What is normal BC for contacts?

Your prescription will also contain an expiration date. This is typically one year from the date that the contact lenses were fitted. BC values range from about 8.0 to 10.0. The doctor fits the lens with the curvature most appropriate for your eye.

What does BC mean on contact?

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.

What does power and BC mean for contacts?

Here’s what those abbreviations mean: OD: Oculus dexter, the Latin term for right eye. OS: Oculus sinister, the Latin term for left eye. PWR: Power (also referred to as Sphere or SPH) BC: Base Curve (usually a number between 8 and 10)

What is BC and DIA for contacts?

Base Curve (BC): the number that indicates your contact lens’ shape. According to the steepness or flatness of your cornea, your prescription indicates how large your contact lens should be. 2. Diameter (DIA): a number indicating your contacts’ length to make sure they’ll cover your cornea properly.

What is normal eye base curve?

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 is the normal eye contact size?

Usually, the number is between 13 and 15. This value determines how the contact lens sits on your eye, and when it isn’t appropriate for you – the contact lens will be uncomfortable.

How do you calculate BC for contacts?

Simple Rule for estimating lens base curve on a PLUS POWER lens

  1. For plus power use the spherical equivalent (SE) and add 4.00 diopters to that. For example, if you have an Rx of + 2.00 sphere, the base curve for the lens will be approximately 6.00.
  2. Rx +2.00Sph -> [+2.00 +4.00D] = 6.00BC.

What is normal axis of eye?

If you have “normal” eyesight, there would not be an axis number, as you would not have astigmatism. However, the most “normal” eyes with this condition would tend to have approximately 0.50 dioptres of negative cylinder power with a 180 axis number.

How do you calculate BC for contact lenses?

Simple Rule for estimating lens base curve on a MINUS POWER lens

  1. For minus power lenses take half of the spherical equivalent and add 4 diopters to that. For example a -4.00 sphere power you would use -2.00 (half of the SE) + 4D, which would give you a 2BC.
  2. ie Rx -4.00sph -> [(-4.00 x 0.50)+ 4.00D] = 2.00BC.

How do I choose contact lens power?

If a GP lens is selected with a base curve radius that’s one-half diopter flatter (less curved) than the cornea, a contact lens power of -2.75D would be predicted. If the base curve radius is a half diopter steeper (more curved) than the cornea, a contact lens power of -3.75D would be predicted.

What is a 005 axis for glasses?

Axis (AXI) – The axis value is the angle of the astigmatism correction. If you have a cylinder reading on your prescription then you should have an axis reading. An axis of 5 (or 05) is the same as 005; 90 are the same as 090.