the i kone lensikonelens.com/images/ikoneslidepresentation.pdf · –spectacle rx, keratometry,...
TRANSCRIPT
Contact Lens Fitting Goals for Keratoconus
• Vision• Comfort• Corneal Health• Fit / Centration• Happy Patient
Selecting the Best Contact Lens Option
• Assessment of all of the Information– History includes lens failures & why ! – Spectacle Rx, Keratometry,
Topography– Size, shape, location of effected area
Modern Keratoconic Corneal Lenses
• Fitting – standardized– trial lens sets or topography – realistic increments
• Troubleshooting– logical, incremental changes– flexibility
A Systematic approach to:
I-Kone Design
• Anterior and posterior aspheric design.
• 10.4 mm, 9.6 mm, 8.8 mm • Boston XO®• Adjustable periphery• 14 lens fitting set
Diagnostic FittingI-Kone Keratoconus Design
Initial Base Curve fit on “Steep K” reading1. centration2. central clearance
Example:K’s 52.25 / 57.50 @ 45 5.92 mm (57.00 D)
9.6 mm diameter
The Keratoconic Cornea
• Assessment of ectatic area– Size – Location – Shape– Degree of Irregularity
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
The Keratoconic Cornea
• Assessment of ectatic area– Keratometry– Photokeratoscopy– Topography– Fluorescein Pattern Analysis– Slit Beam– 90 degree spin
Classifications of Keratoconus
• Shape– Mild < 45.00 D average K– Moderate 45.00 -> 52.00 D average K– Advanced 52.12 -> 60.00 D average K– Severe > 60.00 D average K
• Size– Nipple < 5 mm– Oval 5 -> 6 mm– Globus > 6 mm
Keratoconic Corneal Lens Options
The First Generation
• Soper (circa 1970)
– 1st significant KC design– Steep, fixed POZ
• McGuire Lens (circa 1980)
– Like Soper but multicurve
Keratoconic CornealLens Options
The Second Generation
• Valley Kone (Valley Contax, 1990)
– Smooth, continuous back surface• Rose K (Lens Dynamics, 1990)
– POZ varies with BC– Standardized fitting system
• Rose K II (Blanchard, 2005)
– Aspheric front surface to reduce Spherical Lens Aberration
Keratoconic Lens Optionsthe Third Generation
• I-Kone (Valley Contax, 2005)– Bi-surface aspheric– Balanced zone design
(central zones to fit cone area)– BC radius varied to achieve fit– Periphery fits non-ectatic area
Keratoconic Lens Optionsthe Third Generation
Balanced Zone Design• As BC radius steepens • POZ decreases• While Second Aspheric Width Increase• Eccentricity of Zones Increase
Advantages of fitting the I Kone Design
• Central Fit– extends the concept of 3 point touch– high eccentricity back surface spreads bearing
• Vision– front surface eccentricity to CANCEL out
aberrations induced by eccentric BC – and reduces other aberrations
• Comfort– reduced pressure points
• Corneal Health– Excellent tear flow
More advantages of fitting the I-Kone Design
• Aspheric Optics– Controls spherical aberration– Reduces lens mass
• Larger Diameter– Distributes weight more evenly across
corneal surface– Reduces glare / halos– Improves lens stability