How to understand your glasses /eyeglasses prescription

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A guide to help understand your eye prescription

The first thing you need is a copy of your prescription valid within the last two years. Every optician is required by law to give you a copy of your prescription when you go for your eye test.

An example glasses prescription:

Rx                SPH        CYL        AXIS        PRISM        ADD 
Right Eye     -0.75       -0.50        005           N/A            +2.50 
Left Eye       -1.75        DS                           N/A            +2.50

What the above abbrevations mean:

SPH: The sphere (Sph) specifies the strength of lens required to correct your focus - a plus sphere to correct long-sightedness (hyperopic - difficulty focusing on close objects) and a minus to correct short sightedness (myopia - difficulty focusing on distant objects.)

CYL & AXIS: The cyl and axis compensate for an astigmatism. So what's an astigmatism? An astigmatism is where the eye is shaped slightly like a rugby ball not a perfect sphere like a football. This just means the eye has difficulty focusing at certain angles.

PRISM: A Prism is to try and correct a lazy eye and indicates a more delicate condition. If your prescription contains a prism we recommend you have your frames glazed at your opticians because accurate measurements will need to be taken when you're wearing the frames.

ADD: The Add, short for Reading Addition, is the additional correction required for reading, this can be used to make either reading glasses, bifocal glasses or Varifocal glasses.

Some more common prescription abbreviations:

SPH or Sph = Sphere power
CYL or Cyl = Cylinder power indicating the amount of astigmatism
If you see X after the CYL, this means AXIS. i.e. X 90 = AXIS 90
DS = Dioptres Sphere (this means you only have a sphere power and no cylinder).
ADD = this is how much power is added to the distance prescription to determine your reading prescription, or for your Bifocals.
PLANO, PL, pl = this is a placeholder for the number zero, it is said to be infinity.
D.V. = Distance Vision
N.V. = Near Vision (Reading)


We hope that this guide helps you to understand your eye prescription better. If you found it helpful please vote 'yes' for it below.

Thank you
Designer Eyewear 4u Team

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