Understanding Your Contact Lens Prescription

A contact lens prescription is not the same as a glasses prescription. Glasses sit in front of your eyes, while contact lenses rest directly on the surface of the eye. Because of that, the measurements need to account for lens shape, fit, movement, and comfort.

At Texas State Optical, we help patients understand what their prescription means so they feel confident wearing their lenses every day.
 

What The Numbers Mean

Your contact lens prescription may include several abbreviations. Sphere, or SPH, refers to the lens power needed to correct nearsightedness or farsightedness. Cylinder and axis are used when correcting astigmatism. These numbers help guide the clarity and accuracy of your vision.

Even small changes in these measurements can affect how well you see, which is why regular contact lens exams are important.
 

Base Curve And Diameter

Two measurements that are unique to contact lenses are base curve and diameter. The base curve describes the curve of the lens, while the diameter refers to the lens width.

These details help determine how the lens sits on your eye. A lens that is too tight, too loose, or poorly centered can cause blurry vision, dryness, irritation, or reduced wearing time.
 

Why Brand And Lens Type Matter

Your prescription may also list a specific contact lens brand or material. This matters because different lenses are made with different designs, moisture levels, oxygen permeability, and replacement schedules.

During a contact lens exam, we consider:

• Your eye shape and prescription needs
• Dryness, allergies, or sensitivity
• How many hours you wear lenses each day
• Whether you need toric, multifocal, colored, or specialty contact lenses
• Your lifestyle, work habits, and screen use

This helps us recommend lenses that support both clear vision and long-term eye health.
 

Contact Lenses For Astigmatism And Presbyopia

If you have astigmatism, your prescription may require toric contact lenses, which are designed to stay properly aligned on the eye. If you have presbyopia, which affects near vision with age, multifocal contact lenses may help you see at multiple distances.

These prescriptions can be more detailed because lens position and design play a larger role in how clearly you see.
 

When Your Prescription Should Be Updated

Contact lens prescriptions expire because your vision, eye health, and lens fit can change over time. Even if your lenses still feel comfortable, an updated exam can help detect dryness, corneal changes, or other concerns before they become more noticeable.

If you are experiencing blurry vision, redness, discomfort, or lenses that shift throughout the day, it may be time to schedule a contact lens exam.
 

Get Help Understanding Your Contact Lens Prescription

Your contact lens prescription should help you see clearly and wear your lenses comfortably. If you have questions about your prescription or want to explore better-fitting contact lens options, contact Texas State Optical in Richmond, Texas by calling (346) 210-5200.