Fitting Guides > Essential & Ess. Xtra
Fitting Guides
The Essential &
Essential Xtra GP Multifocal
Fitting Guide
- Valley Contax offers the best choices among translating aspheric multifocal lenses for today's presbyopic population.
- The Essential & Essential Xtra GP Multifocal is available in add ranges, Series I, Series II, and Series III.
- The Essential GP Multifocal is exclusively manufactured in Boston ES® material.
- The Essential GP Xtra Multifocal is exclusively manufactured in Boston XO® material.
The Essential & Essential Xtra GP Multifocal translating designs use a unique patented S Type technology to place all of the add on the back surface in Series I (add of +1.25), Series II (add of +1.75) and Series III.
The fitting for the Essential and Essential Xtra Multifocal is simple and sure.
Ask for the use of a diagnostic set to fit the Essential. Select a slightly flatter base curve than a single vision lens.
The Essential and Essential Xtra Multifocal are the preferred Multifocal exclusively from Valley Contax.
That means Valley Contax has complete and ultimate parameter control for quality and reproducibility. Purchase the Essential
and Essential Xtra Multifocal with the Valley Contax Failsafe Warranty.
The Essential and Essential Xtra are available exclusively from Valley Contax in a wide range of parameters:
Base Curves: Any base curve radius
Powers: Made to order
Diameters: Suggested sizes, 9.0 through 10.0
Edge Lift: Standard
Parameter Selection:
Base Curve
We recommend that a slightly flatter base curve than a single vision GP lens is used to ensure translation and allows for a larger optic zone providing a large vertical distance field.
| Corneal Astigmatism | Base Curve |
| 0.00D | 1.00 D flatter than K |
| 0.50D | 0.50 D flatter than K |
| 1.00D | Use the flat K |
| < 1.00D | Steeper than flat K by a 1/4 of the amount of corneal astigmatism |
Distance Power
The distance power is calculated by adding plus or minus to the sperical power of the manifest refraction depending on whether the base curve selection is flatter or steeper than the flattest K reading. For best results over refract with hand held lenses in normal lighting over the best fitting diagnostic lens.
Add Power
Lens Fitting
| Centration is important. The over-refraction is valid only when the lens centers well. | |
| 1. | Lens should be well centered with mid-peripheral alignment and slight central pooling. |
| 2. | With lens centered, check distance acuity monocularity. Over-refract if necessary in 0.25D steps using hand held lenses to 20/20. |
| 3. | Check distance acuity binocularly. Over-refract if necessary in 0.25D steps using hand held lenses to 20/20. |
| 4. | Check near acuity with distance over-refraction still in place. If near vision has been compromised, add +0.25D to the non-dominant eye. |
| Problem solving techniques | |
| 1. | A decentered lens may require a steeper base curve of at least 0.1 mm. |
| 2. | A superior positioning lens with too much edge lift may require a reduction of edge lift by 10% or (Golden Eye™ A). |
| 3. | A superior positioning lens with normal edge lift may require increased center thickness or steeper base curve. |
| 4. | A lens that is not positioning laterally may require a larger diameter. |
When a lens is not centered, measure the position.
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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