What do the symbols on my prescription mean?
On your glasses prescription, you’ll find different symbols and terms. Let’s get you familiar with these to help you to read your prescription. In the diagram below, click the fields within the black circles to understand what they mean.
What does SPH mean on my glasses prescription?
The ‘+’ or ‘–’ sign that you see on your eye prescription with a number is the SPHERE (SPH) value measured in dioptres (D), going up in steps of 0.25. '+' means you are long-sighted, unable to see close-up objects clearly; and '-' means you are short-sighted and face difficulty in seeing distant objects. If you see Plano, PL Infinity (∞) or 0.00 mentioned on your prescription, this equals zero and means there is no spherical correction.
What does CYL mean on my glasses prescription?
You’ll also see a cylinder (CYL) number on your prescription, usually in a ‘+’ or ‘–’ format. This refers to the level of astigmatism and it can start as small as +/-0.25 for spectacle prescriptions. An empty box or DS means there is no astigmatism and your eyes are perfectly spherical.
What does AXIS mean on my glasses prescription?
The axis number on a prescription indicates which angle and direction they should position the CYL or cylinder. This is required for people with astigmatism. This can range between 1 and 180 degrees for spectacle prescriptions.
What does PRISM mean on my glasses prescription?
This shows if you have a muscle imbalance in your eyes and is prescribed to prevent headaches or double vision. The amount of prism is recorded in dioptres and can be written in decimal form or sometimes as a fraction and will always have a direction, for example, 1.50D Base UP.
What does BASE mean on my glasses prescription?
This base signifies the prism base direction. It can be UP, Down, In or Out.
What does ADD mean on my glasses prescription?
ADD is the additional correction required for reading, usually for people struggling with presbyopia. It is also written as near addition, near add or NV. This value is added to the sphere to calculate your near vision prescription. An ADD can range from +0.25 to +4.00 (going up in steps of 0.25). You may also come across Intermediate ADD (IV) on your prescription. This is for those who struggle to see at arm’s length distance, like when using a computer screen.
Other terms as a part of your glasses prescription
There could be other, slightly lesser used terms on your prescription like:
1. PD (pupillary distance)
What is pupillary distance (PD) on your prescription? It’s the distance between your eyes, measured from the centre point of one pupil to the other. This is not usually mentioned on your prescription after an examination but you can simply measure it yourself. You will need this information when ordering your glasses as it is used to ensure your vision is comfortable and clear.
2. OS and OD
OD refers to the right eye. OS refers to the left eye. In some cases, you may come across ‘OU’ or ‘ODS’, referring to both the eyes.
3. Other symbols
You may come across other symbols on your prescription, such as BAL (balance), VA (visual acuity), and BVD (back vertex distance). However, VA and BVD are not required to place your order online.
Different types of glasses prescriptions
Prescriptions vary per individual. Here are the different variations of prescriptions:
1. Single-vision prescription
Single-vision lenses are used in glasses to correct short-sightedness (myopia), farsightedness (hyperopia) and presbyopia, which is a gradual loss of the eye’s ability to focus close up. They use just one prescription and can be used for everyday use, such as reading or driving.
2. Lined bifocal prescription
Lined bifocal lenses contain two prescriptions. One is for near vision and the other is for distance. Usually, the top half of the glasses is for distance and the bottom half is for near vision. Traditional lined bifocal lenses have a clear, visible line to separate the two prescriptions. Bifocal prescriptions will have the numbers in the ADD column on a glasses prescription.
3. Progressive or multifocal prescription
Progressive lenses contain three prescriptions: one for distance vision, one for intermediate vision and one for near vision. Progressive lenses allow you to experience all three visions without a visible line of separation and are ideal for people who need multiple vision correction in one pair of glasses. This also includes the numbers in the ADD column on a glasses prescription. The ADD value will not always be mentioned or necessary if you’re entering a prescription for distance.
What does Rx mean in glasses?
Rx is short for a medical prescription. This term on your glasses prescription is just a customary superscription or heading.
How long does a prescription last?
A glasses prescription typically lasts for about 1-2 years after the date of test. Expert opticians advise to get your eyes thoroughly checked at least every 2 years. In case of any vision difficulty or discomfort with your present glasses, you should immediately go for an eye checkup, even if your last prescription falls under the 2-year time frame.
What is the minimum prescription for glasses?
The smallest usable glasses prescription is +0.25 or -0.25 dioptres. Patients with one of these values on their glasses prescription can still have a 20-20 vision and see perfectly.
Which type of prescription frame should I go for?
Once you have got your eye prescription, you can easily get your choice of glasses. If you’re unsure, you can consult your optician and ask for their advice about the material of the frame you should go for. For instance, those with high power are advised to go for plastic/acetate frames as the acetate material conceals the thickness of the lens. You can also consider your face shape to find the perfect pair.
How do I get a copy of my eye prescription?
You can simply contact the optician who tested your eyes and request a copy of your glasses prescription. You might need to provide some personal information for the optician to track your details. Please note that some opticians may charge for extra copy of prescription.
Have a question regarding your glasses prescription? Get in touch with our insightful customer service team, who will be more than happy to help you.
Disclaimer: The advice in this article is for informational purposes only and does not replace medical care or an in-person check-up. Please check with an eyecare professional before purchasing any products or remedies. For information on our article review process, please refer to our Editorial Policy.
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