Understanding Your Optical Prescription

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Understanding Your Optical Prescription
By Tina Mason 28 November 2014

Following the completion of your eye test, the optometrist will give you a copy of your prescription. This contains all the precise measurements that have been taken to correct your vision. What does it all mean? This is a guide to understanding your optical prescription.

Right Sph Cyl Axis Prism Base
+1.00 -2.00 90    
Left Sph Cyl Axis Prism Base
-2.00 -2.00 100   IN


SPH (Sphere):

Sph is the spherical part to your prescription. If the box contains a (+) this indicates that you are long sighted, meaning you find it difficult to see things up close. If the box contains a (-) this indicates that you are short sighted and unable to see things in the distance. The number may be very small such as 0.25 or a large number such as 7.00. The higher the number, the more powerful the prescription.

CYL (Cylinder):

The Cyl represents the amount of astigmatism in your prescription, this is caused by an irregular shaped cornea. If the box doesn’t contain anything, this means that your vision is purely spherical, like a football. If the number is a small number like 0.25 then your eyes are slightly round but not fully. If the number is a large number it means your eye is more oval in shape, like a rugby ball.


The axis represents the direction of your astigmatism in degrees.


This represents a muscle imbalance between your eyes. Prism in your lenses will provide correction to double vision and headaches.


This is the direction in which the prism is set. This can be: IN, OUT, UP or DOWN.


This is for patients who are 45 and over and require extra power for their reading. The term ‘ADD’ relates to the amount of additional correction needed to improve focus at closer distances. If you have a number in this section it means you will require different prescriptions for distance and reading. Usually require varifocals or bifocals.
If you do need help understanding your optical prescription, make sure you get in touch with the team, you can call us on 01400 282028 or you can click here to contact us online.


With love,

Tina and the GF&L Team!