How to read prescription for glasses


Published on January 27, 2020, 8:11 am

How to read prescription for glasses

Knowing how to read eyeglasses prescription turns helpful for you when you are shopping online for your prescription glasses. While many of us struggle with that piece of the paper that our optometrist handed over to us when visited for an eye test but it turns out to tell the state of your eyes and what problems you are facing. If you are also failing to read your prescription then don’t quit it yet just because there are too many numerical signs and medical stuff. You must know your eye condition as it helps you to find the right type of glasses and also be informed about your eye condition.

Buying eyewear has become so simple with the advent of the online marketplaces. Now, you do not have to rush from one high-end shop to the other to get your favourite pair as everything is available at the click of a button.  You can even book eye-test at home or eye test at work to get the prescription for glasses. With every facility being provided by online eyewear manufacturers while you sit relaxed at home without the trouble of stepping out of the house. By following some easy steps, you can place the order of your favourite pair of eyeglasses and get same day dispatch.

The only problem that many people face while placing an order at online purchase of eyeglasses is filling up details of the prescription. Although, it is very clear and easy to understand, however, there are still a few points of technicalities that may sound unknown to many. Therefore, many people end up filling either incorrect information of prescription or they simply upload the picture of prescription provided by the ophthalmologist or eye optician. 

So what are those terms and terminologies that are holding you from filling the prescription online? Here is the list of the vital terms that can help you understand how to read prescription for glasses as handed by the eye care practitioner or optometrist which you can fill easily online.

OD and OS

The OD and OS are abbreviations that stand for oculus dexter and oculus sinister. These are Latin terms which refer to ‘right eye’ and ‘left eye’. Apart from this, the prescription may have a column of ‘OU’ which is a Latin word oculus uterque and means "both eyes." 

Nowadays, some of the prescriptions do not use OD or OS. Instead, they use the words as the right eye and left eye itself. Generally, prescriptions have a column for OD/  right eye before OS/ left eye.


Sphere means the amount of power that is measured in diopters (D) which is required to correct myopia, hypermetropia and presbyopia. This is denoted by negative (-) and positive (+) sign. A plus sign is mentioned against the power that is required to treat farsightedness and presbyopia whereby the lenses are required to correct nearby vision disorder.  Whereas a minus sign is mentioned before the power lenses that are used to correct nearsightedness. 


When multifocal lenses such as bifocals and varifocals are used, this term ‘Ádd’ is used which means the power of the bottom part of the lenses which acts as reading glasses. This is required when a person suffers from hypermetropia or presbyopia along with the degree of myopia.  This column of ‘Ádd’ is denoted by a plus sign in the prescription for glasses.


A cylinder is referred for the power for astigmatism. Not every prescription has astigmatism power. It is written after the spherical symbol of minus or plus sign. In many cases, cylinder column is left blank which means there is no astigmatism power associated with the eyes.


Axis could be any degree from 0 to 180 which is used to define the orientation of the astigmatism degree.  This degree mentions the curvature where the astigmatism is occurring in the eyes and how much it is. The axis states the degree that helps in crafting the eyeglasses for correcting astigmatism.


Prism is referred to prismatic power which is measured in prism diopters i.e. “p.d.”. It is also denoted with a small triangle figure in the prescription for glasses, just like the shape of a prism. The prism powered glasses are used by people who have alignment problems.  A very small section of society suffers from this problem though.


Pupillary distance measures the distance between the centers of the eye’s pupils. This is required to measure the focus point in the lenses. The average PD for the adult lies between 54 to 77 mm whereas for kids it is between 43 to 58 mm. It can be easily measured by using a ruler from the center of the right eye to the center of the left eye in millimetres. 

Lens Coating

Apart from the above, you need to fill in the type of lens coating you require that ranges from anti-UV, anti-glare and, anti-blue light and photochromic lenses.  Every coating of the lenses provides their own unique benefits that protect eyes from one or the other harmful rays.

Where most of the eyewear manufacturers charges for the coating of anti-UV and anti-glare. Specscart’s eyeglasses come with automatically loaded with free of cost anti-UV, anti-glare, anti-scratch and shock-resistance properties.

How to read the prescription for glassesExample 

It may sound little confusing for you, thus, for better understanding, see the following example:

OD  -1.50 SPH +1.00 add 0.75 p.d.

Here,  -1.50 D is the correction of myopia in the right eye (OD). While +1.00 D is for the correction of myopia in the right eyes. As there is no astigmatism correction, there is no power for astigmatism. However, there is the prismatic correction of 0.75 diopters in the eye. 

In another example, 

OS -1.50 -0.50 x 180 +1.00 add 0.75 p.d.

Here -1.50 D is the correction of myopia in the left eye (OS), 0.50 D is the cylinder for correcting the error of astigmatism along with that there is Cylinder power axis at 180 degrees.  Further, there is an addition of +1.00 for correcting hypermetropia or presbyopia. Besides, 0.75 diopters of the prismatic correction in the left eye.


Our Latest Stories

Specscart Blog

Want the latest update on designer eyewear, shades or glasses? Our blogs give exceptional insights into the latest eye care measures and eyewear trends, fashion and style hitting the streets of United Kingdoms. From finding an optician or optometry near you to the latest designer glasses or sunglasses for the summer and spring fashion, you’ll learn something useful every day. We publish regular informative measures on eye care, the latest design in eyeglasses and sunnies, celebrity specs and fashionable choices you can make in your lifestyle to up your fashion game. Read on to find information about various glasses types, eye condition and fashion trends in a fun and simple way that you would fancy with a cuppa tea.

X-Blue lenses at £25

X-Blue Lenses

Gamer or hustler, your eyes can take only so much of digital blue light.
Give them the protection they deserve.

Buy Now Read More

24 Hr Dispatch Fastest Delivery in UK

Specscart Rocket | 24 Hr Dispatch

Surprisingly fast delivery for every last minute occasion.

Order Now Read More

Cleaning Kit

Specscart’s Eyewear Cleaning Kit

Let no virus threaten you. Clean your spectacles with an antibacterial eyeglass cleaner that comes with a washable cleaning cloth of the finest quality.

Buy Now

Try At Home

Free Try At Home

3 lenses, 4 frames, 7 days - direct to your home for free.
Time to get choosy.

Try Now Read More

fellow reader!

An exciting offer is on the way to your inbox!

You like to read stuff, and we love that about you.

Enter your email-ID below and we will send you an exclusive offer!

15% Off|New Year Offer

Start 2022 in style

Get 15% off on order above £99

FREE Protective Coating With Every Frame

Free Anti-UV Coating


Free Anti-Glare Coating


Free Impact Resistance Coating

Impact Resistance

Free Anti Scratch Coating


Specscart Shop Online Womens Glasses Shop Women Specscart Shop Online Mens Glasses Shop Men
Specscart Shop Online Womens Sunlasses Shop Women Specscart Shop Online Mens Sunlasses Shop Men