Understanding your eye prescription

Understanding your eye prescription

When you have an eye exam, the optometrist tests your eyes in different ways. They record the measurements in your eye prescription.

If that eye prescription is incomprehensible to you – this article will help! With this information, you’ll understand what all those symbols and letters mean. And, it should help you make an informed decision about what kind of laser eye surgery you might need.

Sphere (SPH)

The Sphere column in your prescription (often abbreviated to SPH) refers to spherical correction. That’s the lens power you need to correct your vision across the curve of your eye. If you don’t have astigmatism, it should be the same all the way around.

Your ‘refractive error’ is measured in diopters, or D for short. Usually, the numbers range from -6.00D (which is very nearsighted) to +6.00D (which is very farsighted).

Cylinder (CYL)

Sometimes, people have irregularly shaped eyes. That’s called astigmatism. If you have astigmatism, your prescription will have a cylinder measurement. The abbreviation for a cylinder is CYL. The CYL will have a plus sign in front of it if you are farsighted. It will have a minus sign in front of it if you are nearsighted. You will need special lenses to correct your vision.

Axis

Axis also relates to astigmatism. For those with astigmatism, the axis column describes the angle or direction. If you are astigmatic, your eyes are shaped like a football rather than a soccer ball.

There’s a position on the front of your eye where the cylindrical lens should go to correct your vision. The axis measurement describes that placement in degrees, so the axis will be a number between 1 and 180.

ADD

If you wear reading glasses or bifocals, the ADD part of your prescription will tell how powerful they need to be. ‘ADD’ refers to any ‘added’ lens power you may need to focus on close objects, like a screen. The numbers for ADD range from +0.75 to +3.00D.

Abbreviations

But wait, there’s more. Above all that, there’s also the abbreviations optometrists use for your eyes:

• OD: short for Oculus Dextrus which is Latin for ‘right eye’
• OS: short for Oculus Sinistrus which is Latin for ‘left eye’
• OU: short for Oculus Uterque which is Latin for ‘both eyes’
• DV: short for Distance Vision
• NV: short for Near Vision and sometimes used instead of ADD

Contact lens prescriptions

Contact lens prescriptions differ slightly from glasses prescriptions. Because contact lenses sit on your eye as opposed to some distance away, they need to be shaped differently than glasses to correct your vision. Contact lens prescriptions require more details, like measurements of the curve and the diameter of your eye.

If your eye prescription is incomprehensible to you – this article will help! With this information, you’ll understand what all those symbols and letters mean. And, it should help you make an informed decision about what kind of laser eye surgery you might need.

So, do you have any related questions to the one we answered just now? Let’s see your question in the comments below and we promise to reply!