Understand Spectacle/Glasses Prescription

Glasses prescriptions can look scary intimidating and are usually filled with complex jargon.  Registered Opticians can take many years of studying before they fully understand how an eye prescription is interpreted. That is why we suggest if you are struggling with understanding your prescription email or upload your prescription and we will advise you on what it all means.

The law in the U.K requires opticians must give you a copy of your prescription after you have completed your test and have paid for it. If a eye examination has been advertised as FREE the Optician is still obliged to hand you over a written prescription.

You may already know what your glasses are for or your Optometrist will explain it to you. If you have been wearing glasses for a while you may already know what type of glasses, you wear.

Let us simplify the types of glasses, there are 2 main types:

  1. Single vision (sv) single vision are the most common types of glasses, it means your glasses have one single prescription and you use them to see in the distance for things such as driving, watching TV or maybe at college or university when you need to see far away.  Most people who wear single vision distance glasses tend to keep them on all the time as it is inconvenient to have to remove your glasses all the time. Single vision glasses can also be used for intermediate and near for example when you use a computer or when you are reading.
  2. Multifocals ( bifocals or Varifocals) Multifocals are worn mainly by people over the age of 40. At some stage you may visit your optician and complain about your near vision. This is often but not always something called presbyopia. The lens inside the eye is not able to focus on close objects meaning you will need glasses to help you to read, sew or do detailed tasks.  When you are prescribed a multifocal or glasses to read the Optometrist will add an extra set of numbers to your prescription. This number is called the reading ADD.

Let us look at a prescription?

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) -1.00 56 1/2 +2.00 +1.25
LE (OS) -3.00 DS +2.00 +1.25

Prescriptions can be written in many ways, providing the Optician has written it to a standard format, it can be interpreted by most. More often most opticians print prescriptions rather then write them by hand, so it has become easier to read.

RE = Right eye sometimes you may see it as “OD” ocular dextra Latin for right eye
LE = Left eye sometimes you may see it as “OS” ocular sinister Latin for Left eye
BE = both eyes Rarely you might see “OU” oculus uterque Latin for both eyes.

In the UK we rarely see the above latin abbreviations on glasses prescriptions.

Other abbreviations you may encounter on an eyeglasses prescription are : SPH, CYL, Axis, Add, Prism, BASE

 

SPH (sphere)

SPH is an Abbreviation for the term Sphere. This indicates the power required to correct your vision. If you are short-sighted (myopia) this number will have – /minus sign before it or above it.

If you are longsighted (hypermetropia) this number will have + / plus sign before it or above it. (refer below)

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) +2.25 -1.00 56 1/2
LE (OS) -3.00

 

Cyl (Cylinder)

Cyl is an abbreviation for Cylinder. A cylinder lens is a separate lens the Optometrist includes in your prescription to correct Astigmatism. The higher the value of the number the more curved your eye is. Sometimes there is no number in this box or it is left empty. This is because the front of your eye is spherical and does not have much curvature. This number has a “+ or –“ before or above it.

Astigmatism means the front of the eye is not perfectly spherical but is slightly curved. This requires the Optometrist to cylinder to your prescription to correct the increased curvature of the eye. (See below)

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) +2.25 -1.00 56 1/2
LE (OS) -3.00 -0.75 175

 

Axis

If you have a Cyl you must also have an axis. These numbers cannot exist without each other. The axis will be a number between 0-180. It can also include ½ numbers. Such as 7.5 or 7 ½.

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) +2.25 -1.00 56 1/2
LE (OS) -3.00 -0.75 175

 

Add (Reading Addition)

This will always be a positive + number. This is usually found on prescriptions of people who are over 40 and the optometrist has advised you need reading glasses.  Usually is written to 2 decimal places (+2.00). The Add is commonly the same for both eyes but in rare circumstances it can be different numbers.

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) +2.25 -1.00 56 1/2 +2.00
LE (OS) -3.00 -0.75 175.5 +2.00

 

Intermediate Add
Your intermediate add is a number added to your distance prescription to help you see at about an arm’s length. This is mainly given to office workers or computer screen users. They find that distance glasses are not quite strong enough to focus on a computer and reading glasses are too strong. The intermediate add allows the wearer to focus clearly on things which are about an arm’s length. Usually written to 2 decimal places (+2.00).

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) +2.25 -1.00 56 1/2 +2.00 +1.25
LE (OS) -3.00 -0.75 175.5 +2.00 +1.25

 

Prism

Prism is not often seen on prescriptions. A prism is often prescribed where the eyes are mildly imbalanced. This left uncorrected can cause eyestrain and sometimes double vision. If you have a prism in your prescription, please email or upload your prescription before you place an order.

 

Other abbreviations on a spectacle prescription: See Figure below

∞ /Plano: thin infinity symbol and the word Plano mean 0.00 . If you see these symbols, they need to be replaced with 0.00.

Sphere (Sph) Cylinder (Cyl) Axis (Ax) Near Add (Add) Intermediate (Add)
RE (OD) ∞ / Plano -1.00 56 1/2 +2.00 +1.25
LE (OS) -3.00 DS +2.00 +1.25

DS: If you look at the prescription above DS is placed after -3.00. You may see this on some prescriptions where the Optometrist makes it clear there is no Cylinder or Axis in the eye. Hence No significant Astigmatism is present.

BVD : Back vertex distance.  This refers to the distance from the front of the eye surface to the rear part of the spectacle lens. This is sometimes specified by the Optometrist in higher prescriptions. You do not need to enter this value.

VA : Visual acuity.  Visual acuity is sometimes specified on prescriptions by the Optometrist. This is simply your visual ability and its measurement when you have your glasses on. Again, you do not need to enter this number.

 

Prescription Layouts NHS ( GOS style )

The above image shows us the prescription following an NHS eye examination.  These are quite common.  The distance prescription is at the top so if you would like just Single vision distance glasses only enter the top segment of the prescription:

If you would like reading or near glasses enter the add.  If you would like to order multifocal seg varifocals or Bifocals enter the distance prescription and the add.

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