Fitting Guides > Valley Kone
Fitting Guides
The Valley Kone™ Lens
Fitting Guide
- Valley's own keratonconus lens.
- The Valley Kone™ is a back aspheric design.
- Manufactured in the material of your choice.
The fitting for the Valley Kone™ is simple and sure.
Order a fitting set or send us a corneal topography to order the first lens that smoothly aligns with the contour of a keratoconus patient. We'll design the back surface for a healthy comfortable fit.
The Valley Kone™ is one of the preferred keratoconus lenses exclusively from Valley Contax.
That means Valley Contax has complete and ultimate parameter control for quality and reproducibilty. Purchase the Valley Kone™ keratoconus lens with the Valley Contax Failsafe Warranty.
The Valley Kone™ is available exclusively from Valley Contax in a wide range of parameters:
Base Curves: Any base curve radius
Powers: Made to order
Diameters: Made to order
Edge Lift:
| Valley Kone™ A | 10% - 15% less edge lift than standard |
| Valley Kone™ B | Standard edge lift |
| Valley Kone™ C | 10% - 15% more edge lift than standard |
| Valley Kone™ D | 20% - 25% more edge lift than standard |
Parameter Selection:
Base Curve Selection
An initial lens is selected with a base curve equal to the median K reading. If corneal topography data is available, select the base curve .50 steeper than the radius located at the 4mm temporal position on the radius version of the topography mappings.
Diameter Selection
A diameter range of 8.5 through 9.5 is available. The steeper base curves usually coincide with the smaller diameter sizes as the flatter base curves coincide with the larger diameter sizes.
Periphery/Edge Lift
The standardized periphery can be ordered steeper or flatter than standard. The standard lift is identified by a Valley Kone™ B or Valley Kone™ C for the flatter than standard edge lift and the Valley Kone™ A for the steeper than standard edge lift. (Refer to edge lift as noted above.)
Ordering the Valley Kone™ Lens
The specifications needed are:
- Base Curve Radius
- Lens Power
- Diameter
- Edge Lift Only (only if standard lift is not acceptable.)
| Lens Fitting | |
| 1. | Begin with a base curve from the trial lens that is closest to the median K reading or at the 4 mm temporal location or the radius version of the corneal topography mapping. |
| 2. | After evaluating the fluorescein pattern, make adjustments to the base curve, if necessary. |
| 3. | When the proper superior alignment has been achieved the lens with exhibit 2 to 4 mm of "feather" apical touch in the fluorescein pattern, a smooth transition throughout the rest of the lens with a slight edge lift inferiorly. |
| 4. | The intermediate zone should appear as close to an alignment fit as possible with the periphery of the lens showing a standard edge lift. However, the beauty in fitting this back aspheric lens is the ease in adjusting the intermediate and peripheral curve design independent of the fit of the base curve. The trial lens has a standard rate of flattening (B). For increased rate of flattening (C) should be ordered. For decreased rate of flattening (A) should be ordered. |
| 5. | The power is determined by a spherical refraction over the best best fitting lens. The result should give a stable endpoint with acuity comparable to the best acuity comparable to the best acuity expected from this patient. When ordering, adjust the lens power to reflect any change from the diagnostic base curve used in the over refraction. Also, remember to vertex over-refraction greater than 4.00 diopters. |
| 6. | The larger diameter of 9.0 is generally used for the flatter range of base curves. While the smaller diameter of 8.5 usually works well for the steeper base curve range and the high astigmatic cornea. |
| Problem solving techniques | |
| 1. | Once a decentered lens is manually centered, you may determine that a steeper base curve of a least 0.1 mm, a steeper peripheral curve or a larger diameter is required. |
| 2. | A lens with excessive inferior edge lift may require a smaller diameter. |
| 3. | An inferior positioning lens may require a larger diameter. |
| 4. | A lens that exhibits mid peripheral bearing may need a larger optic zone or flatter periphery. |
Steve
President
"Valley Contax feels proud to be one of the select laboratories who have earned this prestigious award..."
"...as a reflection of the importance we place on quality."
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