When it comes to correcting vision, both glasses and contact lenses play an important role. However, many patients wonder: Are contact lens and glasses prescriptions the same?
The answer is no—while both types of prescriptions aim to sharpen your vision, they are written differently and tailored to the way that each corrective option interacts with your eyes. Understanding the difference can help you make informed decisions about your eye health and avoid confusion when switching between contacts and glasses.
Why Glasses & Contact Lens Prescriptions Differ
Glasses sit a short distance away from your eyes, typically about 12 millimetres from the surface. Contact lenses, on the other hand, rest directly on your eye. This difference in placement means that the lens power must be calculated differently.
For example, a glasses prescription may correct your vision perfectly at the standard distance, but if the same prescription were used for contact lenses, it might feel too strong or too weak. Optometrists take measurements of your eyes and tear film to make sure that your contact lenses not only correct your vision, but also fit comfortably and safely.
What’s Included in Optical Prescriptions
A glasses prescription usually contains:
- Sphere (SPH): Indicates nearsightedness (-) or farsightedness (+).
- Cylinder (CYL) and Axis: Measurements for astigmatism correction.
- Add Power: For multifocal lenses used in presbyopia.
A contact lens prescription includes these same measurements, but also:
- Base Curve (BC): The curvature of the lens that matches your eye.
- Diameter (DIA): The size of the lens, so that it properly fits your cornea.
- Brand/Material: Since lenses differ in design and oxygen permeability, your prescription specifies the exact product.
This added detail ensures your lenses provide clear vision while protecting your eye health.
Why It’s Important to Get the Right Prescription
Wearing contact lenses without the correct prescription can cause blurred vision, discomfort, and even harm your eyes. An improper fit may lead to dryness, corneal scratches, or infections. On the other hand, glasses with the wrong prescription can cause headaches, eyestrain, and difficulty focusing.
Your optometrist tries to make sure that your prescription is accurate, up to date, and safe for your eyes. If you notice changes in your vision, increased eye strain, or discomfort with your current eyewear, it’s a sign you should schedule an eye exam.
When to Update Your Prescription
You should book an eye exam every 1–2 years, or sooner if you experience:
- Blurred or fluctuating vision
- Frequent headaches or eyestrain
- Difficulty driving at night
- Discomfort or dryness with contacts
- Eye redness or irritation that doesn’t improve
Keeping your prescriptions current helps protect your vision and ensures both glasses and contacts work effectively.
FAQs About Glasses & Contact Lens Prescriptions
Can I Use My Glasses Prescription to Buy Contacts?
No, you need a separate contact lens prescription. While both prescriptions correct vision, contact lenses require extra measurements to ensure a safe and proper fit.
Why Does My Contact Lens Prescription Look Different?
Contact lens prescriptions may show lower or slightly altered powers compared to your glasses prescription, especially if you have higher nearsightedness. This adjustment compensates for how the lens sits directly on your eye.
Do I Need Both Prescriptions?
Yes. If you plan on wearing both glasses and contacts, you’ll need a valid prescription for each. Glasses and contacts have slightly different use cases, and having both ensures you always have a backup option.
Can I Wear Contact Lenses All the Time Instead of Glasses?
Many patients wear contacts daily, but it’s important to give your eyes a break. Wearing glasses in the evenings or only on some days can help maintain eye comfort and reduce the risk of dryness or irritation.
How Long Are Prescriptions Valid?
In the United States, glasses prescriptions are usually valid for 1–2 years, depending on state law. Contact lens prescriptions often expire after 1 year, since eye health must be monitored closely for safe lens wear.
Are Contact Lenses More Expensive Than Glasses?
Costs vary depending on the type of lenses and how often they are replaced (daily, bi-weekly, or monthly). While glasses are a one-time purchase until your prescription changes, contact lenses are an ongoing expense. Your optometrist can help you find the most cost-effective option for your needs.
Which Is Better—Contacts or Glasses?
Neither is universally “better.” Glasses are lower maintenance and may be preferred for comfort, style, or cost. Contact lenses provide freedom of movement, don’t fog up, and offer wider peripheral vision. Many patients choose to alternate depending on the needs of their lifestyle.
Update Your Prescription in Colorado Springs
While both glasses and contact lens prescriptions aim to improve your vision, they are not the same. Each requires unique measurements and specifications to keep your eyes healthy and your vision clear. If you’re considering switching between glasses and contact lenses—or using both—it’s important to have updated prescriptions for each. At Impressive Eyes Optical in Colorado Springs, CO, we provide comprehensive eye exams and personalized fittings for both glasses and contact lenses. Whether you’re new to contacts or need to update your eyewear, our team is here to help you see clearly and comfortably. Schedule your appointment today and get expert care tailored to your eyes.
