If you’ve recently had an eye test, you might be looking at your eye prescription chart. With letters, numbers and lots of acronyms, you’d be forgiven for not knowing what it all means. Often coming across as another language in itself, your eye prescription chart isn’t the easiest of things to understand. There are plenty of people just like you, searching for answers on glasses prescription meaning.

To help you in your quest to uncover the true meaning of your eye prescription chart, we’ve got the download on those mysterious acronyms and phrases.

Your glasses prescription meaning uncovered

What is the Sph (Sphere)?
The sphere value is measured in dioptres and describes the strength of your glasses and the level of correction required. If you have a minus number like -25.0, it means you’re short-sighted, i.e. you can see things close up to you, and find it difficult to focus on things further away.

A plus number on your prescription means you are long-sighted, that is to say, you can see things far away, but not so well close up.

If your prescription is over +/- 4.00, your optometrist may also take a ‘back vertex distance’ measurement, which you’ll often see shortened to ‘BVD’.

What does Cyl (cylinder) mean?
If you’ve been told you have an astigmatism, you may have come across this acronym. The cyl measures the degree of astigmatism you have, or how irregular the shape of your cornea is. A useful way of explaining it is that the more your eye looks like a rugby ball rather than a basketball, the greater your astigmatism.

What is the axis on my glasses prescription?
The axis number tells your optometrist the direction to position any cylindrical power in your lenses, which is required for people with astigmatism. The number shows the angle in degrees from 1 to 180, with 180 horizontal.

A higher axis doesn’t mean your prescription is stronger, it just describes the position of the astigmatism.

What is the glasses prescription meaning of prism and base?

If your eye muscles don’t work in tandem, prism and base are used to correct them.

What is prism?
Only a small number of prescriptions require a prism. Prism is used to correct eye alignment problems and can be a metric or fractional value. The prism value is followed by a directional value – the base.

What is base?
Base is the direction of a prism value and is only stated if your prescription has a prism value. You’ll see this displayed as BU or UP (base up), BD or down (base down), BI or IN (base in) or BO or OUT (base out).

What is back vertex distance (BVD)?
Back vertex distance is the distance required from your cornea to the back surface of the corrective lens. If your optician has given you a BVD value, be sure to include it if you’re getting prescribed glasses from anywhere other than your opticians.

Still confused about your eye prescription chart?

If you still have questions about glasses prescription meaning, a reputable optician will be able to talk you through your prescription and what it means. At Dominic Tunnell Opticians, we’d always recommend getting your spectacles from a high street optician, who can take all the small details into account.

While some online glasses retailers may have cheaper options available, they may not take the same level of eye prescription chart detail, leaving you with inaccurate spectacles and a flurry of other potential eyesight problems.

Alongside these eye prescription chart acronyms, there are a number of eyesight conditions you may have been told you have. As with all things medical, the more information you have about your eyesight, the better. To book an optician’s appointment in Worcester, please contact us on: 01905 613020 and we’ll see you as soon as we can.

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