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Matched Legal Cases: ['art 23', 'art 23', 'art 23', 'art 35', 'art 35', 'art 31', 'art 35', 'art 31', 'art 23', 'art 11', 'art 23', 'art 23', 'art 210', 'art 220', 'art 230', 'art 250', 'art 260', 'art 210', 'art 23', 'art 35', 'art 54', 'art 220', 'art 230', 'art 210', 'art 23', 'art 23', 'art 23', 'art 111', 'art 111', 'art 111', 'art 111', 'art 111']

Patent US7311402 - Eye optical characteristic measuring instrument - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsScattering can be measured by using an optical system having a Hartman-Shack wave-surface sensor. An eye optical characteristic measuring instrument comprises a light source unit 10 for emitting a light beam of a wavelength in the near-infrared region, an illumination optical system 40 for illuminating...http://www.google.com/patents/US7311402?utm_source=gb-gplus-sharePatent US7311402 - Eye optical characteristic measuring instrumentAdvanced Patent SearchPublication numberUS7311402 B2Publication typeGrantApplication numberUS 10/488,790PCT numberPCT/JP2002/008197Publication dateDec 25, 2007Filing dateAug 9, 2002Priority dateSep 7, 2001Fee statusPaidAlso published asDE60239278D1, EP1437084A1, EP1437084B1, US7677731, US20050073647, US20080123053, WO2003022138A1Publication number10488790, 488790, PCT/2002/8197, PCT/JP/2/008197, PCT/JP/2/08197, PCT/JP/2002/008197, PCT/JP/2002/08197, PCT/JP2/008197, PCT/JP2/08197, PCT/JP2002/008197, PCT/JP2002/08197, PCT/JP2002008197, PCT/JP200208197, PCT/JP2008197, PCT/JP208197, US 7311402 B2, US 7311402B2, US-B2-7311402, US7311402 B2, US7311402B2InventorsToshifumi Mihashi, Yoko Hirohara, Takashi Fujikado, Naoyuki MaedaOriginal AssigneeKabushiki Kaisha TopconExport CitationBiBTeX, EndNote, RefManPatent Citations (7), Non-Patent Citations (11), Referenced by (3), Classifications (8), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetEye optical characteristic measuring instrumentUS 7311402 B2Abstract Scattering can be measured by using an optical system having a Hartman-Shack wave-surface sensor. An eye optical characteristic measuring instrument comprises a light source unit 10 for emitting a light beam of a wavelength in the near-infrared region, an illumination optical system 40 for illuminating a small area of the retinal of an eye to be measured with the light beam from the light source unit 10, a light-receiving optical system 20 for receiving a part of the reflected beam of the light beam from the light source unit 10 reflected from the retina through a converting member for converting the part of the reflected light beam into at least substantially 17 light beams, a light-receiving section 23 for receiving the received light beam directed by the light-receiving optical system 20 and generating a signal, and a calculating unit for determining the wavefront aberration of the light beam entering the light-receiving optical system 20 and the degree of scattering of the received light beam on the basis of the signal from the light-receiving section 23. Images(10) Claims(14)
wherein the arithmetic part obtains a point spread function based on a signal from the light receiving part, and estimates crystalline lens scattering and retina scattering by comparing the obtained point spread function with a point spread function obtained from the wavefront aberrations of the subject eye which are obtained on the basis of the signals from the light receiving part.
wherein the arithmetic part obtains a scattering degree of the received light flux on the basis of the signals from the light receiving part and, obtains a distribution of relations between the wavefront aberrations of the light flux incident on the light receiving optical system and the scattering degree of the received light flux.
wherein the arithmetic part is constructed to judge that, as the scattering degree of the received light flux becomes high, an influence of a cataract becomes large.
4. An eye optical characteristic measuring apparatus according to claim 3,
5. An eye optical characteristic measuring apparatus according to claim 2,
6. An eye optical characteristic measuring apparatus according to claim 1,
7. An eye optical characteristic measuring apparatus according to claim 6,
wherein the arithmetic part is constructed to judge that as the spot diameter of the received light flux becomes large, an influence of cataract or the like becomes large.
8. An eye optical characteristic measuring apparatus according to claim 1,
wherein the arithmetic part obtains a scattering degree of the received light flux on the basis of the signals from the light receiving part and, obtains a distribution of relations among the wavefront aberrations of the light flux incident on the light receiving optical system, the scattering degree of the received light flux, and a spot diameter of the received light flux.
wherein the arithmetic part is constructed to judge that, as the obtained wavefront aberrations of the light flux incident on the light receiving optical system and the scattering degree of the received light flux become high, or as the spot diameter of the received light flux becomes large, an influence of a cataract large.
10. An eye optical characteristic measuring apparatus, comprising:
an arithmetic part for obtaining a point spread function obtained from wavefront aberrations of the light flux incident on the light receiving optical system and an actually measured spot diameter of the received light flux on the basis of the signals from the light receiving parts,
wherein crystalline lens scattering and retina scattering are estimated by subtracting a diameter of the point spread function from the obtained spot diameter of the received light flux.
wherein the arithmetic part is constructed to judge that, as a diameter of the obtained point spread function and/or the spot diameter of the received light flux becomes high, an influence of cataract or the like becomes large.
13. An eye optical characteristic measuring apparatus according to claim 10,
14. An eye optical characteristic measuring apparatus comprising:
a light source part for emitting a light flux of a specificed wavelength;
a light receiving optical system for receiving a part of a reflected light flux which is the light flux emitted from the light source part and reflected by the retina of the subject eye, through a conversion member for converting it into at least 17 beams;
wherein the arithmetic part obtains a minimum intensity and a maximum intensity in predetermined range with a point image as the center, and obtains a Michelson contrast ratio or an area at an intermediate point between the minimum intensity and the maximum intensity on the basis of this, and estimates crystalline lens scattering and retina scattering.
Since a Hartman-Shack wavefront sensor can accurately measure wavefront aberrations of an eye, it has recently attracted considerable attention. This wavefront sensor can become a necessary apparatus in eye surgery in near future especially for the purpose of the planning and follow-up of cornea refractive surgery.
As an object of the eye optical system wave front aberrations measurement, an objective evaluation of visual functions can be named. As the evaluation of the visual functions, a subjective examination has been conventionally recognized as a reliable measurement method as compared with an objective examination. Especially, this is true to such an extent that with respect to an auto-refractometer as a former wavefront sensor, a lens interchange method as the subjective examination is called a gold standard.
In the measurement of eye optical characteristics, in the case of aging, cataract, or the like, light scattering from an eye optical system is large, and for the purpose of the objective evaluation of the visual functions, measurement of the light scattering is necessary in addition to the aberrations. An apparatus is desired which enables simultaneous measurement of the light scattering by an optical system of a Hartman-Shack wavefront sensor which has an established reputation in measurement of the wavefront aberrations. On the other hand, the wavefront aberrations measurement by the Hartman-Shack wavefront sensor is already in practical use.
In view of the above, the present invention has an object to provide an eye optical characteristic measuring apparatus which can accurately evaluate visual functions by enabling a Hartman-Shack wavefront sensor, which has a main object of performing wavefront aberrations measurement, to perform light scattering measurement and by performing the light scattering measurement.
Besides, the invention has an object to provide an eye optical characteristic measuring apparatus which enables simultaneous measurement of scattering of the eye by an optical system of the Hartman-Shack wavefront sensor by developing, as a scattering measurement method by the Hartman-Shack wavefront sensor, a scattering analytic method for estimating a scattering amount from SIR (Scatter Intensity Ratio) of background light of a Hartman image.
The first light receiving optical system 20 includes, for example, a collimator lens 21, a Hartman plate 22 as a conversion member for converting a part of a light flux (first light flux) reflected and returned from the retina 61 of the eye 60 to be measured into at least 17 beams, and a first light receiving part 23 for receiving the plural beams converted by the Hartman plate 22, and is for guiding the first light flux to the first light receiving part 23. Besides, here, a CCD with little readout noise is adopted for the first light receiving part 23, and as the CCD, a suitable type of CCD, for example, a general low noise type of CCD, a cooling CCD of 1000*1000 elements for measurement, or the like can be applied.
The second light receiving optical system 30 includes a condensing lens 34 and a second light receiving part 35. The second light receiving optical system 30 guides a light flux (second light flux), which is originated from the pattern of the Placido's disk 71 illuminated from the second illuminating optical system 70 and is reflected and returned from the anterior eye part or the cornea 62 of the eye 60 to be measured, to the second light receiving part 35. Besides, it can also guide a light flux, which is emitted from the second light source part 31 and is reflected and returned from the cornea 62 of the eye 60 to be measured, to the second light receiving part 35. Incidentally, as the second wavelength of the light flux emitted from the second light source part 31, for example, a wavelength different from the first wavelength (here, 780 nm) and longer than that (for example, 940 nm) can be selected.
The beam splitter 45 is inserted in the first light receiving optical system 20, and by this beam splitter 45, the light from the first illuminating optical system 10 is sent to the eye 60 to be measured, and the reflected light from the eye 60 to be measured is transmitted. The first light receiving part 23 included in the first light receiving optical system 20 receives the light transmitted through the Hartman plate 22 as the conversion member and generates a received light signal.
Besides, the first light source part 11 and the retina 61 of the subject eye 60 form a conjugated relation. The retina 61 of the subject eye 60 and the first light receiving part 23 are conjugated. Besides, the Hartman plate 22 and the pupil of the subject eye 60 form a conjugated relation. Further, with respect to the first light receiving optical system 20, the cornea 62 as the anterior eye part of the subject eye 60 and the pupil, and the Hartman plate 22 form a substantially conjugated relation. That is, the front focal point of the afocal lens 42 is substantially coincident with the cornea 62 as the anterior eye part of the subject eye 60 and the pupil. Besides, the plane of the rotary prism 16 inclined with respect to the optical axis is disposed at a substantially conjugated position with respect to the pupil.
The lens 12 converts a diffused light of the light source 11 into a parallel light. A diaphragm 14 is positioned at an optically conjugated position with respect to the pupil of the eye or the Hartman plate 22. The diaphragm 14 has a diameter smaller than an effective range of the Hartman plate 22, and the so-called single path aberrations measurement (method in which the aberrations of the eye has an influence on only the light receiving side) is established. In order to satisfy the above, the lens 13 is disposed such that the conjugated point of the retina of the real light beam coincides with the front focal position, and further, in order to satisfy the conjugated relation between the lens and the pupil of the eye, it is disposed such that the rear focal position coincides with the diaphragm 14.
Next, the Hartman plate 22 as the conversion member will be described.
The Hartman plate 22 included in the first light receiving optical system 20 is a wavefront conversion member for converting a reflected light flux into plural beams. Here, plural micro-Fresnsel disposed on a plane orthogonal to the optical axis are applied to the Hartman plate 22. Besides, in general, with respect to the measuring object part (the eye 60 to be measured), in order to measure a spherical component of the eye 60 to be measured, a third-order astigmatism, and other higher order aberrations, it is necessary to perform the measurement with at least 17 beams through the eye 60 to be measured.
Besides, the reflected light from the retina 61 of the eye 60 to be measured passes through the afocal lens 42 and the collimate lens 21, and is condensed on the first light receiving part 23 through the Hartman plate 22. Accordingly, the Hartman plate 22 includes a wavefront conversion member for converting the reflected light flux into at least 17 beams.
FIG. 3 is a block diagram roughly showing an electrical system 200 of the eye optical characteristic measuring apparatus of the invention. The electrical system 200 of the eye optical characteristic measuring apparatus includes, for example, an arithmetic part 210, a control part 220, a display part 230, a memory, 240, a first driving part 250, and a second driving part 260.
The arithmetic part 210 receives a received light signal (first) (4) obtained from the first light receiving part 23, a received light signal (second signal) (7) obtained from the second light receiving part 35, and a received light signal (10) obtained from the third light receiving part 54, and performs an arithmetical operation on the origin of coordinates, a coordinate axis, movement of coordinates, rotation, ocular aberrations, corneal higher order aberrations, Zernike coefficients, aberration coefficients, a Strehl ratio, a white light MTF, a Landolt's ring pattern and the like. Besides, signals corresponding to such calculation results are outputted to the control part 220 for performing the whole control of an electric driving system, the display part 230, and the memory 240, respectively. Incidentally, the details of the arithmetic part 210 will be described later.
FIG. 5 is a view in which a part of an image received by the first light receiving part 23 is enlarged. The drawing (A) shows a keratoconic eye, and the drawing (B) shows an example of a Hartman image in the case of a cataractous eye. The Hartman image received by the first light receiving part 23 is, for example, the image on the basis of the reflected light from the subject eye, and includes plural area points (circles, ellipses, etc. in the drawing) in the case where the reflected light is received onto the first light receiving part 23 as light fluxes diffused generally outward through the Hartman plate 22. An optical signal of the Hartman image in this example is converted into an electrical signal, and is inputted (or captured) as the first signal to the analysis part 111′.
As stated above, the information from the Hartman-Shack wavefront sensor includes the following.
Besides, with respect to the eye with much scattering, the blur of an image which can not be explained from only the wavefront aberrations are observed in the Hartman image. Besides, it is conceivable that the scattering amount is estimated by comparing the Hartman image obtained by the measurement with the Hartman image restored from the wavefront aberrations.
The analysis part 111′ regards the plural area points as one of the received light fluxes, and obtains the spot diameter of the received light flux and the ratio of the maximum value of the light amount of the received light flux to the minimum value, that is, the scattering degree of the received light flux. The analysis part 111′ obtains the distribution indicating the relation between the wavefront aberrations of the light flux incident on the light receiving optical system and the scattering degree of the received light flux. Besides, it obtains the distribution indicating the relation between the wavefront aberrations of the light flux incident on the light receiving optical system and the spot diameter of the received light flux. Incidentally, since the analysis part 111′ obtains the distribution concerning the correlation among the wavefront aberrations of the light flux incident on the light receiving optical system, the catering degree of The received light flux, and the spot diameter of the received light flux, a limitation is not made to the foregoing distribution.
Incidentally, the foregoing analysis of the analysis part 111′ may correspond to plural specified point images of the Hartman image, and in this condition, as the result of one measurement, the respective point images may be analyzed in the calculation, or an average value of actually measured values may be used.
The wavefront of the light flux reflected from the retina of the subject eye passes through the Hartman plate, and the wavefront aberrations RMS in a lenslet are obtained from the inclination of the light flux at that time, and a factor such as an area of a half-value portion of the point spread function PSF is obtained.
Index=√{square root over (A)}−(a�RMS SL −c) (1) Index: scattering prediction coefficient (also called scattering prediction index) A: area (average) of the half-value portion of the PSF RMSSL: wavefront aberrations (average) in the lenslet portion a: constant obtained by non-cataractous eye measurement c: scattering correction constant of measuring apparatus. Incidentally, a and c are coefficients of a regression line obtained in FIG. 7 by using a keratoconic eye and a normal eye. In this case, a: first-order coefficient of 28.894, and c: constant term of 8.6623.
In the actual analysis, there is also a case where the area A is obtained for the plural point images of the Hartman image, this is subjected to the processing of the above expression and is averaged to obtain the result of one measurement.
As the result of the analysis, as an example, there were obtained SIR (scatter intensity ratio)=0.460�0.067 for the normal eye, SIR=0.495�0.098 for the keratoconic eye, and SIR=0.667�0.148 for the cataractous eye (ANOVA (dispersion analysis), P<0.01). Besides, the scattering coefficient was 2.61�0.70 for the normal eye, 3.38�2.73 for the keratoconic eye, and 10.13�7.25 for the cataractous eye. Besides, although there was no significant difference between the normal eye and the keratoconic eye (P<0.122), there was significant difference between the normal eye and the cataractous eye, and between the keratoconic eye and the cataractous eye (P<0.01). Incidentally, 9 normal eyes with little scattering, 24 keratoconic eyes, and 17 cataractous eyes with large scattering were measured.
By this, possibility of measurement of the scattering amount by the Hartman-Shack wavefront sensor is suggested. After this, evaluation standards comparable to visual functions are examined, and clinical effectiveness is confirmed.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide the eye optical characteristic measuring apparatus which enables the scattering measurement by the Hartman-Shack wavefront sensor whose main object is wavefront aberration measurement, and can accurately estimate the visual functions by performing the scattering measurement.
Besides, according to the invention, as the scattering measurement method by the Hartman-Shack wavefront sensor, the scattering analytic method is developed in which the scattering amount is estimated from the scatter intensity ratio (SIR) of background light of the Hartman image, and the eye optical characteristic measuring apparatus which can enable simultaneous measurement of scattering by the optical system of the Hartman-Shack wavefront sensor can be provided.
Besides, according to the invention, the eye optical characteristic measuring apparatus can be provided which can make the judgment that from the distribution of relations between the wavefront aberrations of the light flux incident on the light receiving optical system and the scattering degree of the received light flux, as the wavefront aberrations of the light flux incident on the light receiving optical system and the scattering degree of the received light flux become nigh, the influence of the cataract becomes large.
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S3.Referenced byCiting PatentFiling datePublication dateApplicantTitleUS7832864Jun 16, 2008Nov 16, 2010The Arizona Board Of Regents On Behalf Of The University Of ArizonaInverse optical designUS8646915 *Jul 7, 2011Feb 11, 2014Canon Kabushiki KaishaOphthalmic apparatus, control method for the same, and storage mediumUS20120019780 *Jul 7, 2011Jan 26, 2012Canon Kabushiki KaishaOphthalmic apparatus, control method for the same, and storage medium* Cited by examinerClassifications U.S. Classification351/221, 351/205, 351/211International ClassificationA61B3/10, A61B3/103Cooperative ClassificationA61B3/1015European ClassificationA61B3/10F, A61B3/103Legal EventsDateCodeEventDescriptionMay 25, 2011FPAYFee paymentYear of fee payment: 4May 4, 2004ASAssignmentOwner name: KABUSHIKI KAISHA TOPCON, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MIHASHI, TOSHIFUMI;HIROHARA, YOKO;FUJIKADO, TAKASHI;AND OTHERS;REEL/FRAME:015294/0597;SIGNING DATES FROM 20040302 TO 20040305RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google