Rose k

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  • Les indications de ces 3 lentilles sont… Pour chaque lentille, le protocole d’adaptation est le même : centre, périph,diam…
  • Pour un rayon central cambré et un diam.donné
  • For 8.7 diamètre Trial set. Different OZ for different diamètres.Set OZ for any base but does vary with diamètre.
  • Rose k

    1. 2. Contact Lens Optics Dr. Mohammad Amiri , OD Department of Optometry ,Faculty of Rehabilitation Shahid Beheshti Medical Sceince University Vision Care of Menicon
    2. 3. <ul><li>Vertex all powers >4D to corneal plane </li></ul><ul><li>Vertex equation: </li></ul><ul><ul><li>Fcornea=Fspec/(1-dFspec) </li></ul></ul><ul><ul><li>F=power </li></ul></ul><ul><ul><li>d=vertex distance in meters </li></ul></ul><ul><ul><li>Must vertex both meridians </li></ul></ul><ul><li>Example: -5D Rx at 15mm </li></ul><ul><li>-4.62=-5.00/[1-(.015X5)] </li></ul>
    3. 4. Soft Contact Lenses <ul><li>Spherical </li></ul><ul><ul><li>Disposables </li></ul></ul><ul><ul><li>Dailies </li></ul></ul><ul><li>Toric </li></ul><ul><ul><li>Disposables </li></ul></ul><ul><ul><li>Dailies </li></ul></ul><ul><ul><li>Custom </li></ul></ul><ul><li>Multifocals </li></ul>
    4. 5. Soft Contact Lenses <ul><li>Sphericals </li></ul><ul><ul><li>Essentially no tear layer </li></ul></ul><ul><ul><ul><li>Must have tear exchange for health </li></ul></ul></ul><ul><ul><ul><li>Does not change refractive status </li></ul></ul></ul>
    5. 6. Soft Lenses <ul><li>Variety of powers </li></ul><ul><ul><li>-20 to +20 </li></ul></ul><ul><li>Use spherical equivalent for up to 3 steps of cylinder </li></ul>
    6. 7. Soft Contact Lenses <ul><li>Torics </li></ul><ul><ul><li>Now in XR series- extended series </li></ul></ul><ul><ul><ul><li>up to -6 cyl </li></ul></ul></ul><ul><ul><ul><li>Toric Multifocal </li></ul></ul></ul><ul><ul><ul><li>2 designs </li></ul></ul></ul><ul><ul><ul><ul><li>Prism ballasted </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Thin zone design </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Slab off , Prism ballasted </li></ul></ul></ul></ul>
    7. 8. Soft Toric <ul><li>Most all toric designs have marking indicators on surface. </li></ul><ul><ul><li>3,6,9 o’clock </li></ul></ul><ul><ul><li>6,12 </li></ul></ul><ul><ul><li>15 degrees apart </li></ul></ul><ul><ul><li>Can be used to identify lens- Tyler’s/contact lens quarterly </li></ul></ul>
    8. 9. Soft Contact Lenses Material <ul><li>HEMA – 1 st soft </li></ul><ul><ul><li>Dk dependent on hydration i.e. higher water content =higher Dk </li></ul></ul><ul><ul><ul><li>D=diffusion coefficient </li></ul></ul></ul><ul><ul><ul><li>k=solubility coefficient </li></ul></ul></ul><ul><ul><ul><li>Dk=“Oxygen permeability” </li></ul></ul></ul><ul><ul><li>Dk=8-30 </li></ul></ul><ul><ul><li>Early lenses </li></ul></ul><ul><ul><ul><li>B&L </li></ul></ul></ul><ul><ul><ul><li>Acuvue </li></ul></ul></ul>
    9. 10. Soft Contact Lens Materials <ul><li>Non-HEMA </li></ul><ul><ul><li>Dk 12-30 </li></ul></ul><ul><ul><li>Dk less dependent on hydration </li></ul></ul><ul><ul><li>Better for dry eye patients </li></ul></ul><ul><ul><ul><li>CSI </li></ul></ul></ul><ul><ul><ul><li>Proclear </li></ul></ul></ul>
    10. 11. Soft Contact lenses <ul><li>Silicone Hydrogel </li></ul><ul><ul><li>Dk independent of hydration </li></ul></ul><ul><ul><li>Dk=60-161 </li></ul></ul><ul><ul><li>Dk in order (high to low) </li></ul></ul><ul><ul><ul><li>Focus Night & Day </li></ul></ul></ul><ul><ul><ul><li>Biofinity </li></ul></ul></ul><ul><ul><ul><li>Acuvue Oasys </li></ul></ul></ul><ul><ul><ul><li>O2 Optix </li></ul></ul></ul><ul><ul><ul><li>Purevision </li></ul></ul></ul><ul><ul><ul><li>Premio Q </li></ul></ul></ul>
    11. 12. Soft Contact Lenses <ul><li>Parameters </li></ul><ul><ul><li>Power </li></ul></ul><ul><ul><li>Base Curve – typically 1-2 choices </li></ul></ul><ul><ul><ul><li>Flatter – Asian eyes, smaller eyes, less vault </li></ul></ul></ul><ul><ul><li>Diameter (13.8-14.5mm) </li></ul></ul><ul><ul><li>Optical zone diameter </li></ul></ul><ul><ul><li>Material </li></ul></ul><ul><ul><li>Center thickness – comfort and hydration </li></ul></ul><ul><ul><ul><li>Only power and BC is adjustable – rest cause a change in type of lens selected </li></ul></ul></ul>
    12. 13. <ul><li>4 groups of classifications </li></ul><ul><ul><li>Group 1= low water/ non-ionic </li></ul></ul><ul><ul><li>Group 2=high water/non-ionic </li></ul></ul><ul><ul><li>Group 3=low water/ionic </li></ul></ul><ul><ul><li>Group 4=high water/ionic </li></ul></ul><ul><ul><li>Low water=38-50% - low evap, low DK </li></ul></ul><ul><ul><li>High water =60% - high evap, thick, use in dry eye </li></ul></ul>
    13. 14. Extended Wear Soft Lenses <ul><li>Open eye =21% oxygen </li></ul><ul><li>Closed eye =7% oxygen </li></ul><ul><li>Overnight with closed eye & CL </li></ul><ul><ul><li>Some swelling expected </li></ul></ul><ul><ul><li>4-5% safe </li></ul></ul><ul><ul><li>10-15% folds </li></ul></ul><ul><ul><li>15-20% pathological </li></ul></ul>
    14. 15. Fitting Soft Lenses <ul><li>Evaluation: </li></ul><ul><ul><li>Fitting </li></ul></ul><ul><ul><ul><li>Movement -Want .5 to 1mm of movement on blink- too tight conjunctival drag </li></ul></ul></ul><ul><ul><ul><li>Centration </li></ul></ul></ul><ul><ul><ul><li>Lag- position of contact on sup and side gaze </li></ul></ul></ul><ul><ul><ul><li>Edge appearance </li></ul></ul></ul>
    15. 16. Edge Appearance
    16. 17. Changes to fit <ul><li>Go to looser fit: </li></ul><ul><ul><li>Need to decrease sagittal depth </li></ul></ul><ul><ul><li>How? </li></ul></ul>
    17. 18. Looser Fit <ul><li>Decrease sagittal depth </li></ul><ul><li>Corneal flattens in periphery </li></ul><ul><ul><li>Flatten base curve </li></ul></ul><ul><ul><li>Decrease diameter </li></ul></ul><ul><li>Opposite for tighter fit </li></ul>
    18. 19. Summary of Market <ul><li>Total Share of Market by Manufacturer </li></ul><ul><ul><li>J&J – Acuvue – 50% </li></ul></ul><ul><ul><li>Copper-23% </li></ul></ul><ul><ul><li>Ciba-18% </li></ul></ul><ul><ul><li>B&L – 16% </li></ul></ul><ul><li>In US dailies now about 10% </li></ul><ul><li>As of Q2 2007 silicone hydrogel>Hema lenses </li></ul>
    19. 20. Where is the optics?
    20. 21. <ul><li>Not a lot </li></ul><ul><ul><li>Tear layer non-existent in soft contact </li></ul></ul><ul><ul><li>Accommodative demand </li></ul></ul><ul><ul><li>Convergence demand </li></ul></ul><ul><ul><li>Astigmatism issues </li></ul></ul><ul><ul><li>Spectacle magnification </li></ul></ul>
    21. 22. Accommodative Demand <ul><li>Accommodation: Difference of vergence at the first principle point of the eye(1.35mm behind the cornea) between rays from infinity and rays from a near point </li></ul><ul><li>myopes in CL </li></ul><ul><li>hyperopes in CL </li></ul>
    22. 23. Accommodative Demand <ul><li>AD=(verg N-Verg Infinity) </li></ul><ul><li>Accom need=1/focal length (m) </li></ul><ul><li>In contacts no vertexing </li></ul><ul><ul><li>Verg N= Accom + Power RX </li></ul></ul><ul><ul><li>Verg infinity=power of Rx lens </li></ul></ul><ul><li>In glasses – have to vertex </li></ul><ul><ul><li>Verg N=(accom +power Rx) vertexed </li></ul></ul><ul><ul><li>Verg Infinity=power of spec (vertexed) </li></ul></ul>
    23. 24. Accommodative Demand <ul><li>Back to Vertex equation: </li></ul><ul><li>Fcornea=Fspec/(1-dFspec) </li></ul><ul><ul><li>d=vertex distance in meters </li></ul></ul><ul><li>Example: What is the accommodative demand of -9 D viewing an object at 40cm? </li></ul>
    24. 25. Accommodative Demand <ul><li>CL’s: 2.50D </li></ul><ul><ul><li>AD=Verg N-Verg infinity =(11.5-9)=2.5 </li></ul></ul><ul><ul><ul><li>1. Verg N=9 + accom need(1/focal length) </li></ul></ul></ul><ul><ul><ul><li>2. Verg Infinity=9 </li></ul></ul></ul><ul><li>Glasses:1.45D </li></ul><ul><ul><li>AD=Verg N-Verg Infinity=(9.37-7.92)=1.45D </li></ul></ul><ul><ul><ul><li>1. Verg N=9.37 </li></ul></ul></ul><ul><ul><ul><li>2. Verg Infinity = 7.92 </li></ul></ul></ul>
    25. 26. Accommodative Demand <ul><li>Simply </li></ul><ul><li>1. find accom need (1/focal length) </li></ul><ul><li>2. CL or glasses </li></ul><ul><ul><li>CL=accom demand=accom need </li></ul></ul><ul><ul><li>Glasses= </li></ul></ul><ul><ul><ul><li>[rx +accom need (vertexed)] –[rx(vertexed)] </li></ul></ul></ul>
    26. 27. Accommodative Demand <ul><li>What is another scenario where we are inducing more accommodative demand for myopes? </li></ul>
    27. 28. Convergence Demand <ul><li>As eyes converge contact moves with eyes – spectacles do not. </li></ul><ul><li>Convergence demand in contact lenses vs. glasses </li></ul><ul><ul><li>More with myopes in CL </li></ul></ul><ul><ul><li>Less with hyperopes in CL </li></ul></ul><ul><li>Spectacle lenses induce prism </li></ul>
    28. 29. Convergence Demand <ul><li>Spectacles – myopic lenses induce BI prism – aid reading </li></ul><ul><li>Hyperopic lenses induce BO prism- more difficult for near work </li></ul>
    29. 30. Convergence Demand <ul><li>Prentice’s Rule: </li></ul><ul><li>P=(dxD)/10 </li></ul><ul><ul><li>P=induced prism </li></ul></ul><ul><ul><li>d=distance from optical center </li></ul></ul><ul><ul><li>D=power of lens </li></ul></ul>
    30. 31. Astigmatism <ul><li>CL vs. glasses: Less meridional aniseikonia created with contact lenses due to correction at corneal plane. </li></ul><ul><li>Making the next choice: Soft vs. Hard </li></ul><ul><li>Answer lies in where the astigmatism is located. </li></ul><ul><li>Mostly lenticular = soft better choice </li></ul>
    31. 32. Astigmatism <ul><li>First convert minus cyl </li></ul><ul><li>Second vertex </li></ul><ul><li>Refractive astigmatism=corneal astigmatsim+lenticular astigmatism </li></ul><ul><ul><li>Compare: </li></ul></ul><ul><ul><ul><li>Rx=refractive ( or total) </li></ul></ul></ul><ul><ul><ul><li>K’s = corneal astigmatism </li></ul></ul></ul><ul><ul><ul><li>If lenticular astigmatism>corneal - SOFT </li></ul></ul></ul>
    32. 33. Astigmatism <ul><li>Example: </li></ul><ul><ul><li>-4.00+0.50x090 with K’s: 42.50/44.00 </li></ul></ul><ul><ul><ul><li>1. Convert: -3.50-0.50x180 </li></ul></ul></ul><ul><ul><ul><li>2. vertex if needed </li></ul></ul></ul><ul><ul><ul><li>3. refractive =corneal+lenticular </li></ul></ul></ul><ul><ul><ul><ul><li>Refr= 0.50x180 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Corneal=1.50x180 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Lent= </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Best choice??? </li></ul></ul></ul></ul></ul>
    33. 34. Relative Spectacle Magnification <ul><li>Spectacle Magnification=1/(1-aF) </li></ul><ul><ul><li>F=power of lens </li></ul></ul><ul><ul><li>a=distance in meters from lens to entrance pupil of eye (3mm behind corneal) </li></ul></ul><ul><ul><li>Example: </li></ul></ul><ul><ul><ul><li>+14.00 D lens, 15mm vertex </li></ul></ul></ul><ul><ul><ul><li>Spec mag=1/(1- 0.018x14)=1.33 </li></ul></ul></ul>
    34. 35. Relative Spectacle Magnification <ul><li>In Contacts versus glasses: </li></ul><ul><li>Mag=1-dF </li></ul><ul><ul><li>d=vertex distance </li></ul></ul><ul><ul><li>F=spectacle power </li></ul></ul><ul><ul><li>Example: </li></ul></ul><ul><ul><li>+14.0 D lens, 15mm vertex </li></ul></ul><ul><ul><li>Mag=1-(0.015x14)=.79 or 21% less mag with CL </li></ul></ul>
    35. 36. Image Size <ul><li>Anisometropia- monocular aphakes </li></ul><ul><ul><li>Mag is reduced as the forward facing plus lens is moved closer to site of former lens. </li></ul></ul><ul><ul><li>Most mag=glasses<cl<pcIOL </li></ul></ul><ul><li>Telescope </li></ul><ul><ul><li>In aphakics- reversed Galilean telescope helps equalize the image </li></ul></ul><ul><ul><li>Correct phakic eye with CL to Inc image size </li></ul></ul><ul><ul><li>Over + CL add minus to spec RX </li></ul></ul>
    36. 37. Complications <ul><li>CLARE/SLACH </li></ul><ul><ul><li>Treatment </li></ul></ul><ul><ul><li>Ulcer </li></ul></ul>
    37. 38.
    38. 39. Complications <ul><li>Neovascularization </li></ul><ul><li>Allergy- </li></ul><ul><ul><li>Environmental vs. solution </li></ul></ul><ul><li>Dry eye </li></ul><ul><li>Epithelial split- </li></ul><ul><li>Acanthamoeba </li></ul>
    39. 40. Acanthamoeba
    40. 41. Hard Contact Lenses
    41. 42. <ul><li>Original – PMMA </li></ul><ul><ul><li>Polymethylmethacrylate </li></ul></ul><ul><li>Now – rigid gas permeable </li></ul>
    42. 43. Power Cross <ul><li>Tear layer- 2x players </li></ul><ul><ul><li>Posterior tear layer= curvature due to front surface of cornea </li></ul></ul><ul><ul><ul><li>Secondarily to assumed equal index of refraction for tears and corneal tissue </li></ul></ul></ul><ul><ul><li>Anterior tear layer=curvature due to back surface of contact lens </li></ul></ul><ul><ul><li>Thus Power of TL =CL BC- corneal K </li></ul></ul>
    43. 44. Power Cross <ul><li>Minus Cylinder </li></ul><ul><li>Base Curve–K- readings= Tear Layer </li></ul><ul><li>TL+Spec Rx(vertexed if necess) =CLRX </li></ul>
    44. 45. Power Cross <ul><li>Each of these calculations must be performed for each meridian separately </li></ul><ul><li>If 2 different powers are obtained order spherical equivalent </li></ul><ul><li>If residual cylinder is >.75 rethink RGP vs. bitoric </li></ul>
    45. 46. Tear Lens <ul><li>K readings =Diopters </li></ul><ul><li>Radius =mm </li></ul><ul><li>R=337.5/K </li></ul><ul><li>Example </li></ul><ul><ul><li>K=42.5 </li></ul></ul><ul><ul><li>R=337.5/42.5=7.95 </li></ul></ul>
    46. 47. Example <ul><li>PT: </li></ul><ul><ul><li>Manifest ref: -3.25-1.00x180 </li></ul></ul><ul><ul><li>K’s:44.50 @090/43.50@180 </li></ul></ul><ul><ul><li>Order? </li></ul></ul><ul><ul><li>44.00/-4.00/9.2 </li></ul></ul>
    47. 48. Tear Lens <ul><li>Tear layer functions as a lens </li></ul><ul><li>Power of tear lens .25D for every.05mm radius of curvature difference b/w BC and corneal </li></ul><ul><li>Rule: SAM/FAP </li></ul><ul><ul><li>Steep add minus/Flat add plus </li></ul></ul>
    48. 49. Tear Lens <ul><li>SAM/FAP </li></ul><ul><li>Example: </li></ul><ul><ul><li>Spec=-3.00 </li></ul></ul><ul><ul><li>K=43.25(7.80) </li></ul></ul><ul><ul><li>BC of RGP=42.5(7.95) </li></ul></ul><ul><ul><li>RGP =.75 flatter than K </li></ul></ul><ul><ul><li>Order:-2.25/7.95/9.0 </li></ul></ul><ul><li>On K fit – Use base curve of flatter meridian </li></ul>
    49. 50. Parameters of Change <ul><li>Power </li></ul><ul><li>Base Curve </li></ul><ul><li>OZ </li></ul><ul><li>Diameter </li></ul><ul><li>Peripheral curves </li></ul><ul><li>Ct </li></ul><ul><li>Blend </li></ul><ul><li>Can change each independently in RGP </li></ul>
    50. 51. Hard Contact Lenses <ul><li>Power= </li></ul><ul><ul><li>Change Base curve by flatten – need to increase rx by equal amount (-) </li></ul></ul>
    51. 52. Hard Contact Lenses <ul><li>Base Curve </li></ul><ul><ul><li>Flatten BC =Decrease sag depth </li></ul></ul><ul><li>OZ= optical zone </li></ul><ul><ul><li>If large pupil </li></ul></ul><ul><ul><li>Shadows </li></ul></ul><ul><ul><li>Blend </li></ul></ul><ul><li>Diameter 9.0-11.0 </li></ul><ul><ul><li>Increase diameter= increase edge lift </li></ul></ul>
    52. 53. Hard Contact Lens <ul><li>PC= Peripheral curves </li></ul><ul><ul><li>Secondary </li></ul></ul><ul><ul><li>Tertiary </li></ul></ul><ul><ul><ul><li>For comfort </li></ul></ul></ul><ul><ul><ul><li>Edge lift </li></ul></ul></ul><ul><li>CT= Center thickness </li></ul><ul><ul><li>Request – again for comfort </li></ul></ul><ul><ul><li>Polycon design </li></ul></ul>
    53. 54. Hard Contacts <ul><li>Bitorics </li></ul><ul><ul><li>Greater than 3D of astigmatism </li></ul></ul><ul><ul><li>Rx= 2 base curves/2 powers </li></ul></ul><ul><ul><ul><li>Ordering </li></ul></ul></ul><ul><ul><ul><ul><li>Match K’s </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Match sph and total rx in cyl meridian </li></ul></ul></ul></ul><ul><ul><ul><li>Warpage </li></ul></ul></ul><ul><ul><ul><li>Example= +1.00-4.50x135/K=43/47.25 </li></ul></ul></ul><ul><ul><ul><li>Order:(+1.00)(-3.50)/44x47.25/9.0 </li></ul></ul></ul>
    54. 55. Hard Contacts <ul><li>Materials </li></ul><ul><ul><li>Boston ES (Dk=18) </li></ul></ul><ul><ul><li>Boston XO (Dk=100) </li></ul></ul><ul><ul><li>Boston XO2 (Dk=150) </li></ul></ul><ul><ul><li>Increase DK increase lens buildup </li></ul></ul>
    55. 56. Fit & Evaluation <ul><li>Position: </li></ul><ul><ul><li>Lid attached/Apical/Korb- </li></ul></ul><ul><ul><ul><li>Under upper lid- best comfort </li></ul></ul></ul><ul><ul><li>Intrapalperal- </li></ul></ul><ul><ul><ul><li>Large fissure </li></ul></ul></ul>
    56. 57. Fit & Evaluation <ul><li>Centration: </li></ul><ul><ul><li>Centered/temporal/nasal </li></ul></ul><ul><ul><li>Falls down and out=too flat </li></ul></ul>
    57. 58. Centration
    58. 59. Fit & Evaluation <ul><li>Fluorescein eval </li></ul><ul><ul><li>Clearance </li></ul></ul><ul><ul><li>Edge lift </li></ul></ul>
    59. 60. Fluorescein Pattern
    60. 61. Fluorescein
    61. 62. Alignment
    62. 63. <ul><li>Wettability </li></ul><ul><ul><li>Lathe cut </li></ul></ul><ul><ul><li>Cleaning – at night </li></ul></ul>
    63. 64. Wettability
    64. 65. Plasma Surface Treatment <ul><li>Started offering in late 2005 </li></ul><ul><li>Aids in early wetting for sure- lenses are shipped wet </li></ul><ul><li>How long lasting is the effect? </li></ul><ul><ul><li>Claim 6-9 months </li></ul></ul><ul><li>Boston Cleaner contra-indicated </li></ul>
    65. 66. Plasma Treatment <ul><li>Is really just “super cleaning” </li></ul><ul><li>Can prove better wetting – clinically for weeks </li></ul><ul><li>Shipped wet </li></ul>
    66. 67. RGP Complications <ul><li>3 & 9 staining- </li></ul><ul><ul><li>Assoc w/ low riding CL </li></ul></ul><ul><ul><li>Decrease edge lift </li></ul></ul><ul><ul><li>Increase diameter </li></ul></ul><ul><li>GPC- Giant papillary Conjunctivitis </li></ul><ul><li>Corneal warpage- spec blur </li></ul><ul><li>Acanthamoeba </li></ul>
    67. 68. GPC
    68. 69. Use of Contacts in Clinical Practice
    69. 70. Corneal <ul><li>Keratoconus </li></ul><ul><li>Salzmann Nodules </li></ul><ul><li>Post transplant, RK, Lasik </li></ul><ul><li>Bandage contact lens </li></ul><ul><li>Ortho K </li></ul>
    70. 71. Keratoconus <ul><li>How to fit a GP to Keratoconic cornea </li></ul><ul><ul><li>K’s & spec Rx </li></ul></ul><ul><ul><li>Trial lenses set </li></ul></ul><ul><ul><ul><li>Rose K </li></ul></ul></ul><ul><ul><ul><li>Soper </li></ul></ul></ul><ul><ul><ul><li>McGuire </li></ul></ul></ul><ul><ul><ul><li>Apex </li></ul></ul></ul><ul><ul><li>Goal – improve VA, comfort, corneal health </li></ul></ul><ul><ul><ul><li>3 point touch- apical, 3 & 9 </li></ul></ul></ul>
    71. 72. Keratoconus
    72. 73. Keratoconus
    73. 74. Synergeyes <ul><li>4 series – including post surgical and KCN lens </li></ul><ul><li>Need significant, definite apical clearance </li></ul><ul><li>Opposite to normal fit </li></ul><ul><li>Versus piggybacking </li></ul>
    74. 75. Synergeyes
    75. 76. Corneal <ul><li>Bandage contact lens </li></ul><ul><ul><li>Abrasions, erosions, burns </li></ul></ul><ul><ul><li>Enhances comfort </li></ul></ul><ul><ul><li>Only SH lenses </li></ul></ul><ul><ul><li>Procedure code 92070 </li></ul></ul><ul><ul><ul><li>Fitting of contact lens for treatment… </li></ul></ul></ul><ul><ul><ul><li>Fee includes supply of the lens </li></ul></ul></ul>
    76. 77.
    77. 78. 3 lenses for most of the situations The most common cones : nipple and ovale
    78. 79. <ul><li>Keratoconus show high flattening between the very steep apex of the cone (forward) and the flat periphery (behind). </li></ul>2 mm 6.70 8.70
    79. 80. The more advanced is the cone , higher the slope (flattening) is.
    80. 81. <ul><li>Lenses have to follow as close as possible this very prolate cornea in order to : </li></ul><ul><ul><li>respect the cornea </li></ul></ul><ul><ul><li>Stabilize properly </li></ul></ul><ul><ul><li>Be comfortable </li></ul></ul><ul><li> Need to have « very » steep lenses in the center that get flatter « quickly ». </li></ul>
    81. 82. Good center and periphery
    82. 83. A lens is expressed by <ul><li>Material </li></ul><ul><li>Geometry </li></ul><ul><li>Diameter </li></ul><ul><li>Base Curve </li></ul><ul><li>Power </li></ul>
    83. 84. <ul><li>Different expressions of the lens flattening </li></ul><ul><li>Axial Edge Lift </li></ul><ul><li>Sagittal depth </li></ul><ul><li>Excentricity </li></ul>
    84. 85. Axial Edge Lift AEL AEL is the height that seperates the edge of the lens and the edge of the lens if this one wouldn’t have peripheral curves.  For known BC and total diameter the higher AEL is, the higher the flattening is
    85. 86. <ul><li>For a good fitting, AEL of the lens have </li></ul><ul><li>to be close to the cornea one </li></ul>
    86. 87. How can we increase the AEL ? <ul><li>By decreasing Optic Zone size </li></ul>OZ OZ AEL small OZ > AEL large OZ
    87. 88. <ul><li>By increasing peripheral curves </li></ul>How can we increase the AEL ? Rayon périphérique Rayon périphérique
    88. 89. AEL Periph.curves ++ > AEL Periph.curves +
    89. 90. Rose K Principle Lens changes with the cone evolution <ul><li>When a keratoconus is getting more and more advanced, the apex of the cone is getting steeper but the periphery remains the same. </li></ul><ul><li>For a known apex of the cone, the periphery is often the « same » fom one patient to another : Paul Rose’s Statistic and mathematic models : correlation between BC and slope </li></ul>
    90. 91. Rose K lenses principle <ul><li>For each BC that respects the apex of the cone, an unique AEL will be associated to it </li></ul><ul><ul><li>Unique Optic Zone </li></ul></ul><ul><ul><li>Unique Peripheral curves </li></ul></ul><ul><ul><li>World sales indicate that the original AEL </li></ul></ul><ul><ul><li>represent 65% of sold lenses </li></ul></ul>
    91. 92. For a 8.70mm diam.
    92. 93. Axial Ege Lift (AEL)  Edge Lift (EL) <ul><li>Rather than talking about AEL in mm which is difficult to evaluate for the fitter, Paul Rose simplified and reduced this notion to a simple number without unit : Edge Lift (EL) </li></ul><ul><ul><li>EL = 0 = standard corresponds to the AEL associated to the curve </li></ul></ul><ul><ul><li>EL > 0 correspond to lenses that are flatter in periphery than standard </li></ul></ul><ul><ul><li>EL < 0 correspond to lenses that are steeper in periphery than standard </li></ul></ul>
    93. 94. available EL +3.00 à -1.3 / 0.1 <ul><li>EL Standard “0” 65% </li></ul><ul><li>EL “quick” +1.0 20% </li></ul><ul><li>EL “slow” -0.5 10% </li></ul><ul><li>Others 5 to 10% </li></ul>The majority of Rose K are done with 3 EL
    94. 95. Trial Box <ul><li>Std EL for all lenses (but AEL unique for each BC) </li></ul><ul><li>Powers increase in steep curves : the more advanced is the cone, the more myopia there is  important for assessing precisely centration and mobility . </li></ul><ul><li>Diameter decreases when the cone is getting advanced (difficult for large lenses to follow the very flat periphery) </li></ul>
    95. 96.
    96. 97. Fitting steps <ul><li>Keratometry from a keratometer or a topograph </li></ul>7,00 mm 12 ⁰ 6,60 mm 102⁰ Km. 6.80 Cyl. 3,00
    97. 98. <ul><li>In the trial box, choose the lens according to the rule : </li></ul><ul><li>BC = av.K -0.10 </li></ul><ul><li>Assess the contact at the apex of the cone </li></ul><ul><ul><li>If too much contact (Flat)  decrease BC </li></ul></ul><ul><ul><li>If not enough contact (Steep)  increase BC </li></ul></ul>STEEP FLAT OPTIMALE
    98. 99. Remarques <ul><li>Wait 1 minute before evaluation </li></ul><ul><li>Analyze fluo pattern, lens centered </li></ul>
    99. 100. <ul><li>After finding the best BC </li></ul><ul><ul><li>If too thin periphery (< 0.6 mm)  EL « quick » +1.0 </li></ul></ul><ul><ul><li>If too wide periphery (> 0.8mm)  EL « slow » -0.5 </li></ul></ul>Too thin Optimal Too wide
    100. 101. <ul><li>Centration and mobility </li></ul>Up riding .steep the lens .and/or reduce diameter .and/or reduce EL Low riding .Flatten the lens .and/or increase diameter .and/or increase EL Optimal
    101. 102. <ul><li>This is not the central fitting that involves discomfort but the periphery </li></ul><ul><li>Too steep periphery involves discomfort ++, physiology -- </li></ul><ul><li>Too flat periphery involves discomfort +, decentration, mobility + </li></ul><ul><li> With Rose K, good control of this periphery </li></ul>
    102. 103. <ul><li>Find the best sphere giving the best </li></ul>
    103. 104. Spherical Aberrations <ul><li>Peripheral rays are more refracted than central rays. </li></ul><ul><li>Ex : -7.00 in the center, -7.75 in periphery </li></ul>
    104. 105. <ul><li>Those aberrations induced by the lens are higher when : </li></ul><ul><ul><li>Pupil is large </li></ul></ul><ul><ul><li>Power of the lens is high </li></ul></ul><ul><ul><li> More benefits for high myopic patients </li></ul></ul>
    105. 106. Rose K2 Advantages <ul><li>Easy to fit </li></ul><ul><ul><li>Only 1 trial box : one lens name </li></ul></ul><ul><ul><li>Lens changes with the cone (AEL changes with BC) </li></ul></ul><ul><ul><li>Std EL works in main cases </li></ul></ul><ul><ul><li>2 other EL slow and quick cover most of the modifications </li></ul></ul><ul><ul><li>6 steps fitting </li></ul></ul><ul><li>Maximum physiological respect </li></ul><ul><ul><li>Material Z </li></ul></ul><ul><ul><li>Special Geometry for the best compromise physiology/vision </li></ul></ul><ul><li>Vision </li></ul><ul><ul><li>Control of the spherical aberrations </li></ul></ul>
    106. 107.
    107. 108. Indications <ul><li>Pellucid Marginal Degeneration - PMD </li></ul><ul><li>Keratoglobus </li></ul><ul><li>P ost lasik ectasy, Post Graft </li></ul>PMD DMP Globus Lasik
    108. 109. <ul><li>reversed design for BC > 7.20 </li></ul><ul><li>flatter the BC is, more reversed the design is </li></ul><ul><li>Larger optical zone </li></ul><ul><li>OZ decreases with BC </li></ul><ul><li>EL steeper than Rose K </li></ul><ul><li>Total diameter larger than graft diameter </li></ul><ul><li>Also used on post lasik ectasy </li></ul>
    109. 110.
    110. 111. 5 Edge Lift +0.6 /+1.2 / -0.5 / -1.0
    111. 112. 1st lens: BC = K’ +0.30 mm Fitting: 1. Keratometry 2. BC 3. central Fitting 4. peripheral fitting 5. Centration/Mobility (=>Diameter) 6.Power Ex. 6.80/5.50  5.50 +0.30 = 5.80
    112. 113. BC plat OK / serré serré
    113. 114. EL périphérie très serrée EL Lent (-) périphérie serrée EL standard Périphérie ok EL rapide (+)
    114. 115. Mobility Look for enough mobility to insure enough tear flow Mobility ++ Mobility -- increase diameter Decrease diameter decrease BC Flatten BC 0 decrease l’Edge Lift increase l’Edge Lift
    115. 116. <ul><li>Same design as RoseK2 IC </li></ul><ul><li>Diameter 10.40 </li></ul>
    116. 117. 1st lens = Km - 0.30 mm Fitting : 1. Keratometry 2. BC 3. central fitting 4. peropheral fitting 5. Centration / mobility 6. Power Ex. 6.80/5.50  6.15 - 0.30 = 5.85
    117. 118. ROSE K2 Post Graft: Rose K2 PG <ul><li>the hardest fitting </li></ul><ul><li>irregular cornea shape </li></ul><ul><li>High astigmatism, often irregular </li></ul><ul><li>sensitives eyes </li></ul>
    118. 119.
    119. 120. <ul><li>Optimal </li></ul>
    120. 121. 5 Edge Lift +0.6 /+1.2 / -0.5 / -1.0
    121. 122. www.menicon.fr [email_address] [email_address] [email_address] Thank you for your attention

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