there. Therefore, in order to increase the accuracy while performing the measurement quickly, it is preferable to process the response data in S424. S426 to S430 correspond to S126 to S130 of FIG. 3 described above, respectively.
[0047]
In the above embodiment, the test target is sent from the first illumination optical system 110 and the pedestal target is sent from the second illumination optical system 130. However, the target plates 114 and 134 are replaced. The pedestal target may be sent from the first illumination optical system 110 and the test target may be sent from the second illumination optical system 130. Moreover, although the structure which changes the contrast of a pedestal target and a test target using the target plate 114 was shown, the structure which changes the light quantity of the light source 131 and the light source 111, and the transmittance | permeability of the ND filter 135 and the ND filter 115 A configuration in which (density) is changed may be used.
[0048]
Further, in the above embodiment, the case where the contrast sensitivity is measured for each eye of the subject is shown. However, when measuring both eyes of the subject at the same time, the subject wears polarized glasses. And full-scale stereo test is possible. Further, in the above-described embodiment, the test target display control unit 120 having a function as a visual target brightness control unit, a visual target brightness adjustment unit 125, and a pedestal target display control unit 140 having a function as a background illumination control unit. In addition, although the case where the background illumination adjusting unit 145 is provided in the contrast visual target presenting unit 100 has been described, it may be provided on the central processing unit 300 side. On the central processing unit 300 side, a test target display control unit 120 having a function as a visual target brightness control unit, a visual target level adjustment unit 125, a pedestal target display control unit 140 having a function as a background illumination control unit, and a background Even when the illumination adjustment unit 145 is provided, the test target display control unit 120, the target brightness adjustment unit 125, the pedestal target display control unit 140, and the background illumination adjustment unit 145 serve as the first illumination optics. It only needs to function integrally with the system 110 and the second illumination optical system 130.
[0049]
【The invention's effect】
As described above, according to the contrast sensitivity measuring device of the present invention, the contrast target presenting unit that displays the first and second contrast targets side by side and the image of the anterior segment of the subject are formed, A pupil data measurement unit that measures the pupil diameter of the subject, and a measurement timing of the pupil data measurement unit is formed based on a timing at which the contrast target presenting unit presents the first and second contrast targets. And a measurement timing forming unit. Therefore, the contrast sensitivity of the subject can be accurately measured, and the inspection time can be shortened.
[0050]
Further, according to the contrast sensitivity measuring apparatus of the present invention, the stimulus presentation and the capture of the subject response are performed by the contrast target presenting unit and the measurement timing forming unit. The examination time can be shortened because it is only necessary to examine whether or not an abnormality has occurred in the examiner.
[0051]
Further, in the contrast target presenting unit as in the embodiment of the present invention, if the configuration is randomly updated for each presentation, the memory regarding the contrast target position immediately before the subject is useless. The subject's response is only the information visible from the stimulus at that time. Therefore, it becomes possible to accurately measure the contrast sensitivity of the subject.
[0052]
Further, according to the contrast sensitivity measuring apparatus of the present invention, the pupil diameter of the subject is measured by the pupil data measuring unit, so that the pupil diameter of the subject or the retinal illuminance of the subject eye becomes a substantially constant value. Since the adjustment signal can be adjusted so as to be output to the visual target brightness adjustment means, the background illumination adjustment means, or the anterior ocular segment illumination control means, the visual function inspection in the dark place can be performed very easily.
[Brief description of the drawings]
FIG. 1 is a configuration diagram for explaining first and second embodiments of the present invention;
FIG. 2 is an explanatory diagram of contrast using a contrast sensitivity target.
FIG. 3 is a flowchart for explaining the first embodiment of the present invention, in which the brightness of the test target is adjusted so that the pupil diameter of the subject becomes a predetermined value.
FIG. 4 is an explanatory diagram showing an example of a contrast sensitivity target presented by an up-and-down method.
FIG. 5 is a diagram illustrating an example of contrast change by an up-down method.
FIG. 6 is a diagram illustrating an example of a response history of a subject with respect to contrast sensitivity targets having different spatial frequencies.
FIG. 7 is a diagram showing the relationship between contrast sensitivity and spatial frequency.
FIG. 8 is a flowchart for explaining a second embodiment of the present invention, in which the brightness of the anterior ocular segment illumination unit is adjusted so that the pupil diameter of the subject becomes a predetermined value.
FIG. 9 is a configuration diagram illustrating third and fourth embodiments of the present invention.
FIG. 10 is a flowchart for explaining a third embodiment of the present invention, in which the brightness is adjusted so that the retinal illuminance of the subject becomes a predetermined value.
FIG. 11 is a flowchart for explaining a fourth embodiment of the present invention, and measures the pupil diameter of a subject when the contrast sensitivity is measured with the brightness of a uniform contrast target, and at a predetermined pupil diameter; The case of converting to the contrast sensitivity is described.
[Explanation of symbols]
100 Contrast target presentation part
110 First illumination optical system
120 test target display control unit (target brightness control means)
130 Second illumination optical system
140 Pedestal target display control unit (background illumination control means)
151, 152, 153 Mirror
200 Pupil data measurement unit
300 Central processing unit (measurement timing formation unit)
400 Eye to be examined
500 Anterior segment illumination unit
510 Anterior segment illumination control means
550 Retina illuminance calculation means
560 Retina illuminance adjustment means

Claims (11)

A contrast optotype presenting unit for displaying two contrast optotypes side by side;
A pupil data measurement unit that forms an image of the anterior segment of the subject and measures the diameter or / and area of the pupil region of the subject;
A measurement timing forming unit that forms a measurement timing of the pupil data measurement unit based on a timing at which the contrast target presenting unit presents the two contrast targets;
The diameter or / and area of the pupil region of the subject measured by the pupil data measurement unit is input, and the brightness of the contrast target is adjusted so that the diameter or / and area of the pupil region becomes a predetermined value. Brightness adjustment means for adjusting at least one of the brightness of the background illumination or the brightness of the anterior segment illumination unit;
Contrast sensitivity measuring device comprising a. A contrast optotype presenting unit for displaying two contrast optotypes side by side;
  A pupil data measurement unit that forms an image of the anterior segment of the subject and measures the diameter or / and area of the pupil region of the subject;
  A measurement timing forming unit that forms a measurement timing of the pupil data measurement unit based on a timing at which the contrast target presenting unit presents the two contrast targets;
  Brightness adjustment for adjusting at least one of the brightness of the contrast target, the brightness of the background illumination, or the brightness of the anterior ocular segment illumination unit so as to keep the retinal illuminance of the subject at a substantially predetermined value. With means;
  Contrast sensitivity measuring device. The brightness adjusting means;
  A target brightness adjusting means for adjusting the brightness of the contrast target;
  Target brightness control means for sending a brightness control signal to the target brightness adjustment means;
  The contrast sensitivity measuring apparatus according to claim 1, comprising: The brightness adjusting means;
  Background illumination adjusting means for adjusting the brightness of the background illumination of the contrast target;
  Background illumination control means for sending a background illumination control signal to the background illumination adjustment means;
  The contrast sensitivity measuring apparatus according to claim 1, comprising: The brightness adjusting means;
  An anterior segment illuminating unit that illuminates the anterior segment;
  Anterior segment illumination control means for transmitting an illumination control signal for adjusting the brightness of the anterior segment illumination unit;
  The contrast sensitivity measuring apparatus according to any one of claims 1 to 4, further comprising: A retinal illuminance calculating means for calculating the retinal illuminance of the eye to be examined from the diameter or / and area of the pupil region of the eye to be examined and the brightness of the contrast target;
  Retinal illuminance adjustment means for outputting a brightness adjustment signal of the contrast visual target to the brightness adjustment means so that the retinal illuminance of the eye to be examined has a substantially constant value;
  A contrast sensitivity measurement is performed in a state where the retinal illuminance of the eye to be examined is substantially constant;
  The contrast sensitivity measuring device according to any one of claims 1 to 5. The two contrast targets are:
  7. The contrast sensitivity measuring apparatus according to claim 1, wherein one is a target with zero contrast and the other is a target having contrast for measuring contrast sensitivity. A contrast visual target presenting unit that randomly presents the two contrast visual targets at one of at least two positions;
  A measurement timing forming unit that forms a measurement timing of the pupil data measurement unit based on a timing at which the contrast target presenting unit presents the contrast target;
  The contrast sensitivity measuring apparatus according to any one of claims 1 to 7, further comprising: The pupil data measuring unit;
  An image of a subject's anterior eye before and during contrast sensitivity measurement is formed, and the diameter or / and area of the pupil region of the subject is measured. The contrast sensitivity measuring apparatus according to any one of 8. The pupil data measurement unit:
  9. The diameter or / and area of the pupil region of the subject is measured at the timing when the contrast target is presented or when the subject responds. The contrast sensitivity measuring device according to any one of the above. A luminance measuring unit for measuring the luminance of the presentation target of the contrast target presentation unit;
  A luminance calibration unit for calibrating the luminance of the contrast target based on the luminance measured by the luminance measurement unit;
  The contrast sensitivity measuring apparatus according to claim 1, comprising:

Images