CN101732030A - Device and method for measuring cornea curvature - Google Patents
Device and method for measuring cornea curvature Download PDFInfo
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- CN101732030A CN101732030A CN200910223924A CN200910223924A CN101732030A CN 101732030 A CN101732030 A CN 101732030A CN 200910223924 A CN200910223924 A CN 200910223924A CN 200910223924 A CN200910223924 A CN 200910223924A CN 101732030 A CN101732030 A CN 101732030A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/107—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining the shape or measuring the curvature of the cornea
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/02—Testing optical properties
- G01M11/0242—Testing optical properties by measuring geometrical properties or aberrations
- G01M11/025—Testing optical properties by measuring geometrical properties or aberrations by determining the shape of the object to be tested
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0181—Memory or computer-assisted visual determination
Abstract
The present invention provides a device and a method for measuring cornea curvature by using microreciprocal degree ring lights and focused lights for automatically eliminating measurement error caused by position change of an eye to be measured. The device for measuring cornea curvature comprises a microreciprocal degree ring light source for emitting ring lights to the cornea of an eye to be measured, a focused light source for emitting two spot type focused lights to the cornea of the eye to be measured, an image optics system for detecting an microreciprocal degree ring light image and focused light images that are reflected from the cornea, and an operation and control unit for obtaining the diameter R of the microreciprocal degree ring light image at a measurement mode and distance F between spots of the focused light images at the measurement mode from the microreciprocal degree ring light image and the focused light images detected by the image optics system, for compensating the diametric error of the microreciprocal degree ring light image as a consequence of position change of the eye, and calculating the cornea curvature of the eye to be measured according to the compensated microreciprocal degree ring light image.
Description
The application requires in the priority of the 10-2008-0117273 korean patent application of submission on November 25th, 2008.All disclosures of this korean patent application are incorporated this paper by reference into.
Technical field
The present invention relates to a kind of method and apparatus of measuring corneal curvature, relate more specifically to a kind of like this method and apparatus of measuring corneal curvature, wherein, can be by using mired ring (mirering) light and focused light automatically to compensate because the measurement error that tested eyes change in location causes.
Background technology
Be used to diagnose the ophthalmological instrument of eye situation to have a variety of, as, the refractometer that is used for objective measurement ophthalmic refractive power is used to measure the device (being commonly referred to ophthalmometer (opthalmometer)) of cornea shape/curvature, and measures tonometer of intraocular pressure or the like by non-contacting method.Especially, the keratometry device is made up of optics, electronic unit and mechanical part as photoeletric measuring system.The optics of keratometry device comprises: light emission portion, to tested eye cornea emission collimated light and measuring light; Optical detection part, the light detecting sensor that comprises reflecting mirror that the route to the light of returning from corneal reflex changes and the light of returning from corneal reflex or optical signal are detected.This light detecting sensor is converted to optical signal the signal of telecommunication and sends it to CPU.Then, CPU obtains the eye's cornea curvature value with the signal that algorithm process within it receives being installed.The corneal curvature value that obtains becomes the prescription criterion of the contact lens of the cornea shape that is applicable to tested eyes.If a people has worn the contact lens with wrong corneal curvature value, can cause that then contact lens comes off, has the scratch or the inflammation of foreign body sensation or cornea.Therefore, the accurate corneal curvature value that calculates tested eyes is crucial.
Optical detection part in the keratometry device is designed to form when locating when the focal length (focus length) that tested eyes are positioned at light detection optical portion optical axis the image of the most accurate corneal reflex light.Based on the image of the most accurate corneal reflex light, can calculate accurate corneal curvature value.Yet the situation of shown reflected light image is determined the exact position of tested eyes and is not easy from the monitor of keratometry device.The measuring position of eyes may produce displacement because of the eye motion in the corneal curvature value measuring process.In addition, the degree of accuracy of determining the measuring position depends on the skill of survey crew.Therefore, invent a kind of method, when the position of eyes or the distance between tested eyes and optics change, still can obtain minimum error or free from error corneal curvature value is very important.
Fig. 1 and Fig. 2 illustrate the conventional equipment of keratometry, and wherein, Fig. 1 shows and opening the situation of aperture, and Fig. 2 shows the situation of inserting aperture.As depicted in figs. 1 and 2, the conventional equipment of keratometry comprises: mired ring 20 produces ring-like measuring light pattern; Light source 21a and 21b produce mired ring measuring light; Measure lens 31, receive from the mired ring light of cornea 3 reflections of eyes 1; Two dimension photodetector 32 is to the reflection mired ring photoimaging by 31 transmission of measurement lens; Aperture 14 is inserted in the light path of measuring between lens 31 and the two-dimentional photodetector 32 and limiting mired ring light under measurement pattern; Aperture motor 10 drives aperture 14; And computing and control unit 40, drive aperture motor 10 and calculate the corneal curvature value of two-dimentional photodetector 32 detected mired ring light images.
The work process of the conventional equipment of keratometry illustrated in figures 1 and 2 is as follows.Pass mired ring 20 from the measuring light that mired ring light source 21a and 21b send, on the cornea 3 of tested eyes 1, form the shape of mired ring, then from the mired ring light of cornea 3 reflections by measuring lens 31 imaging on two-dimentional photodetector 32.Computing and control unit 40 output to the mired ring image that forms on the monitor of keratometry device.The eyes survey crew examines the situation of mired ring image, and the position of adjusting the keratometry device begins measurement pattern then to find mired ring image the most clearly.Computing and control unit 40 drive aperture motor 10 aperture 14 are inserted between measurement lens 31 and the two-dimentional photodetector 32, as shown in Figure 2.The marginal portion of the mired ring light that reflects from cornea 3 is stopped by aperture 14 then, and the part that mired ring light is not blocked imaging on two-dimentional photodetector 32.
When eyes 1 changed to the distance between the keratometry device, the size of the mired ring image on photodetector 32 also changed.Especially, bigger in the variation that aperture shown in Figure 1 is opened mired ring image size under the situation than the amplitude of variation of mired ring image size under the situation of aperture insertion shown in Figure 2.Therefore, the mired ring size that fluctuates in response to the measuring position when opening and inserting by comparing aperture 14, computing and control unit 40 just can obtain because the focusing error amount that measuring position fluctuation causes, thus the corneal curvature value after calculating the focusing error amount and being compensated.
In the conventional equipment of keratometry illustrated in figures 1 and 2, by the mired ring light that reflects from cornea 3 is realized that centrifugal effect comes the compensating focusing error.Centrifugal effect is realized by aperture 14 and aperture motor 10.Therefore,, must when aperture is opened, calculate the size of mired ring, after driving aperture motor 10 insertion apertures, calculate the size of mired ring then once more for the compensating focusing error.
This just makes conventional equipment have such shortcoming: total Measuring Time is elongated, if the position of tested eyes when inserting aperture 14 variation has taken place, may obtain wrong corneal curvature value.This be because the prerequisite of conventional equipment to be tested eyes constant in insertion aperture 14 front and back with the distance between the device.And the eyes survey crew also is difficult to the change in location of the tested eyes of perception in measuring process.Conventional equipment also has a shortcoming: the control circuit that conventional equipment needs aperture 14, is used to drive the precision motor 10 of aperture 14 and is used to drive them.This makes product cost increase, and mechanical realization is more complicated.Simultaneously this has also increased and has measured the probability that calculates the sum of errors mechanical breakdown, and these be owing to aperture in use depart from or the change in the heart far away zone of the measuring light that aperture motor performance fault causes causes.
Summary of the invention
Thereby, the purpose of this invention is to provide the method and apparatus of measuring corneal curvature, this device need not independent equipment or element to since the measurement error that the fluctuation of measuring position causes compensate and have simple frame for movement.
Another object of the present invention provides the method and apparatus of measuring corneal curvature, can realize measurement Error Compensation accurately and fast, simply.
In order to realize these and other purposes, the invention provides the device of measuring corneal curvature, comprising: mired ring light source, launch ring-like measuring light to tested eye's cornea; Focused light source is to two some type focused lights of tested eye's cornea emission; Imaging optical system detects light image of mired ring and focused light image from corneal reflex; And computing and control unit, from imaging optical system detected mired ring light image and focused light image, obtain respectively the light image of mired ring at the point-to-point between the focused light image under diameter R under the measurement pattern and the measurement pattern apart from F, to because the error of the diameter of the mired ring light image that the displacement of tested eyes causes compensates, and calculate the corneal curvature of tested eyes according to the diameter of the mired ring light after the compensation.
The present invention also provides the method for measuring corneal curvature, may further comprise the steps: a) to tested eye's cornea emission mired ring measuring light and focused light, to detect the light image of mired ring and the focused light image of returning from corneal reflex; B) respectively from the light image of detected mired ring and focused light image obtain the light image of mired ring at the point-to-point between the focused light image under diameter R under the measurement pattern and the measurement pattern apart from F, and obtain focusing distance (focus distance) D (D=R-F) under the measurement pattern apart from F from the point-to-point of mired ring light image focused light image under diameter R under the measurement pattern and measurement pattern; C) obtain and the corresponding diameter R ' of mired ring light image under mode standard of focusing distance D under the measurement pattern by curve L, wherein, by obtaining focusing distance apart from F from the diameter R of the mired ring light image that when tested eye's cornea is positioned at the focal length of measuring light, obtains and the point-to-point of focused light image, and derive the diameter R of mired ring light image and the relation curve L of focusing distance, thereby obtain described curve L; D) the diameter R ' under mode standard obtains focusing error Δ R (Δ R=R-R ') at diameter R under the measurement pattern and the light image of mired ring from the light image of mired ring; E) whether in allowed limits to determine focusing error Δ R; F) as focusing error Δ R not in allowed limits the time, the light image of mired ring is compensated at diameter R under the measurement pattern and the focusing distance D under the measurement pattern; G) as focusing error Δ R in allowed limits the time, measure the corneal curvature of tested eyes according to the diameter R of mired ring light image under measurement pattern.
In the method and apparatus of measurement eyes corneal curvature according to the present invention, the measuring position error is compensated by mired ring light and the focused light that in the device of measuring the eyes corneal curvature, provides.Therefore, even the measuring position of tested eyes in measurement pattern and compensation model change has taken place, also can accurately measure corneal curvature, and can not produce focusing error.And, because being the light image of mired ring and the focused light image that directly form when measurement pattern begins, corneal curvature obtains, therefore can not produce because tested eyes change the error that causes at the measurement pattern upper/lower positions yet, thereby obtain the corneal curvature value apace.Method and apparatus according to measurement corneal curvature of the present invention is very simple, because they do not need independent equipment or device to adjust the measuring position, thereby has saved manufacturing cost and maintenance cost.
Description of drawings
Fig. 1 is the figure of conventional equipment under its aperture open mode that illustrates keratometry;
Fig. 2 is the figure of conventional equipment under its aperture insertion state that illustrates keratometry;
Fig. 3 is the figure that illustrates according to the keratometry device of an embodiment of the invention;
Fig. 4 illustrates the figure that in according to the keratometry device of an embodiment of the invention mired ring light and focused light incide the situation on the cornea;
Fig. 5 illustrates in the keratometry device according to an embodiment of the invention, is positioned at the figure of the light image of mired ring and focused light image under focal length, focal length place and the exfocal three kinds of situations of measuring light when the tested eye eyes;
Fig. 6 is the relation that illustrates between the focusing distance of the diameter of mired ring light image in keratometry device according to the present invention and focused light image;
Fig. 7 a illustrates when tested eyes are positioned at outside the focal position of measuring light, in according to the keratometry device of an embodiment of the invention to because the figure of the process that the measurement error that the variation of tested eye position causes compensates;
Fig. 7 b illustrates when tested eyes are positioned at the focal position of measuring light, the figure of the process that the measurement error that in according to the keratometry device of an embodiment of the invention the variation owing to tested eye position is caused compensates;
Fig. 8 illustrates the process that in according to the keratometry device of an embodiment of the invention the measurement error that causes owing to the eye position variation is compensated and obtains focusing error curve " M
k" process;
Fig. 9 shows the flow chart according to the keratometry process of an embodiment of the invention.
The specific embodiment
By with reference to below in conjunction with the detailed description of accompanying drawing, will more fully understand the present invention and bonus thereof.
Fig. 3 is the keratometry device that illustrates according to an embodiment of the invention.Fig. 4 illustrates the figure that in according to the keratometry device of an embodiment of the invention mired ring light and focused light incide the situation on the cornea.
As described in Figure 3, keratometry device according to an embodiment of the invention comprises mired ring optical system 20, imaging optical system 30 and computing and control unit 40, also comprises the reflecting mirror and the relay lens that are used for the measuring light that tested eyes 1 reflect is transferred to imaging optical system 30 as light transmitting device.
Mired ring optical system 20 will be used to measure the mired ring light of corneal curvature and the anterior corneal surface that focused light is transmitted into tested eyes 1.Mired ring optical system 20 comprises: mired ring light source 21a and 21b; Mired ring 28 receives from the light of mired ring light source 21a and 21b producing ring-like measuring light, and it is transferred to cornea 3; Focused light source 26 and 27 is transmitted into two some type focused lights the left and right sides of mired ring 28 middle bodies; Collimating lens 22 and 23 makes the focused light collimation that sends and pass pin hole 24 and 25 from focused light source 26 and 27.
Ring-like light emitting diode (LED) can be used as mired ring light source 21a and 21b, and the LED of same-type can be used as focused light source 26 and 27.Therefore, as shown in Figure 4, the mired ring light that sends from mired ring light source 21a and 21b forms ring-like light image 101 at the cornea 3 of tested eyes 1, and the focused light that sends from focused light source 26 and 27 forms two some type focused light images 102 and 103 at the cornea 3 of tested eyes 1.The size of ring-like light image (light image of mired ring) 101 represents with the diameter R of mired ring light image 101, and the size of focused light image 102 and 103 with focused light image 102 and 103 apart from F (being called as " point-to-point distance " apart from F in the following description) expression.
30 pairs of mired ring light and focused light imagings that reflect from tested eyes 1 of imaging optical system.Imaging optical system 30 comprises: lens 31 are used to receive mired ring light and focused light from cornea 3 reflections of tested eyes 1; And photodetector 32, being used to form light image of mired ring and focused light image, the optical signal with light image of mired ring and focused light image is converted to the signal of telecommunication then.Photodetector 32 is connected to computing and control unit 40, and the mired ring light image of imaging and focused light image are transferred to computing and control unit 40.Like this, based on image information, computing and control unit 40 obtain the corneal curvature value of tested eyes 1.Conventional two-dimensional imaging equipment can be used as photodetector 32.
40 pairs of computing that is connected with imaging optical system 30 and control units be owing to the measurement error of the corneal curvature that the change in location of tested eyes 1 causes compensates, and by obtaining correct corneal curvature value based on the diameter in detected mired ring light image of imaging optical system 30 places and the light image of focused light image rectification mired ring.In the following description, " because measurement error of the corneal curvature that the change in location of tested eyes 1 causes " is called as " measuring position error ".
Below with reference to the accompanying drawings 5,6,7a, 7b, 8 and 9 describe the accurate Calculation with corneal curvature of remedying of computings and 40 pairs of measuring position errors of control unit in detail.
In Fig. 4, when tested eyes are positioned at accurate measurement point, that is, when being arranged in the focal length place of optical system (20 and 30) of keratometry device, on the cornea 3 of tested eyes 1, form the brightest and mired ring image the most clearly.The size of mired ring image depends on the degree of the corneal curvature of tested eyes 1.If tested eyes 1 be positioned at the measurement light source 21a of mired ring optical system 20 of keratometry device and 21b focal length before or after, then the periphery of mired ring image will fog, the lightness and the definition of mired ring image can weaken.The size of the mired ring image of catching when mired ring image size is positioned at the focal length place with tested eyes 1 is compared increase or is reduced.This will produce incorrect corneal curvature value.On the other hand, focused light projects on the cornea 3 after becoming directional light by collimating lens 22 and 23, thereby no matter how fluctuate the position of tested eyes 1, these focused lights form focused light image 102 and 103 at the place, fixed position of cornea 3.
Fig. 5 illustrates when tested eyes and is positioned at the focal length, focal length place of optical system and the figure of mired ring light image and focused light image when out-of-focus.In Fig. 5, the diameter Rb of the mired ring light image that forms when tested eyes 1 are positioned at the focal length place of mired ring optical system 20 is a standard.The diameter Ra of the mired ring light image that forms when tested eyes 1 are positioned at this focal length is greater than Rb, and is positioned at the diameter Rc of this mired ring light image of formation when out-of-focus less than Rb when tested eyes 1.In the diameter R of mired ring light image, set up the relation of " Ra＞Rb＞Rc ".On the other hand, in each case, the position of focused light image remains unchanged, that is, the point-to-point between the focused light image is much at one apart from F, that is, and and Fa ≈ Fb ≈ Fc.When tested eyes 1 are positioned at the focal length place, the proportional increase of corneal curvature between the diameter R of mired ring light image and focused light image apart from F and tested eyes 1.Compare with the amount that the diameter R of mired ring image increases, point-to-point is very little apart from the amount that F increases.Thereby, proportional with the corneal curvature of tested eyes 1 basically as the focusing distance D (D=R-F) of difference between R and the F.
Fig. 6 illustrates the diameter R of mired ring light image in keratometry device of the present invention and the figure of the relation between the focusing distance D.In Fig. 6, the curve L of form of straight lines is illustrated under the situation at focal length place that tested eyes 1 are positioned at optical system (20 and 30), the relation of the focusing distance D of the diameter R of mired ring light image and focused light image when corneal curvature increases.Last data R of curve L and D are called as the data under the mode standard.Curve L can form according to the following procedure: i) when the cornea 3 of tested eyes 1 is positioned at the focal length place, the diameter R of measurement mired ring light image and the point-to-point of focused light image are apart from F, ii) calculate focusing distance D apart from F, iii) derive the diameter R of mired ring light image and the relation between the focusing distance D according to the diameter R of mired ring light image and the point-to-point of focused light image.In EEPROM (EEPROM) (not shown) of data storage in being installed in computing and control unit 40 with curve L.Curve M
kThe expression corneal curvature is when being k, the diameter R of the mired ring light image that causes and the relation between the focusing distance D because the measuring position of eyes 1 changes.Curve L and curve M
kCross point 121 expression when corneal curvature be the diameter r of the tested eyes 1 of k mired ring light image when being positioned at the focal length place
kWith focusing distance d
k
When corneal curvature is the tested eyes of k when measured, imaging optical system 30 actual detected to the diameter r and the focusing distance d of mired ring light image be positioned at curve M
kOn.And curve M
kThe data of actual measurement under the expression measurement pattern (r, d).Can obtain curve L and go up mired ring light image the diameter r ' under mode standard corresponding, and calculate the difference DELTA r between r and the r ' with focusing distance d.Can determine that then the measuring position changes focusing error Δ r degree and the measuring position error degree that causes.
When the position of tested eyes 1 was positioned at optical system (20 and 30) out-of-focus, the diameter r of mired ring light image reduced.The diameter r of mired ring light image is positioned at curve M shown in Figure 6 like this
kThe left side of last intersection point 121.When the position of tested eyes 1 was positioned at focal length, diameter r increased.Thereby diameter r is positioned at curve M shown in Figure 6
kThe right side of last intersection point 121.
Below, diameter R by using the light image of mired ring and the relation property of focusing distance D are described the method for compensated measurement site error.The method that according to an embodiment of the invention the measuring position error is compensated when Fig. 7 a and 7b illustrate respectively in tested eyes lay respectively at out-of-focus and focal length.
Fig. 7 a has described by obtaining the diameter r that tested eyes 1 are positioned at accurate measurement point (focal length) gauged mired ring light image when locating
k, the process that the measuring position error when eyes are positioned at optical system out-of-focus compensates.In Fig. 7 a, when eyes are positioned at when out-of-focus,, the diameter r of the mired ring light image of extracting and focusing distance d start compensation process from imaging optical system 30 detected mired ring light images and focused light image by being checked.By using curve L and M shown in Figure 6
kCarry out the measuring position compensation of error continuously.Thereby obtain being positioned at the diameter r of accurate measurement point (focal length) mired ring light image when locating when tested eyes 1
k
Equally, Fig. 7 b has described by obtaining the diameter r that tested eyes 1 are positioned at accurate measurement point (focal length) gauged mired ring light image when locating
k, the process that the measuring position error when eyes are positioned at the focal length of optical system compensates.In Fig. 7 b, when eyes are positioned at focal length,, the diameter r of the mired ring light image of extracting and focusing distance d start compensation process from imaging optical system 30 detected mired ring light images and focused light image by being checked.By using curve L and M shown in Figure 6
kCarry out the measuring position compensation of error continuously.Thereby obtain being positioned at the diameter r of degree of accuracy measurement point (focal length) mired ring light image when locating when tested eyes 1
k
In brief, by obtaining the diameter r of gauged mired ring light image
kThe method that the measuring position error is compensated be by the data of the diameter r and the focusing distance d of the mired ring light image of using actual measurement (r, d) and curve L and curve M shown in Figure 6
kRealize.
With reference to figure 7a, proposed when tested eyes are positioned at optical system out-of-focus, by obtaining diameter r
kThe process that the measuring position error is compensated.
When eyes are positioned at optical system when out-of-focus, detect the diameter r (the initial diameter of measuring) of mired ring light image and the point-to-point between the focused light image at imaging optical system 30 places apart from f, obtain focusing distance d (d=r-f) then.Find the diameter r ' (diameter under the mode standard) of mired ring light image by curve L.Be positioned under the situation at focal length place at tested eyes 1, diameter r ' is corresponding to the focusing distance d on the curve L.Diameter r and the diameter r ' under the mode standard under measurement pattern calculate focusing error Δ r (Δ r=r-r ').Determine that then focusing error Δ r is whether in the range of error that allows.
Focusing error Δ r represents because the eyes measuring position changes the error amount of the diameter of the mired ring light image that causes.Focusing error Δ r (Δ r=r-r ') expression in the range of error that allows can obtain believable corneal curvature from the diameter r of mired ring light image under measurement pattern.Usually the range of error that allows is from 0.54mm to 0.72mm.If focusing error value Δ r in allowed band, then can determine the diameter r of mired ring light image under measurement pattern and be approximately equal to the diameter r of the mired ring light image that obtains in accurate measurement point
k
If focusing error Δ r has departed from the range of error that allows, then can find the focusing distance d ' corresponding (value under the mode standard under the accurate measuring distance situation) by curve L with the diameter r of mired ring light image.The focusing error curve M
D 'Be to try to achieve from the focusing distance d ' under the mode standard by interpolation shown in Figure 8 (interpolation) method.Pass through curve M
D 'Can find by the focusing distance d of actual measurement and the difference DELTA d of standard focusing distance d ' (the diameter r of the mired ring light image of compensation of Δ d=d '-d) ".That is, from curve M
D 'Find the diameter r of the mired ring light image corresponding " with focusing distance d ' under the mode standard.Thereby, when focusing error Δ r is not in the allowable error scope, can be " rather than, measure the corneal curvature value of tested eyes 1 according to the diameter r of the mired ring light image of initial measurement according to the diameter r of the mired ring light image of up-to-date compensation.
Obtain focusing error Δ r, determine focusing error Δ r whether in allowed band, and the diameter R of mired ring light image is carried out gauged process all be equally applicable to the situation that the tested eyes 1 shown in Fig. 7 b are positioned at focal length, just repeated no more herein.
After all, " enter into the range of error of permission, " because the focusing error that the variation of tested eyes measuring position causes can be by repeating the diameter r of said process up to the light image of mired ring and the diameter r of the focusing distance d ' replacement mired ring light image of measurement before and focusing distance d and obtain sufficient compensation then with the diameter r of the up-to-date mired ring light image that obtains.Therefore, the diameter r of the mired ring light image after can fully being compensated
k
Correspondingly, can compensate based on the mired ring light image of actual detected and focused light image diameter according to keratometry device of the present invention, and not need independent measurement Error Compensation equipment the light image of mired ring.Therefore, by using,, also can accurately measure corneal curvature apace in measuring process even the position of tested eyes changes according to keratometry device of the present invention.
Fig. 8 illustrates the method for compensated measurement site error and obtains focusing error curve " M
k" method.As shown in Figure 8, below the diameter r of the mired ring light image after being compensated will be described by mathematical formulae
kProcess.Suppose that when focus error compensation, the diameter of n mired ring light image is r
n, its focusing distance is d
n, and the equation of curve L can be expressed as y=px+q, the diameter r under the mode standard
n' and because the focusing error Δ r that the variation of eyes measuring position causes
nCan be expressed as follows:
r′
n＝pd
n+q------------------------(1)
|Δr
n|＝|r
n-r′
n|-----------------------(2)
If focusing error | Δ r
n| departed from the range of error that allows, then the focusing distance d under the mode standard
N+1With r
nRelation can be expressed as follows according to curve L:
Suppose that corneal curvature is respectively k
jAnd k
J+1, accurately the focusing distance at place, measuring position is respectively d
jAnd d
J+1And d satisfies condition
j＜d
n＜d
J+1The focusing error curve M of two model eyes
jAnd M
J+1Be expressed as y=a respectively
jX+b
jAnd y=a
J+1X+b
J+1, then focusing distance is d
N+1The time the focusing error curve M
Dn+1Slope k
N+1Can be expressed as:
By focusing distance difference Δ d
N+1Size compensation and be d at focusing distance
N+1The time according to the focusing error curve M
Dn+1Slope k
N+1The diameter r of the mired ring light image that obtains
N+1As follows:
r
n+1＝r
n+k
n+1(d
n+1-d
n)--------------(5)
Again according to diameter r by formula (3) and (5) up-to-date mired ring light image that obtains
N+1With focusing distance d
N+1Determine focusing error | whether Δ r| is in the range of error that allows.Repeat that said process obtains the diameter of new mired ring light image and the focusing distance of new focused light image is used to measure accurate corneal curvature.Has fixedly curvature k respectively according to shown in Figure 8
jAnd k
J+1With approach d
N+1" focusing distance d
jAnd d
J+1(d
j＜d
N+1＜d
J+1) the focusing error curve M of two model eyes
jAnd M
J+1, by to focusing distance d
N+1Interpolation is tried to achieve focusing distance d
N+1The focusing error curve M at place
Dn+1Before measurement pattern, by diameter r according to the mired ring light image of the measure of the change model eyes of model eye position
jAnd r
J+1And focusing distance d
jAnd d
J+1Obtain curve M
jAnd M
J+1With curve M
jAnd M
J+1Data storages be stored among the EEPROM of computing and control unit 40.
To explain the method for the measurement corneal curvature that the measuring position error is compensated according to the present invention below in more detail.
Fig. 9 shows the flow chart according to the process of the measurement corneal curvature of an embodiment of the invention.Keratometry method according to an embodiment of the invention may further comprise the steps: in allowed limits whether the measuring position of determining tested eyes (S10, S12, S14, S16, S17 and S18), compensate the measuring position error (S20, S22, S24, S26) of tested eyes, and measure corneal curvature (S30).
As shown in Figure 9, determine the measuring position whether in allowed limits step comprise: step S10, detect mired ring light image and focused light image; Step S12, obtain the light image of mired ring under measurement pattern diameter R and measurement pattern under the point-to-point of focused light image apart from F, and obtain focusing distance D (D=R-F) under the measurement pattern; Step S14 obtains the diameter R ' of mired ring light image by the curve L under the mode standard, and wherein curve L has shown the diameter of mired ring light image under mode standard and the relation of the focusing distance under the mode standard; Step S16 obtains focusing error Δ R (Δ R=R-R '); Whether in allowed limits step S18 determines focusing error Δ R.If focusing error Δ R in allowed limits, then carry out keratometry step (S30).If focusing error Δ R is not in allowed limits, then carry out measuring position compensation of error step (S20, S22, S24, S26).
In the step S10 that detects mired ring light image and focused light image, from mired ring light source 21a and 21b and focused light source 26 and 27 cornea 3 emission mired ring measuring light and focusing measuring light, detect mired ring image 101 and focused light image 102 and 103 (see figure 3)s that reflect from cornea 3 in computing and control unit 40 places then to tested eyes 1.In the step S12 that obtains focusing distance D (D=R-F), the point-to-point that obtains the diameter R of mired ring light image and focused light image from detected mired ring light image 101 and focused light image 102 and 103 is apart from F respectively, calculates focusing distance D (D=R-F) from the point-to-point of mired ring light image focused light image under diameter R under the measurement pattern and measurement pattern apart from F.In the step S14 that obtains the diameter R ' of mired ring light image under mode standard, find the curve L of mode standard to go up and the diameter R ' of the mired ring light image that the focusing distance D under the measurement pattern is corresponding, to identify the measuring position error of tested eyes 1.The process of derived curve L is as follows.When the cornea 3 of tested eyes 1 is positioned at the focal length place of measuring light, promptly, when tested eyes 1 are positioned at the accurate measuring position that can accurately measure, measure the diameter of mired ring light image and the point-to-point distance between the focused light image, calculate focusing distance from the diameter of mired ring light image and the distance of focused light image then.Then, derive the diameter of mired ring light image and the relation curve L between the focusing distance.With this profile memory in the EPROM of computing and control unit 40.Among the step S16 of focusing error Δ R (Δ R=R-R ') under obtaining measurement pattern, the diameter R ' under mode standard obtains focusing error Δ R (Δ R=R-R ') at diameter R under the measurement pattern and the light image of mired ring from the light image of mired ring.Determine focusing error Δ R whether in allowed limits step S18 determine whether tested eyes 1 are positioned at the scope accurately measured of can realizing.The scope that allows is normally from 0.54mm to 0.72mm.
The step that tested eyes measuring position error is compensated is as focusing error Δ R not in allowed limits the time, and the diameter of computing and control unit 40 initial detected mired ring light images is compensated.The step of compensated measurement site error comprises: step S20 obtains the focusing distance D ' under the mode standard; Step S22 is from focusing distance D ' derivation focusing error curve M
D 'Step S24 obtains the diameter R of the mired ring light image after the compensation that the difference to D and D ' responds "; And step S26, with the diameter R of mired ring light image " and the previous data of measuring of focusing distance D ' replacement, that is, and the diameter R of mired ring light image and focusing distance D.
Among the step S20 of focusing distance D ' under obtaining mode standard, obtain and the focusing distance D ' of mired ring light image under the corresponding mode standard of the diameter R under the measurement pattern from relation curve L.Deriving the focusing error curve M
D 'Step S22 in, according to the D ' of the focusing distance under mode standard derivation focusing error curve M
D 'In detail, based on by having fixing curvature and near the focusing distance D of focusing distance D '
jAnd D
J+1(D
J1＜D '＜D
J+1) the measuring position of model eyes change the curve M obtain
jAnd M
J+1, by focusing distance D ' interpolation is obtained the focusing error curve M
D ', as shown in Figure 8.Obtain the diameter R of mired ring light image " step S24 the measuring position error of the diameter of mired ring light image is compensated.That is, in focusing error curve M d ', obtain the diameter R of the mired ring light image corresponding " with focusing distance D ' under the mode standard.In step S26, respectively with the diameter R of mired ring light image after the compensation " and the focusing distance D ' replacement mired ring light image under the mode standard under measurement pattern diameter R and the focusing distance D under the measurement pattern.Then, in step S16, based on the diameter R of the mired ring light image after the compensation that replaces " and focusing distance D ', obtain the diameter R ' of mired ring light image under mode standard.And then carry out whether in allowed limits the process of step S18 of the step S17 obtain focusing error Δ R (Δ R=R-R ') and definite focusing error Δ R.Repeat said process, the focusing error Δ R after determining renewal in allowed limits.
The step S30 that measures corneal curvature is when the scope of focusing error Δ R in permission, and the diameter of the mired ring light image after compensating at the diameter under the measurement pattern or to the measuring position error according to the light image of mired ring is measured the corneal curvature of tested eyes.That is to say, computing and control unit 40 receives the diameter R of the detected mired ring of imaging optical systems 30 (as shown in Figure 3) light image and obtain the corneal curvature value of tested eyes 1, perhaps receives the diameter R of the mired ring light image after the compensation " and obtains the corneal curvature value of tested eyes 1.When obtaining the corneal curvature value, the measurement of corneal curvature finishes.
Claims (5)
1. device of measuring corneal curvature comprises:
Mired ring light source is launched ring-like measuring light to tested eye's cornea;
Focused light source focuses on measuring light to two some types of tested eye's cornea emission;
Imaging optical system detects light image of mired ring and focused light image from described corneal reflex;
Computing and control unit, respectively from the detected mired ring light image of described imaging optical system and focused light image obtain the light image of mired ring at the point-to-point between the focused light image under diameter R under the measurement pattern and the measurement pattern apart from F, to because the error of the diameter of the mired ring light image that the displacement of tested eyes causes compensates, and calculate the corneal curvature of tested eyes according to the diameter of the mired ring light image after the compensation.
2. device as claimed in claim 1, wherein, described computing and control unit comprise the curve L that concerns between the focusing distance of the diameter of expression mired ring light image when the focal length place of tested eye's cornea in measuring light and focused light image, and the focusing distance of focused light image is the diameter of mired ring light image and the difference between the distance of the point-to-point between the focused light image; And
Wherein, described computing and control unit
A) calculate focusing distance D (D=R-F) under the measurement pattern according to the light image of mired ring apart from F at the point-to-point between the focused light image under diameter R under the measurement pattern and the measurement pattern;
B) obtain and the corresponding diameter R ' of mired ring light image under mode standard of focusing distance D under the measurement pattern by curve L;
C) according to the light image of mired ring at diameter R under the measurement pattern and the light image of mired ring the diameter R ' under mode standard, obtain focusing error Δ R (Δ R=R-R ');
D) whether in allowed limits to determine described focusing error Δ R;
E) as described focusing error Δ R not in allowed limits the time, the light image of mired ring is compensated at diameter R under the measurement pattern and the focusing distance D under the measurement pattern;
F) as described focusing error Δ R in allowed limits the time, measure the corneal curvature of described tested eyes according to the diameter R of mired ring light image under measurement pattern.
3. device as claimed in claim 2, wherein, step e) comprises:
E-1) obtain and the focusing distance D ' of mired ring light image under the corresponding mode standard of the diameter R under the measurement pattern from relation curve L;
E-2) according to the D ' of the focusing distance under mode standard derivation focusing error curve M
D '
E-3) from described focusing error curve M
D 'Obtain the diameter R of the mired ring light image corresponding " with focusing distance D ' under the mode standard;
E-4) respectively with the diameter R of mired ring light image after the compensation " and the focusing distance D ' under the mode standard substitute the light image of mired ring under measurement pattern diameter R and the focusing distance D under the measurement pattern, return step b) then; And
E-5) repeating step b) to step e) and step e-1) to e-4), up to described focusing error Δ R in allowed limits.
4. a method of measuring corneal curvature comprises the steps:
A) to tested eye's cornea emission mired ring measuring light and focusing measuring light, to detect light image of mired ring and focused light image from described corneal reflex;
B) respectively from the light image of detected mired ring and focused light image obtain the light image of mired ring at the point-to-point between the focused light image under diameter R under the measurement pattern and the measurement pattern apart from F, obtain focusing distance D (D=R-F) under the measurement pattern apart from F from the point-to-point of mired ring light image focused light image under diameter R under the measurement pattern and measurement pattern;
C) obtain and the corresponding diameter R ' of mired ring light image under mode standard of focusing distance D under the measurement pattern by curve L, wherein, by obtaining focusing distance from the diameter of the mired ring light image that when tested eye's cornea is positioned at the focal length of described measuring light, obtains and the point-to-point distance of focused light image, and derive the diameter of mired ring light image and the relation curve L of focusing distance, thereby obtain described curve L;
D) the diameter R ' under mode standard obtains focusing error Δ R (Δ R=R-R ') at diameter R under the measurement pattern and the light image of mired ring from the light image of mired ring;
E) whether in allowed limits to determine described focusing error Δ R;
F) as described focusing error Δ R not in allowed limits the time, the light image of mired ring is compensated at diameter R under the measurement pattern and the focusing distance D under the measurement pattern;
G) as described focusing error Δ R in allowed limits the time, measure the corneal curvature of tested eyes according to the diameter R of mired ring light image under measurement pattern.
5. the method for measurement corneal curvature as claimed in claim 4, wherein step f) may further comprise the steps:
F-1) obtain and the focusing distance D ' of mired ring light image under the corresponding mode standard of the diameter R under the measurement pattern by curve L;
F-2) the focusing distance D ' derivation focusing error curve M under the mode standard
D '
F-3) from described focusing error curve M
D 'Obtain the diameter R of the mired ring light image after the compensation corresponding " with focusing distance D ' under the mode standard; And
F-4) respectively with the diameter R of mired ring light image after the compensation " and the focusing distance D ' under the mode standard substitute the light image of mired ring under measurement pattern diameter R and the focusing distance D under the measurement pattern, return the step c) in the claim 4 then; And
F-5) repeating step c) to f) and step f-1) to f-4) up to described focusing error Δ R in allowed limits.
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| KR1020080117273A KR101056960B1 (en) | 2008-11-25 | 2008-11-25 | Corneal curvature measuring method to compensate for measurement position error and optometry using the same |
| KR10-2008-0117273 | 2008-11-25 |
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| CN102715886A (en) * | 2012-06-21 | 2012-10-10 | 宁波明星科技发展有限公司 | Computerized refractometer capable of automatically compensating corneal curvature measuring accuracy and corneal curvature calculation method |
| CN103340596A (en) * | 2013-07-20 | 2013-10-09 | 太原中北新缘科技中心 | Device and method for measuring corneal curvature |
| CN104095610A (en) * | 2014-07-25 | 2014-10-15 | 上海展志光学仪器有限公司 | Optical system for measuring eyes diopter and cornea curvature radius of human |
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| CN104887176A (en) * | 2015-06-18 | 2015-09-09 | 苏州四海通仪器有限公司 | Handheld independent vision measurement device and method |
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| KR100320670B1 (en) * | 1999-05-14 | 2002-01-17 | 김현수 | Device for measuring the corneal curvature |
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| CN102715886A (en) * | 2012-06-21 | 2012-10-10 | 宁波明星科技发展有限公司 | Computerized refractometer capable of automatically compensating corneal curvature measuring accuracy and corneal curvature calculation method |
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| CN103340596B (en) * | 2013-07-20 | 2014-08-06 | 太原中北新缘科技中心 | Device and method for measuring corneal curvature |
| CN104095610A (en) * | 2014-07-25 | 2014-10-15 | 上海展志光学仪器有限公司 | Optical system for measuring eyes diopter and cornea curvature radius of human |
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| CN105581770A (en) * | 2014-11-12 | 2016-05-18 | 尼德克株式会社 | Ophthalmic device and ophthalmic treatment method |
| CN105581770B (en) * | 2014-11-12 | 2019-10-11 | 尼德克株式会社 | Ophthalmoligic instrument and ophthalmic procedures method |
| CN104887176A (en) * | 2015-06-18 | 2015-09-09 | 苏州四海通仪器有限公司 | Handheld independent vision measurement device and method |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN101732030B (en) | 2012-05-30 |
| KR101056960B1 (en) | 2011-08-16 |
| KR20100058756A (en) | 2010-06-04 |
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