Table of Contents
Is there a big 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) |
---|---|---|
3 | 8.6 | 14.2 |
4 | 8.4, 8.6 | 13.8 |
5 | 8.6 | 14.0 |
6 | 8.5, 9.0 | 14.2 |
What is the average contact lens base curve?
between 8.0 and 10.0 mm
Typical base curve values range between 8.0 and 10.0 mm, though it can be flatter (from 7.0mm) if you have a rigid gas-permeable lens. A person with a higher base curve number has a flatter cornea (the clear, front surface of the eye) compared to someone with a lower base curve number, which indicates a steeper cornea.
How do I figure out my contact lens base curve?
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)
Is there a big difference between 8.3 and 8.7 base curve?
No, the difference is small. The 8.7 curve is . 1mm flatter, but since these are soft lens curvatures, and soft lenses assume some of the shape of the cornea, the fitting value won’t be changed dramatically.
What happens if you wear the wrong base curve?
If your lenses have the wrong diameter or base curve, you’ll likely feel that something is always in your eye. If the lenses are too flat, your eyelids will tend to dislodge them when you blink. The wrong size lenses can even cause an abrasion of your cornea.
What is the best base curve for contacts?
Typical base curve values range between 8.0 and 10.0 mm, though it can be flatter (from 7.0mm) if you have a rigid gas-permeable lens. A person with a higher base curve number has a flatter cornea (the clear, front surface of the eye) compared to someone with a lower base curve number, which indicates a steeper cornea.
What base curve do I need?
The most basic rule is that you always want the base curve to be as close to +6.00 as you can get and still have the Rx work. The more minus the power (less plus power to minus power) the lower plus the base curve will become. A high minus Rx may even have a base curve of +0.25 or even 0.00.
What is the best base curve for a lens?
To give eyeglass wearers close to the same range of vision, the backside of an optical lens should be close to a 6 base curve. Much flatter or steeper will affect the field of view and result in more head-turning.
Can I wear a different base curve?
Yes they do matter. The BC, or base curve, is measured based on your cornea’s curvature. If the base curve is too small, it’ll squeeze your eye, and if it is too big, it won’t stay on your cornea. These both may cause damage to your eye.
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.