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Are Contact Lens And Eyeglass Prescriptions The Same?

19-06-2023

Contact Lens Prescriptions Differ From Eyeglass Prescriptions

When it comes to vision correction, many individuals turn to either eyeglasses or contact lenses to help improve their eyesight. Both options have their benefits and considerations, but one common question that arises is whether a contact lens prescription differs from an eyeglass prescription. While the goal of both prescriptions is to enhance vision, there are some key differences between the two. Let's explore the dissimilarities to gain a better understanding.

Eyeglass Prescriptions

Eyeglasses are a popular choice for vision correction and are typically made up of lenses that are placed in a frame and worn on the face. An eyeglass prescription, also known as a spectacle prescription, provides specific details about the lenses needed to correct the vision of an individual. These prescriptions are typically written by optometrists or ophthalmologists after a comprehensive eye examination.

An eyeglass prescription includes several elements:

  • Sphere (SPH). This measurement indicates the lens power required to correct nearsightedness (myopia) or farsightedness (hyperopia). It is denoted with a plus sign (+) for farsightedness and a minus sign (-) for nearsightedness.
  • Cylinder (CYL). This measurement determines the lens power needed to correct astigmatism, which is a condition that causes blurred vision due to an irregularly shaped cornea. It may be accompanied by an axis value, denoting the orientation of the astigmatism.
  • Axis. This value is provided for astigmatism correction and indicates the orientation of the cylindrical lens required.
  • Addition (ADD). This measurement is typically mentioned for individuals who need correction for presbyopia, an age-related condition that affects near vision. It indicates the additional power needed for reading or other close-up activities.
  • Prism. Prism corrects double vision (diplopia).

Contact Lens Prescriptions

Contact lenses, on the other hand, are directly placed on the surface of the eye to correct vision. Due to their proximity to the eye, contact lens prescriptions require additional information that differs from an eyeglass prescription. A contact lens prescription includes the same elements as an eyeglass prescription, but also includes specific measurements related to the fit of the contact lenses.

In addition to the elements found in an eyeglass prescription, a contact lens prescription includes:

  • Base Curve (BC). This measurement determines the curvature of the contact lens to match the shape of the cornea.
  • Diameter (DIA). This value represents the size of the contact lens and ensures a proper fit on the eye.
  • Brand and Material. The specific brand and material of the contact lens are indicated to ensure the prescribed lenses are obtained.
  • Prescription Expiration. Contact lens prescriptions typically have an expiration date due to the importance of regular eye examinations to monitor eye health and ensure accurate vision correction.

Please note that a contact lens prescription is not a substitute for an eyeglass prescription. Since contact lenses rest directly on the eye, they require a more precise fit and specific measurements to ensure comfort, proper vision correction, and optimal eye health. Therefore, it's crucial to obtain a contact lens prescription from an eye care professional, even if an individual already has an eyeglass prescription.

While both eyeglass and contact lens prescriptions serve the purpose of correcting vision, there are notable differences between the two. Eyeglass prescriptions primarily focus on lens power and correction, while contact lens prescriptions include additional measurements for proper fit and eye health. It is essential to consult with an eye care professional to obtain the appropriate prescription for your vision needs, whether you choose eyeglasses or contact lenses. They will conduct a comprehensive eye examination and determine which option is most suitable for you based on your visual requirements, lifestyle, and overall eye health. Remember, both eyeglasses and contact lenses have their advantages and considerations. Eyeglasses offer convenience, easy maintenance, and a fashion statement, while contact lenses provide a more natural field of vision, freedom of movement, and the option to participate in sports and other physical activities without obstruction. Regardless of your choice, always prioritize regular eye exams and follow your eye care professional's recommendations. They will ensure that your prescription is up to date, monitor any changes in your vision, and address any concerns or issues you may have.

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If you live in Canada, you cannot buy contact lenses without a valid prescription from an optometrist or ophthalmologist. This is because contact lenses are considered medical devices and require a proper fitting and evaluation by a licensed eye care professional.

A contact lens prescription is valid for one year.