JP4562234B2 - Eye characteristic measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an eye characteristic measuring apparatus capable of measuring optical characteristics of an eye to be examined with high accuracy.
[0002]
[Prior art]
Conventionally, an eye refractive power measuring apparatus for objectively measuring the refractive index of an eye to be examined has been known. In this type of apparatus, a measurement light beam is projected onto the fundus of the eye to be examined through a specific region of the pupil, generally a ring-shaped region having a specific radius on the pupil, and the measurement light beam is used. It measures the spherical power, astigmatism power, and astigmatism axis of the eye to be examined.
[0003]
[Problems to be solved by the invention]
However, this device only knows the characteristics of a specific zonal region of the pupil, and accurately determines the refractive characteristics of the entire pupil, which may include spherical power, astigmatism power, and higher-order aberrations other than the astigmatic axis. Could not be measured. Currently, corneal correction surgery is widespread, but after corneal correction surgery, the frontal shape of the cornea changes in a complex manner as shown in FIG. 8 (B). It is expected that the number of eyes to be examined whose refractive characteristics change in the band-like region will increase, and a device that accurately measures the refractive power not only in a specific region but also in the entire pupil has been particularly required.
[0004]
Therefore, a point light source image is projected onto the fundus of the eye to be examined, and the wavefront of the light beam passing through the entire pupil area is detected from the point light source image, and the refractive characteristics of the entire pupil area including higher-order aberrations are detected. Devices have also been proposed. However, in this apparatus, a wavefront sensor comprising a Hartmann diaphragm having a plurality of apertures and a photoelectric element for detecting the arrival position of each beam passing through each aperture. It is necessary to detect the wavefront by such means as described above, and there is a disadvantage that the structure must be complicated.
[0005]
The present invention solves these problems of the prior art, and does not measure the wavefront of the light beam emitted from the entire pupil area with a wavefront sensor, but the refractive characteristics in a ring-shaped region having a specific diameter on the pupil. It is an object of the present invention to propose a device capable of measuring different annular refractive characteristics, and consequently the refractive characteristics of the entire pupil region, based only on the measurement results of the shape of the cornea.
[0006]
[Means for solving the problems]
The present invention relates to a refractive power measurement system for objectively detecting the refractive power in a predetermined first region of the pupil, a corneal shape measurement system for measuring the shape of the corneal surface, and a corneal shape measurement. An eye having an arithmetic unit for calculating refractive power data in a region different from the first region based on shape data at each point of the cornea measured by the system and refractive power measured by the refractive power measurement system It relates to a characteristic measuring apparatus, and also includes a refractive power measurement system for detecting the refractive power of the pupil by a subjective value, a corneal shape measurement system for measuring the shape of the corneal surface, and each of the corneas measured by the corneal shape measurement system. Based on the shape data before cornea correction surgery at the point and the refractive power measured by the refractive power measurement system, from the shape data after cornea correction surgery at each point of the cornea measured by the cornea shape measurement system in all areas The present invention relates to an eye characteristic measuring device having an arithmetic unit for calculating refractive power data, The shape data relates to an eye characteristic measuring device that is a corneal tilt angle value at each surface position of the cornea, and the calculation unit calculates corneal front refractive power data at each point of the cornea from the corneal tilt angle value. And an eye characteristic measuring device for calculating refractive power data in a region different from the first region based on the refractive power data of the front surface of the cornea and the refractive power data of the first region. A refractive power displacement amount comprising a difference between a first refractive power in the first region in the pupil measured before the corrective surgery and a second refractive power in the same region as that after the corneal corrective surgery; Corneal shape displacement data consisting of a difference between first corneal shape data at each point of the cornea before corrective surgery and second corneal shape data at each point of the cornea after corrective surgery, and the second refractive power Based on the refractive power in a region different from the first region after corneal correction surgery. The calculation unit relates to an eye characteristic measurement device that calculates refractive power data in the entire pupil region, and also measures the eye refractive power of a subjective value before cornea correction surgery. In addition, the present invention relates to an eye characteristic measuring apparatus that obtains a bias value of eye refractive power from the subjective eye refractive power and the first refractive power, and corrects the refractive power data using the bias value.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0008]
The basic configuration of the eye characteristic measuring apparatus according to the present invention is equivalent to a conventionally known apparatus capable of measuring the refractive power and the corneal shape in a specific region.
[0009]
First, referring to FIG. 1, the basic configuration of the eye characteristic measuring apparatus will be described.
[0010]
The eye characteristic measuring apparatus shown in FIG. 1 has both functions of a keratometer (corneal shape measuring system) for measuring a corneal shape and a refractometer (refracting power measuring system) for objectively measuring refractive power. This is an auto-keratrrefractometer, and includes an optical element described below that constitutes the optical path 1 to the optical path 5 facing the eye E.
[0011]
The optical path 1 is an optical system for projecting a ring-shaped visual target image for measuring eye refractive power onto the eye E, and is positioned at a position conjugate with the light source 11, the collimator lens 12, the conical prism 13, and the pupil of the eye E. The ring-shaped diaphragm 14, the relay lens 15, the perforated prism 16, the half mirrors 17 and 18, and the objective lens 19 are arranged.
[0012]
The optical path 2 is an optical system for receiving the ring target image reflected from the fundus of the eye E by the area sensor 26. The objective lens 19, the half mirrors 18 and 17, the perforated prism 16, the mirror 20, and the relay lens 21 are used. The movable lens 22 is movable along the optical axis direction, the mirror 23, the half mirror 24, the imaging lens 25, and the area sensor 26. A display 61 is connected to the area sensor 26 and frame memories 63 and 64 are connected via a changeover switch 62.
[0013]
The optical path 3 is an optical system for fixing and clouding the eye E when measuring the refractive power of the eye E, and includes a light source 31, a collimator lens 32, a fixation target 33, a relay lens 34, a mirror 35, and a half. It consists of mirrors 17 and 18 and an objective lens 19.
[0014]
The optical path 4 is an optical system for projecting a multi-ring index image image toward the subject's eye cornea, and includes a plurality of light sources 41, a diffuser plate 42, a multi-ring-shaped aperture stop arranged in a ring shape in front of the eye to be examined. It is comprised with the ring-shaped visual target plate 43 which has.
[0015]
The optical path 5 is an optical system for receiving a multiple ring-shaped aperture image reflected by the eye cornea together with the anterior eye image of the eye E, and includes an objective lens 19, a half mirror 18, an aperture 51, a relay lens 52, a collimator. The area sensor 26 includes a meter lens 53, a half mirror 24, an imaging lens 25, a CCD element, and the like.
[0016]
A refractive power calculation unit 65 is connected to the frame memory 63, and the refractive power calculation unit 65 has a function of calculating the spherical power, the astigmatic power, and the refractive power of the astigmatic axis. The calculation result of the refractive index calculation unit 65 is input to the main calculation processing unit 67. A corneal shape calculation unit 66 is connected to the frame memory 64, and the corneal shape calculation unit 66 has a function of calculating a corneal shape such as a corneal inclination value. The calculation result of the corneal shape calculation unit 66 is input to the main calculation processing unit 67. A subjective optometer 68 is connected to the main arithmetic processing unit 67, and the refractive index calculated by the subjective optometer 68 can also be input. The main calculation processing unit 67 controls the measurement operation of the eye characteristic measurement device and creates a map of eye refractive power in the entire pupil region based on the calculation results from the refractive index calculation unit 65 and the corneal shape calculation unit 66. In addition, it has a function of calculating an optimum refractive characteristic.
[0017]
Next, the operation of the autokeratorefractometer having the above configuration will be described.
[0018]
First, the examiner observes the anterior segment of the eye to be examined displayed on the display 61 based on the video signal from the area sensor 26, adjusts the alignment, and then presses a measurement switch (not shown). When the measurement switch is turned on, an image of the fixation target 33 is projected onto the eye E through the optical path 3 to fix the eye E to be clouded, and then the light source 11 is turned on and the eye E through the optical path 1 is turned on. A ring-shaped index image is projected onto the fundus of the eye to be examined through a ring-shaped region having a predetermined radius at the pupil of the eye. The reflected light beam from the fundus passes through the optical path 2 and forms a ring-shaped visual target image on the area sensor 26. The image signal of the ring visual target image is stored in the frame memory 63 via the changeover switch 62. The refractive power calculation unit 65 calculates the refractive power composed of the spherical power, the astigmatism power, and the astigmatism axis by a known calculation method based on the video signal of the ring-shaped index image recorded by the frame memory 63, and the calculation result Is output to the main arithmetic processing unit 67.
[0019]
Next, the light source 41 is turned on, a multiple ring-shaped visual target image is projected toward the eye cornea through the optical path 4, and the light beam reflected by the cornea surface is reflected on the area sensor 26 via the optical path 5. A target image is formed. The video signal of the multiple ring visual target image is stored in the frame memory 64 via the changeover switch 62. The corneal shape calculation unit 66 calculates the shape of the entire area of the front surface of the eye cornea by a known method based on the image signal of the multiple ring-shaped target image stored in the frame memory 64, and the calculation result is subjected to main calculation processing. The data is output to the unit 67. The main calculation processing unit 67 calculates the refraction characteristics of the entire pupil region of the eye E based on the calculation result from the refraction degree calculation unit 65 and the calculation result from the corneal front shape calculation unit 66.
[0020]
The first embodiment will be described below with reference to FIG.
[0021]
STEP 1: When the measurement is started, first, the eye refractive power is measured by the refractometer function. A ring-shaped index image 10 (see FIGS. 3A and 3B) is projected on the eye E by the optical path 1, and the ring-shaped index reflected from the fundus of the eye E by the optical path 2 is the area sensor 26. Is imaged. The changeover switch 62 connects the area sensor 26 and the frame memory 63 so that an image signal from the area sensor 26 is input to the frame memory 63, and the frame memory 63 is connected to the image of the area sensor 26. Record the signal. The refractive index calculating unit 65 calculates from the image signal stored in the area sensor 26 the refractive power Sr, Cr, Axr in the area where the ring-shaped index image 10 is projected, and further in the area of the ring-shaped index image 10. The eye refractive power (diopter value) Dr = Sr + Crcos ² (θ−Axr) is calculated.
[0022]
STEP 2: Next, the frontal shape of the cornea is measured by the keratometer function. A multiple ring index is projected onto the cornea of the eye E by the optical path 4, and the optical path 5 guides the multiple ring index reflected by the eye E to the area sensor 26 to form an image. The changeover switch 62 connects the area sensor 26 and the frame memory 64, and the image signal of the area sensor 26 is stored in the frame memory 64. The corneal shape calculation unit 66 calculates a corneal front shape such as a corneal inclination over the entire pupil region from the image signal stored in the frame memory 64.
[0023]
STEP 3: An arbitrary measurement cross section passing through the optical axis of the eye E (xf (x) cross section, see FIG. 3B), for example, the eye refractive power at a vertical measurement cross section (angle θ) passing through the optical axis. Measure. As shown in FIG. 4, the corneal front refractive power at the point P (coordinate: x) is obtained by the following formula 1. In FIG. 3B, 9 indicates a crystalline lens.
[0024]
φpc (x) = n / f (x) (1)
[0025]
Here, f (x) is the distance from the vertex 0 of the cornea to the intersection of the optical axis and the light beam incident parallel to the point P and refracted at the front of the cornea, and n is the refractive power of the cornea (about 1.375).
[0026]
The angle between the refracted light beam and the optical axis is U, the angle between the optical axis and the line connecting the corneal vertex 0 and the point P is α, the incident angle, that is, the perpendicular at the point P and the optical axis. If the angle between the perpendicular line and the refracted ray is I ′,
[0027]
f (x) = x / tan U + x / tan α (2)
[0028]
U = I−I ′
α = (180 ° −I) / 2, and from Snell's law, sinI = nsinI ′, that is, I ′ = sin ⁻¹ (sinI / n)
It becomes. The incident angle I is equal to the corneal tilt angle value K (x). Thus, f (x) is obtained, and further, φpc (x) is obtained.
[0029]
That is, the corneal front refractive power φpc (x) at an arbitrary point P (coordinate: x) is obtained by measuring the inclination angle value of the cornea. The eye refractive power is obtained by adding the refractive power inside the eye E such as the crystalline lens 9 to the corneal front refractive power φpc (x).
[0030]
STEP 4: The corneal front refractive powers φrc1 and φrc2 at the point P1 (coordinate x1) and the point P (coordinate x2) (see FIG. 3) in the (xf (x) cross section) of the ring-shaped index image 10 are also described. It is obtained in the same manner based on the inclination angle values at P1 (coordinate x1) and P point (coordinate x2).
[0031]
STEP 5: Further, regarding P1 and P2, the eye refractive power is actually measured in STEP 1, and it is known that the internal refractive power of the crystalline lens 9 of the eye E to be examined is substantially equal throughout the entire area. Therefore, from the relationship that the eye refractive powers φrc1 and φrc2 calculated in STEP3, the actually measured eye refractive power, and the internal refractive power of the eye E to be examined are equal in the entire area, The refractive power can be obtained.
[0032]
Dp (x) = (φpc (x) − ((x−x2) / (x1−x2)) × (φrc1−φrc2) + (Dr−φrc2) (3)
[0033]
In Formula 3, the term ((x−x2) / (x1−x2)) × (φrc1−φrc2) is corrected when the corneal front refractive powers φrc1 and φrc2 at the points P1 and P2 are different. Term.
[0034]
STEP 6: That is, the eye refractive power in the entire range from the radius R = 0 to the maximum pupil diameter in an arbitrary cross section is calculated.
[0035]
STEP 7 and STEP 8: The measurement cross section is rotated by a predetermined angle θ ′, and it is determined whether the measurement cross section is the measurement start cross section. If the measurement cross section is different, the eye refractive power is similarly determined from STEP 4 to STEP 6 for the rotated cross section. Ask.
[0036]
STEP 7: It is determined whether or not the measurement cross section has returned to the original position. When it is determined that the measurement cross section has returned, the measurement of the eye refractive power in the cross section is completed.
[0037]
STEP 9: A map of the eye refractive power Dp (x, θ) over the entire pupil surface is created.
[0038]
STEP 10: Optimal Sr, Cr, and Axr are predicted from the created map. When obtaining the optimum Sr, Cr, Axr from the map, the following least square method is used.
[0039]
In the measurement cross section at the angle θ, the eye refractive power is Dper = S + Ccos ² (θ−Ax),
[0040]
SS = ₀ ∫ ^{2 π} ₀ ∫ ^R (Dper (θ) −Dp (r, θ)) ² rdrdθ
= ₀ ∫ ^{2 π} ₀ ∫ ^R ((S-Ccos ² (θ−Ax)) − Dp (r, θ)) ² rdrdθ (4)
[0041]
Here, by substituting an arbitrary value of R in the above equation, the optimum Sr, Cr, Axr at an arbitrary pupil diameter (= 2R) can be calculated, and the pupil diameter (for example, 3 mm, 7 mm) The difference in refractive power due to the difference can be calculated.
[0042]
Thus, only the functions of both a keratometer and a refractometer can be used, and the eye refraction characteristics over the entire pupil can be accurately measured without using a wavefront sensor or the like.
[0043]
Hereinafter, a second embodiment will be described with reference to FIG.
[0044]
In the second embodiment, the ratio of change in corneal tilt angle value before and after refractive power correction surgery is used. The mechanical configuration of the eye characteristic measuring apparatus is the same as that shown in FIG.
[0045]
STEP 15: When the measurement is started, the eye refractive power is measured by the refractometer function. First, a ring-shaped index image 10 (see FIGS. 3A and 3B) is projected on the eye E by the optical path 1, and the ring index reflected from the fundus of the eye E by the optical path 2 is the area sensor. 26 is imaged. The changeover switch 62 connects the area sensor 26 and the frame memory 63 so that an image signal from the area sensor 26 is input to the frame memory 63, and the frame memory 63 is connected to the image of the area sensor 26. Record the signal. The refractive index calculating unit 65 calculates from the image signal stored in the area sensor 26 the refractive power Sr, Cr, Axr in the area where the ring-shaped index image 10 is projected, and further in the area of the ring-shaped index image 10. The eye refractive power (diopter value) Dr ′ = Sr + Crcos ² (θ−Axr) is calculated.
[0046]
STEP 16: Next, the frontal shape of the cornea is measured by the keratometer function along the optical path 4. A multiple ring index is projected onto the cornea of the eye E, and the optical path 5 guides the multiple ring index reflected by the eye E to the area sensor 26 to form an image. The changeover switch 62 connects the area sensor 26 and the frame memory 64, and the image signal of the area sensor 26 is stored in the frame memory 64. The corneal shape calculation unit 66 calculates a corneal front shape K ′ (r, θ) such as a corneal inclination value in the entire pupil region from the image signal stored in the frame memory 64.
[0047]
STEP 17: A refractive power correction operation is performed.
[0048]
STEP 18: As in STEP 15, the eye refraction characteristic is normally measured, and the eye refractive power (diopter value) Dr = Sr + Crcos ² (θ−Axr) in the region of the ring-shaped index image 10 is calculated.
[0049]
STEP 19: Similar to STEP 16, the anterior corneal shape K (r, θ) such as the corneal inclination in the entire pupil region after corrective surgery is calculated.
[0050]
STEP 20: As in the first embodiment, an arbitrary measurement cross section (xf (x)) passing through the optical axis of the eye E (see FIG. 3B), for example, a vertical measurement cross section (angle) passing through the optical axis Start measuring eye refractive power at θ).
[0051]
STEP 21: Calculate the difference dKr between the corneal inclination values before and after the operation at an arbitrary point P from the results obtained in STEP 16 and STEP 19 in the measurement cross section.
[0052]
STEP 22: The difference dDr between the two eye refractive powers obtained in STEP 15 and STEP 18 is calculated.
[0053]
STEP 23: The eye refractive power Dp at the point P is calculated by the following calculation.
[0054]
If the measured values of refractive power before and after refractive power correction surgery measured by the refractometer function are (Sr ′, Cr ′, Axr ′) and (Sr, Cr, Axr), the eye refractive power Dr ′ at this time , Dr is
[0055]
Dr ′ = Sr ′ + Cr′cos ² (θ−Axr ′), Dr = Sr + Crcos ² (θ−Axr), and the difference between them is
dDr = Dr−Dr ′ (5)
[0057]
The corneal inclination values calculated by measuring the anterior corneal shape before and after the refractive power correction power operation at an arbitrary point P are set as K ′ and K, respectively, and the difference is expressed as follows.
dK = K−K ′ (6)
[0059]
Kr1 ′, Kr2 ′ are the corneal inclination values before the refractive power correction operation in the ring-shaped index image 10 region of the vertical measurement section passing through the optical axis, and Kr1, Kr2 are the corneal inclination values after the operation,
[0060]
dKr = ((Kr1-Kr1 ') + (Kr2-Kr2')) / 2 (7)
Then, the refractive power of the eye at an arbitrary point P is
Dp = dK × dDr / dKr + Dr (8)
It can be asked.
[0062]
The eye refractive power in the entire range from the arbitrary point on the measurement cross section, that is, from the radius R = 0 to the maximum pupil diameter in the arbitrary cross section is calculated.
[0063]
STEP 25, STEP 26: The measurement cross section is rotated by a predetermined angle θ ′, and it is determined whether or not the measurement cross section is the same as that at the start of measurement. If the measurement cross section is different, the eye refractive power is similarly determined from STEP 22 to STEP 24 for the cross section after the rotation. Ask.
[0064]
STEP 25: It is determined whether or not the measurement cross section has returned to the original position, and when it is determined that the measurement cross section has returned, the measurement of the eye refractive power in the cross section is completed.
[0065]
STEP 27: A map of eye refractive power Dp (x, θ) over the entire pupil surface is created.
[0066]
STEP 28: Optimal Sr, Cr, and Axr are predicted from the created map as in the first embodiment. The optimum Sr, Cr, and Axr are obtained by the following least square method.
[0067]
In the measurement cross section at the angle θ, the eye refractive power is Dper = S + Ccos ² (θ−Ax),
SS = ₀ ∫ ^{2 π} ₀ ∫ ^R (Dper (θ) −Dp (r, θ)) ² rdrdθ
= ₀ ∫ ^{2 π} ₀ ∫ ^R ((S-Ccos ² (θ−Ax)) − Dp (r, θ)) ² rdrdθ (4)
[0068]
Thus, in the second embodiment, it is possible to accurately measure the eye refraction characteristics over the entire pupil without using a wavefront sensor or the like, only having the functions of both a keratometer and a refractometer. Can do.
[0069]
Hereinafter, a third embodiment will be described with reference to FIG.
[0070]
The eye refractive power measured objectively, such as the eye refractive power measured by the refractometer, may not always coincide with the subjective value, and the third embodiment is conscious of the second embodiment. The value is taken into account. In the flowchart of FIG. 6, STEP14, STEP16a, and STEP29 are added to the second embodiment.
[0071]
STEP 14: When the measurement is started, the eye refractive power Ds of the subjective value is measured.
[0072]
STEP 15: The eye refractive power Dr 'is measured by the refractometer function (objectively measured).
[0073]
STEP 16a: The bias value of the eye refractive power is calculated by comparing the eye refractive power Ds of the subjective value with the eye refractive power Dr ′ of the objective measurement.
[0074]
In the following, STEP 16 to STEP 28 are the same as those in the second embodiment, and a description thereof will be omitted.
[0075]
STEP 29: When the optimum Sr, Cr, Axr is obtained from the generated map by the least square method, the bias value of the eye refractive power is further added, and the optimum Sr, which is suitable for the subject's awareness value, Cr and Axr are calculated.
[0076]
Thus, in the third embodiment, it is possible to measure the eye refraction characteristics in the entire pupil area suitable for the subject's awareness.
[0077]
FIG. 7 shows a fourth embodiment in which a map of the eye refractive power of the entire pupil surface is created based on the subjective eye refractive power and the corneal frontal shape measured by a keratometer.
[0078]
STEP 31: Subjective eye characteristic measurement is performed, and eye refractive power (S, C, Ax) based on the subjective value is calculated.
[0079]
STEP32: Corrected visual acuity is measured.
[0080]
STEP 33: It is determined whether or not the corrected visual acuity is 1.2 or more. If the corrected visual acuity is less than 1.2, it is determined that the corneal correction surgery is inappropriate, and studies other than the corneal correction surgery are performed (STEP 34). ). Corneal correction surgery is performed when the corrected visual acuity is 1.2 or more.
[0081]
STEP 35: Next, the corneal anterior shape is measured by the keratometer function. A multiple ring index is projected onto the cornea of the eye E, and the optical path 5 guides the multiple ring index reflected by the eye E to the area sensor 26 to form an image. The changeover switch 62 connects the area sensor 26 and the frame memory 64, and the image signal of the area sensor 26 is stored in the frame memory 64. The corneal shape calculation unit 66 calculates a corneal front shape K ′ (r, θ) such as a corneal inclination value in the entire pupil region from the image signal stored in the frame memory 64.
[0082]
STEP 36: A refractive power correction operation is performed.
[0083]
STEP 37: Similar to STEP 35, the anterior corneal shape K (r, θ) such as the corneal inclination in the entire pupil region after corrective surgery is calculated.
[0084]
STEP38: As in the first embodiment, an arbitrary measurement cross section (xf (x)) passing through the optical axis of the eye E (see FIG. 3B), for example, a vertical measurement cross section (angle) passing through the optical axis Start measuring eye refractive power at θ).
[0085]
STEP 39: The corneal front refractive power is determined by the above formulas (1) and (2) based on the corneal inclination value, the refractive index of the cornea, etc., at an arbitrary point P in the same measurement cross section before and after the operation. The eye refractive power in the entire range from the arbitrary point on the measurement cross section, that is, from the radius R = 0 to the maximum pupil diameter in the arbitrary cross section is calculated.
[0086]
STEP 40: A change in the corneal inclination value before and after the operation is obtained for the measurement cross section.
[0087]
STEP 41: The internal refractive power is obtained from the relationship between the subjective eye refractive power before the operation determined in STEP 31 and the corneal front refractive power before the operation determined in STEP 39, and the internal refractive power does not change before and after the operation. The eye refractive power after the operation is obtained from the refractive power and the corneal front refractive power after the operation obtained in STEP39. The arbitrary point P is from the radius R = 0 of the measurement cross section to the maximum pupil diameter, and the eye refractive power of the entire pupil range is calculated.
[0088]
STEP42, STEP43: The measurement cross section is rotated by a predetermined angle θ ′, and it is determined whether or not the measurement cross section is the same as that at the start of the measurement. Ask.
[0089]
STEP 42: It is determined whether or not the measurement cross section has returned to the original position. When it is determined that the measurement cross section has returned, the measurement of the eye refractive power in the cross section is completed.
[0090]
STEP 44: A map of pseudo refractive power Dp (x, θ) on the entire pupil surface is created.
[0091]
STEP 45: Optimal Sr, Cr, and Axr are predicted from the created map as in the first embodiment. The optimum Sr, Cr, and Axr are obtained by the least square method (the above formula (4)).
[0092]
Thus, in the fourth embodiment, without using a wavefront sensor or the like, even if there is no function of the refractometer, only the function of measuring the eye refractive power by the consciousness and the function of the keratometer are provided. The eye refractive power can be measured.
[0093]
【The invention's effect】
As described above, according to the present invention, it is sufficient to have an optical system that can measure the refractive power in a specific region that is conventionally known as an apparatus configuration and an optical system that can measure the corneal shape. There is an excellent effect that the accurate refraction characteristics of the eye to be examined can be measured without requiring a large-scale device using a wavefront sensor.
[Brief description of the drawings]
FIG. 1 is a basic configuration diagram showing an embodiment of the present invention.
FIG. 2 is a flowchart showing a first embodiment of the present invention.
FIGS. 3A and 3B are explanatory diagrams when the eye refractive power is measured for a specific area with a refractometer. FIGS.
FIG. 4 is an explanatory diagram for calculating the corneal front refractive power from the corneal tilt value.
FIG. 5 is a flowchart showing a second embodiment of the present invention.
FIG. 6 is a flowchart showing a third embodiment of the present invention.
FIG. 7 is a flowchart showing a fourth embodiment of the present invention.
8A and 8B are diagrams showing changes in the corneal shape before and after refractive power correction surgery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Optical path 2 Optical path 3 Optical path 4 Optical path 5 Optical path 14 Ring-shaped aperture plate 26 Area sensor 43 Ring-shaped target plate 61 Display 62 Changeover switch 63 Frame memory 64 Frame memory 65 Refractive-index calculating part 66 Corneal shape calculating part 67 Main calculation processing Part 68 A subjective optometer

Claims (5)

Measured by a refractive power measurement system for objectively detecting the refractive power in a predetermined first region of the pupil, a corneal shape measurement system for measuring the shape of the corneal surface, and a corneal shape measurement system. was based on the power measured by the shape data and the refractive power measuring system of cornea at each point, have a computing unit for calculating the refractive power data in a region different from the said first region,
The arithmetic unit is a refraction composed of a difference between a first refractive power in the first region in the pupil measured before the cornea correction surgery and a second refractive power in the same region as the region after the cornea correction surgery. Corneal shape displacement data comprising the difference between the force displacement amount and the first corneal shape data at each corneal point before corneal correction surgery and the second corneal shape data at each corneal point after corneal correction surgery; An eye characteristic measuring device that calculates refractive power data in a region different from the first region after cornea correction surgery based on the second refractive power . The eye characteristic measuring device according to claim 1, wherein the shape data is a corneal inclination angle value at each surface position of the cornea. The calculation unit calculates corneal front refractive power data at each point of the cornea from the corneal tilt angle value, and based on the corneal front refractive power data and the refractive power data of the first region, The eye characteristic measurement device according to claim 2 , wherein refractive power data in different regions is calculated.   The eye characteristic measurement device according to claim 1, wherein the calculation unit calculates refractive power data in the entire pupil region. The eye refractive power of a subjective value is measured before cornea correction surgery, a bias value of the eye refractive power is obtained from the subjective eye refractive power and the first refractive power, and the refractive power data is corrected by the bias value. Item 1. An eye characteristic measuring device according to item 1 .

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