Prescription of color contacts is different than prescription of glasses. Therefore; you should have a fresh prescription in hand before placing an order for prescription colored contacts. Contrary to this; if you are looking for non-prescribed (power 0.00) colored contacts, you only need to choose the right pair of colored contacts.
If you have Astigmatism; you definitely need “Toric contact lenses”.
Q: How to read the specification of colored contacts?
We should understand the following before choosing colored contacts.
a. Water content
Refers to the ratio of quality of water in the lens and the the total mass of the lens. Water content determine the characteristics of the lens, water content can be divided into:
The higher water content, the more flexible the lens are, it is easier to deform in hand. In contrast, the lower the water content, lens are easier to form in hand. If water content is too high, the lens will reduce the moisture as it absorbs water from the eyes, causing discomfort to the eyes. If water content is too low, it will result in poor oxygen permeability, causing dryness to your eyes too, because oxygen is passing through the water content. IDEAL water content should be between 50% - 60%, but it varies among people. Experts recommend contact lenses with high water content to those eyes are easily to get dry.
It is the size of the lens. The bigger size of diameter, the more obvious the big eyes effect. Basically bigger diameter lens needs higher percentage of water content because water tends to be absorbed faster. You may notice that majority of the big eyes lenses (16mm) have 42% and above water content.
c. Base Curve
It is the center area of the curvature of the lens. Basic rule to select Base Curve is: it should not be tight. Experts advise common Base Curve are between 8.3 to 8.9. This helps it fit your cornea more comfortably since some corneas are "steeper" or "flatter" than others. The higher the base curve number the "flatter" the curvature of the cornea.
d. Center Thickness:
It is the thickness of center of contact lens. Experts remind those who have astigmatism, should select slightly thicker lens.
e. Oxygen Permeability:
It refers to the ability of oxygen permeate to eyes. Oxygen permeability varies from every type of lens, it depends on the material and thickness of lens. Generally the greater the diameter of the lens, the greater the coverage, oxygen permeability will be relatively poor.
Q. How to read the prescription by optometrist?
a. OD and OS
They are abbreviations for oculus dexter and oculus sinister, which are Latin terms for RIGHT EYE (OD)and LEFT EYE (OS).
Your prescription also may have a column labeled "OU." This is the abbreviation for the Latin term oculus uterque, which means "both eyes."
Your eyeglass prescription contains other terms and abbreviations as well. These include:
b. Sphere (SPH)
This indicates the amount of lens power, measured in diopters (D), prescribed to correct nearsightedness or farsightedness. If the number appearing under this heading has a minus sign (–), you are nearsighted; if the number has a plus sign (+) or is not preceded by a plus sign or a minus sign, you are farsighted.
The term "sphere" means that the correction for nearsightedness or farsightedness is "spherical," or equal in all meridians of the eye.
c. Cylinder (CYL)
This indicates the amount of lens power for astigmatism. If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.
This describes the lens meridian that contains no cylinder power to correct astigmatism. The axis is defined with a number from 1 to 180. The number 90 corresponds to the vertical meridian of the eye, and the number 180 corresponds to the horizontal meridian.
If an eyeglass prescription includes cylinder power, it also must include an axis value, which follows the cyl power and is preceded by an "x" when written freehand.
The axis is the lens meridian that is 90 degrees away from the meridian that contains the cylinder power.
Q: How to choose the color of Circle Lens?
Sometimes it is difficult to pick which color suits you best. If you want people to notice your new eye color and ask you about it, or if you are those bold, dramatic and confident people who are comfortable being the center of attention, then you will want an eye color that everyone notices immediately. For instance:
If you want people to notice you look different, but can not tell why, or if you are shy, conservative, or want that natural look, you probably want an eye color that creates a more subtle change.