| SUGGESTED PATIENT CRITERIA |
- For ADDs of +2.00D to +3.00D
- Corneal astigmatism:
Up to -0.75 x180
Up to -0.50 x090
- Habitual distance Rx (greater than ±0.75D)
Standard Parameters
- Base Curve / Diameter: 8.4/14.5, 8.7/14.5, 9.0/14.5
- Powers: -8.00D to +6.00D in 0.25D steps
- ADD Powers: +2.00, +2.50D, +3.0D, +3.50D*
- Central ADD Diameter: 2.35mm and 2.55mm
- Custom Parameters available
* Available in limited parameters
| Flat 'K' |
Base Curve |
Diameter |
| 43.50D and steeper |
8.4 |
14.5 |
| 40.25D to 43.25D |
8.7 |
14.5 |
| 40.00D and flatter |
9.0 |
14.5 |
 |
Calculating Distance Power
Use spherical equivalence from spectacle Rx in minus cylinder form. Vertex if necessary. order this distance power.
Calculating Near Power
Add +0.50D to spectacle ADD. Order this near power.
ADD Diameter
Dominant eye: 2.35mm (smaller) central ADD diameter Non-dominant eye: 2.55mm (larger) central ADD diameter
- Equilibrate for 20 minutes. (ESSENTIAL for accurate over-refraction and evaluation of fit.)
- Lens should be well centered, with 0.5 to 1.0mm movement in primary gaze, 1.0 to 1.5mm upward gaze. The central ADD should stay within the pupil area, but not necessarily centered.
- Check distance acuity monocularly. Over-refract if necessary in 0.25D steps to 20/20. Check binocular acuities.
- Check near acuity monocularly, with distance over-refraction still in place. Over-refract if necessary. Check binocular acuities.
|
|
PROBLEM SOLVING
- Acuity
- 0.25D makes a significant difference in acuity.
- Always leave over-refraction in place and re-check near and distance acuities.
- Distance acuity not acceptable
- Change power and/or use 2.55mm segment both eyes
- Near acuity not acceptable
- Change power and/or use 2.55mm segment both eyes
- Abnormal pupil size
- Very small pupils: 2.35mm segment both eyes
- Very large pupils: 2.55mm segment both eyes
- Centrition
- ADD zone should cover at least 50% of pupil
- Shadowing or 3-D effect at near after adaption period of 10 days
- Change power and/or increase near ADD diameter
- At distance, try 2.35mm ADD diameter OU
- At near, try 2.55mm ADD diameter OU
- Resulting ADD power in the contact lens will be at least +0.50D to as much as +1.00D more than the spectacle.
- If intermediate vision is required, try System 250 combination fit - Unilens 38 (dominate eye) and SimulVue (non-dominate eye) OR SoftSITE (dominant eye) and (non-dominate eye).
|
