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 is the normal size of contact lens?
The diameter of regular contact lenses that are sold in the United States are on average 14mm–16mm. Similar to the diameter of regular contact lenses, circle lenses have no more than 15mm diameter since larger sizes would be harmful to the eyes at daily wear.
Do contact lenses come in sizes?
Contacts come in a variety of sizes, and the doctor will need to measure your eyes to get the right fit. The size will also depend on the type of lenses you want. The most common are soft lenses and RGP,or Rigid Gas Permeable lenses (read our RGP article here).
How do you know if contact lenses will fit?
Contact Lens Fitting
In order to assure that the fitting curve of the lens properly fits the curve of your eye, your doctor will measure the curvature of the cornea or front surface of the eye. The curvature is measured with an instrument called a keratometer to determine the appropriate curve for your contact lenses.
What does 8.4 mean on contacts?
A BC of 8.4 mm of radius is more curved, and therefore a tighter fit, than 8.8 mm base curve. People who have steeper corneas require tighter fitting contacts. If a contact is too loose, it may be uncomfortable, fold, or come right out.
How do I know what contact lenses to buy?
You can find your lens specifications on the side of your current contact lens box. All the essential information is printed on the side or back of every box. If you have different prescriptions for each eye always check the details for both your right and left eye.
How do I know what contacts I need?
The first step in determining which contacts are best for you is to schedule an eye exam and discuss available options with your optometrist or ophthalmologist. Keep in mind, though, that initial plans may change during your contact lens fitting.
Are contact lenses One size fits all?
If you ever find yourself in the contact lens room at Ardsley Eye Care, you’ll see stacks and stacks of different types of lenses. Where to even begin? There are several things to consider when determining what sort of contact lens to fit for a particular patient.
What size is 55 in glasses?
Small to Medium: 50-52mm. Medium to Large: 52-55mm. Large to XL: 55+mm.
How do you know if contacts are too big?
If your eye is shaped flat like a plate, and you wear a contact lens that is shaped like a bowl, the lens is going to fit too tight. You will feel the edge of the lens where it rests on your eye, your eye may become red as the day progresses, and you may develop inflammation.
What happens if you wear contacts that are too big?
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.
Is there a big difference between 8.3 and 8.4 base curve?
Usually yes, that is a big difference. 8.3 are for corneas that are steeper than average , while 8.6 is for flatter curvatures. Someone who requires an 8.3 or 8.4 usually can’t wear an 8.6 because they just keep sliding all over the eye.
Is 8.4 or 8.8 base curve more common?
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.
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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.