Contact lens parameters

 Contact lenses are medical devices that are worn directly on the cornea of the eye to correct vision or for cosmetic purposes. There are various parameters associated with contact lenses that are important for fitting and prescribing the right lenses for individuals. Here are some common parameters:


1. Power (Refraction): Contact lenses are available in different powers to correct nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. The power is measured in diopters (D) and can be positive (+) or negative (-) depending on the type of vision correction needed.


2. Base Curve (BC): The base curve determines the curvature of the contact lens. It is typically measured in millimeters (mm) and represents the curvature of the inner surface of the lens. The base curve is chosen to match the curvature of the cornea for proper fit and comfort.


3. Diameter (DIA): The diameter of a contact lens is the measurement across the lens from edge to edge. It is usually measured in millimeters (mm) and can vary depending on the type and brand of the lens. Diameter affects how the lens fits on the eye.


4. Cylinder (CYL) and Axis: These parameters are specific to toric contact lenses used for astigmatism correction. Cylinder indicates the amount of astigmatism correction needed, measured in diopters (D), and the axis represents the orientation of the astigmatism correction in degrees.


5. Add Power (for multifocal lenses): This parameter is applicable to multifocal contact lenses used to correct presbyopia. The add power is an additional power incorporated into the lens to provide different focal distances for near, intermediate, and distance vision.


6. Material: Contact lenses are made from different materials, such as soft hydrogel or silicone hydrogel. The choice of material depends on factors like oxygen permeability, comfort, and wearing schedule.


It's important to note that these parameters may vary depending on the specific brand, type, and prescription requirements of the contact lenses. Consulting with an eye care professional, such as an optometrist or ophthalmologist, is essential for obtaining accurate and personalized contact lens parameters.

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