Classifications

• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/0002—Inspection of images, e.g. flaw detection
  • G06T7/0012—Biomedical image inspection
• • 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
• • 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
  • A61B3/0016—Operational features thereof
  • A61B3/0025—Operational features thereof characterised by electronic signal processing, e.g. eye models
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T7/00—Image analysis
  • G06T7/60—Analysis of geometric attributes
  • G06T7/66—Analysis of geometric attributes of image moments or centre of gravity
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2207/00—Indexing scheme for image analysis or image enhancement
  • G06T2207/30—Subject of image; Context of image processing
  • G06T2207/30004—Biomedical image processing
  • G06T2207/30041—Eye; Retina; Ophthalmic

Definitions

• online aberrometry information referred to herein as "online” aberrometry.
• Hartman-Shack wavefront sensor typically includes a microlens array that
• the image produced by the microlens array comprises an
• centroid This aspect of the wavefront analysis process is known as centroid
• Hartmann-Shack wavefront sensors and other well-known types such as
• Tscherning typically measure single images of centroids or,
• a single wavefront image requires about 400Kb of
• aberration measurements e.g., sphere
• Figure 1 is a flow chart schematic of a fast centroid detection
• Figure 2 is a reproduced photographic of a Hartmann-Shack
• Figure 3 is a drawing representation of a wavefront (centroid) image
• Figure 4 is a flow chart schematic of a sorting algorithm according to
• Figure 5 is another drawing representation of a wavefront (centroid)
• Figure 6 is a schematic illustration representing another algorithm
• Figure 7 is an illustration representing another algorithm process
• Figure 8 is a reproduced photographic of part of a Hartmann-Shack
• Figure 9 is a flow chart schematic directed to another embodiment of
• Figure 10 is a block diagram of an apparatus embodiment of the invention.
• the image may comprise, for illustration purposes only, centroids in a
• centroids 32 in a CCD image can be located and sorted in
• taken from a CCD camera usually consist of an array of pixels in which
• every pixel is assigned a number proportional to the amount of charge
• This number is referred to as the signal of the pixel.
• the image is compressed from
• next pixel is set to the average of the next (second) square, and so on,
• the compressed image is then divided into square
• one tile is a square of 64x64 pixels, but other
• a signal-to-noise ratio of two was improved to a signal-to-noise ratio of 10 by
• a maximum is defined as the highest signal in the
• the maximum is determined by a scan through the
• the first entry (highest signal value) is defined as the first rough structure
• the pre-set is defined as rough structure points.
• condition is that the position of the particular entry is farther away from all
• the distance is 17 pixels.
• step 108 can be repeated as shown at block 110, setting a new
• the ultimate centroid positions are determined. Since, the
• each square is smaller than 2x the
• this value is larger than the centroid itself. In the exemplary embodiment this value is
• step 112 can be repeated, for
• structure point can also be assigned a quality factor depending on how much
• this distance is five pixels.
• an aspect 200 of the embodiment as illustrated in Figure 4 is directed to the
• the desired sorting configuration is selected.
• the configuration is a square grid based upon the
• the centroid with the smallest nj value is assigned to
• Row 1 and is stored in memory as the last centroid of Row 1.
• the last centroids of the existing rows are stored in
• a region 610 is defined that, in an exemplary embodiment, comprises an area to the right of the last centroid
• search area 610 for the next centroid Any shape suited for detecting other
• parameters include maximum angle 702, minimum distance 704, maximum
• centroid of that row If no, than that centroid is assigned the last centroid of
• Steps 214-216 are now repeated for all centroids. In this
• This step facilitates marking of the top row as Row 1,
• optional step 222 involves merging these rows.
• the criteria for merging rows j and k is: If y j -y ⁇
• f is a variable parameter in the range between about 0.1-0.7, that is set by
• a is the mean distance between rows (see above);
• P k ,&st is the x value of the first (left-most) centroid of the k row
• P k jast is the x value of the last (right-most) centroid of the k row.
• the rows are merged if they are much closer in the, y-position
• row j is either completely to the
• the process for sorting the columns begins at step 224 where the list
• centroid with the smallest nj is assigned to Column 1 and is stored in memory as the last centroid of Column 1.
• the last centroid of Column 1 is assigned to Column 1 and is stored in memory as the last centroid of Column 1.
• centroids of an existing column are always stored in memory during step
• a region is defined that, in the exemplary embodiment,
• nj value is selected and that centroid is checked, with respect to all existing
• centroid is assigned as the last centroid of that column. If no, than
• This step facilitates marking ofthe left-most column as Column 1, the next
• 236 involves merging these columns. This is accomplished by the following sub-steps: From the mean average x-position for each column
• f is a variable parameter in the range between about 0.1-0,7, that is set by
• a is the mean distance between columns
• P k ,- Brst is the y value ofthe first (top-most) centroid ofthe k column
• column j is either
• Pupil coordinate location (optional): ⁇ 6-8ms;
• centroid position data results in data storage requirements of only about 700Kb of memory for a 20 second measurement at 25Hz, which will yield
• the method comprises at step 902 acquiring a plurality of wavefront
• each ofthe images includes
• the images are acquired at a rate
• the images are
• the display will be limited to second order aberrations (sphere
• a pupil diameter value can be selected prior to measurement allowing
• any Zernike order e.g., coma, spherical aberration, higher-orders
• diameters is between about 2mm to 10mm.
• the first 125 images might be obtained for pupil diameter, D
• step 910 an average value of a selected Zernike order can be calculated
• blinking periods can be determined which
• step 914 a In a related aspect according to this embodiment, at step 914 a
• sequence of pupil images corresponding to the wavefront images can also be
• the apparatus includes an illumination component 1010 that delivers a
• a detector 1040 adapted to acquire the
• a display component 1060 operatively connected
• pupil camera 1080 and pupilometer 1090 is also shown, where components 1015 are beam splitters or optical equivalents thereof.

Landscapes

• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• General Health & Medical Sciences (AREA)
• Medical Informatics (AREA)
• Theoretical Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Veterinary Medicine (AREA)
• Biophysics (AREA)
• Animal Behavior & Ethology (AREA)
• Molecular Biology (AREA)
• Public Health (AREA)
• Heart & Thoracic Surgery (AREA)
• Surgery (AREA)
• Biomedical Technology (AREA)
• Ophthalmology & Optometry (AREA)
• Geometry (AREA)
• Signal Processing (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Radiology & Medical Imaging (AREA)
• Quality & Reliability (AREA)
• Image Analysis (AREA)
• Eye Examination Apparatus (AREA)
• Testing Of Optical Devices Or Fibers (AREA)
• Image Processing (AREA)
• Length Measuring Devices By Optical Means (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (2)

Family

ID=34071891

Family Applications (1)

Country Status (11)

Cited By (2)

Families Citing this family (9)

Family Cites Families (5)

• 2003
  • 2003-07-24 DE DE10333813A patent/DE10333813A1/de not_active Withdrawn
• 2004
  • 2004-07-22 WO PCT/EP2004/008205 patent/WO2005015495A2/en not_active Ceased
  • 2004-07-22 AU AU2004263957A patent/AU2004263957B2/en not_active Ceased
  • 2004-07-22 SG SG200805750-7A patent/SG145707A1/en unknown
  • 2004-07-22 CA CA002539944A patent/CA2539944A1/en not_active Abandoned
  • 2004-07-22 ES ES04763406.8T patent/ES2689935T3/es not_active Expired - Lifetime
  • 2004-07-22 JP JP2006520794A patent/JP2006528499A/ja active Pending
  • 2004-07-22 KR KR1020067001479A patent/KR20060080578A/ko not_active Ceased
  • 2004-07-22 US US10/565,703 patent/US7708411B2/en active Active
  • 2004-07-22 EP EP04763406.8A patent/EP1658587B1/en not_active Expired - Lifetime
  • 2004-07-22 CN CNA2004800274699A patent/CN1856803A/zh active Pending

Non-Patent Citations (8)

Also Published As

Similar Documents

Legal Events