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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 Rose k Presentation Transcript

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