Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
  • A61B3/107—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining the shape or measuring the curvature of the cornea
• • 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
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
  • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
  • A61B3/14—Arrangements specially adapted for eye photography
• • G—PHYSICS
  • G02—OPTICS
  • G02C—SPECTACLES; SUNGLASSES OR GOGGLES INSOFAR AS THEY HAVE THE SAME FEATURES AS SPECTACLES; CONTACT LENSES
  • G02C7/00—Optical parts
  • G02C7/02—Lenses; Lens systems ; Methods of designing lenses
  • G02C7/04—Contact lenses for the eyes
  • G02C7/047—Contact lens fitting; Contact lenses for orthokeratology; Contact lenses for specially shaped corneae

Definitions

• Scleral lenses have been used to restore sight to those with injured or diseased corneas and to relieve discomfort from dry eye disorders.
• the incidence of dry eyes in the general population is estimated to be 15%, of which nearly 2 in 10 have symptoms severe enough to significantly impact their quality of life. Globally, this corresponds to 3% of the worldwide population and approximately 9,240,000 severe dry eye patients in the United States alone.
• a scleral lens is a large contact lens that rests on the white scleral region of the eye and is vaulted over the cornea as shown in Figure 1.
• the gap 103 between the back-interior surface of the lens and cornea is typically filled with saline solution which acts like a liquid bandage to soothe the thousands of nerves on the corneal surface.
• medication can be added to, or replace, the saline solution to assist in healing of an injured eye.
• the shape of the bearing surface 100 must match the unique three-dimensional shape of the patient's sclera, including the regions normally covered by the eyelids.
• scleral lenses are manually selected from a set of up to 2000 trial lenses to find a suitable fit to the patient's scleral surface. This is an iterative, expensive, and time- consuming process which can take several weeks. If a close-fitting trial lens can be found, frequently it must be further modified to optimize fit.
• the next step in the prior art approach is to determine the optical properties of the vaulted optics that needs to lie in front of the patient's cornea to properly focus light onto the retina.
• the doctor or eye care practitioner performs an optical refraction (i.e. places different known lenses in front of the trial scleral lens) to determine the optical power of the scleral lens optics. Once the refraction is completed, then knowing the required optical power and the bearing surface shape of the best fitting trial lens, a patient specific custom scleral lens can now be manufactured.
• an optical refraction i.e. places different known lenses in front of the trial scleral lens
• FIG. 3b shows multiple independent meridians in a quadrant over an injured region to enable the back-lens surface to better conform to eye surface topology. Each radial meridian can have different independent spatial Z height values.
• the cross-sectional sagittal image shown in Figure 3a could easily correspond to a scan taken across line 301-307 in Figure 3b, which does not reveal the presence of the injury shown by scan lines 302, 303,304, and 305, such scan lines also referred to as meridians.
• attempts to approximate the three-dimensional shape by acquiring multiple independent two-dimensional scans around the eye has failed in the past because the spatial position of the eye moves between scans.
• U.S. Patent 7,296,890 B2 entitled “Contact Lens with Controlled Shape” presents means for creating a contact lens that sits on the cornea and whose back-surface shape is defined by four (4) base curves, effectively one curve per quadrant.
• This technique for designing a scleral lens bearing surface has multiple limitations. First, it cannot conform to small injuries, protrusions or irregular shapes within a region of a generally different shape, as shown in Figures 2a, 2b, 2c, and 2d herein. Second, the base curve of the cornea is almost always different from that of the sclera with the demarcation point being the limbus.
• a scleral lens that straddles both regions must conform to this complex change in curvature across the region boundaries (as illustrated in Figure 10 at arrow 1003) and Svochak is only concerned with lenses conforming to the cornea.
• the four-base-curve solution cannot follow all possible three-dimensional topology changes in an eye. If an eye or optimized well-fitting lens requires more than 4 base curves to define its shape, as the injured eyes in Figures 2a-d, Svochak' s method is not applicable.
• a first method is described to enable the design of a scleral lens bearing surface so that it follows the actual three-dimensional shape of the sclera, without the need of using trial lenses.
• the lens bearing or back surface that rests on the eye is described by a three-dimensional array of data points each representing an independently measured x, y, z location on the surface of the eye.
• This new capability is applicable for the design of any scleral lens, independent of whether the lens is to relieve dry eye symptoms or to restore sight to patients with injured or diseased corneas.
• every data point on the lens bearing surface can correspond to a uniquely measured three-dimensional x, y, z value on the patient's eye.
• lens design is not limited to four base curves, one per quadrant, and the maximum number of radial meridians used to design the lens is limited only by the spatial-resolution of the topographer and each meridian can be, and typically will be, different from each other, as shown in Figure 3b.
• Figure 3d is an actual three-dimensional, high-resolution, high density scan of a patient's eye showing the three-dimensional array of independently measured data points on the surface of the eye and the ability to conform to fine surface detail.
• Figure 3d was obtained using the Bishop topographer shown in Figure 4.
• Figure 3c shows how this data can be used to make a contact lens whose back surface is shaped to the unique topology of a patient's eye.
• a second method is described to enable the design of just the scleral lens optics without needing to perform a refraction with a scleral lens placed on the eye. This is applicable for those patients that already have good vision, or use eyeglasses or contacts to obtain good vision and want to wear a scleral lens to relieve dry eye symptoms or for any other reason.
• a third method is described is to enable the design of the entire scleral lens, including the bearing surface and optics without the need of a trial lens.
• the bearing surface of the patient specific scleral lens follows the true three-dimensional shape of the patient's eye without requiring the use of a trial lens to determine this shape. This is applicable for those patients that already have good vision, or use eyeglasses or contacts to obtain good vision and want to wear a scleral lens to relieve dry eye symptoms or for any other reason.
• a fourth method enables the 3D printing of a lens designed using the methods described.
• Figure 1 shows the cross section of a scleral lens placed on an eye
• Figure 2a to 2d show injuries on the eye
• Figure 3a is a cross-sectional sagittal image of an eye
• Figure 3b is an image of an injured eye with multiple independent meridians in a quadrant
• Figure 3c is a cross section of a lens showing that the front and back surfaces can be independently designed
• Figure 3d is a motion compensated scan of a human eye acquired by the Bishop scanner;
• Figure 4 is a picture of the Bishop Topographer;
• Figure 5a is a three-dimensional model of a human eye, showing the front view
• Figure 5b is a three-dimensional model of a human eye, showing the side view
• Figure 5c is a three-dimensional topology map of a human eye, showing the front view
• Figures 6, 7a and 7b show multiple gaze images of an eye stitched together to create a topology map and three-dimensional model of the entire eye;
• Figure 8a shows central corneal and scleral data superimposed on a scanned eye
• Figure 8b shows central corneal and scleral data superimposed on a topology map of an eye
• Figure 9a shows the selected bearing surface of the eye superimposed on the three- dimensional model
• Figure 9b shows the selected bearing surface of the eye superimposed on the topology map
• Figure 10a shows the central corneal surface of the eye superimposed on the three- dimensional model
• Figure 10b shows the central corneal surface of the eye superimposed on the topology map
• Figure 10c is the side view of an eye model showing the lens bearing surface shaped to the topology of the eye
• Figure 11 shows a scleral lens with vaulted optics, transition region, and bearing surface
• Figure 12a shows an eye with corrective eyeglasses
• Figure 12b shows a scleral lens placed on the eye
• Figure 13a shows optical rays traveling through eyeglasses into an eye
• Figure 13b shows optical rays traveling through a scleral lens into an eye
• Figure 14a and 14b shows relationship between eyeglass and scleral lens optical rays;
• Figure 15 shows the visual field of an eye at a fixed gaze;
• Figure 17 is an illustration of Snell's Law at air-cornea boundary
• Figure 18 is an illustration of Snell's Law at saline-cornea boundary
• Figures 19a and 19b show the first and second computer model required to design scleral lens optics
• Figure 20 is an enlarged section of FIG. 19b showing optical rays close to eye
• Figure 21 is an enlarged superposition of FIG. 19a and 19b, showing the relationship between optical rays close to the eye;
• Figure 22a is the three-dimensional representation of FIG. 19a
• Figure 22b is the three-dimensional representation of FIG. 19b;
• Figure 22c is the superposition of FIG. 22a and FIG. 22b, showing the relationship between optical rays;
• Figure 23a shows optical rays traveling through air into an eye
• Figure 23b shows optical rays traveling through a scleral lens into an eye
• Figure 24a and 24b shows relationship between optical rays with and without a scleral lens on the eye
• Figure 25a and 25b show the first and second computer model required to design scleral lens optics
• Figure 26 is an enlarged superposition of FIG. 25a and 25b, showing the relationship between optical rays close to the eye;
• Figure 27a is the three-dimensional representation of FIG. 25a
• Figure 27b is the three-dimensional representation of FIG. 25b
• Figure 27c is the superposition of FIG. 27a and FIG. 27b, showing the relationship between optical rays.
• FIG. 28 is a block diagram of a preferred embodiment of a system that may be used to implement the methods described herein. Detailed Description of the Preferred Embodiment
• Figure 5 shows the three-dimensional topology scan of a human eye obtained using the Bishop Topographer. To expose the upper and lower scleral regions, a speculum was used to hold the eyelids open as the eye was scanned.
• Figure 5a shows the resulting front view
• Figure 5b the resulting side view
• Figure 5c a resulting contour map with intensity proportional to height.
• Figures 5a, b, c were all generated from a single 3 second scan of the eye.
• the Bishop Topographer can also acquire and stitch together multiple scans of the eye, each acquired with the eye at a different gaze to expose a different region of the sclera, as shown in Figure 6.
• the topographer can then combine the scans into a single three-dimensional model from which the bearing surface can be extracted.
• the scanner compensates for all motion of the eye during and between scans.
• Figure 7a shows the height contour map
• Figure 7b shows the three-dimensional model generated by stitching together the gaze scans shown in Figure 6.
• FIGS 8a and 8b are an example of the bearing region being in the sclera as shown by arrow 801 in Figure 8a and arrow 802 in Figure 8b.
• the topology information obtained as a set of data points, provided must be free from motion blur to represent the true shape of the eye. As shown in Figures 8a and 8b, each data point represents an independently measured x, y, z location on the surface of the eye.
• Figures 9a and 9b show the bearing surface residing in the sclera as indicated by arrow 901 in Figure 9a, arrow 902 in Figure 9b and arrow 1001 in Figure 10c.
• the bearing surface can also straddle the cornea and sclera or contact the eye in any location. Create the back surface of the lens from the bearing surface information, so that it follows the actual three-dimensional topology of the eye with a high density of sample points within the entire 360 degree bearing region, as shown in Figures 9a and 9b.
• This method of design yields a back surface shaped like a molded impression of the eye, which may include injured and/or irregular regions on the bearing surface.
• the lens is to vault over the central corneal region, extract from a three-dimensional model, or three-dimensional topology map obtained from the topographer, the maximum height of the central corneal surface over the pupil relative to the scleral lens bearing surface, such as height HI indicated by arrow 1002 in Figure 10c.
• a vaulted scleral lens that contains fluid between the cornea and central back surface of the lens
• gaps also prevent excessive suction from forming between the lens and eye which if not prevented could make lens removal difficult.
• Such valleys can be identified upon manipulation and examination of the three-dimensional topology map, and or model, and or the video image.
• each data point of the lens back surface represents an independently measured x, y, z location on the surface of the eye
• a patient wants to wear a scleral lens to relieve dry eye or contact lens induced dry eye symptoms, and has good vision defined as producing a sharp image on their retina without the need for eyeglasses or corrective lenses, then the scleral lens must be designed to maintain the same quality of vision when applied to the eye as existed prior to its application.
• this vision correction function can be incorporated into the scleral lens optics.
• the scleral lens must be designed such that when it is placed on the eye, it recreates the same image on the retina as is formed by the corrective lens placed in front of the eye as shown in Figures 12a and 12b. Therefore, the total light bending properties between the object (candle in Figures 12a and 12b) and retina must be the same for both optical configurations illustrated in Figures 12a and 12b.
• Figures 13a and 13b describe these two optical configurations in more detail with the image projected onto the retina being the same again for both configurations.
• Figures 13a and 13b The only difference between Figures 13a and 13b is what happens outside the eye in front of the cornea. Since in both configurations nothing within the patient's eye changes and in both configurations a sharp image must be projected onto the retina, one can conclude that the optical rays within the cornea must be the same in Figures 13a without the scleral lens, as in Figure 13b with the scleral lens, to produce an in-focus image on the retina. Therefore, the optical rays only need to be matched up to the interior side of the cornea as illustrated in Figures 14a and 14b.
• optical rays need only to be matched over the fixed gaze viewing angle of the eye which is typically +/- 10 degrees for text and +/- 30 degrees for shape, as given in Xthona, A., "Optimizing Image Quality in the Radiologist's Field of Vision", Barco Healthcare, 03 November 2015, and as illustrated in Figure 15.
• oii angle of incidence of the incident beam relative to a perpendicular line drawn to the entering surface
• Ir index of refraction of the refracted beam material
• the corrective lens eyeglass or refractive lens
• reference surface 1404a is not important as long as it is a plane or some other known 3D shape entirely located within the eye. However, placing it toward the front of the eye within the cornea simplifies the calculations because the optical rays do not need to be traced past this point.
• Figure 14a shows the reference surface 1404a located entirely within the cornea.
• Reference Ray Set The set of optical rays from the source to the reference surface created by the corrective lens is referred to as the "Reference Ray Set.” and contains the following ray subsets indicated in Figure 14a:
• the degree of light bending by the corrective lens is determined using Snell's law and the known shape of the corrective lens 1402.
• the degree of light bending at the air-corneal surface is determined using Snell's law and the shape of the cornea 1403 a provided by the three- dimensional topographer.
• the goal is to design the scleral lens so that it places the optical rays from the source at the same approximate position within the cornea as did the corrective lens, within the limits imposed by Snell's law and the technology used to fabricate the three-dimensional scleral lens surface shape. To accomplish this goal the following steps are performed (with reference to Figure 14b):
• Reference Surface 1404b in Figure 14b is the same Reference Surface as 1404a in Figure 14a redrawn for convenience.
• Cornea 1403b is the same cornea as 1403a redrawn for convenience.
• each optical ray determines how much each optical ray is bent at this boundary.
• Each optical ray then continues at its new projected angle through the saline fluid (1405) to the back surface of the scleral lens 1406.
• Snell's law is then applied at the scleral lens (1406) back surface - saline fluid (1405) boundary and the scleral lens (1406) front surface - air boundary.
• the shape of the three- dimensional front and back scleral lens surfaces are adjusted so that the optical rays exiting the front surface of the scleral lens (1406) retraces, as close as possible, within the limits of Snell's law, the equivalent rays in the Reference Ray Set existing between the source 1401a and corrective lens 1402, indicated by arrow 1410a in Figure 14a.
• This conceptual scleral lens optical design procedure can be implemented to create actual scleral lens optics to replace eyeglasses worn to correct for nearsightedness.
• Design performance can be evaluated by superimposing the reference ray set for the eyeglass configuration onto the corresponding optical rays for the scleral lens configuration.
• the front surface of the scleral lens will bend light more than the back surface for the same incident light angle because the difference in the index of refraction between the scleral lens material (1.424) and saline (1.335) on the back surface is 0.089 and the difference between air (1.00) and the scleral lens material (1.424) on the front surface is 0.424, a factor of 4.7 times greater. It is for this reason that the design example provided uses a spherical shape for the back surface and an aspheric shape for the front surface. However, more complex shapes can be used to achieve closer matches to a reference ray set if desired.
• scleral lens To design the scleral lens: a. Create a first computer model ( Figure 19a) containing an optical source 1901a, typically placed at infinity, a corrective lens 1902 that when placed in front of a patient's eye improves their vision, a three-dimensional model of the patient's corneal front surface 1903 a, and a Reference Surface 1904a placed behind the cornea within the eye. b. Trace optical rays from the source (1901a), through air, to the front
• optical source 1901b identical optical source 1901b, eye 1903b, and Reference Surface (1904b) as in the first computer model, where optical source 1901b is identical to optical source 1901a, eye 1903b is identical to eye 1903a, and Reference Surface 1904b is identical to Reference Surface 1904a.
• Place the optical source 1901b the same distance from the eye as in the first computer model.
• Place the Reference Surface at the same location within the eye as in the first computer model.
• j Knowing the three-dimensional shape of the front surface of the cornea 1903b, the three-dimensional shape of the cornea-fluid boundary, the index of refraction of the cornea (typically 1.376), and the index of refraction of the fluid (typically 1.336 for saline), apply Snell's law to the cornea- (saline) fluid boundary to determine the path of the optical rays from the front surface of the cornea through the fluid 1905 to the back- surface of the scleral lens 1906.
• k Adjust the height of the back surface of the scleral lens, indicated by H2 (1107) in Figure 11, to vault over the cornea. Vaulting height is not critical, but is typically less than 300 microns.
• Figure 21 is the superposition of the examples of Figures 19a and 19b zoomed in around the cornea and enlarged to show how well the optical rays from the Scleral Lens design match the Reference Ray Set from the corrective lens configuration. Optical rays are shown entering the eye at approximately 0, 10, and 20 degrees relative to a line perpendicular to the front surface of the cornea.
• Figure 22a is the three-dimensional representation of Figure 19a and is the first three- dimensional model that is needed by the computer to design the scleral lens.
• Figure 22b is the three-dimensional representation of Figure 19b and is the second three-dimensional model that is needed by the computer to design the scleral lens.
• Figure 22c is the superposition of the examples of Figures 22a and 22b showing the alignment of the ray bundles and more specifically how well the scleral lens is able to duplicate the Reference Ray Set.
• the front surface curvature 1902F of corrective lens 1902 in Figure 19 is 150mm and the back-surface radius of curvature 1902B is 100mm.
• the scleral lens 2006 in Figure 20 has a back surface spherical radius of curvature 2006B equal to 10.64mm.
• the front surface of scleral lens 2006 is an even Asphere with a radius of 38.473mm, a conic of -4.75mm, 2 nd order term of 0.058, 4 th order term of 0.000623, 6 th order term of -0.0001804, 8th order term of 0.00003288, 10 th order term of - 2.947E-6, and 12 th order term of 1.06E-7.
• the parameters used to specify an aspheric surface are described in an article by Czajkowski, A., entitled "Specifying an Aspheric Surface," OPT 521 - Report #2, December 14, 2007.
• Figure 23a illustrates the patient's eye focused on an object 2301a (typically placed at infinity). It is assumed that the patient sees the object clearly.
• Figure 23b shows a scleral lens 2304a placed on the eye. The scleral lens must be designed to maintain the same quality of vision when applied to the eye as was obtained prior to its application.
• the goal is to project the same image onto the retina in Figure 23b as in Figure 23a, within the limits of Snell's law.
• this can be achieved by matching the optical rays inside the eye to a reference surface (2412a and 2412b).
• the reference surface can be placed anywhere inside the eye behind the surface of the cornea (in front of, within, or behind the crystalline lens).
• the optical rays are also matched outside the eye prior to and after application of the scleral lens. Matching rays outside the eye correspond to matching reference rays 2410a to rays 2410b.
• optical rays 2410a ⁇ 2410b and 2412a ⁇ 2412b within the limits imposed by Snell's law and the scleral lens manufacturing process.
• Snell's law the scleral lens manufacturing process. The precise steps required to design such a scleral lens will now be described in the second design example.
• the back surface of the scleral lens will be made spherical and the front aspheric in shape. More complex shapes can be used to achieve closer matches to the Reference Ray Set if desired.
• a. Create a first computer model ( Figure 25a) containing an optical source 2501a, preferably placed at infinity, the patient's eye (2502a) a three- dimensional model of the patient's corneal front surface 2503a, obtained from a topographer, and a Reference Surface 2504a placed behind the cornea within the eye.
• b. Trace optical rays from the source (2501a), through air, to the front
• c. Determine the path of the optical rays from the front surface of the cornea 2503Fa to a Reference Surface 2504a placed within the eye. Knowing the three-dimensional shape of the front surface of the cornea 2503Fa, supplied by the topographer, apply Snell's law at the front surface air- cornea boundary and at any material boundary within the eye lying between the cornea and the Reference Surface 2504a.
• the Reference Surface can be planar or curved.
• d. Store the three-dimensional path of the optical rays traveling from the source 2501a to the Reference Surface 2504a and refer to this set of rays as the Reference Ray Set 2507a.
• Figure 25b containing the same
• optical source 2501b, eye 2502b, and Reference Surface (1904b) as in the first computer model, where optical source 2501b is identical to optical source 2501a, eye 2502b is identical to eye 2502a, cornea 2503a is identical to cornea 2503b, and Reference Surface 2504b is identical to Reference Surface 2504a.
• a scleral lens 2506 over the eye in the second computer model, Figure 25b, filling the gap between the cornea and back surface of the scleral lens with fluid 2505, typically saline.
• the three-dimensional shape of the cornea-fluid boundary, the index of refraction of the cornea (typically 1.376), and the index of refraction of the fluid (typically 1.336 for saline) apply Snell's law to the cornea- (saline) fluid boundary to determine the path of the optical rays from the front surface of the cornea 2503F through the fluid 2505 to the back-surface of the scleral lens 2506.
• Snell's law to the cornea- (saline) fluid boundary to determine the path of the optical rays from the front surface of the cornea 2503F through the fluid 2505 to the back-surface of the scleral lens 2506.
• H2 (1107) in Figure 11 Adjust the height of the back surface of the scleral lens, indicated by H2 (1107) in Figure 11, to vault over the cornea. Vaulting height is not critical, but is typically less than 300 microns.
• Figure 26 is the superposition of Figures 25a and 25b zoomed in around the cornea and enlarged to show how well the optical rays from the Scleral Lens design match the Reference Ray Set computed without the scleral lens on the eye. Optical rays are shown emanating 0, 10, and 20 degrees from a source located at infinity.
• Figure 27a shows the actual first three-dimensional computer model used to calculate the Reference Ray Set, with three optical ray bundles emanating 0, 10, and 20 degrees from the source at infinity.
• Figure 27a is the three-dimensional drawing corresponding to the two- dimensional drawing shown in Figure 25a.
• Figure 27b shows the actual second three-dimensional computer model used to design the scleral lens also with ray bundles emanating at 0, 10, and 20 degrees from the infinity source.
• Figure 27b is the three-dimensional drawing corresponding to the two-dimensional drawing shown in Figure 25b.
• Figure 27c is the superposition of Figures (27a and 27b showing how well the optical rays from the scleral lens design are able to duplicate the Reference Ray Set.
• the back surface has a spherical radius of curvature equal to 16.473mm.
• the front surface is an Even Asphere with a Radius of 8.866mm, a conic of -0.053, 2 nd order term of -1.727E-4, 4 th order term of 1.251E-4, 6 th order term of -6.553E-5, 8th order term of 9.107E-6, 10 th order term of -4.023E-7 and 12 th order term of 0.0.
• Figures 25 through 27 were generated by a ray tracing lens design program called Opticstudio by Zemax LLC of Kirkland, WA. Again, it is emphasized that Figures 25 through 27 correspond to the design of a real scleral lens.
• scleral lens optics, bearing surface shape, and vaulting height can be manufactured either by using a precision lathe or using a 3D printer.
• An example of a precision lathe is the "Nanoform X” manufactured by Ametek Precitech, Inc. of Keene, H.
• An example of a precision 3D printer is the "Photonic Professional GT” by Nanoscribe GmBH of Eggenstein-Leopold Shafen, Germany.
• scleral lenses that incorporate a soft material, such as for example a silicone hydrogel, for the bearing surface.
• a soft material such as for example a silicone hydrogel
• Such pliable materials frequently referred to as “skirts” conform to the shape of the eye in the bearing region.
• a rigid optical lens, vaulting over the cornea, is supported by the soft conforming skirt.
• An example of a scleral lens with a soft skirt is manufactured by SynergEyes, Inc. of Carlsbad, CA.
• Scleral lens optics designed using the procedure described herein can also be combined with a soft skirt or incorporated into a pliable bearing surface lens, thereby greatly reducing the time and complexity of such scleral lens design.
• Figure 28 is a block diagram of a preferred embodiment of a system 2800 that may be used to implement the methods described herein.
• This implementation uses a topographer 2810, a Digital Signal Processor (DSP) / computer 2820, a display 2830, and data storage 2840 to process and/or generate one or more three- dimensional model(s) 2850 of an eye and/or the resulting lens.
• the lens model(s) may then be provided to a precision lathe 2860 and/or 3D printer 2870 to produce a physical lens.
• the topographer 2810 may use a video camera and a line scan device to obtain a 3D model of an eye.
• Other topographers as described in the above-referenced U.S. Patent 9,489,753 by Bishop et al. use Optical Coherent Topography to measure eye topology.
• Optical Coherent Topography to measure eye topology.
• there are topographers that project patterns onto the eye and measure pattern distortion to determine corneal shape such as the Placido Disc topographers.
• Other topographers insert fluorescent dyes into the eye and project patterns onto the fluorescing material to determine the shape of the eye.
• the topographer 2810 thus typically includes a number of components (not shown in detail here) such as a two dimensional (2D) digital video camera to take a sequence of images of an eye including at least one feature on the eye.
• the camera may be a television camera or other digital camera capable of capturing a sequence of images.
• the topographer 2810 also includes a scanner that measures distances to the surface of the eye to produce a set of independently measured data points in 3D space - that is, each "pixel" in the sequence of camera images is thus associated with an x, y, z location on the surface of the eye.
• the DSP/computer 2820 may further include storage 2840, a display 2830 and / or other peripheral components.
• the DSP/computer 2820 executes program code to perform some or all of the steps of the methods described herein for determining the design of a lens.
• One or more three-dimensional models 2850 specifying a lens design may then be provided as output data files to a lens manufacturing machine (or process) such as the precision lathe 2860 or the 3D printer 2870.
• the DSP/computer 2820 shown here may act as both the computer for the topographer as well as the platform that executes the lens design method described herein.
• the topographer 2810 may have its own DSP and/or computer arranged to operate on the output of the camera and the scanner to produce topology data points from the eye with a separate DSP/computer executing the lens design procedure. Scanned eye data from the topographer may be transferred in the form of a data file that is transferred over a network, or on a portable storage media such as a memory stick, disk, or magnetic tape, to the lens design computer.
• the precision lathe 2860 and/or 3D printer 2870 may typically have their own processors and may be located remotely from the DSP/computer 2820, and operate on 3D model designs provided to them in the form of a data file that is transferred over a network, or on a portable storage media such as a disk or magnetic tape.
• the DSP/computer may also directly control a local or remote precision lathe 2860 and/or 3D printer 2870 over a network connection. Still other arrangements are possible.
• a method for determining one or more characteristics of a design of a lens can include receiving, from an ocular topographer, an array of data points from which at least the three dimensional position of each data point can be extracted.
• the data points are such that each data point represents an independently measured x, y, z location on a surface of an eye, the spatial relationship accurately representing a true topology of the eye, free from motion blur artifacts that occur during acquisition of the data points, and a sampling density of the data points being sufficiently high to characterize anomalies in the eye.
• the method then proceeds to analyze the data points for determining an array of independent data points to define the back surface of the lens, such that the resulting lens is a contact lens that conforms to or vaults over said anomalies on the eye.
• the data points can be further used for grouping together independent data points either as used from the topographer or as determined to define a lens back surface into meridians, the meridians being of any shape, with the meridians being independent from each other, and with a meridian data point density being sufficiently high so as to characterize anomalies anywhere in the eye that compromise lens comfort and fit.
• the method may also include steps for determining one or more characteristics of a design of a lens, the lens comprising a front surface and a back surface, that involves receiving, from an ocular topographer, an array of data points from which at least the three dimensional position of each data point can be extracted with each data point used from the topographer representing an independently measured x, y, z location on a surface of an eye, the spatial relationship between the data points used from the topographer accurately representing a true topology of the eye, free from motion blur artifacts that occur during acquisition of the data points, a sampling density of the data points used from the topographer being sufficiently high to characterize anomalies in the eye that compromise lens comfort and fit; and determining, from the data points used from the topographer, a lens back-surface with quadrant or sub-division boundaries defined by multiple independent data points, with additional independent data points within each quadrant or sub- division that are not used to define the boundaries, and with a density of independent data points within each quadrant or sub-division being sufficiently high so as to
• the methods may also involve determining one or more characteristics of a design of a lens, comprising receiving, from an ocular topographer, an array of data points from which at least the three dimensional position of each data point of an eye can be extracted; determining characteristics of the lens including an optical region, a transition region, and a bearing surface, with the optical region focusing incoming light into an eye,the transition region connecting the optical region to the bearing surface, the bearing surface comprising a region of the lens that rests on a surface of an eye, the bearing surface further defined as an array of independent data points conforming to the three-dimensional data point positions of the eye extracted from the topographer, and with the resulting lens being a scleral lens that conforms to or vaults over said anomalies anywhere on the eye, such that
• lens optics in the optical region are vaulted over a cornea of the eye to create a fluid reservoir between a back surface of the optics and the cornea,
• the bearing surface resting either solely on a sclera and conforming to a three- dimensional shape of the sclera, or the bearing surface straddling a limbus, such that the bearing surface rests partially on and conforms to the three-dimensional shape of sclera and rests partially on and conforms to a three-dimensional shape of the cornea, and containing:
• the method may further involve determining one or more characteristics of a design of lens optics without applying a trial lens to a patient's eye, by creating a first computer model containing an optical source, an eye with a three-dimensional model of a corneal front surface of the patient's eye as provided by a topographer, and a Reference Surface placed behind the corneal front surface within the eye, where the Reference Surface may be planar or curved, and further when the patient requires corrective lenses, or eyeglasses, to produce a sharp image on their retina,
• the method(s) may further involve using the three-dimensional shape of the front surface of the cornea, the index of refraction of the cornea, and the index of refraction of the fluid, applying Snell's law to the cornea- fluid boundary to determine the path of the optical rays as they travel from the front surface of the cornea through the fluid to the back surface of the scleral lens; such that

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