FITTING GUIDE: Clarity Plus
Lens Design
Clarity Plus is an aspheric multifocal translating lens design. It is indicated for presbyopic corrections up to and including a +2.25 add. Its proprietary dual aspheric design allows for an alignment fit eliminating the need to fit excessively steeper than flat "K". Patients who wear Clarity Plus have clear stable vision at all distances.
Base Curve Selection
On corneas that have two diopters or less of with the rule astigmatism the initial base curve should be fit 1.00 D steeper than the flattest "K". On corneas with more than 2.00 D of cylinder fit the base curve an additional 0.25 D steeper. You are trying to create an alignment fit.
| EXAMPLE |
| OD |
42.00 / 43.00 (42.00 + 1.00 = 43.00 or 7.85 mm base curve) |
| OS |
42.50 / 45.00 (42.50 + 1.00 = 43.50 or 7.76 mm base curve) |
|
Diameter Selection
The most common diameter used is 9.5. mm. However, if the cornea is on the steep side fit a smaller lens and if it is on the flat side fit a larger lens.
| EXAMPLE |
| Flat "K" |
Diameter (mm) |
| 41.50 & Flatter |
9.7 |
| 41.75 - 46.50 |
9.5 |
| 46.75 & Steeper |
9.3 |
|
Power Determinations
- Clarity Plus should be fit on patients who have add
powers up to and including +2.25. However, consider using high index material when add powers are greater than +1.75.
Recommended high index materials: Paraperm 02 1.473 Boston IV 1.468
- An over-refraction in spheres must be performed separately for distance and near.
- The distance over-refraction is done first and the result should be the most plus power that provides a slow 20/20 or 20/25 vision monocularly.
- Place the over-refraction in a trial frame and have the patient read binocularly.
- If near acuity is J-1 or J-2, order the lenses. If near acuity
is less than J-2 order in a high index material or a Clarity Plus Extended Add.
- Fit Clarity Plus Extended Add for those exceptionally
high add patients who are not able to read with Clarity
Plus.
Near/Far Power Balance
If near vision is not acceptable with Clarity Plus, begin adding plus BINOCULARLY in + 0.25 steps in a trial frame. As you add plus keep rechecking both near and distance acuity. NOTE: You are trying to achieve good visual acuity for distance and near simultaneously.
Therefore, it is important to add only + 0.25 sphere at a time to the distance Rx so that a correct power balance is achieved. Maximum plus at distance is the key, especially for those older patients.
| EXAMPLE |
| |
OD |
OS |
| Power of trial lens |
-3.00 |
-3.00 |
| Over Rx (distance) |
-0.50 |
-1.00 |
| Total Power (distance) |
-3.50 |
-4.00 |
| Visual acuity (distance) |
20/25 |
20/25 |
| Visual acuity (near) |
J-1 |
J-1 |
| Power adjustment O.U. |
-0.25 |
-0.25 |
| Visual acuity O.U. |
J-2 |
J-2 |
| Visual acuity O.U. |
20/20 |
20/20 |
| Final Power |
-3.75 |
-4.25 |
|
Conclusions
Beware of patients with high adds. These patient will read better if fit in a high index material or Clarity Plus Extended Add. A proper fit lens will have good papillary coverage and center well. Maximum plus must be pushed when over refracting for distance. When performing the power adjustment make sure to use trial lenses only and to recheck distance and near acuity frequently.
Important Criteria
- Fit lenses on patients with who do not have excessive high corneal astigmatism.
- The base curve should be fit 1.00 D steeper than the flattest K.
- The lens must center well.
- Over refraction should be done with trial lenses only.
- Use high index material on add powers greater than +1.75.
- Maximum plus must be prescribed for distance.
- When performing the distant/near power balance, keep rechecking distance and near acuity. If you cannot obtain good visual acuity for near and distance simultaneously consider Clarity Plus High Add or Extended Add.
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