Learn about your glasses prescription

The Sphere

The sphere (Sph) specifies the strength of lens required to correct your focus - a plus sphere to correct long-sightedness (difficulty in seeing close objects) and a minus to correct short sightedness (difficulty in seeing distant objects.) Most values range from +/-0.25 to +/- 20.00 go up in steps of 0.25.

The Cylinder

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 or referred to as ‘Toric’, not a perfect sphere like a football. This just means the eye has difficulty focusing at certain angles.

This box maybe empty or have a plus or a minus value in it. The measurement is the Dioptre. Most values range from +/- 0.25 to +/- 4.00 and will go up in steps of 0.25.

The Axis

The AXIS  only present if there is a value in the CYL box, the AXIS tells us where the astigmatism is in your eye. The measurement is in Degrees. The values range between 0 and 180


PD / Pupillary Distance

The Pupillary distance is an essential measurement. It is the distance from the center of one pupil to the center of the other pupil measured in mm (ranges from 50 to 70mm). Each spectacle lens will have an ‘optical center’, this is a point on the lens where it performs the best and has the least distortion. The optical centre of each lens should be placed directly in front of the center of each of your pupils. That way, your eyes are looking through the best point on each lens, some prescriptions may have the PD/Pupillary Distance listed for each eye respectively, for example RE: 32 LE: 32, or one single PD example 64 .

The ADD (Addition)

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 Progressive glasses.

This figure is an indication of how much extra power is required ‘on top’ of the distance prescription for near or intermediate glasses. This extra power will ALWAYS be the same for each eye and may only appear once on your prescription but it is understood to be meant for both eyes. The measurement is the Diopter, and most values range from +0.50 to +3.50 .

Single vision prescription

PROGRESSIVE OR READING PRESCRIPTION

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