How do I choose a base curve for soft contact lenses?
Adjusted base curve in mm + 0.3mm = soft lens base curve….Still another method is to use the following as a guide for selecting base curves:
- If Low K is >45.00D, then fit the steeper BCR.
- If Low K ranges from 41.00D to 45.00D, then fit the median BCR.
- If Low K is <41.00D, then fit the flatter BCR.
What is the difference between 8.4 and 8.6 base curve?
Studies show that a single base curve of 8.4mm managed a “good or better” fit in approximately 90% of individuals,1 and base curves of 8.4mm and 8.6mm together encompassed 98% of individuals….
| LENS | BASE CURVES AVAILABLE (mm) | DIAMETERS AVAILABLE (mm) |
|---|---|---|
| 5 | 8.6 | 14.0 |
| 6 | 8.5, 9.0 | 14.2 |
| 7 | 8.4, 8.8 | 14.0 |
| 8 | 8.7 | 14.2 |
What is rule of thumb in contact lens?
A simple rule of thumb exists. For every 0.05mm that the BOZR is steeper than K, the tear lens power increases by +0.25D. Therefore you must counter this by adding -0.25D to the power of the contact lens.
Can my base curve change?
Base curve can also change as you wear a contact lens based on environmental factors like the lens drying out, temperature changes, and exposure to makeup or soaps.
Does base curve have to be exact?
The base curve number would be a number between 8.0 and 10.0 millimeters and would be more precise because these lenses need to fit just right. Now that most contact lenses dispensed are soft lenses, this measurement doesn’t need to be quite as precise.
How do I know the base curve of my contacts?
Base curve = 0.95 * 34.82 D = 33.07 D and then round up or down to the nearest whole diopter to arrive at the following final base curve to use for a contact lens over-refraction: Base curve = 33.00 D (actual measured base curve is 32.95 D)
Can the base curve of your eye change?
When should soft contact lenses be fitted?
Classical soft lens theory states that the lens should settle for 20 to 40 minutes before the fit is assessed. More recent work by Brennan et al6 looked at changes in fitting characteristics in low and high water content lenses over an eight-hour wearing period.
What is spherical soft contact lens?
Spherical contact lenses have the same lens power throughout the entire optical part of the lens to correct myopia (nearsightedness) or hyperopia (farsightedness). Toric soft contact lenses have different powers in different meridians of the lens to correct astigmatism as well as nearsightedness or farsightedness.