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.
Does the BC on contacts 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.
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)|
Is there a big difference between 8.5 and 8.6 base curve?
No there is not a big diff between the two base curves. However, it’s the relationship between diameter and base curve that is more important. Also, the material of the lens can also affect the fit. You can have 3 diff contact lenses with the same BC, Diameter and power and they will all fit differently.
Is there a difference between 8.4 and 8.6 BC?
You should stick to BC of 8.4. Any deviation from this would result in discomfort in your eyes manifesting itself as blurred vision or red eye (secondary to irritation). Within the same frame, a base curve of 8.4 is not too different from 8.6.
Can I wear a different base curve?
Can I order contact lenses with a different base curve? 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.
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.
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.
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.
Does diameter of contact lenses matter?
It is not recommended to wear contact lenses with a different diameter from your prescription. If the diameter is too wide, the lens will be loose in the eye and may slip out of place. If the diameter is too small, the lens will have a tight fit, causing discomfort.
What happens if you wear the wrong size contacts?
A corneal abrasion is a scratch on the surface of your eye. It is most often the result of wearing ill-fitting contact lenses that are not suited to your eyes. … This can result in permanent damage to your eye, or even vision loss.
What is the difference between 14.0 and 14.2 diameter contacts?
14.0mm and 14.2mm contacts
In fact, there is not much difference between these two. Some manufacturers only make 14.2mm diameter contacts, and some others produce 14.0mm diameter contacts. … Many 14.0mm contacts users use 14.5mm or 14.8mm contacts to demonstrate dolly effects on their eyes.
How do you measure BC for contacts?
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 does BC mean on contact lens prescription?
Basecurve (BC): This number indicates how curved your contact lens is. Your optician will try and match the curve of your contact lens to the curve of your eye to find the best fitted contact lens for you. E.g. BC 8.4.
Is there a big difference between 8.5 and 8.8 base curve?
The 8.8 BC is “flatter” than the 8.6 lens, meaning that the 8.6 lens has slightly more curvature or “steeper”. The 8.6 base curve will be a better fit for most people. In general, 8.8 BCs are more likely to fit loose and move excessively on the eye.