Optical Prescriptions

To anyone not in the optical industry, prescriptions can look very confusing. However, feel assured that anyone fully trained will understand all aspects of an optical prescription.

Ophthalmic prescriptions and optical lenses are an extremely technical subject to understand and take years to learn about. This makes it a difficult subject to condense into a page of information. To make it a little easier to understand, here is a brief description of what each section of a prescription means, without using all of the technical jargon normally associated with optical prescriptions.

An NHS prescription form, a Boots Opticians or a Vision Express prescription form will all look completely different, as will prescriptions given out at all independent opticians.

To illustrate how different they can look – take a look at this image below taken directly from a Google image search showing ptical prescriptions from different shops:

Google-Images-Optical-Presc

Here’s the link to this page: http://goo.gl/90iIL4

The look of a prescription makes no difference though as, they will all contain all of the crucial information gained from a full, thorough eye examination, necessary to make up whatever type of lenses you may need.  The forms are simply of a different design.

No matter what the layout looks like, with the exception of the intermediate box all optical prescriptions will contain all of the following boxes for the Right eye and the Left eye. Please see the example below

Example-of-Blank-Optical-Prescription

Example of Blank Optical Prescription

Lots of the boxes will be left blank , this just means there is no Prism etc needed in the prescription. It doesn’t mean that part of the prescription has been missed out.

Without going into a too detailed explanation of what the abbreviations are,  listed below is what you might find written (or printed) in the boxes:

Sphere

(This will begin with a +or- sign before any numbers eg. +2.25)

Cyl/Cylinder

(This will begin with a +or- sign before any numbers eg. -1.50)

Axis

(This will be a number between 1 and 180)

Near/Add/Addition

(This will be a number, it might have a + sign first eg. +2.50)

Prism

(This will be a number, or just a fraction of a number eg. 2)

Base

(This will contain one of the words Up Down In or Out)

There are three different types of prescription. Distance. Near. Intermediate.

Distance Prescription

This is a prescription which is given to correct vision from about two meters away from the eyes, to looking into the far distance. Lenses made up to correct a distance prescription would be used for driving, watching TV, cinema etc.

Here is an example of what the figures could look like if your optician has determined that you have a distance prescription:

Example-of-a-distance-optical-prescription

Example of a distance optical prescription

Near Prescription

This is a prescription which is given to correct near vision, up to about two feet away from the eyes. Lenses made up to correct a near prescription would be used for reading, close needlework etc.

Intermediate Prescription

This is a prescription which is given to correct middle distance vision, up to about a metre away from the eyes. Lenses made up to an intermediate prescription would be used for computer work, reading music, playing cards etc.

All glasses can be made up to hold lenses which hold just one prescription (Single vision lenses) . These glasses would be for the wearer to see clearly at that one distance.  However, vision at other distances is then restricted. For example, if someone is wearing distance glasses they can see perfectly to watch TV. They will struggle to read the TV magazine with their glasses on though, as their glasses are to correct vision in the far distance only. They will have to either take their glasses off to read the magazine, or they might need to have lenses made which will correct more than one type of vision which are called multi focal lenses. This way vision will be clear to see the TV in the far distance, as well as close up to read the TV magazine.

Example of a completed prescription

Example of a completed prescription

The opposite will be found with near vision glasses used for reading. Anyone wearing reading glasses will find that objects in the far distance will appear blurred when seen through reading glasses. Again multi focal lenses are a good alternative. These multi focal lenses are called bifocal and varifocal lenses.

If there are just numbers written in the Sphere, Cyl and Axis boxes, there is only a distance prescription required to see clearly. As the Add/Near box is left blank, the person requiring the prescription will be able to see anything up close without the aid of prescription lenses.( See the 2nd image above)

The exception here would be for anyone who is fairly young (20’s ) who finds they have eye strain when using a computer or reads very close. They would have a prescription which looks very similar to the distance prescription image above. The numbers would be lower though, about +0.75 in each eye would be an accurate average prescription in these circumstances. These glasses would be worn purely for computer work or reading up close etc. No glasses would be needed otherwise.

If there are numbers written in the Sphere boxes but not in the Cyl or Axis, this is fine. There could be numbers in the Cyl and Axis in one eye, and just the Sphere in the other eye. This is also fine. If there are just numbers in the Sphere, there might be DS written in the next Cyl box. (See 3rd image above)

If however, there are numbers written in the Add/Near box as well as the Sphere Cyl and Axis, then lenses are needed to correct close vision as well as distance vision. This means either separate pairs of glasses are needed to see at each distance, or a pair of multifocal lenses would be more practical. (See 3rd image above)

There might be numbers written in a box that says Inter. This is the extra part of a prescription which gives the power of an intermediate prescription which is for computer use, reading sheet music etc. A separate pair of glasses just to see at this distance can be used, or Varifocal lenses would be an excellent, practical option.

If there are numbers written in one or both of the Prism boxes, there will also be something written in the next base boxes. Not many prescriptions contain prism. (See 3rd image above)

For further reading check out this link – although bear in mind it’s aimed at an American audience:

http://www.webmd.com/eye-health/how-read-eye-glass-prescription

As ever, if there is anything you are not sure about; please feel free to call me on: 01253 795523 – I’ll be happy to help.