Yes it matters. The diameter and its base curve should be according to your size of your cornea and its curvature. This two parameters are also useful to achieve optimal fit of C.L on eyes.
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.
What happens if you wear the wrong base curve contacts?
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.
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.
How do I choose the right base curve for contacts?
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.
What is the most common base curve for 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 base curve of your eye change?
You will want to remember that the higher the plus power, the higher plus the base curve will become. 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.
Is the a big 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 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.
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.
Why my contacts are blurry?
Dirty lenses are one of the leading causes of blurry contacts. Many people who wear contacts wear them for longer than is recommended, which can lead to protein deposits on the lenses. These deposits can blur your vision, and can also cause major health issues.
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 is thumb rule in contact lens?
A simple rule of thumb exists. For every 0.05mm that the BOZR is steeper than K, the tear lens power increases by +0.25D. Therefore you must counter this by adding -0.25D to the power of the contact lens.
How do I choose a base curve for soft contact lenses?
Soft Contact Lens
5. 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.
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