Glasses what is cyl

Notable terms include:. This indicates the amount of lens power, measured in diopters D , prescribed to correct nearsightedness or farsightedness. Cylinder CYL — This indicates the amount of lens power for astigmatism and represents the difference in the greatest and weakest powers of the eye, usually separated by 90 degrees.

If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not necessary to correct it with your eyeglass lenses. If you do not see a number listed, good news, that means you do not have astigmatism. AXIS defines the direction of your astigmatism.

This number ranges from 1 to ADD is additional lens power in the bottom portion of a multi-focal lens to assist with focusing on objects up close.

If you require an add power, you have a condition called presbyopia. Prism indicates the amount of prismatic power to counteract for any eye alignment problems. Meanwhile, the Base shows the direction of a prism by marking the relative position of its densest edge. Now that you decoded your RX, what type of vision do you have?

Single vision means your lens power will correct for either nearsighted or farsighted, but not both. If the Optometrist states that you require bifocal or multifocal lenses, your lens power will need to correct for both far away and up close, and occasionally intermediate range vision. 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. A cylinder power with an axis at the meridian.

This means that the horizontal degree meridian of the eye has no added power for astigmatism and the vertical degree meridian gets the added Prismatic correction of 0. In the right eye, the prism is base down BD ; in the left eye, it's base up BU. Your eye doctor may also write specific lens recommendations on your eyeglass prescription.