Glasses Prescription Explained & Meaning

GLASSES PRESCRIPTION EXPLANATION

SPH (sphere): the amount of long (+) or short (-) sight. The higher the number, the stronger the prescription lens required.

CYL (cylinder): the amount of astigmatism, or visual distortion, caused by an irregularly shaped cornea.

AXIS: the direction of the astigmatism, measured in degrees.

PRISM: correction needed to balance the eyes.

ADD: the amount of additional correction needed to focus at close distances. If you have a measurement shown in this section, it means that you have different prescription requirements for distance and reading. This can be solved by having different spectacles, or bifocal or varifocal lenses.

INT (intermediate): the amount of correction needed to cope with intermediate distances, such as working at a PC or reading music. In many cases, rather than having separate spectacles for this, customers are prescribed varifocal lenses.

GLASSES PRESCRIPTION ABBREVIATIONS

• -50 = -0.50
• +100 = +1.00
• SPH or sph = SPHERE power; the “overall” power
• D.S. or DS = diopters sphere (means you have sphere power only)
• CYL or cyl = CYLINDER power; the amount of astigmatism
• X = axis; X 90 means AXIS 090
• ADD = how much power gets added to the distance Rx, for your reading-only Rx or for the bottom half of your bifocals/progressives
• Pl or 00 or PLO = PLANO; it’s a placeholder for the number zero
• O.D. or OD = right eye
• O.S. or OS = left eye
• O.U. or OU = both eyes
• NV or NVO = near-vision or near-vision-only; your doctor is recommending “reading-only” glasses
• P.D. or PD = pupillary distance (the distance in between your right pupil and your left pupil), in millimetres

If any of the details require explanation or appear ambiguous please contact us for confirmation before proceeding. Errors made inputting your prescription cannot be corrected after manufacturing your specs.

MY PRESCRIPTION DOESN’T HAVE ANYTHING WRITTEN FOR CYL OR AXIS OR ADD. WHAT SHOULD I ENTER?

You can leave those fields blank. Cylinder and Axis are for astigmatism correction. If your doctor didn’t write it in, you don’t have to either.

The ADD power is for people (typically over 40) who now have different prescriptions for distance and near vision. Younger people don’t have trouble up close with their distance prescription on, so their ADD is technically zero; in actuality, it’s just not written at all. If you don’t have an ADD on your Rx, or if you want distance-only glasses, leave those fields blank.

WHAT IS PUPILLARY DISTANCE (PD)?

PD is the distance from the centre of the pupil (black spot) in one eye to the centre of the pupil in the other eye. This measurement is necessary to ensure the correct positioning of your lenses within the frame you have chosen.

Your optician can be requested to provide you with this as part of your prescription; alternatively, you can measure this by your friend. It’s simple, just like measuring a line connecting the two black dots!

To measure your PD:

• Place the millimetre ruler on the bridge of your nose.
• Have a friend face you about arm’s length away.
• Have your friend measure the distance between the centre of your pupils (the black dots in the middle of your eyes).

WHAT IF MY PD WAS MEASURED BUT THERE’S MORE THAN ONE NUMBER?

If you have two different numbers, you have either been given both the Distance/Reading or Right Eye/Left Eye:

If the numbers are higher (and different), like 62/59, then the first number is your Distance PD and the second is your Near PD (for reading-only glasses).

If the two numbers are lower (and different), like 30.5/31.5, then you had someone take your PD one eye at a time (called “monocular PD”).

The first number is for the right eye (O.D.) and the second number is for the left eye (O.S.). If you have a monocular PD available, put it in the “Customer notes” section of the order form and we”ll use it.

If the two numbers are the same, like 30.5/30.5, you can just add them together (61 in this example) and we’ll automatically divide it equally.

WHAT TYPE OF LENSES DO I REQUIRE?

Distance Glasses are for seeing things more clearly and comfortably when they are well beyond arm’s length typically for TV, Driving, Cinema, Sports watching etc., in some cases these may be described as general wear and can be used to do close work as well.

Near: Only for close work within arm’s length. These glasses will usually make more distant objects less clear. Typically this is for Reading or Fine Details on objects Less than 3 Feet (1 Metre) away.

Intermediate: This is mainly used for viewing at just beyond arm’s length. Typically use with a Computer Screen, which is beyond a normal Reading Distance. Some work or hobby situations benefit from specs with this type of prescription when you spend a lot of time viewing at this sort of distance.