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Why Are Contact Lens Prescriptions Different from Eyeglasses?

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Contact lenses and eyeglasses help people with refractive errors to see clearly. Both types of eyewear work to correct nearsightedness, farsightedness, astigmatism, and other vision conditions. While many people use both kinds of prescription eyewear, switching back and forth depending on their mood and daily activities, the vision prescription for contacts and glasses isn’t perfectly interchangeable. A different prescription is necessary for each type of eyewear. Annual eye exams are the only way to verify that your vision hasn’t changed with time, and

your prescription is still current.

At the end of your eye exam in Manhattan Beach and Redondo Beach, California, our eye doctor will issue your separate vision prescription for eyeglasses and/or contact lenses, depending on your needs. Why can’t you use the same prescription?

Eyeglasses and contact lenses aren’t made the same

Different types of materials are used to construct contact lenses versus glasses lenses. In general, modern contacts are made from hydrogel or silicone hydrogel. This material is oxygen permeable, keeping your eyes healthy and helping to preserve the moisture in your contacts. Newer eyeglasses are made from advanced plastics, which are thinner, lightweight and more scratch-resistant than older glass versions. The different materials affect the refractive qualities of eyewear, leading to different prescriptions. Using the results of your personalized eye exam and taking your choice of eyewear into consideration, our eye doctor at Advanced Eyecare Center will determine your prescription for eyeglasses and/or contact lenses.

Glasses and contacts aren’t worn the same way

The positioning of contact lenses and eyeglasses varies greatly with respect to your eyes. Eyeglasses sit at a distance of about 12mm from your eyes, whereas contacts sit directly on your eyeballs. Different types of tests and measurements are therefore required during an eye exam for fitting contact lenses or glasses, and a mathematical calculation will be made to decide the most appropriate contact lens power. Due to the closer distance to your eyes, the lens powers of a contact lens will generally be slightly lower than eyeglasses.

Contact lenses prescriptions have more numbers

Your eyeglasses prescription includes info about your vision and the requirements for correction, which are the focusing power of the lenses that you need to see clearly. If you have astigmatism, the prescription will also include the sphere, cylinder, and axis of your lens curvature. In addition to these numbers, your prescription for contact lenses will also include the base curve (BC), which is the curvature of the back surface of the contacts, and the diameter (DIA), which is the overall size of the lens.

Not everyone is a candidate for contact lenses

There’s much more to qualifying for contact lenses than just ordering contacts with the powers listed in your eyeglasses prescription. An eye exam by a qualified professional is needed to check if your eye health is suitable for wearing contacts – and to determine which particular type of contact lenses. We offer comprehensive contact lenses eye exams and fittings in Manhattan Beach and Redondo Beach, California.

Precise vision depends on having a precise eye exam

Whether you wear eyeglasses or contact lenses, enjoying clear and healthy vision starts with having an eye exam from an experienced eye doctor. At our eye care centers in Manhattan Beach and Redondo Beach, California, we take the time to perform a detailed assessment of your eye health and vision – so you have an accurate vision prescription for every type of eyewear you wear. To ensure that your eyesight remains crisp and clear, annual eye exams are essential.

At Advanced Eyecare Center, we put your family's needs first. Talk to us about how we can help you maintain healthy vision. Call us today: 310-620-1345 or book an appointment online to see one of our Manhattan Beach eye doctors.

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