Method for measuring behind the iris after locating the scleral spur

Abstract

A method is disclosed for using a precision ultrasound scanning device to image the anterior segment of the human eye, automatically locate the scleral spur, and, using the scleral spur as a fiduciary, to automatically make measurements in front of and behind the iris. The scleral spur can be used as a fiduciary to make measurements that characterize the normal and abnormal shapes of components within this region of the anterior segment of the eye. One or more of the measurements of the iridocorneal angle and the anterior chamber depth can be related to other measurements behind the iris including the iris lens contact distance, the iris zonule distance and the trabecular ciliary process distance. Over a period of time, these measurements can change and can indicate a change, or be a precursor for a change, of intraocular pressure (IOP), and therefore can determine an earlier onset of glaucoma.

Claims

1. A method for detecting a scleral spur in an eye of a patient, comprising: providing an ultrasound device having (i) a scan head with an arcuate guide track and a carriage movable along the arcuate guide track; (ii) an eyepiece configured to maintain the eye of the patient in a fixed location with respect to the arcuate guide track; and (iii) a transducer connected to the carriage; emitting, from the transducer, ultrasound pulses as the carriage moves along the arcuate guide track; storing received ultrasound pulses on a non-transitory computer readable medium; forming, by at least one electronic device, a B-Scan of the eye of the patient based on the received ultrasound pulses; binarizing, by the at least one electronic device, the B-Scan from a grayscale color palette to a black/white color palette; determining, by the at least one electronic device, an average surface of a sclera of the eye; and locating, by the at least one electronic device, a bump of the average surface of the sclera that corresponds to a scleral spur.

2. The method of claim 1, further comprising: smoothing, by the at least one electronic device, the average surface of the sclera by deleting discrete areas on both sides of the average surface.

3. The method of claim 2, further comprising: locating, by the at least one electronic device, the bump of the average surface of the sclera by identifying an inflection point of a slope of a posterior side of a pigment epithelium of a pupil dilator muscle.

4. The method of claim 1, further comprising: determining, by the at least one electronic device, an angle-opening distance from a cornea to an iris of the eye at a predetermined distance from the scleral spur.

5. The method of claim 1, further comprising: beginning on a left side of a region of interest and moving right until a black discrete area; inverting, by the at least one electronic device, the black/white color palette; and locating, by the at least one electronic device, a leftmost white discrete area, which corresponds to a point of interest.

6. The method of claim 5, wherein the point of interest is at least one of a root of an iris of the eye or a root of a ciliary sulcus of the eye.

7. The method of claim 1, further comprising: determining, by the at least one electronic device, an iris-lens contact distance between a surface of an iris of the eye and a surface of a lens of the eye.

8. A system for detecting a scleral spur in an eye of a patient, comprising: an ultrasound device, having: a scan head comprising an arcuate guide track and a carriage movable along the arcuate guide track; an eyepiece configured to maintain the eye of the patient in a fixed location with respect to the arcuate guide track; a transducer connected to the carriage, wherein ultrasound pulses are emitted into the eye of the patient, and received ultrasound pulses are stored on a non-transitory computer readable medium; and at least one electronic device comprising the non-transitory computer readable medium, the non-transitory computer readable medium comprising instructions that, when executed, cause the at least one electronic device to: form a B-Scan of the eye of the patient based on the received ultrasound pulses; binarize the B-Scan from a grayscale color palette to a black/white color palette; determine an average surface of a sclera of the eye; and locate a bump of the average surface of the sclera that corresponds to the scleral spur.

9. The system of claim 8, further comprising: instructions that, when executed, cause the at least one electronic device to: smooth the average surface of the sclera by deleting discrete areas on both sides of the average surface.

10. The system of claim 9, further comprising: instructions that, when executed, cause the at least one electronic device to: locate the bump of the average surface of the sclera by identifying an inflection point of a slope of a posterior side of a pigment epithelium of a pupil dilator muscle.

11. The system of claim 8, further comprising: instructions that, when executed, cause the at least one electronic device to: determine an angle-opening distance from a cornea to an iris of the eye at a predetermined distance from the scleral spur.

12. The system of claim 8, further comprising: instructions that, when executed, cause the at least one electronic device to: begin on a left side of a region of interest and move right until a black discrete area; invert the black/white color palette; and locate a leftmost white discrete area, which corresponds to a point of interest.

13. The system of claim 12, wherein the point of interest is at least one of a root of an iris of the eye or a root of a ciliary sulcus of the eye.

14. The system of claim 12, further comprising: instructions that, when executed, cause the at least one electronic device to: determine an iris-lens contact distance between a surface of an iris of the eye and a surface of a lens of the eye.

15. A system for binarizing a B-Scan of an eye of a patient, comprising: an ultrasound device, having: a scan head comprising an arcuate guide track and a carriage movable along the arcuate guide track; an eyepiece configured to maintain the eye of the patient in a fixed location with respect to the arcuate guide track; a transducer connected to the carriage, wherein ultrasound pulses are emitted into the eye of the patient, and received ultrasound pulses are stored on a non-transitory computer readable medium; and at least one electronic device comprising the non-transitory readable medium, the non-transitory computer readable medium comprising and having instructions that, when executed, cause the at least one electronic device to: form a B-Scan of the eye of the patient based on the received ultrasound pulses; determine an average intensity of a grayscale color palette of the B-Scan of the eye; and binarize the B-Scan of the eye from the grayscale color palette to a black/white color palette, wherein discrete areas of the B-Scan above a predetermined intensity are binarized to white and discrete areas of the B-Scan below the predetermined intensity are binarized to black, and the predetermined intensity depends on the average intensity.

16. The system of claim 15, wherein the predetermined intensity is greater than the average intensity.

17. The system of claim 15, further comprising: instructions that, when executed, cause the at least one electronic device to: determine an average surface of a sclera of the eye; and locate a bump of the average surface of the sclera that corresponds to a scleral spur.

18. The system of claim 15, where a discrete area is a pixel and the B-Scan is a rasterized image.

19. The system of claim 17, further comprising: instructions that, when executed, cause the at least one electronic device to: smooth the average surface of the sclera by deleting discrete areas on both sides of the average surface.

20. The system of claim 19, further comprising: instructions that, when executed, cause the at least one electronic device to: locate the bump of the average surface of the sclera by identifying an inflection point of a slope of a posterior side of a pigment epithelium of a pupil dilator muscle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. In the drawings, like reference numerals may refer to like or analogous components throughout the several views.

(2) FIG. 1 shows the anatomy of the eye in the region near the scleral spur.

(3) FIG. 2 shows an alternate diagram of the anatomy of the eye in the region near the scleral spur.

(4) FIG. 3A is a B-scan of the anterior segment of a human eye.

(5) FIG. 3B is a diagram of the anatomy of the eye.

(6) FIG. 4 is a binarized image of the B-scan of the anterior segment.

(7) FIG. 5A is a binarized image of the B-scan of a part of the anterior segment.

(8) FIG. 5B is a diagram of the anatomy of the eye.

(9) FIG. 6A is a binarized image of the region of interest containing the scleral spur.

(10) FIG. 6B is a diagram of the anatomy of the eye.

(11) FIG. 7A is a further isolated and smoothed binarized image of the region of interest containing the scleral spur.

(12) FIG. 7B is a diagram of the anatomy of the eye.

(13) FIG. 8 is a binarized image of a close-up of a further smoothed and shortened image of the isolated sclera, including the scleral spur.

(14) FIG. 9 is an inverted binarized image of the root of the iris.

(15) FIG. 10A is a B-scan of the anterior segment showing ACD and ILCD measurements.

(16) FIG. 10B is a diagram of the anatomy of the eye.

(17) FIG. 11 shows the ILCD (the iris lens contact distance) region of interest of the B-Scan for one side of the eye.

(18) FIG. 12A is a B-scan of half of the anterior segment showing the location of features to be measured.

(19) FIG. 12B is a diagram of the anatomy of the eye.

(20) FIG. 13 is a B-scan of the whole anterior segment showing the location of features to be measured.

(21) FIG. 14 shows a binarized smoothed image of the scleral region of interest with cross hatching to indicate the TISA areas.

(22) FIG. 15A shows the inverted binarized TISA area object used for measuring the TISA area.

(23) FIG. 15B is a diagram of the anatomy of the eye.

(24) FIG. 16 shows the binarized region of interest for isolating the root of the iris.

(25) FIG. 17 shows the binarized image of the isolated iris.

(26) FIG. 18A shows the point of intersection of the iris root and sclera, along with potential points of the scleral spur detected with shortened isolated sclera object.

(27) FIG. 18B is a diagram of the anatomy of the eye.

(28) FIG. 19A shows the point of intersection of the iris root and sclera, along with potential points of the scleral spur detected with a longer isolated sclera.

(29) FIG. 19B is a diagram of the anatomy of the eye.

(30) FIG. 20 is a B-scan of the anterior segment showing the location of measured features of the left and right eye along with the tables of actual measurements.

(31) FIG. 21 illustrates another measurement of the iris zonule distance IZD. This measurement is also made through the iris.

(32) FIG. 22 illustrates geometric structures used in detecting the scleral spur.

(33) FIG. 23 is a close-up of geometric structures used in detecting the scleral spur.

(34) FIG. 24A illustrates the interface line between the sclera and ciliary muscles.

(35) FIG. 24B is a diagram of the anatomy of the eye.

(36) FIG. 25A illustrates various measurements that can be made using ultrasound technology.

(37) FIG. 25B illustrates various measurements that can be made using ultrasound technology.

DETAILED DESCRIPTION OF THE DRAWINGS

(38) One of the applications of a precision ultrasound scanning device or instrument is to image the region of the eye around the confluence of the cornea, iris, sclera and ciliary muscle. By using a knowledge of the structure of the eye in this region along with binary filtering techniques, the position of the scleral spur can be determined with respect to a known point (the visual axis intersection with the anterior or posterior cornea, for example). Once the position of the scleral spur is determined, a number of measurements that characterize the normal and abnormal shapes of components within the anterior segment of the eye can be made. Over a period of time, these measurements can change and can indicate a change or be a precursor to a change of intra ocular pressure (IOP).

(39) IOP is the pressure in the eye created by the continual renewal of fluids within the eye and drainage of fluids from the eye. The intraocular pressure is normally stable (fluid generated equals fluid drained) but can increase when the canal and trabecular mesh through which the fluid normally drains becomes progressively blocked. Increasing IOP is a sign of the onset of glaucoma and, if left untreated, causes damage to the retinal cones leading to progressive loss of sight which is known as glaucoma.

(40) IOP can be measured with a goniometer. However, changes in the measurements that can be made as disclosed herein can be precursors to a measurable change in IOP and therefore can allow the ophthalmologist to take preventative measures to prevent the progression of glaucoma before permanent damage to the retina occurs.

(41) The following measurements as denoted by their abbreviations are referenced in this disclosure:

(42) ACD which is the anterior chamber depth

(43) AOD which is the angle opening distance 500 (500 microns from the scleral spur)

(44) ID which is the iris thickness (must measure through the iris)

(45) ILCD which is the iris lens contact distance (must measure through the iris)

(46) IZD which is the iris zonule distance (must measure through the iris)

(47) ROI which is the Region of Interest.

(48) TCPD which is the trabecular ciliary process distance (must measure through the iris)

(49) TIA is the trabecular iris space area

(50) These measurements are illustrated in FIGS. 25A and 25B and are discussed in “Anterior Segment Imaging: Ultrasound Biomicroscopy”, Hiroshi Ishikawa, MD* and Joel S. Schuman, MD, Ophthalmol Clin North Am. 7-20, March 2004 which is incorporated herein by reference.

(51) In all the figures, left and right are referenced to the page. Left and right directions are illustrated in FIG. 1.

(52) FIG. 1 shows the anatomy of the eye in the region near the scleral spur. This figure illustrates the geometry of the region of interest in which the scleral spur can be found. The iris, ciliary process, cornea and sclera all come together in this region. As in all subsequent figures, left and right, as shown in this figure, are referenced to the page.

(53) FIG. 2 shows an alternate diagram of the anatomy of the eye in the region near the scleral spur. The iridocorneal angle is the angle between the iris and the cornea. The iridocorneal angle is also known as simply the angle.

(54) The following steps are performed to determine noted points of interest (including the scleral spur as a fiduciary) and the measurements dependent on those points, including points/measurements both in front of and behind the iris:

Acquire and Binarize B-Scans

(55) 1. Using an ultrasound arc scanning device, form a B-scan image of the anterior segment (anterior cornea to approximately mid lens, wide angle sclera to sclera) including the left and right sides of the scleral/iris region. FIG. 3A is a B-scan of the anterior segment of a human eye and a line drawing of the region of the eye shown in the B-scan. This image was obtained by a precision ultrasound arc scanning device.
2. Select a threshold value from 1 to 255 for pixel intensity and form a corresponding binary image wherein pixels that are greater than or equal to the specified threshold are converted to 1 (white) and pixels that are less than the specified threshold are converted to 0 (black). Starting threshold depends on the average background pixel intensity. Threshold is then increased iteratively to identify objects of interest.
3. Eliminate extraneous objects such as the anterior lens surface, cornea, electronic noise, reflections, cataracts, etcetera. As the image is further thresholded, the region of the cornea nearest the sclera disappears, leaving the sclera and iris isolated. The same process removes the ciliary muscle at the bottom of the sclera. Part of the thresholding process comprises deleting the pixels less than the threshold value, then filling in any holes in the objects, then deleting any remaining small objects whose area, defined by the number of pixels they contain, are less than a specified area.
4. Binarize the whole anterior segment image—from 0 to 255 grades of grayscale to black and white. FIG. 4 is a binarized image of a B-scan of the anterior segment and is similar to the B-scan image shown in FIG. 3A.

Determine ILCD and ACD

(56) 5. Create left and right halves of the binarized image.

(57) FIG. 5A is a binarized image of the B-scan of the region of interest in the anterior segment for detecting the scleral spur. FIG. 5a is the B-scan image and FIG. 5b is a line drawing of the region of the eye shown in the B-scan.

(58) FIG. 6A is a binarized image of the region of interest of the local region containing the scleral spur. FIG. 6a is the B-scan image and FIG. 6b is a line drawing of the region of the eye shown in the B-scan.

(59) 6. From the binarized B-scan, create a left and right binarized region of interest around the intersection of the lens/iris (see FIGS. 5 and 6).

(60) FIG. 7A is a further isolated and smoothed binarized image of the region of interest containing the scleral spur. FIG. 7a is the B-scan image and FIG. 7b is a line drawing of the region of the eye shown in the B-scan. The line drawing illustrates the interface curve formed by the interface between the sclera and ciliary muscle and the Schwalbe line which is the line formed by the posterior surface of the cornea.

(61) FIG. 8 is a binarized image of a close-up of a further smoothed and shortened image of the isolated sclera, including the scleral spur. This image is a further processed version of the image shown in FIG. 7A.

(62) 7. From each iris/lens ROI, determine the iris/lens contact distance (ILCD) on right and left sides.

(63) a. Using the binarized ROI, locate the center of the lens, then move outward along the top surface of the lens until detecting the iris. b. Keep moving outward along the lens until a gap is detected between the bottom of the iris and the lens, then determine the actual intersection of the bottom of the iris and the lens (the contact point between the iris and the lens furthest from the center of the anterior segment.) c. Repeat for the right side d. The iris-lens contact distance (“ILCD”) is the distance between the first iris lens contact point and the second iris lens contact point. FIG. 11 is a B-scan of half of the anterior segment showing the location of the right and left ILCD. e. Determine the minimum distance from the anterior lens surface to the posterior cornea surface (“ACD”). This is illustrated in FIG. 10A which is a B-scan of the anterior segment illustrating the ACD and ILCD measurements.

Locate the Root of the Iris

(64) 8. Now look for the left iris root (a first region of interest)

(65) a. On the left, create a region of interest near where the sclera and iris meet. This binarized ROI is illustrated in FIG. 6A.

(66) b. Start at the right side of the region of interest and move to the left until black pixels are encountered

(67) c. Invert the polarity of the image (black vs. white). This image is illustrated in FIG. 9 which shows the inverted binarized image of the root of the iris.

(68) d. Find the leftmost white point shown in FIG. 9 which is the root of the iris.

(69) e. Repeat step 8 for iris root on the right side.

Locate the Root of the Ciliary Sulcus

(70) 9. Now look for the left and right ciliary sulcus roots (a second region of interest). This is the same procedure as finding the left and right roots of the iris

(71) a. On the left, create a region of interest near the iris root

(72) b. Start at the right side of the region of interest and move to the left until black pixels are encountered

(73) c. Invert the polarity of the image (black vs. white)

(74) d. Find the leftmost white point which is the root of the ciliary sulcus

(75) e. Repeat step 9 for ciliary sulcus root on the right side

Isolate the Sclera

(76) A limbus-parallel ring of fibers forms the inner surface of the sclera at the junction of the scleral and corneal curvatures and projects inward to inter digitate with the tendon fibers of the meridional ciliary muscle. The sessile group of limbus-parallel fibers of the sclera is called the scleral roll and the inward-projecting group of limbus-parallel fibers is the scleral spur. The scleral roll thus forms the posterior wall of the canal of Schlemm and the roll and spur together form the posterior wall of the internal scleral sulcus. The spur extends inward from the inner sclera toward the axis of the eye for about 0.09 mm. The scleral roll lies at the junction of the scleral curvature with the corneal curvature and the scleral spur lies between the meridional portion of the ciliary muscle and the trabecular mesh.

(77) 10. From the left and right side binarized images, create a binarized region of interest near the iris root. This binarized ROI is illustrated in FIG. 6A.

(78) 11. For left and right sides, further isolate the sclera from the cornea, ciliary process and iris by increasing the threshold until the sclera is separated from the other objects

(79) 12. For left and right, completely isolate sclera by deleting all objects except the sclera

(80) 13. Smooth the boundary of the isolated sclera. The isolating and smoothing steps are illustrated in FIGS. 7A and 8.

Locate the Scleral Spur

(81) The curve formed by the interface between the lighter sclera and darker ciliary muscle is referred to herein as the “interface curve”. A line projected from a point on the interface curve at the local slope is referred to herein as a “scleral slope line”. The protruding structure located at the intersection of the interface curve and the curve formed by the posterior of the cornea is referred to herein as “the bump”. These features are illustrated in FIGS. 22, 23, and 24A.

(82) FIG. 22 illustrates geometric structures used in detecting the scleral spur. The cornea 2201, the iris 2202, the lens 2203, the sclera 2204 and the ciliary body 2205 are the main components shown. The ciliary body 2205 includes the ciliary muscle 2209. The ciliary sulcus 2211 is shown between the iris 2202 and the ciliary body 2205. Schlemm's canal 2207 is also shown for reference. The interface curve 2210 is formed by the interface between the sclera 2204 and the ciliary muscle 2209. Interface curve 2210 intersects Schwalbe line 2212 and this intersection is called the bump 2208.

(83) FIG. 23 is a close-up of geometric structures used in detecting the scleral spur. This figure includes the sclera 2304 and the ciliary body 2305, the ciliary muscle 2309 (shaded). The ciliary sulcus 2311 is shown below the iris. Schlemm's canal 2311 is also shown for reference. The interface curve 2310 is formed by the interface between the sclera 2304 and the ciliary muscle 2309. Interface curve 2310 intersects Schwalbe line 2312 and this intersection is called the bump 2308.

(84) FIG. 24A further illustrates the interface line between the sclera and ciliary muscles. FIG. 24a is a B-scan of the region and FIG. 24b is a line drawing showing the various features of interest. The interface line as shown in FIG. 24a is shown as a boundary between the lighter sclera and the darker ciliary muscle.

(85) The methods of locating the scleral spur used herein include:

(86) 1. Method 1 referred to as the Ciliary Muscle method (CM method)

(87) 2. Method 2 referred to as the first variation of the Bump method (BM1 method)

(88) 3. Method 3 referred to as the second variation of the Bump method (BM2 method)

(89) 4. Method 4 referred to as the third variation of the Bump method (BM3 method)

(90) There is also another method known as the Schwalbe Line Method but it is not used in this disclosure.

(91) A general description of these methods can be found in “The Effect of Scleral Spur Identification Methods on Structural Measurements by Anterior Segment Optical Coherence Tomography” Seager, Wang, Arora, Quigley, Journal of Glaucoma, Vol. 23, No 1, January 2014, which is incorporated herein by reference.

(92) 14. Now look for the scleral spur on the binarized isolated sclera object

(93) Method 1: the Ciliary Muscle method comprises projecting the curve formed by the interface between the sclera and ciliary muscle (referred to herein as the interface curve—see FIG. 24A) to where it intersects the curve formed by the posterior of the cornea (also known as the Schwalbe Line). The scleral spur is at the intersection of these two curves. To find this intersection point, determine the local slope (computed as a moving average) along the interface curve between the lighter sclera and the darker ciliary muscle and, while moving toward the iris (left to right as shown in FIG. 1), find the minimum slope or apex of the bump (the inflection point where the slope changes from decreasing to increasing). Identify this point as a possible first scleral spur.

(94) The local slope is computed as a moving average because of the unevenness of the interface curve on the scale of the resolution of a precision arc scanning device (about 25 microns range resolution and about 40 microns lateral resolution).

(95) Method 2: starting at a point on the interface curve about 1 mm to the left of the first scleral spur found by Method 1, form a line from this point to a point on the Schwalbe curve about 1 mm to the right of the scleral spur found by Method 1. Call this the first “scleral slope line”. Slide a perpendicular to this scleral slope line along the scleral slope line. For each perpendicular, measure the distance from the first scleral slope line to the interface curve. The maximum distance recorded will be the apex of the bump. Identify this point as a possible second scleral spur.

(96) Method 3: determine a second scleral slope line by starting at a point on the interface curve about 2 mm to the left of the first scleral spur found by Method 1, form a line from this point to the rightmost point used in Method 1. Call this the second “scleral slope line”. Slide a perpendicular to this second scleral slope line along the second scleral slope line. For each perpendicular, measure the distance from the second scleral slope line to the interface curve. The maximum distance recorded will be the apex of the bump. Identify this point as a possible third scleral spur.

(97) Method 4: starting with a horizontal line anchored at the leftmost point used in Method 3, rotate this horizontal line about this left most point in a counterclockwise direction until it intersects the posterior side of the interface curve between the sclera and ciliary muscle and identify that point as a possible fourth scleral spur.

(98) Schwalbe's line is formed by the posterior surface of the eye's cornea. The Schwalbe Line Method was not used in the method described in this disclosure.

(99) 15. Determine the best prediction of the scleral spur location by comparing the locations of the potential spurs determined using the four methods above, considering proximity to each other, and proximity to the iris root. Calculate a score or confidence factor based on those factors.
16. Repeat steps 17-23 using a shortened ROI. Compare the confidence factors of spurs found by both the shortened sclera and the longer one and use the point with the best confidence factor. The results of locating the potential scleral spurs are illustrated in FIGS. 19A and 20. Examples of a final determination of the location of the spurs can be seen in FIGS. 12A, 13, and 18A.

(100) Determine Measurements Referenced to the Scleral Spur and or Sulcus Points

(101) FIG. 12A is a B-scan of half of the anterior segment showing the location of features to be measured.

(102) FIG. 13 is a B-scan of the whole anterior segment showing the location of features to be measured.

(103) FIG. 14 shows a binarized smoothed image of the scleral region of interest with cross hatching to indicate the TISA areas.

(104) FIG. 15A shows the inverted binarized TISA area object used for measuring the TISA area.

(105) FIG. 16 shows the binarized region of interest for isolating the root of the iris.

(106) FIG. 17 shows the binarized image of the isolated iris.

(107) FIG. 18A shows the point of intersection of the iris root and sclera, along with potential points of the scleral spur detected with shortened isolated sclera object.

(108) FIG. 19A shows the point of intersection of the iris root and sclera, along with potential points of the scleral spur detected with a longer isolated sclera.

(109) FIG. 25A illustrates various measurements that can be made using ultrasound technology. FIG. 25a illustrates the iridocorneal angle or simply “angle”. FIG. 25b shows the other measurements which are made with reference to the location of the scleral spur. The measurements of ICPD, IZD, ILCD, ID1, ID2 and ID3 all require ultrasound technology to be imaged and require precision ultrasound technology to be measured with accuracy and reproducibility.

(110) FIG. 21 illustrates another measurement of the iris zonule distance IZD.

(111) 17. Once the scleral spur has been located, then the other measurements can be made. These are:

(112) a. Scleral Thickness (ST) is the thickness from the scleral spur to the anterior surface of the sclera, along a line perpendicular to anterior surface of the sclera.

(113) b. Angle-opening distance AODn μm is the distance from cornea to iris at nμm from the scleral spur, along the scleral wall (n typically=250, 500 and 750)

(114) c. Trabecular-iris contact length TICL μm is the linear distance of contact between iris and cornea/sclera beginning at scleral spur

(115) d. Angle-recess area ARAn μm2 is the area of triangle between angle recess and iris and cornea nμm from scleral spur (n typically 250, 500 and 750)

(116) e. Trabecular-iris space TISA μm2 is the area of trapezoid between iris and cornea from sclera to nμm (n typically 250, 500 and 750). Images showing the TISA are illustrated in FIGS. 14 and 15A.

(117) f. Trabecular-iris angle TIA Degrees is the angle formed from angle recess to points 500 μm from scleral spur on trabecular meshwork and perpendicular on surface of iris

(118) g. Trabecular-ciliary process distance TCPD μm is measured from point on endothelium 500 μm from scleral spur through iris to ciliary process (not implemented yet, but on our radar)

(119) h. Iris-zonular distance IZD μm is the distance from posterior iris surface to first visible zonule at point closest to ciliary body (not implemented yet, but on our radar)

(120) i. Iris Thickness (IT) is the thickness of the iris. The IT500 thickness is measured along a line perpendicular to the iris axis that intersects the AOD500 point along the sclera. The IT2 mm thickness is measured with a line parallel to the IT500 line, 2 mm from the iris root, and the IT3 thickness is measured with lines parallel to the IT500 line at the thickest point of the iris. The iris thickness is determined by creating a binarized region of interest including the iris (illustrated in FIGS. 12A and 20), isolating the iris object by increasing the threshold (illustrated in FIG. 17), and making the measurements based on the previously found scleral spur and AOD500 point.

(121) j. Scleral spur-iris insertion distance SS-IR is the linear distance from scleral spur to iris insertion

(122) k. Iris radius of curvature IRC mm is the radius of posterior iris surface using an arc transecting three points: iris root, pupil margin and point of maximal iris displacement

(123) l. Iris convexity IC mm is the maximum distance from the posterior surface of the iris to the line from posterior iris at pupillary margin to the iris root

(124) m. Iris-lens contact distance ILCD mm is the length of contact between surfaces of lens and iris

(125) n. Anterior-posterior chamber depth ACD/PCD is the ratio of anterior chamber to posterior chamber depth measured 1 mm from the scleral spur.

Prepare an Automated Report

(126) 18. Some of the measurements described above are shown in FIGS. 13, 14, and 22 on a typical output report format with the original B-scan as a background is shown in FIG. 20.

(127) Based on the paper “Ultrasound Biomicroscopy in Plateau Iris Syndrome” by Pavlin, Ritch and Foster, which is incorporated herein by reference, another measurement called the iris to zonule distance (IZD) may also be made by the methods described in the present disclosure. The IZD measurement is illustrated in FIG. 21.

(128) FIG. 22 illustrates geometric structures used in detecting the scleral spur. The curve 2210 formed by the interface between the lighter sclera 2204 and darker ciliary muscle 2209 is referred to herein as the “interface curve”. The protruding structure 2208 located at the intersection of the interface curve 2210 and the curve formed by the posterior of the cornea 2201 is referred to herein as “the bump”. FIG. 22 also shows the natural lens 2203 and the zonules 2206 that attach lens 2203 to the ciliary body 2205. Also shown is Schlemm's canal 2207 and the ciliary sulcus 2211 formed at the junction of the ciliary body 2205 and the iris 2202.

(129) FIG. 23 is a close-up of geometric structures used in detecting the scleral spur. The curve 2310 formed by the interface between the lighter sclera 2304 and darker ciliary muscle 2309 is interface curve. The protruding structure 2308 located at the intersection of the interface curve 2210 and the curve formed by the posterior of the cornea 2301 is referred to herein as “the bump”. FIG. 23 also shows the zonules 2306 that attach lens to the ciliary body 2305. Also shown is Schlemm's canal 2307 and the ciliary sulcus 2311 formed at the junction of the ciliary body 2305 and the iris.

(130) A number of variations and modifications of the inventions can be used. As will be appreciated, it would be possible to provide for some features of the inventions without providing others.

(131) The present disclosure, in various embodiments, includes components, methods, processes, systems and/or apparatus substantially as depicted and described herein, including various embodiments, sub-combinations, and subsets thereof. Those of skill in the art will understand how to make and use the present disclosure after understanding the present disclosure. The present disclosure, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, for example for improving performance, achieving ease and\or reducing cost of implementation.

(132) The foregoing discussion of the disclosure has been presented for purposes of illustration and description. The foregoing is not intended to limit the disclosure to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the disclosure are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed disclosure requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the disclosure.

(133) Moreover though the description of the disclosure has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.