what is bc on 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.

Does the BC of contacts matter?

You should never order contact lenses with a base curve that is different from your prescription. This can damage your eyes and cause problems with vision. This is especially important for people who purchase cosmetic coloured contact lenses, which are often of a standardised size.

How do I know my 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.

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. In theory +6.00 should always give you the best possible combination of curves for weight, optics, etc.

How important is BC contact lenses?

The ‘BC’ or base curve measurement indicates the back curvature of your contact lens, in millimetres. This is important for comfort, as the BC of your contact lenses should match your eye’s natural curve as closely as possible to ensure a better fit when you are wearing your contact lenses.

Can your contacts 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. As a doctor, selecting a contact lens for best fit is also challenging because the sagittal depth of any contact lens is not notated on the packaging.

How do I choose a base curve for soft contact lenses?

Base Curve Many lens fabricators suggest starting with a base curve radius (BCR) that is 4.00D to 5.00D flatter than flat K. Another method is to trial-and-error fit by selecting the middle BCR available. Most soft lens designs feature three BCRs: Steep, median and flat.

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)

What happens if you wear the wrong size contacts?

If you continue wearing a contact lens that fits too tightly, it can lead to serious eye problems, such as: Corneal ulcers. Loss of vision. Eye infections.

What is the strongest contact lens strength?

What is the strongest contact lens prescription? Contact lenses can be prescribed for extreme degrees of myopia, even for those who need correction of more than -20 Dioptres. Some lenses can go over -30 Dioptres. For monthly soft contact lenses, the highest level of corrective power is about -12 Dioptres.

What is the smallest contact lens size?

The smallest sclerals are approximately 14.5 mm in diameter, and the largest can be up to 24 mm. Lenses that are 18 mm or smaller are subcategorized as mini-sclerals.

What is the base curve of my eye?

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.

How do you know your contact size?

Generally, your eye doctor will use a keratometer to measure the curve of your cornea, which is the front surface of the eyes – where contacts rest. These numbers help to determine the lens diameter and base curve that appear on your contact lenses prescription.

What contacts are best?

8 Best Daily Contact Lenses
Best Overall Daily Contacts: Acuvue Oasys 1-Day with HydraLuxe™Runner Up: Dailies Total 1.Best Daily Contacts for Dry Eyes: 1-Day Acuvue Moist.Most Breathable Daily Contacts: 1-Day Acuvue TruEye.Best Daily Contacts for Astigmatism: 1-Day Acuvue Moist Astigmatism.