The Difference Between Contact Lenses and Glasses Prescriptions

by Sep 12, 2023

Have you ever wondered why your contact lens prescription differs from your glasses prescription? The variation in these prescriptions can be confusing, but it’s important to understand the reasons behind these differences. In this article, we will explore the factors that contribute to the variance between contact lenses and glasses prescriptions.


  1. Distance Between the Eye and the Glasses

One primary reason for the dissimilarity between contact lenses and glasses prescriptions lies in the distance between the eye and the lenses. Glasses sit about 12 millimeters away from the eyes, while contact lenses sit directly on the surface of the eyes. This disparity in proximity can necessitate a modification in the prescription values to optimize visual clarity.

Since contact lenses are in direct contact with the eye, they generally require a slightly different prescription to account for the altered positioning. This adjustment ensures that the corrective power is appropriately distributed on the eye’s surface to provide optimal vision correction.

  1. Design of the Contact Lens

Contact lenses are available in various designs to address different visual needs. Depending on the specific design attributes, such as material, curvature, and shape, the prescription values may need to be adjusted accordingly.

For example, toric contact lenses are specifically designed to correct astigmatism, a common vision condition caused by an irregularly shaped cornea. The prescription for toric lenses incorporates additional indicators such as cylinder and axis values to correct both the spherical and astigmatic components of the eye’s refractive error.

Moreover, multifocal contact lenses, which are designed to provide both distance and near vision correction, may require a multifocal prescription that incorporates multiple focus zones. This enables seamless visual transitions between different distances, accommodating the eye’s natural focusing ability.

  1. Available Contact Lens Parameters

Another factor influencing the difference between contact lens and glasses prescriptions is the range of available contact lens parameters for a specific prescription. Contact lenses are manufactured in standardized parameters such as base curve, diameter, and power increments. These parameters may provide a narrower range of options compared to the broader range of parameters available for glasses.

The limited availability of certain parameters may require slight adjustments to the prescription values to accommodate the specific contact lens options. This ensures that the prescribed contacts align with the available range of parameters, providing the best possible fit and visual correction for the individual.

Consultation with an Eye Care Professional

The decision to choose contact lenses over glasses or vice versa should always involve consultation with an eye care professional. They will evaluate your eye health, assess your prescription, and consider your lifestyle and preferences to recommend the best option for you.

During an eye examination, your eye care professional will carefully analyze your visual needs, taking into account the distance between your eyes and the glasses, your eye shape, and any specific visual conditions you may have. This thorough evaluation will guide them in providing an accurate prescription for either glasses or contact lenses.

By consulting with an eye care professional, you can ensure that your prescription is tailored to your specific requirements, maximizing visual clarity and comfort.


Our eye doctors at Perception Eyecare + Eyewear in Richardson, TX excel in the prescription of contact lenses, glasses and various eye diseases.  Call our optometrists at 972-250-0700 or schedule an appointment online if you would like to learn more about contact lenses and glasses prescriptions. Our optometrists provide the highest quality optometry services and eye exams in Richardson, TX and the surrounding vicinities of Garland, University Park, Sachse, and Highland Park.


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