Your Prescription Guide

To produce your prescription glasses accurately we need some information from your prescription. Here is a simple guide to your prescription with some explanations of what everything means. We have also included some examples to show what they look like. If you have any concerns when entering your prescription information please call us. You can always email or post a copy when ordering your glasses.
optical prescription sample
SPH (sphere) – spherical power, the back of the eye is shaped like a football only requiring 1 power for correction. Long-sighted plus (+) sign or short-sighted minus (-) sign.
CYL (cylinder) – cylindrical power, the back of the eye is shaped like a rugby ball, light hits the back of the eye on 2 curvatures giving a sphere and cylinder power (this requires an axis). It measures the astigmatism. If no CYL required it may say DS which means SPH power only.
AXIS – only given if a cylinder is required (between 1 & 180 degrees) enables us the set the CYL correctly (will only have an axis is there is a Cyl value).
ADD – addition, a power added to the distance sphere to give extra magnification for close up work, can be Inter (intermediate) or Near (reading).
PRISM – this corrects a muscle imbalance (squint). NB there is usually an extra charge for PRISM, please contact us for a quote.
BASE – the prism direction either up, down, in or out.
Some more typical glasses prescription examples:
optical prescription sample 3
optical prescription sample 2

Here are some other terms often used by opticians:
PD (pupillary distance) – this is the measurement between the pupil centres, also known as OC – optical centres, it is measured in mm. Average distance PD for male is 63mm and female is 61mm.
DIOPTRE – this is the unit of lens powers, they are in .25 (1/4) * .25, .50, .75, 1.00 etc.
MYOPIC – myopia, short-sighted, can see more clearly close up need help with distance.
HYPEROPIC – hyperopia, long-sighted, can see more clearly far away need help with close up.
PRESBYOPIC – presbyopia, the eye looses the ability to focus close up (age related, around mid 40’s onwards), requires a reading prescription.
ASTIGMATIC – astigmatism, requires a Cylinder to correct curvature at the back of the eye (see CYL).
INDEX – the higher the index the thinner the lens of the same power.
· CR39 - 1.498, std plastic
· Polycarbonate – 1.59, approx 30% lighter, 20% thinner & 12x stronger than std plastic lenses, 100% UVA & UVB protection
· 1.67 – approx 40% thinner than std plastic, 100% UVA & UVB protection
· 1.74 – approx 50% thinner than std plastic (thinnest possible plastic lens), 100% UVA & UVB protection

Scratch resistant coating – hard coating on lenses, helps resist scratching, doesn’t stop it all together, anything abrasive across the surface of the lens can cause scratching.
MAR – multi anti-reflection coating, a coating applied to lenses to reduce glare from artificial lighting i.e. computer screens, overhead lighting & night-driving car headlights and street-lights. They are automatically hard coated too.
BlueV-Light - reflects unwanted blue-violet light transmitted from modern digital devices that can cause eye fatigue (special order lens - please contact us for a quote)
TRANSITION – new generation is the Transition 8, 100% UVA & UVB protection. Virtually clear indoors, faster fade back, suitable for night-driving. Performance is severely reduced in cars as UV changes the crystals in the lens and car windscreens stop UV passing through.
TRANSITION XTRACTIVE - these do darken to sunglasses behind the windscreen, they have a slight tint when indoors/unactivated (special order lens - please contact us for a quote)
POLARISED - permanant dark tinted lenses, give 100% UVA & UVB protection, not only reduce glare they make images appear sharper and clearer, increasing visual clarity and comfort (special order lens - please contact us for a quote)
SV – single vision, a single powered lens which corrects one focal length either distance, intermediate or reading.
BIFOCAL - 2 powered lens, usually distance at the top and reading at the bottom but can also be distance at the top & intermediate at the bottom OR intermediate at the top and reading at the bottom.  The regular Bifocal is a D28 segment (other options available please contact us for a quote)
VARIFOCAL– (multifocal/progressive) looking straight ahead through the lens is distance then as you lower your eyes the power gradually increases towards the bottom of the lens, through the intermediate to the reading/close work. No visible line like the bifocal, cosmetically more appeasing – younger looking as looks like a single vision lens, gives full focal range. THESE CAN ONLY BE ORDERED BY PHONE as there are different designs with differing peripheral vision available.
OFFICE PROGRESSIVE - (occupational lenses / office lenses) at the age of around 40+ we lose the ability to focus properly at multiple distances. Perfect for those working in an office who need help for computer screen and reading/close work. (special order lens - please contact us for a quote)
A copy of your prescription is not required before you order with Specs-By-Post but if unsure of the figures you can email a copy to us at Providing your existing prescription is less than two years old, you may use this to order from us. However, if your prescription is over two years old, you will need to see your optician in order to obtain an up-to-date one. It is worth pointing out that you are under no obligation to purchase your glasses from the shop where you had your eye test. The optician is, however, obligated to provide you with a copy of your prescription.
Now you have your prescription, you can proceed to order your glasses from Specs-By-Post online at by either clicking on one of the frame selections above, on the Homepage or by telephoning us on 01709 769 402. 
Following your frame selection, key in your prescription details online and choose your lens. Our website safely accepts most types of credit cards and also by Paypal.


Varifocal orders can only be made over the phone - the website does not show these lens options. You may place your order for reglazing your glasses via post.
To print off a printer-friendly form, simply click here to download a reglazing form. You should then complete the order with your glazing information and post it to us by
Royal Mail:-
Specs-By-Post Ltd
PO BOX 689
South Yorkshire
S66 6AR
United Kingdom
Or by Courier to:-
Specs-By-Post Ltd
The Granary
Fish Pond Lane
South Yorkshire
S66 7AA
United Kingdom
Either your prescription (or a copy of the document) should be sent with your order. This will be kept on file (unless you specifically request us not to do so). In this way, if you would like to place a further order with us, your details are on file. This method of ordering, i.e. mail order is preferable for people who are not fully conversant with their prescription details. You can either send a cheque or ask us to contact you by phone when we receive the order, you can then pay securely using using Mastercard, Visa, Visa Electron/Debit, Solo or Maestro card. We can also send a request through Paypal for you to authorise.
Once again, select your frame and order either from our website or by telephone. Our customer service team can be contacted on 01709 769 402 and they are available to accept your order. You can discuss various lens options with them, and they will request details of your prescription. Once again, most credit cards are accepted as payment over the telephone.
Most of our customers require single vision lenses. These are made to your prescription strength and are most suitable for people who are short-sighted or long-sighted. These are recommended by us for those people who have not been advised to purchase miltifocals (bifocals or varifocals) or other types of lenses. However, it is possible to order bifocal lenses at a further cost starting from £27.50 for those people who need two strengths of lenses. We must stress, however, that these should only be purchased on the advice of your optician. Specs-By-Post advise customers requiring bifocal lenses to request that their optician prescribe for their glasses assuming that the glasses are worn 12-13mm from the eye (the back vertex distance).
You need not understand the details on your prescription, but it is vital that you are able to read the numbers written. For example; in certain hand writing styles a "1” may look like a "7”.
If you are able to read all the details on your prescription, then you can browse our website for the product you prefer, and simply enter your prescription details. It is imperative that you enter ALL prescription details. Also, there may be a value for your "PD” or pupillary distance. All details on your prescription must be entered into our online order form, put on the mailing document or relayed to our telephone operators.

Should you have difficulty reading your prescription then help is at hand! Call 01709 769 402 where an advisor will talk you through the details on your prescription. Another option would be for you to post it to us at Specs-By-Post, PO BOX 689, Rotherham, South Yorkshire, S66 6AR
OR you can email a copy to