Keratoconus Aspheric

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• Keratoconus Aspheric
• Thin Lens Design

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Keratoconus
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• Superior cornea usually has a more normal
  topographical appearance
• Inferior cornea is much steeper and more
  irregular
• Apex keratoconus design fits the different
  curvatures, provides clear vision and maintains
  corneal integrity

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What is the Apex Keratoconus Design?
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• Minimizes apical interaction
• Avoids impingement of the peripheral cornea
• Places the optical zone over the pupil
• Small spherical optic zone
• Aspheric posterior lens surface aligns with the
  flattening peripheral cornea

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Apex Parameter Availability
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Diameter Base Curve Power Periphery Material

7.9 to 10.3mm 40.00D (8.44mm) to 68.00D
(4.96mm) -20.00D to 20.00D Steep, Medium,
Flat Boston XO
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Apex Keratoconus Evaluation
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• Often, the keratoconus cornea is too irregular
  for K readings to be accurate
• Diagnostic set determined by clinical evaluations
• 39 eyes fit
• Boston XO material
• All subjects paid for lens(es) and services

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Clinical Results
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• Mean parameters 45.00D -3.75D 9.3mm
• Vision, comfort and corneal integrity
  satisfactory

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Apex Diagnostic Set
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Fitting Step 1 Select Base Curve
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• Apply the mean diagnostic lens
• 45.00D -4.00D 9.3mm
• Consider use of a topical anesthetic

• Apical bearing steepen base curve

• Apical vaulting or bubbles flatten base curve

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Fitting Step 2 Evaluate Diameter
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• If lens centers go to step 3

• If lens is centered with inferior edge stand off,
  decrease diameter

• If lens is decentered, increase diameter

• If poor tear exchange over the apex during blink,
  decrease diameter

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Fitting Step 3Determine Periphery
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• Medium axial edge lift is included in the
  diagnostic set

• Steep and flat edge lift values also available

• Insufficient edge lift consider next flatter
  edge lift value

• Excessive edge lift consider next steeper edge
  lift value

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Fitting Step 4 Determine Power
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• Over-refract the most appropriate diagnostic lens
  to determine lens power

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Apex Fitting Summary
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• Step 1 Select the base curve
• Step 2 Evaluate the diameter
• Step 3 Determine the periphery
• Step 4 Determine the power
• Order lenses

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Optimal Fitting Results
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• Maintain centration

• Minimize lens and corneal apex interaction

• Establish grip along horizontal meridian

• Avoid impingement, especially in the superior
  quadrant

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Problem Solving Tips
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• If the lens is decentered inferiorly, consider
  flattening the base curve
• If the lens is decentered laterally, consider
  increasing the diameter
• If the lens centers with inferior edge stand off,
  consider a decrease in lens diameter

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Problem Solving Tips
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• Peripheral seal-off and adherence -
  loosen the fit

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Problem Solving Tips
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• Steep or flat fit choose a flatter or
  steeper base curve

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X-Cel Warranty
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• 90 day guaranteed fit
• 100 credit on two exchanges per eye
• Call or e-mail our experienced fitting
  consultants

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