What Does Your Contact Lens Prescription Mean?

Every year, more and more people swap their glasses for contact lenses. Since 1991, the number of contact lens wearers has increased by 4% per year, while studies show that in 2021, 5.2 per cent of people in the UK and Ireland wore daily disposable lenses. If you’re new to lenses and are wondering how to read your contact lens prescription, here’s what you need to know:

How do contact lenses work?

Made to correct refractive errors and maintain ocular health in between regular eye checks, contact lenses are small prescription lenses that float on the tear film layer on the surface of the cornea. Since they stick to the tear fluid on your eye surface, unlike a pair of glasses, contact lenses move naturally with you.

How to read your prescription

A contact lens prescription isn’t as daunting as it first seems. A lens prescription is typically made up of the following:

• Basecurve (BC): Your optician works hard to try and match the curve of your lenses to the curve of your eye. This number indicates how curved your contact lens is, E.g., BC 7.4.
• Diameter: The diameter is the length of the contact lens from one edge of the lens to the other, e.g., DIA 11.8. This number is used to ensure the contact lens covers the correct parts of your eye.
• Power (pwr) / Sphere (sph) / Dioptre (D): Much like glasses, lenses are used to correct long or short-sightedness. The value of the power of the lens is measured in Dioptres (D). A plus (+) sign indicates that you are long-sighted, while a minus (-) sign shows that you are short-sighted – the higher the number, the stronger your prescription.
• Contact lens name: There are a few different manufacturers that make contact lenses; the most popular ones are: CooperVision, Ciba Vision/Alcon, ACUVUE, and Bausch and Lomb. Working out which company manufactures yours is essential to reorder your lenses.
• Cylinder: If you have astigmatism, a sum will be entered in this box with an Axis. E.g., Left eye: -3.25, Right eye: -2.25.
• Axis: This is the direction where extra power is added to the lenses to correct your astigmatism. It’s measured in degrees and is normally between 0-180.
• Additional power: To help with reading and close work, a magnifying power is added to multifocal contact lenses. This power can be High, Low, Medium or with the power value itself and will always be a + value.

5 helpful tips when wearing contacts

Taking care of your contact lenses is essential for maintaining optimal eye health. Below are 5 helpful tips for wearing contact lenses.

1. If your eyes become red or sore – stop wearing your contact lenses immediately and contact an optician for advice
2. Wash and dry your hands before touching your eyes and handling your lenses
3. Before you use your contact lens solution, check the instructions
4. Clean your lens case regularly then allow it to air dry
5. Make sure the prescription on the lens packaging is correct

With the above help on how to read your prescription and five handy tips for wearing contact lenses, switching from glasses to lenses might be one of the best things you’ve done yet for your eye care.