What do vision prescription numbers mean

This simply means there is no astigmatism, and you can enter either nothing leave the field blank or select the phrase DS in the drop down. All rights reserved. UK company number: Free home trial Free returns. Glasses Direct. CYL or Cylinder number This shows how much astigmatism you have and the number can be negative or positive. AXIS This shows the position of the cylinder. It will be between 1 and PD or Pupillary distance This is the distance between your eyes measured between your pupil centre points.

ADD This will indicate if you need a prescription for reading and is applied to bifocal and varifocal lenses to correct presbyopia. Common layouts of prescriptions Below are examples of prescriptions. It can be hard to tell where one number ends and the next one begins. Astigmatism is a visual distortion that is caused by your cornea being an irregular shape. This is where the cylinder power is applied to oppose the effect of the oval-shaped cornea.

This is measured in prism dioptres and is an indication of whether your eyes work well as a pair or not. The prism lenses provide the correction you need for eye alignment problems and will prevent you from developing headaches or double vision.

It is indicated as either a decimal or fraction. This is to tell the lab where to put the prism in your glasses. There are four main abbreviations used for the prism direction:. You may only see a number here if you are 45 or over as this relates to presbyopia. This is the corrective power needed for reading and to see objects clearly at close distance on top of what is required already to see in the distance.

With technology constantly evolving, there are surgical options that enable your prescription to be corrected as well as any astigmatism. Get rid of the numbers on your prescription and come in for an initial consultation today to see what options are available to you.

Are you feeling unsure? Cylinder indicates the amount of lens power needed for astigmatism. It always follows the sphere power on an eyeglass prescription. The number in the cylinder column may have a minus sign for correction of nearsighted astigmatism or a plus sign for farsighted astigmatism. The term "cylinder" means that this lens power added to correct astigmatism is not spherical, but instead is shaped so one meridian has no added curvature, and the meridian perpendicular to this "no added power" meridian contains the maximum power and lens curvature to correct astigmatism.

Meridians of the eye are determined by superimposing a protractor scale on the eye's front surface. The degree meridian is the vertical meridian of the eye, and the degree meridian is the horizontal meridian.

Axis describes the lens meridian that contains no cylinder power to correct astigmatism. If an eyeglass prescription includes cylinder power, it also needs to include an axis value, which follows the cylinder power. The axis is the lens meridian that is 90 degrees away from the meridian that contains the cylinder power for astigmatism correction.

This is the amount of prismatic power, measured in prism diopters "p. When present, the amount of prism is indicated in either metric or fractional English units 0. Sphere power, cylinder power and add power always appear in diopters. They are in decimal form and generally are written in quarter-diopter 0.

When prism diopters are indicated in decimal form, typically only one digit appears after the period e. No cylinder power or axis , which means no astigmatism is present. This doctor chose to write "SPH," to confirm the right eye is being prescribed only spherical power. Some doctors will add "DS" for "diopters sphere" and others will leave it blank.