It determines the type of fit the lens must have to match the natural curvature of your eye. … 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.
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)|
Does the base curve 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.
What happens if you wear contacts with the wrong 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. This is especially important for people who purchase cosmetic coloured contact lenses, which are often of a standardised size.
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.
What base curve do I need?
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 choose a contact lens base curve?
Base curve : Select the base curve which is 0.4 – 0.6 mm flatter than the flattest ‘K’ for smaller lenses and 0.6 – 1.0 mm flatter for larger lenses. 6. Fit the contact lens to the respected eye and leave the patient to wait for 15-20 minutes to settle the lens well.
What if base curve is too big?
A base curve that is too big will cause the contact lens to not sit properly on the cornea. While less medically dangerous than wearing an overly-small base curve, it can still cause annoyance from the contact lens shifting around or poor vision.
How do I know what base curve my eye is?
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 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 tell if your contacts are not the right size?
Place the contact lens between the tips of your thumb and forefinger, grasping it near the center so the entire edge is free. Gently squeeze the lens, as if you are about to fold it in half. If the edge of the lens points upward (resembling a hard-shell taco), the lens is correctly oriented.
How important is contact lens diameter?
It’s very important because it shows in which part of your eye the edges of the contact lens will rest. If the diameter is wrong, too small or too large it wont be stable on your eye and move around too much or it can be too tight and cause eye irritation and corneal abrasions.
Is there a big difference between 8.6 and 8.7 base curve?
“Is there a big difference between 8.6 and 8.7 base curve in contact lenses?” No, the difference is small. The 8.7 curve is . 1mm flatter, but since these are soft lens curvatures, and soft lenses assume some of the shape of the cornea, the fitting value won’t be changed dramatically.
Is BC important in 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.
Does your eye 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.