What is the base curve(BC) of contact lens?

Base curve(BC) of contact lens is to general measurement of the back surface of contact lens. Base curve of disposable soft contact lenses available in the market varies from 8.4 mm to 9.0 mm. Different individual have different curvature of their eyes. Thus, contact lens wearer using the right base curve is important in order to be comfortable and to facilitate proper tear exchange and oxygen transmission.

How do I know which base curve is suitable for me?

With a keratometer from optical shop, the contact lens practitioner can easily measure the curvature of your eyes. Is their duty to do a proper fitting of contact lenses rather than just picking it off the shelves.

Most brand of the disposable contact lenses only come with one base curve. Base curve values have similarity like our clothes size. Thus, wearing a base curve of 8.6 in one brand of contact lenses do not mean it will be the same in another. Different materials of the contact lenses do affect on the base curve as well.

So, the best option is to get the trial contact lens to try it own personally before purchasing. Generally, the contact lens that slide downwards while wearing indicate the base curve is too loose. Then, you should try steeper base curve. E.g if you are using BC 9.0 (flatter) but sliding downwards in your eye, then change to BC 8.6 (steeper).

A good fitting of soft contact lens wear in the eyes should have movements of ~1-1.5mm each time you blink. To promote tears exchange and oxygen transmission. Thus, if the you wear BC 8.4 lenses that shows no movement in the eye, then you ought to change to BC 8.8. Seek you contact lens practitioner advise on the fitting using the equipment called ‘Slit Lamp’.

How to know the base curve reading from the packaging?

Look for the word BC on the contact lens packaging. Can be seen somewhere near the place where the lens prescription is indicated.

P.s. Any inquiry or need further clarification, don’t hesitate to contact joey@biofilcon.com



2 thoughts on “What is the base curve of contact lens (BC)?”

  1. Hi, I wear BC size 8.7 and if I want to try diffrent brand that only have sizes 8.5 and 9.0. which size fit the best?

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