What Does My Eye Prescription Mean? A Clear and Practical Guide

If you’ve ever picked up a pair of glasses or contact lenses and wondered what all the numbers and symbols mean, you’re not alone. Many people leave their appointment without fully understanding their eye prescription – yet it contains vital information about your vision, your eye health, and the type of correction best suited to you.

Your eye prescription is a set of clinical measurements that shows how well your eyes focus light. It identifies whether you are short-sighted, long-sighted, or have astigmatism, and how much correction is needed to achieve clear vision.

Crucially, an eye prescription is not a “grade” of eyesight or a disease diagnosis – it is simply a technical description of how your eyes process light and what adjustment is needed to sharpen your sight.

Before looking at the numbers, it helps to understand the two most common focusing problems:

Short-sighted people often see well up close but struggle with driving, reading signs, or watching television. Long-sighted people may experience eye strain when reading or working at a screen.

A typical prescription contains abbreviated terms and numbers for each eye. These are the key sections:

SPH (Sphere)

This shows the overall strength of the lens required.

• A minus (-) number means you are short-sighted.
• A plus (+) number means you are long-sighted.

The larger the number (e.g. -5.00 compared to -1.50), the stronger the prescription.

CYL (Cylinder)

This relates to astigmatism, a common condition where the cornea or lens has an uneven curve. Rather than affecting distance alone, astigmatism causes general blurring or distortion.

A higher CYL value indicates a greater degree of irregularity.

AXIS

This tells you the angle of the astigmatism, measured in degrees from 0 to 180. It does not affect strength; it simply shows orientation so lenses can correct the issue in the correct direction.

ADD

Short for “addition”, this is usually found in prescriptions for people over around 40–45. It provides extra focusing power for reading or close work and is commonly used in bifocal or varifocal lenses.

Prism

Not always present. It is used to correct eye alignment problems or double vision by redirecting light to help the eyes work together.

It is extremely common for the prescription of each eye to differ slightly (or even significantly). One eye may compensate for the other, which is why symptoms like headaches, eye strain or blurred vision can creep in gradually.

You will usually see:

• RE / OD – Right Eye
• LE / OS – Left Eye

“Ocular Dexter” and “Ocular Sinister” are traditional medical Latin terms still used in optometry.

• Adults with no symptoms: every 1–2 years
• Over 40s: yearly checks are often recommended
• Contact lens wearers: yearly
• People with diabetes or eye conditions: as advised by a specialist

Regular monitoring helps protect long-term eye health and ensures your prescription remains accurate.

Even a small change in your prescription can affect comfort and clarity. You might benefit from a review if you notice:

Headaches or eye strain
Squinting to read or drive
Blurry vision at certain distances
Dry or uncomfortable eyes when using screens
Needing to hold objects closer or further away

While glasses and contact lenses are the most common solutions, they don’t suit everyone. Many people now choose long-term correction that reduces or eliminates the need for daily eyewear.

Centre for Sight offers several advanced options depending on age, lifestyle, corneal shape and prescription strength.

1. Laser Eye Surgery (LASIK or PRK)

Laser surgery reshapes the cornea to improve focus. It is ideal for those who no longer want to rely on glasses or lenses. Results are immediate or near-immediate and long-lasting.

2. Refractive Lens Exchange (RLE)

Best suited to people aged 45+, especially those beginning to need reading glasses. The natural lens is replaced with a premium intraocular lens, improving both distance and near vision. It also prevents cataracts from developing in the future.

3. ICL (Implantable Contact Lens)

A micro-thin lens is gently placed inside the eye, offering clarity for those unsuitable for laser treatment – often due to high prescriptions or thin corneas.

These solutions are tailored individually rather than “one size fits all”. Your suitability depends on your eye health and your prescription, which is why a consultation is important before deciding which procedure is most appropriate.

Different treatment types suit different lifestyles:

If glasses feel inconvenient, contact lenses are uncomfortable, or you simply want more visual freedom for work, travel or sport, a long-term corrective procedure could be a better option.

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If you’re unsure exactly what your prescription means or would like to explore alternatives to glasses and contact lenses, Centre for Sight can help. Our consultants take the time to review your prescription, assess your suitability for treatment and recommend the most appropriate long-term solution.

Vision correction is not just about clearer sight, it’s about comfort, convenience, and supporting your long-term eye health.