CN1069873A - Ophthalmic diagnostic apparatus and method - Google Patents

Abstract

A kind of ophthalmic diagnostic apparatus, it determines cornea shape by a picture is projected on the cornea.The projected graphics of discrete point source separately is folding, make figure towards the coaxial projection of eye, and gather the reflected light of cornea, this instrument does not require the figure light source near eyes, and the real time imaging of accurate demonstration cornea shape can be provided to the doctor.Therefore the doctor can face visual angle film shape before art, monitor its variation in art, and postoperative can also monitor.In one embodiment, the real image of point source figure becomes in the object lens of instrument, and very near its front surface, makes object lens as field lens thus, and enlarged the visual angle of instrument.

Description

Ophthalmic diagnostic apparatus and method

The present invention relates to ophthalmology analysis and diagnostic system, particularly to human eyes structure such as cornea, the shape of crystal and retina etc. obtains accurate the survey and shows.For example, can be used for ophthalmologic operation and common ophthalmology diagnosis and treatment, be used to measure, calculate and show the shape of the selected section of cornea according to the designed instrument of the present invention.

One of groundwork of eye care professional could (this is meant ophthalmologist and optometrist) is the refractive power that detects the optical system of eye.Because is very main along the light path that enters eyes in the refractive index variation that light at first takes place on air and tear membrane interface, this interface approximately is on the anterior epithelium of cornea surface, and the shape of therefore accurately measuring the cornea epithelial surface is to estimate the key of eye ametropia force to be measured.

Ophthalmologic professional has felt satisfied to the measurement result that obtains from traditional measurement of corneal astigmatism reading.Measurement of corneal astigmatism reading (being called for short the K reading) is corresponding to the rate in the wrong of corneal epithelium and tested eye center optical axis joining.The K reading represents with refractive power that usually refractive power is directly proportional with the inverse of rate radius in the wrong.The K reading is corresponding to any rate in the wrong along two light by this point of corneal epithelium.Usually these two light are corresponding to main semiaxis and time semiaxis, just the nose one temporo axle (trunnion axis) and the last-lower shaft (vertical axis) of eyes of eye.

Since the eye care professional could overriding concern be central shaft to vision, so only provide along perpendicular to the K reading of two rate measured values in the wrong of the primary and secondary semiaxis of the optical axis just expression to the estimation of the refractive power on the most important light path in the human eye.

So far, ophthalmic industry is approximately eyeball surface the combination of a sphere and a cylinder always, thus with 20/20 dioptric as visual standards.This being similar on the joint of the anterior surface of cornea and the optical axis is correct.As everyone knows, this being similar to can not be represented the radially outer result from the center optical axis towards limbus of corneae, and this limbus of corneae is roughly the outermost edge of cornea, is the transition point between cornea, sclera and iris herein.

Existing have several measurement anterior surface of cornea near the position of limbus of corneae and the instrument of central area, forms but the result that these instruments produce supposes normally that eyeball can be approximately by sphere and cylinder.In a sense, there is error in these instruments at approximate anterior corneal surface vpg connection, because anterior corneal surface converges and at a bigger regional internal diffusion towards limbus of corneae.

Noticeable exception is the instrument of those utilization confocal microscopies, and they measure real rate in the wrong, and do not do simple hypothesis.But the system of utilization confocal microscopy has the very limited visual field, and its visual field is significantly less than whole anterior corneal surface.These systems must carry out a series of measurements, and section technology of utilization group subsequently or border cooperate algorithm that each section combined.Insert appears in the border (rather than inner) that this splicing must relate at image.To carry out the number of times insert that measurement produced seldom opposite with those, and confocal technology is to do a large amount of measurements under situation about not finishing simultaneously.Although a series of measurement can promptly be finished, such as everyone knows, the non-autonomic movement of eyeball occurs within the millisecond, and it is faster than the speed that gathers total data with confocal technology, and this will draw error.

Because limited practice sites measured on can only the corneal front surface, so when demonstrating a successive figure according to measurement result, just must utilize interpolation.In most of instruments that present ophthalmic industry uses, when measuring, the measurement error of corneal front surface seldom takes place, but error but usually occurs in the process of utilizing the successive cornea cross-sections shape of interpolation preparation demonstration.

According to system of the present invention, instrument and method can the corneal shape and other structure of eyeball carry out high-precision real-time measurement, calculating and demonstration.

Measure according to a series of given position of interpolation of the present invention on can not only the tear film surface of corneal, and can finish above-mentioned measurement in real time by the mode of separating the non-sex-limited common differential equation of describing this surface.This method also can provide the derivative on high several rank, and it is used for producing successive cornea shape.

Except improving the K reading and reducing the error of approximate anterior surface of cornea vpg connection, method of the present invention and instrument can also provide real cornea shape in real time.In real time the meaning of measuring is meant the variation of observing and discern cornea shape than the observation ability of eye care professional could soon, and the common used time is approximately one second or still less.

The instrument of existing several can the measurement in real time (as above definition) cornea transverse shape, they combine scanning, confocal microscopy and image reorganization art.That is to say, use the pocket of selecting on the confocal microscopy corneal transverse section earlier and carry out a series of high-resolution measurements, and the shape of each piece transverse section analyzed, then their and scanning patter of obtaining are separately in addition compiled, so that a proximate shape to be provided.

The persistent movement of known person eyeball is the nonautonomy again of autonomy, and the activity of these motions and integral body does not have necessary relation, thereby when the different fragments with the scanning corneal scanned, the motion of eyeball and distortion can cause producing error.Utilize the high-velocity scanning machine can reduce this error, but can not eliminate fully.

The advantage of above-mentioned scanning is to carry out a large amount of measurements in a pocket, therefore can produce very high-resolution boundary image accurately to the zone that is limited.In order to obtain the comprehensive equal resolution from the limbus of corneae to the limbus of corneae, just need the cumbersome apparatus of a cover multiple light courcess and many measurement points.Because the effort of piecing together utilizes scanning can realize high-speed and high local definition, is uncertain but its cost is all these.

In one embodiment of the invention, this instrument can be realized higher local resolution, and can not make its overall accuracy be in nondeterministic statement.This realizes by carrying out the integral body measurement, because the visual field of this instrument is adjustable.Like this, in order to obtain the full detail of relevant cornea shape, only need carry out one-shot measurement rather than a series of scanning.And the high-resolution that will obtain a certain special area on the anterior corneal surface is when measuring, and one embodiment of the present of invention can be retracted to the measurement of same number in the finite region that is centered on by given cornea district.

This method is similar in semi-conductor industry comes the processing circuit plate with photoetching technique (plate-making of taking pictures), promptly a big model little by little is focused into the zonule, to produce compact and little effect.In a preferred embodiment of the invention, zoom technology is applied to determining the visual field, and a kind of corresponding zoom technology is used for broadening one's vision, to be full of display monitor.

In order to implement ophthalmologic operation, as: radial keratotomy, cornea epithelial transplantation art, Keratimileusis, Keratophakia, large-area laser break away from art or other operation, and the problem that the ophthalmologist is concerned about most is exactly accurately and reliably to measure the shape of cornea.This not only is important before operation, and during cornea shape develops in art and all be very important in the agglutination after surgery.

Characteristics of the present invention are before not only can satisfying art, the required full-shape film of postoperative is measured, but also the high resolution graphics of reflection surgical effect can be provided in art.For example, in order in radial keratotomy, to measure notch depth, the full degree of depth that the surgeon wants the degree of depth that the chosen in advance diamond blade stretches out from dissecting knife and blade to insert cornea.The surgeon keeps uniform thrust in view of the above on point of a knife when dissecting knife streaks cornea, and believe that the shape of cornea in operation process can not damage.Have been found that cornea often damages when making radial keratotomy.Therefore just require the surgeon to determine the degree of depth of radial slot by supposition and subjective intuition.Because distortion increases, so for each otch that continues, it is uncertain that its notch depth becomes gradually.

In one embodiment of the invention, make the surgeon can before operation is about to begin, at first detect cornea shape, and in art, can observe the incision degree of depth of each otch, so that the measured value according to actual otch is little by little adjusted blade according to need, can provide comprehensive measurement later on once more to the post-operative cornea shape.

Another problem that the present invention emphasizes is to use a kind of measuring device in operation process.Keratometer (as the Terry keratometer) has been used to hands at present and has stated in the chamber, but their effect not only is restricted by the range of information that it can provide, but also be subjected to precision and in measurement patient's eyes to doctor's the restriction that obstruction caused.Causing a reason of this obstruction is the zone that a lighting point need be provided, and keratometer detects these luminous points of coming from corneal reflex then.

In order to obtain near reflection or the data point the optical axis of center, keratometer need be provided with such lighting point near the optical axis of center.These lighting installations are very heavy, can and be arranged on the path of doctor near the art human eye.In one embodiment of the invention, these illuminators are arranged on the place that a suitable segment distance is arranged from eyes, thereby the problems referred to above have been solved, the image of illuminator is folded in operating microscope or other imaging device by beam splitter, rather than with illuminator along optical axis setting, the present invention penetrates a real image of lighting point in the position that needs illuminator.This position is between the object lens of the operating microscope that patient's eyes and instrument or instrument are connect.The relevant surface reflectance from eye of this real image is parallel to the lighting point that the reflection of instrument optical axis comes and is gathered and detect by instrument.Produce the transverse section that preferably has the selected eye of doctor and the real-time demonstration of digital topological data then.

An importance of the present invention is, the optical system in the system is used the field lens of object lens as image, and will be arranged in system object lens back object lens Fourier's plane conversion to a relaying of instrument, remote position.This just provides chance and space length, with one or two light source figure at the Fourier plane of object lens and the planar relaying of Fourier or pass between the change place and fold.In one embodiment, as described below, two different light source figures utilize two different beam splitters to fold in the optical axis of instrument.

In this respect, for doctor's real-time inspection, adopt two independent display.A qualitative figure who is used for showing a facade profile, this obtains from a series of coaxial apertures; Another expression be the cross-sectional view that is used for the cornea shape of qualitative analysis, it is to obtain from the selection figure of discrete luminous point.

Application of the present invention is not limited only to improve radial keratotomy.Any surgical operation of the refractive power of change eye that needs all can obtain income from show operation process and effect exactly.More generally, various operated eyes can both obtain huge benefit from method of the present invention and instrument.And this instrument can be used for diagnostic purpose purely, for example the apolegamy adherent lens that can use of optometrist.

The various embodiment that describe below have different structure according to surgical actual needs.Its common characteristic is can both provide high-resolution in its place of arrival, keeps computational speed and overall accuracy simultaneously, and can relax its limiting resolution at any time.

The objective of the invention is for strengthening instrument, the system and method that ophthalmic diagnosis and operation provide a kind of high speed, accurately monitor cornea-epithelium and inner skin surface and other surface configuration in real time.

From below in conjunction with the accompanying drawing description of a preferred embodiment, can understand other purpose of the present invention, advantage and feature clearly.

Fig. 1 be represent according to a preferred embodiment of the present invention the eye diagnosis system and the schematic diagram of the master-plan of instrument, there is shown a series of optical elements that are used for this embodiment.

Figure 1A is the amplification detailed schematic diagram of some part in the system shown in Figure 1.

Figure 1B is and the similar view of Fig. 1, but it has represented a kind of system form that changes a little, has wherein enumerated distance and other optical value of can be used for this system.

Fig. 2 is the schematic diagram of instrument and the bonded some parts of operating microscope in the presentation graphs 1, and it is preferably with a simple additional camera interface (as C type interface).

Fig. 3 is the sketch map of an example of expression television indicator, and this display can provide the information result of being collected by instrument of the present invention.

Fig. 4 has represented one group of qualitative information, and they can be shown to the user of instrument.

Fig. 5 has represented a kind of surgical microscope of routine, and embodiment shown in Figure 2 can use thereon.

Fig. 6 has represented the simple graph of the point source of one group of linear array, and these point sources can be used to measure cornea according to embodiments of the invention.

Fig. 7 is and the similar sketch map of Fig. 6, represented to can be used for to measure the another kind of figure of the point source of cornea.

Fig. 8 is the concentrically ringed sketch map of expression light, and luminous energy projects on the cornea with Fig. 6 or figure shown in Figure 7 simultaneously, strictly as doctor's qualitative information, is used for comparing with the observation measurements result who obtains by Fig. 6 or figure shown in Figure 7.

Fig. 9 has represented the distortion situation of figure shown in Figure 7, can and analyze with instrument readings of the present invention, to measure cornea shape.

Figure 10 is another sketch map, represented by the reflective graphics that projection produced shown in Figure 8, and the distortion of reflective graphics.

Figure 11 is the sketch map of the reflective graphics of expression discrete point light source, and this figure can receive from measurement projection shown in Figure 6.This figure has also represented the example of secondary reflection, and it occurs in inner skin surface, i.e. the back side of cornea.

Figure 12,13 and 14 is example graph, represent light intensity and passed relation between the distance of cornea, this relation is used for reflective projection shown in Figure 11 and expresses analysis to these reflections, to obtain the information on relevant anterior surface of cornea and back of the body surface (being epithelial surface and inner skin surface).

In the accompanying drawings, Fig. 1 is that expression is according to the schematic diagram that is used for the system of optical elements of ophthalmic diagnosis and analysis of the present invention.

This system represents totally that by label 10 it comprises: illuminator or light source 12; Be used to produce the template 14 of discrete light source figure, have eyelet in the plate, eyelet is formed certain figure; An indeformable spectroscope 16; One with the image projection of target 14 lens 18 to the plane of delineation 22.As plane 22 near or coincide with the system of object lens 20.22 purpose is to make object lens 20 as field lens to the position with image projection, and it makes the light that forms image bend towards patient's cornea 24.

As shown in Figure 1, focusedimage 22 is real images, and it is formed on the place of a certain plane or close lens 20, and between lens 20 and patient.Real image preferably becomes in lens 20, but it also can be positioned at lens nearby (promptly at former millimeters places of lens).In this real image, each point source 22a penetrates a light cone towards patient.Like this, each the point source 22a in the real image produces numerous specular reflection point on the front surface of the cornea 24 of sick eye 26.As explained later, the F number of lens 20 has determined the maximum area of the cornea of institute's energy measurement.Object lens are as field lens, and the patient's eyes cornea must be positioned on the focal length of lens 20.This can guarantee that the light that is parallel to the instrument optical axis of returning from eye reflex is by on the focal length point of poly-lens 20 to lens 20 back.As described below, this can make light echo be subjected to the eyelet effect, so that only select those nearly axis oculi light.This can make system determine to have on the cornea test point one by one of light reflection.If lens 20 it goes without doing field lens, then the outermost luminous point of this figure will be from corneal reflex.As field lens, lens 20 are folded to human eye with outer side spot effectively.

The best long enough of the focal length of lens, so that unobstructed, a suitable distance is provided between instrument and patient, and for the doctor with undergo surgery suitable work space is provided.

When object lens 20 during as field lens, its F number is most important, because it will determine that light can be parallel to the maximum angle that is become with optical axis of optical axis reflection from cornea.If obtainable F/2 eyeglass on the employing market, then the effective range on cornea is the zone that diameter is approximately 3mm.Utilize the less eyeglass of F number, then the effective range on the cornea will increase pro rata.

Shown in Figure 1A, each real image point source 22a produces a reflected light 22b at least, and this reflected light is parallel to the central shaft of object lens 20, and as shown in the figure, all axial reflection ray 22b are parallel to each other.For each point source 22a, axially reflection ray 22b is unique, unless anterior corneal surface has very significantly local damage or distortion, in theory, this can cause from the cornea at interval position to send axial reflection ray 22b more than one.

Other reflection ray of cornea will arrive and scioptics 20, but as following see, have only those very could pass through system near parallel reflection ray, be used for doing analysis.Those are used to provide the light of data point and luminous point and the original figure by template 14 projections is compared, so that provide the data that to be found the solution and then to determine cornea shape.

Shown in the general illustration of Fig. 1, reflection ray passes lens 20 conversely, and scioptics 18, spectroscope 16, aperture or spatial filter 30 and another lens 32 are focused on a detector or the plane 34 of taking pictures at last then.

The rate in the wrong of cornea 24 forms a target as 22 the virtual image 93.In article " new method of keratotomy and the comparison of effectiveness thereof, first " (author S.G.EL Hage, the vision that the U.S. vision that is published in November, 1971 detects association detect and the USA Magazine of archives on) in, EL Hage points out, to only allow the light that is parallel to optical axis pass through at the back focal plane of object lens 20 or the aperture on the Fourier plane or spatial filter, thus the light from set point in the virtual image 93 will be limited in the light that specified point reflects back from cornea 24.In this embodiment, need lens 18 to be set, be used for Fourier's plane conversion of lens 20 is arrived aperture 30 in the compartment of terrain, back of object lens 20.Aperture 30 is arranged in the planar image of Fourier, and it equally only selects those light that is parallel to optical axis that comes from cornea 24 reflections.

The rear portion lens 32 of system focus on the distortion image of the virtual image 93 of point reflection light detector or take pictures plane 34.

Shown in Figure 1A, the plane 34 of taking pictures has a central axis C, and it is positioned on system's optical axis of (comprising object lens).Ideally, this axis is answered the center or the optical axis V of as close as possible cornea.If these axis stagger significantly, the many reflected light that come from cornea can not instead pass system so.Discussed herein is, and these axis of supposition overlap, but have between them under the situation of little skew (as 1 millimeter), also can obtain enough information materials.If the light echo of reflection point is positioned on the central shaft C on the plane 34 of taking pictures, light is to send at the optical axis of cornea with an orthogonal direction upper edge cornea on the plane 34 of taking pictures at least so, and this orthogonal direction is shown in the center line direction on the figure paper plane of Figure 1A.

Equally, if specific luminous point focus on take pictures plane or the detection faces 34 apart from central axis C have distance X ' the place, then this distance corresponding to and the distance X of ratio pip on cornea linearly, distance X is the distance of light 22b to optical axis V.If measure a degree of depth Y-from arbitrarily selected datum level d to cornea on the distance of pip, and measure a series of such X and Y value, so just can separate a differential equation, determining Y, thereby provide cornea in this direction or along the rate in the wrong on main shaft (promptly on Figure 1A plane) as the X function.Similarly, can carry out measurements and calculations, to provide the information of the diagnosis and the required relevant cornea shape of performing the operation along the normal axis (for example nose-temporo axle and last-lower shaft) of cornea.

Y value shown in Figure 1A can derive from the information material of the deformation extent of relevant reflection light point figure and the spatial relationship between luminous point, and these information by with real image 22 in original projecting figure and structure compared and obtained.For this reason, with parallel rays 22b among Figure 1A is example, it is that real image light source 22a from Figure 1A right side sends, if crooking rate of cornea is milder at this pip, the tangent line and the optical axis that are this point on the cornea constitute more shallow angle, then parallel rays 22b can come from a different real image point source, and it is arranged in the more left side of figure.Right endpoint light source 22a also can be only sends reflected in parallel light from another point of cornea, and this point is positioned at the more right side of Figure 1A.Each the reflective spot available electron method that is detected on the plane 34 of taking pictures is discerned, and comes down to count the luminous point in the array.

Fig. 6 has represented the example of a projected light figure, and it can be used in the system and method for the present invention.In this simple graph, a vertical linear arrays 40 is by horizontal linearity array 42 quadratures, and its intersection point is corresponding to the eyes optical axis.This is a simple figure, imagines according to Figure 1A.

Fig. 7 shows a comparatively complicated dot pattern 44.This is the asterism of the linear array of luminous point, and it has provided the data of more a plurality of points on the cornea.It can determine the gabarit of a five-pointed star or any similar pattern, but preferably it has some means of the rotational orientation that shows it.It can have the starlike profile of odd number of apexes, makes its asymmetric performance help to discern reflection light point to be detected, and its method is that reflection light point and primary projecting figure 44 are compared.Fig. 9 has represented a reflective graphics 46, and it can be generated by figure shown in Figure 7 44, but its figure is to come from the cornea reflection with distortion to a certain degree.

Fig. 1 has schematically shown detector or the plane 34 of taking pictures is connected on the microprocessor 50.Microprocessor can be connected to a display device, for example a cathode ray tube (CRT) monitor 52.Receive by microprocessor 50 from the data of systematic collection, and analyzed.Each detected luminous point is all relevant with the position of specific luminous point in the light source figure.Each luminous point is measured the X value, promptly from optical axis V to cornea on the distance of pip of this luminous point.It calculates to determine by direct proportion according to the known amplification of system.Each reflection light point all has an X value of representing the systematic optical axis distance.Must distinguish each linear array of the luminous point in the image and to be analyzed, and want doing mathematics approximate.If adopt the starlike array of complex figure 44(shown in Figure 7), will analyze and calculate along every line of figure.

Utilize method and system of the present invention, analyze the approximate mathematical shape of determining cornea by one of corneal surface hypothesis.Then this is analyzed approximate being updated in the differential equation, and carry out the suitable match of certain form, to determine to satisfy the coefficient of this differential equation.In a preferred embodiment of the invention, carried out the nonlinear least square match.

This this work is carried out in microprocessor 50.This microprocessor has the program of examination detector 34 detected a large amount of X values, all these is worth in substitution differential equations, and draws relational expression as the Y of X function.

Being suitable for a kind of differential equation of this purpose is:

dy/dx＝-（ (a（y）-x)/(b（y）-y) ）±[（ (a（y）-x)/(b（y）-y) ） ²+1] ^1/2。Wherein y is the degree of depth of pip apart from datum level (as the datum level d among Figure 1A), and x is the distance of pip apart from the optical axis, and (a, b) expression is the coordinate of the real image position of lighting point in the space.A represents that specific lighting point 22a(sees Figure 1A) apart from the distance of the optical axis, b represents the degree of depth of this lighting point apart from datum level d.

The differential equation that is used for this process is not new.This is a universal equation that can be used to represent any surface configuration, and this equation was described in the 897th page of above-mentioned EL Hage article.In this article, EL Hage has discussed this various uses that is used to separate the universal equation of anterior corneal surface shape.And he has also discussed the relation of a keratoscope ring in anterior corneal surface shape and the crooking rate of cornea meter.Therefore, this derivation itself does not belong to a part of the present invention, but at this it is incorporated into the application as known technology reference in addition.

The 909th page of this article, EL Hage has showed a kind of optical system, it projects a picture on the cornea, be used for measuring the reflected light on the cornea, his light source and the real image among the present invention are similar, and he is arranged on a series of optical elements between light source and the human eye, is included in a beam splitter is set between object lens and the human eye.

Below numerical table listed some exemplary value, they can be used to measure the X value, and obtain a relational expression y=f(x corresponding to the anterior corneal surface of a given patient in conjunction with known a and b value).

Referring to Fig. 1, lighting source 12 can be a visible light source again, in a preferred embodiment of the invention, does not have a coaxial surgical laser.For example, can use a kind of electric filament lamp.Template or target 14 can be laser instrument or photoetching hole, and its aperture is approximately 30 microns.Spectroscope 16 can be simple non-distortion plate glass spectroscope, and it has reflectance and is about 50% face coat.

In a concrete enforcement just of the present invention, the mutual relation between lens can be selected by Figure 1B.In Figure 1B, provided the focal length and the diameter of the distance between the lens that are used for this embodiment, various lens.For example, object lens to the distance of human eye at least about there being 110 millimeters.Give other relation and distance, comprise the diameter of aperture or spatial filter 30.The system of Figure 1B has shown a single light source 12, and it projects a figure and is folded in the optical axis of instrument.

The detector or the plane of taking pictures for example can comprise a highdensity photodetector array.

As shown in Figure 1, microprocessor 50 is connected to a display monitor 52.A kind of doctor's of offering real-time display graphics 54 has been shown among Fig. 3.At the left upper quadrant of screen, provided patient's recognition data, and K reading and one-tenth-value thickness 1/10.The more detailed example of this information is shown among Fig. 4.

The lower-left of screen display 54 and right lower quadrant show epithelium and esoderma cornea surface at facet A and B(shown in the plane graph of screen right upper quadrant) degree of depth reference value.The position of these facets is preferably selected by the doctor.Be input to microprocessor 50 then.

Deformation pattern 56 shown in the right upper quadrant of Fig. 3 obtains from one second projection, and it preferably is used in a preferred embodiment of the invention.As shown in Figure 1, one second projection folds into by second spectroscope 60 on the axle of lens combination, and the light of template or mask 64 is passed in 60 reflections of second spectroscope from lighting source 62.Mask 64 has a plurality of concentric round otch, so that project concentrically ringed real image before cornea, as the figure 22 of point source.

Fig. 8 has schematically represented the figure 55 that a series of concentric circulars are formed, and it is by template 64 projection pearls.Detector 34 can be pixel (Pixcel) array that density is very high, and it can receive and detect the image of two reflections simultaneously.The concentric circular figure can come with the resolution of point source figure by the profile (Contiguity) of each ring of light.The software that little processing 50 is adopted can be spot-check each pixel that receives light and vouch that the pixel that whether is close to is also receiving light.If so, just indicate the profile of a ring of light; Otherwise the figure of point source (shown in Fig. 6 and 7) will not show tangible profile.Like this, microprocessor 50 can be distinguished and be analyzed each figure respectively.Perhaps, in another embodiment of this system, additional detector and the line bonus light microscopic of taking pictures is set together, is used for the image branch of the image of these continuous rings of light with discrete point source come.

When adopting traditional keratoscope or pula west Duo Shi ring, the ring of light produces corneal reflex with one heart, and this reflective graphics is out of shape corresponding to the distortion of anterior corneal surface.This can cause choppy for example shown in Figure 3 56.

Fig. 1 shows two different light figures is folded on the lens 18 and 20 axle in the system, sets up opposite polarity for two different images giving projection, needs to adopt polarizer 66 and 68.

A polarizer that is used as analyzer (analyser) 94 is rotary, to select wherein any one projected image.

Fig. 2 has represented another embodiment, the some of them element with embodiment illustrated in fig. 1 in identical, but structurally it directly connects a surgery microscope.Surgery microscope can be made by Weck, Nikon, Topcon, Zeiss, Nidek or Wild company, and it generally includes the additional interface or the screw connection of a standard of using for camera.Fig. 5 has represented a typical Standard surgical microscope.Additional interface 70(such as C type interface) be shown among Fig. 5 and and schematically indicate by dotted line among Fig. 2, the system that it will include element 12,14,34,32,18 and 16 is connected on the interface or optical tubes 72 of surgery microscope.Usually, surgery microscope has a series of eyeglasses, so that produce a picture on picture plane 74, this has the distance of standard as the additional interface on the plane separation interface 72, so that the 35mm video camera of a station symbol standard is linked on the surgery microscope 96.Therefore, in this embodiment of the present invention, object lens 20 have been removed, and replace the object lens 98 of surgery microscope 96.The focal length of lens 18 is adjusted to and can be aptly the Fourier plane 95 of the object lens 98 of surgery microscope be transformed on the aperture plane 30.Nearly all others of present embodiment all are similar to previous embodiment.A possible exception is if the F number of the object lens of surgery microscope 98 is not enough to hang down to obtain required effective range on cornea, just must add a plurality of point sources 97 so on a plurality of positions in the object lens outside.These additional optical can be produced by pinhole mask that is subjected to illumination or optical fiber.

Figure 11 to 14 shows an aspect of system of the present invention, and it can side by side detect and show corneal epithelium surface and corneal endothelium surface in real time.Figure 11 shows a kind of reflective graphics 80, and it develops from simple graph shown in Figure 6, appears on the detector 34, and it comprises the array of light spots of pair of orthogonal linearity.As shown in figure 11, detected each luminous point 82(it not on optical axis) a secondary reflection picture point 84 will be arranged, the very weak light intensity that it has from the cornea back side or inner surface emission comes.Detected array for example produces the curve that a light intensity is adjusted the distance, as shown in figure 12.Clutter 88 to a certain degree appears in the reflection that the spike 86 expression discrete point light sources of high light intensity take place from anterior surface of cornea between spike.Near each high light intensity peak 86, there is a light intensity secondary peak or a boundling 90, the luminous point low-intensity reflection that takes place on its expression corneal endothelium surface apparently higher than clutter 88.Curve shown in Figure 12 is easy to be extracted or filtering, so that high light intensity peak 86 is discerned with low light intensity peak 90 and separated.As those of ordinary skill in the art is to understand, the spike that program in the computer can be at first be higher than predetermined threshold from those wave amplitudes is determined signal constituent, remove composition from signal then, to obtain a kind of signal that only comprises low light intensity spike 90 and clutter 88 corresponding to high light intensity spike 86.In order to discern the position of low light intensity spike 90, only need repeat the process of the high light intensity spike 86 of above-mentioned identification, but will adopt lower threshold value.In certain embodiments of the present invention, verified to amplify those signals of therefrom having removed high light intensity spike 86 in advance with the method for electronics be highly effective, and the purpose of doing like this is to help to distinguish low light intensity spike 90 and clutter 88.It is very important understanding more following, and this exactly selection course is very easily by observation, and the concrete amplitude of spike 86 and 90 is also important like that not as their physical location.

Figure 13 and Figure 14 have represented the curve that the light intensity of front-reflection on the anterior surface of cornea and back reflection on the rear surface is adjusted the distance respectively.

In case known and once determined the position, then utilized above-mentioned nearly plan method just can calculate the shape and the rising point of anterior surface of cornea and inner surface, and can provide two groups of data to the doctor with secondary reflection and in Figure 13 and 14.Similarly, as shown in Figure 3, in two quadrants in the bottom of display screen, the numerical value that the transverse section is provided and has matched.

It should be understood that in drawing and description and claims, term " on ", D score, " bottom ", " top ", " left side " and " right side " only be illustrated embodiment for convenience of description, rather than the orientation of restriction instrument or element.Accompanying drawing is not drawn in proportion.In addition, term " object lens " is object lens or the object lens of surgery microscope or the afterbody focus lamp (when this instrument be used as surgery microscope a part of) of expression in this instrument.

Above preferred embodiment is that ultimate principle of the present invention will be described, is not to limit scope of invention.Those those of ordinary skill in the art can propose other embodiment or above preferred embodiment is changed, but this can not exceed the application's inventive concept that claim limited and scope.

Claims (30)

1, a kind of ophthalmic diagnostic apparatus that is used for determining cornea shape comprises:

Object lens as the optical element of instrument, it is arranged on the optical axis of instrument,

The device that is used to throw the figure of discrete point source separately and on position between object lens inside and the eyes, forms a real image of point source figure,

Utilization is expanded the device of effective range on the cornea as the object lens of the field lens of described graph image,

Be used to select and gather described figure at the reflected image of paraxial reflection on the cornea and detect the device that the reflection position that reflects takes place for each point source basically on cornea, it comprises and being used for Fourier's plane conversion of object lens device to a relaying position of instrument, it has and is arranged on described relaying position and is used to limit the paraxial catoptrical iris apparatus of being gathered from cornea, this iris apparatus and object lens keep at a certain distance away

Be used to analyze the reflected image that collects and with itself and the device that the not choppy that is throwed is compared, relative position that comprising compares with the figure that is throwed analyzes the pip light source and dimensional orientation and

Be used for deriving from mathematics a kind of accurate proximate device of anterior corneal surface shape, this being similar to will produce the graph image that collects.

2, according to the instrument of claim 1, the figure that it is characterized in that discrete point source separately comprises the linear order of one or more.

3,, it is characterized in that the figure of discrete point source separately comprises a kind of asymmetric shape with multiple row point source according to the instrument of claim 1.

4,, it is characterized in that this asymmetric shape comprises the star with odd number of apexes according to the instrument of claim 3.

5, according to the instrument of claim 1, the device that it is characterized in that being used for expanding effective range comprises the device that is used for point source image is arranged on object lens, so that use object lens as field lens.

6, according to the instrument of claim 1, it is characterized in that combining a surgery microscope with additional camera interface of standard, described ophthalmic diagnostic apparatus is connected on the surgery microscope by additional camera interface, makes the object lens of the object lens of surgery microscope as this ophthalmic diagnostic apparatus.

7, according to the instrument of claim 1, it is characterized in that comprising a lighting source, a template or a mask that is used to allow light from light source pass, be arranged on and be used for pattern reflection that will projection on the light path of projection light of self-template and fold into light-dividing device on the light path with the light shaft coaxle of instrument, this light-dividing device is arranged between iris apparatus and the object lens, also comprises the Optical devices that are used for the figure of projection is focused on the real image of patient's eyes front between light-dividing device and patient's eyes.

8, instrument according to claim 7, it is characterized in that also comprising and be used to receive from the device of cornea retroeflection by the reflective graphics of described Optical devices and light-dividing device, described relatively Optical devices are positioned at the checkout gear of the opposition side of light-dividing device, and the reflection choppy of reversion focused on another Optical devices on the checkout gear, described aperture is arranged on the Fourier plane of reflective graphics of reversion, so that eliminate those from all other light beyond the reflection ray that is parallel to the instrument optical axis of cornea from checkout gear, thus, the dimensional orientation of detected figure can be compared with the figure of original transmitted on the checkout gear, so that determine cornea shape by the position analysis to the reflection light point of figure.

9, according to the instrument of claim 1, it is characterized in that described ophthalmic diagnostic apparatus also comprises is used for the figure of discrete point source is separately folded into device on the instrument optical axis towards cornea, and the described device that is used for projected graphics comprises the light source of figure of light path of the graph image of a distortion that is separated from optical axis and reversion.

10, according to the instrument of claim 1, it is characterized in that also comprising the device that is used in the figure of the discrete point source separately of projection, throwing one second smooth figure to cornea, this second smooth figure comprises a plurality of concentric circulars, also comprise the reflection ray that is used for analyzing respectively the relevant concentrically ringed distortion that comes from corneal reflex and the device of independent qualitative information is provided, described information can compare with the anterior corneal surface shape that figure obtained of the point source that separates by dispersing.

11, instrument according to claim 10, the device that it is characterized in that the described projection second smooth figure comprises the light source of one second smooth figure, one second template or mask, along the setting of instrument optical axis be used for the figure that projects from second mask is folded into second light-dividing device on the instrument optical axis, with first polarizer on the light path of the projecting figure that is positioned at described discrete point source separately and be positioned at second polarizer on the light path of the second smooth figure, the opposite polarity of being set up by two polariscopic orientations makes two projected graphics be rendered as the real image with opposite polarity, and makes their reflection ray more easily utilize the polarization analysis mirror at checkout gear place to be separated.

12,, it is characterized in that also comprising the device that is used for the secondary reversion reflective graphics image that separate analysis comes from the cornea back of the body or inner skin surface reflection according to the instrument of claim 1.

13, according to the instrument of claim 12, it is characterized in that the described device that is used for separate analysis comprises filtering apparatus, filtering apparatus is used for coming reflection light point on the identification and detection device with the method for electronics by the different wave amplitude scopes of distinguishing detected light, and these reflection light points are from the front surface and the back of the body surface of cornea.

14, according to the instrument of claim 13, it is characterized in that the described device that is used for mathematical derivation comprises computer, it is used for by determine the shape on corneal endothelium surface from the position of reflection light point on checkout gear of corneal endothelium surface reflectance.

15,, it is characterized in that the described device that is used to throw a figure comprises a lighting source and a plate that has discrete photoetching hole pattern, to form discrete point source separately according to the instrument of claim 1.

16, according to the instrument of claim 1, it is characterized in that describedly being used for that the device of derivation anterior corneal surface shape comprises that the dimensional orientation that utilizes detected pip light source to determine the device of cornea along the shape of the selected cutting planes of eye according to following general formula from the mathematics, this formula is:

dy/dx＝-（ (a（y）-x)/(b（y）-y) ）±[（ (a（y）-x)/(b（y）-y) ） ²+1] ^1/2

Wherein: y is the degree of depth of a corneal reflex point apart from a datum level, and x is the distance of this pip apart from the instrument optical axis, and (a b) is the coordinate of the real image of a space lighting point.

17, a kind of method that is used for determining the cornea shape comprises:

Throw a figure of discrete point source separately, and form a real image of this point source figure on before eyes the position,

Select and gather the reflected image that described figure comes from the paraxial reflection of cornea, and detect from the reflection position of each point source basically of corneal reflex,

The graph image that returns that analysis collects is compared it and the not choppy that throwed, this comprise with this not choppy compare the relative position of the point source of analyzing reflection and dimensional orientation and

From mathematics derive one of the anterior corneal surface shape accurate approximate, it will produce the graph image that is collected.

18, according to the method for claim 17, it is characterized in that the figure of described discrete point source separately comprises a kind of general criss-cross figure with pointolite array of intersection, its cross point is positioned on the optical axis of instrument.

19, according to the method for claim 17, the figure that it is characterized in that described discrete point source separately comprises a kind of general starlike figure that an intersection point is arranged on the optical axis of instrument, and comprises the measure of the rotational orientation that is attached to a kind of easy identification that is used to set up described figure on the described figure.

20, method according to claim 17, it is characterized in that comprising a kind of lighting source of employing from axle, and by a mask throw light, then with a spectroscope with the figure reflection of projection and fold in the light path with the instrument light shaft coaxle, the figure that reflects from spectroscope is focused on, so that before patient's eyes, form a real image, this spectroscopical reflective graphics of process that acceptance reflects from cornea also focuses on it on detector, also comprise and allow the reflected light figure that returns pass an aperture that is arranged on the light path of leading to detector, be parallel to instrument optical axis other whole light that reflect from cornea in addition with elimination, the dimensional orientation of detected figure on the detector and the figure of original transmitted can be compared thus, so that determine cornea shape by the position of analyzed pattern pip.

21, according to the method for claim 17, when it is characterized in that also being included in described discrete separately the point source figure of projection, the second smooth figure that has the concentric circular figure to the cornea projection, the relevant concentrically ringed reflection ray of analyzing individually by corneal reflex also provides qualitative information respectively, the anterior corneal surface shape of this information with the figure acquisition of the point source that separates by dispersing can be compared.

22,, it is characterized in that also comprising and analyze the graph image that reflects the secondary reflection that comes from the back of the body or the inner skin surface of cornea individually according to the method for claim 17.

23, according to the method for claim 22, the step that it is characterized in that described separate analysis comprises the luminous point that reflects from anterior surface of cornea and back of the body surface with on the electronics method differentiation detector, and this is to be undertaken by the different wave amplitude scopes of detected light on the identification detector.

24,, it is characterized in that comprising with the computer mathematical derivation going out cornea inner skin surface shape that this is to carry out according to the detected light spot position that is come by the corneal endothelium surface reflectance on the detector according to the method for claim 23.

25, according to the method for claim 17, the step that it is characterized in that described mathematical derivation anterior corneal surface shape comprises that the dimensional orientation of the point source that utilizes detected reflection determines the shape of cornea along the last selected cutting planes of eye according to following general formula, and this formula is:

dy/dx＝-（ (a（y）-x)/(b（y）-y) ）±[（ (a（y）-x)/(b（y）-y) ） ²+1] ^1/2

Wherein: y is the degree of depth of corneal reflex point apart from a datum level, and x is the distance of this pip apart from the instrument optical axis, and (a b) is the position coordinates of the real image of a space lighting point.

26,, it is characterized in that also comprising that information that utilization obtains produces the cross-sectional image of eyes on selected cutting planes with the method for electronics from the mathematical derivation of anterior corneal surface shape according to the method for claim 17.

27,, it is characterized in that described discrete point source figure separately is the object lens projection by a surgery microscope, and comprise the graph image that the object lens of collection by this surgery microscope return according to the method for claim 17.

28,, it is characterized in that also comprising the image that produces and show the concentrically ringed distortion situation of expression institute projection according to the method for claim 21.

29, according to the method for claim 17, it is characterized in that a pre-objective comprises an element of close patient's eyes, this method also comprises makes before this glove mirror from the nearly at least 110 millimeters spacing of eye.

30, according to the method for claim 17, it is characterized in that comprising image forming with the point source figure in object lens, so that utilize object lens, thereby obtain the big visual field of cornea as field lens.

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