A young woman putting in a contact lens for her left eye.

When it comes to correcting your vision, there are 2 common solutions: eyeglasses and contact lenses. But in order to see clearly with contacts or glasses, you need an accurate, up-to-date prescription from your optometrist

Because they’re both designed to correct vision conditions like myopia, you might assume that a contact lens prescription is the same as your eyeglass prescription. However, this is not the case and they cannot be used interchangeably.

Contact Lenses & How They Work

Contacts are thin, curved lenses that are placed onto the cornea to help correct vision. They move with the eye as you look around, providing a more natural field of view and better peripheral vision than glasses.

Similar to glasses, contacts bend incoming light rays as they pass through the lens. This process focuses the light properly onto your retina and helps your brain to produce a clearer image. Because the lens sits directly on your eye, the prescription needs to be measured from the surface of your eye.

Glasses & How They Work

Eyeglass lenses are often made of a composite plastic material because they are lightweight, more impact-resistant, and offer great optics. Similar to contacts, eyeglass lenses are designed to correct refractive errors by changing how light enters your eye. 

The Difference Between Glasses & Contact Lenses

Contact lenses rest on the surface of your eye, unlike glasses which sit a short distance (about 12 millimetres) away from the eye. This distance means that light has to be angled differently to properly reach the eye with glasses. Because of this, your contact lens prescriptions and glasses prescriptions are not the same, and they are not interchangeable.

In addition, contact lens prescriptions include other parameters that a glasses prescription does not, such as the lens diameter, curvature, and brand. This is because everyone’s eyes are unique, and a contact lens needs to fit the eye appropriately to ensure it does not cause harm. This means you need to visit an optometrist for a contact lens fitting and exam when you want new contacts. 

Some of the specific measurements and details included in a contact lens prescription are:

  • The base curve – the curvature of the back of the lens. This is determined by the shape of your cornea.
  • The lens brand – the manufacturer of the contact lens. This is important because manufacturers use different materials in their lenses, which can affect breathability. You shouldn’t switch contact brands without consulting your optometrist, as doing so can negatively affect how well the lenses work.

Contact & Glasses Prescriptions for Astigmatism

The differences between glasses and contact lens prescriptions become all the more important when an eye condition like astigmatism is involved. Astigmatism is an irregular shape or curve of the cornea that causes light to refract improperly. 

Because those with astigmatism have different eye shapes, their contacts must be precisely fitted to provide clear vision. When treating astigmatism with contacts, something called the axis comes into play. 

The axis determines the exact orientation a lens needs to rest at to do its job properly. Unlike glasses, contact lenses do not come in every possible axis measurement. Therefore, sometimes your optometrist will need to take this into consideration when finalizing your contact lens prescription.

A fitting exam with an eye doctor is essential for finding a suitable contact lens when your eyes are affected by astigmatism. We can find the right match for your eyes to help you see clearly without having to worry about your contact lens rotating when you blink. 

Optician helping a woman try on glasses.

Should I Use Glasses or Contacts?

The decision on whether to use glasses or contacts can depend on your personal preference. However, there are some factors that could make one or the other more ideal for you.

For example, you may find eyeglasses to be more comfortable if you experience dry eye syndrome. Dry eye affects the eye’s surface, where a contact lens needs to sit. Some people find contact lenses make their dry eye symptoms worse. However, there are also contact lenses specially designed for those with dry eyes. If you are someone who suffers from dry eyes but wants to wear contacts, ask your optometrist if there is a contact lens suitable for you.

Glasses offer a few advantages to contacts as they are more convenient to put on and take off, can be safely worn around bodies of water, and do not have the strict disinfecting procedures that come with contact lens wear. Glasses can also be an amazing accessory for those who enjoy exploring new fashion styles. Some people might also find contacts uncomfortable or may have an eye condition that stops them from using contacts.

Contact lenses are often preferred by people who live an active lifestyle, as glasses can be jostled, knocked off, or broken. Contacts allow for a full range of movement without worrying about losing or damaging a pair of glasses. Contacts are also a great option for people who do not like wearing glasses, whether for comfort or aesthetic reasons.

When you visit us for an eye exam, we can help you determine whether glasses or contacts are more suited to your specific needs and lifestyle. 

How to Get Your Glasses & Contact Lens Prescription

Fortunately, the process of getting an accurate eyeglass or contact lens prescription is often straightforward—you just need to visit your optometrist! We can perform a thorough, comprehensive eye exam and contact lens fitting to determine the exact prescription you need for clear vision.

At River City Eye Care, we know how important your vision can be for your daily life. To get an accurate and up-to-date prescription for glasses or contact lenses, book an appointment with us today!