If you have a high prescription, the flatter base curve will accommodate the stronger correction. However, the lower the base curve, the more light will be let in through the sides of your sunglasses.29 Apr 2020
What is base curve prescription?
Base Curve (BC): The base curve determines what type of fit is required for the lens to meet the curve of your eye; this is usually written in millimeters or sometimes with the words: flat, median or steep.
Can base curve affect vision?
The base curve of a lens may affect certain aspects of vision, such as distortion and magnification, and wearers may notice perceptual differences between lenses with different base curves. Consequently, some practitioners may specify "match base curves" on a new prescription.
What base curve should I choose?
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.
How do I figure out my contact lens base curve?
Figuring out the proper base curve based upon Rx is fairly simple: Plus Power Use the Spherical Equivalent (Sphere power plus half the cylinder power) and add 4.00 diopter to that. Example Rx of +2.50, the base curve will be approximately 6.50.13 Aug 2021
Do glasses have a base curve?
The base relates to the standard curvature of the frame, also known as wraparound effect. The higher your prescription number, the more wraparound the frame is. On average, eyeglasses should have no more than a base of 4-6. However, the base can go as high as 8, especially for non-prescription sunglasses.1 Oct 2019
What is base curve on eye prescription?
What is the base curve? The base curve of a contact lens is the curvature of the back surface of the lens. It determines the type of fit the lens must have to match the natural curvature of your eye. 1. It is usually expressed in millimetres and may be further characterised as steep, median, or flat.
Does the base curve of contact lenses matter?
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.
What happens if you get 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.
Can the base curve of your eye change?
In fact most labs today will not allow you to change or request a base curve at all. This completely overrides any use of the nominal lens formula or simple base curve calculations. 3) Never attempt to change the lens base curve to match a frame base curve.
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.1 Sept 2017
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.13 Aug 2021