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The following information will assist you in interpreting the information on your optical prescription so that you can fill in your prescription details on our order form accurately.


plus and minus signs

SPH (Sphere) and CYL (Cylinder) values always have a sign to indicate if they are plus or minus.

Occasionally the ADD (Addition), written when the wearer needs an additional strength in near spectacles, has a plus sign. 

In this example the Optometrist has written the signs above the Sph & Cyl values.

i.e. The right SPH is -1.25 and the right CYL is +1.50 





If you are unable to decipher the writing of the Optometrist call them first to clarify the figures they have written. 

In this example the left axis was given to us as 3u!. Sometimes 3s and 5s, 2s and 7s can be poorly written and difficult to distinguish from one another.

The left axis should be 30 

(axis are always a numerical value between 0 & 180) 




symbols and abbreviations

DS is sometimes written to denote sphere only. It can be ignored.

a  or symbols are used in sphere boxes to indicate 'infinity'. The value should be stated as zero.

Plano is also used to denote the sphere value is zero

Examples of abbreviations...

The right sphere is -3.00 and right cyl & axis are zero 

The left sphere is zero. 





Spectacle wearers over 45 yrs often need a different prescription for distance viewing than for near.

The difference between these is the add or addition. The difference only affects the sphere.

Sometimes a different add is specified for viewing at 75-100cm i.e. VDU distance. This may be specified as intermediate add. ('inter add' or 'INT add')

In this example the optometrist has written the distance and near prescriptions out in full rather than specifying just an add.

i.e. The add is the near sphere minus the distance sphere = 1.50




Other prescription information

Prism is seldom used. It is only used in spectacles when wearers have problems aligning their eyes which may result in double vision. Prisms help keep the image single.

Base relates to the prism and can be up, down, out or in.

In this example the triangular symbol used by the optometrist can be ignored. The triangle only symbolises the unit that prism is measured in.



BVD or Back vertex distance is sometimes specified for higher lens powers.


Any other comments on the prescription should be noted. You will have an opportunity to add any special comments when you 'checkout' in the shopping cart


i.e. The Right Prism is 1.5 and Right Base is UP

The left prism is 1.5 and left base is DN (Down)



Back vertex distance = 12mm



If in doubt...


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Alternatively fax your prescription through 

after you have placed your order 

to 01925 357113 


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