Are Contact Lenses the Same Prescription as Glasses?

 

If you wear glasses and are considering switching to contact lenses, you might wonder if your prescription is the same for both. The short answer is no—contact lenses and glasses prescriptions are not the same. This blog will explain the differences between the two, why they exist, and what to expect when getting fitted for contact lenses.

 

Understanding the Basics

Glasses sit about 12 millimeters away from your eyes, while contact lenses rest directly on the surface of your eyes. This difference in distance affects how light is focused, which means the prescriptions need to be adjusted accordingly.

 

 

Key Differences in Prescriptions

Power (Sphere) Adjustment:
The power of your lenses (measured in diopters) may differ between glasses and contact lenses, especially if you have a stronger prescription. This adjustment is needed because the contact lenses sit directly on your eye, altering the way light enters and focuses on the retina.

Base Curve and Diameter:
Unlike glasses, contact lenses require specific measurements for the base curve and diameter. The base curve ensures that the contact lens fits the curvature of your eye comfortably, while the diameter ensures proper coverage of the cornea.

Astigmatism Correction:
If you have astigmatism, your contact lens prescription may include a cylinder and axis value that may not be present in your glasses prescription. These values are crucial for ensuring clear vision, as they correct the uneven curvature of the cornea.

Addition for Multifocal/Bifocal Lenses:
If you need multifocal or bifocal correction, the "Add" power may differ between glasses and contact lenses. This difference ensures that your vision remains clear at various distances, considering the unique fit and design of contact lenses.

 

Why These Differences Matter

Contact lenses need to be customized to fit your eyes properly. A precise fit ensures that the lenses provide clear vision while being comfortable and safe to wear. Using a glasses prescription for contact lenses could result in discomfort, poor vision, and even damage to your eyes.

 

Conclusion

While your glasses and contact lenses serve the same purpose—correcting your vision—the prescriptions are not interchangeable. The differences in how they sit on your eyes and how they correct vision mean you need a specific prescription for each. Always consult an eye care professional to get the right prescription and ensure your eyes stay healthy and your vision remains clear.