Contact Lens and Glasses Prescriptions: A Complete Guide

If you are currently wearing glasses and thinking about switching to contact lenses, you will probably think that your glasses prescription will be enough. Why Are Contact and Glasses Prescriptions Different? However, contact and glasses prescriptions have differences. Understanding their differences helps you order the right lenses that will fit and correct your vision well.

Why Are Contact and Glasses Prescriptions Different?

The answer to this question is the distance between the lens and the eye.

A pair of glasses will be placed at a small distance from your eyes, whereas contact lenses are placed directly on your eyes. The distance makes the correction power different especially in stronger prescriptions.

In weaker prescriptions, the numbers on a glasses and contact lens prescriptions will be almost the same. In stronger prescriptions, differences become bigger.

This is the reason why you should not just take your glasses prescription while buying contact lenses.

What Information Is on a Glasses Prescription?

Information Included in a Glasses Prescription

The following information is provided in a glasses prescription:

SPH – It is an abbreviation for the Sphere, that is, the correction for near-sightedness or far-sightedness.

CYL – It is an abbreviation for the Cylinder, that is, the correction for astigmatism.

Axis – It is a measure for the astigmatism correction.

ADD – It can be mentioned for people requiring additional correction for close-up vision.

Your prescription may also give you the information about pupillary distance (PD).

Information Provided in a Contact Lenses Prescription

A contact lenses prescription gives information about vision correction, along with details that will make sure your lenses fit well on your eyes. Based on the kind of lenses, it provides the following information:

Sphere (SPH)

Cylinder (CYL)

Axis

Base Curve (BC)

Diameter (DIA)

Lens Material / Brand

Additional information for specialized lenses

Base curve and diameter are important because contact lenses should fit properly on the eye surface. Otherwise, even with the correct prescription, there could be problems with discomfort and blurred vision.

Can Your Glasses Prescription Be Used for Contact Lenses?

Normally, you must not place your order for contact lenses based on your glasses prescription alone.

Contact lens fitting is not just about verifying that your eyesight is good enough. The eye care specialist will also assess the dimensions of your eyes, the materials used to manufacture the contact lenses, movement of the lens, and your comfort level.

The outcome of your fitting will be a prescription for your contact lenses.

Why It Is So Important to Have the Right Prescription

Getting the right prescription is crucial for having clear vision and enjoying wearing contacts. Wearing the wrong prescription contacts may cause you problems like blurry vision, irritation, or discomfort.

If you wear glasses but want to try wearing contact lenses, book yourself an eye exam and lens fitting appointment.

It is important to observe that even though both glasses and contact lenses have similar functions, they are not interchangeable. In particular, prescriptions for glasses consider the aspect of vision correction primarily, while those for contact lenses consider both vision correction and the fit and placement of the lens on the eye.

For those who want to change from wearing glasses to wearing contact lenses, the best option would be to get a prescription for the contact lenses.