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How to read your RX prescription for light plastic lenses

Buy Hi Quality, thin, light plastic Rx Lenses
prescriptions explained,and lens info for spectacle purchases
bifocal and progressive lens precriptions explained
 Prescription Information
eyeglass prescription information
Your written prescription from your optician (often called Rx) is a record of the visual correction that your eyesight requires. You must have an eyeglass prescription to fill out your order. The Optometrist who filled your prescription must give this to you by law.

Tip: The law states that if spectacles or contact lenses need to be worn, an optician is obliged to give you a signed, written prescription immediately following a sight test-providing you have paid for it! If no appliance is required, a signed, written statement to this effect must be provided.

Remember you are FREE to choose who you buy your spectacles from.

Tip: The prescription should not be older than 2 years - Always contact us if in doubt!

Filling out the prescription boxes is straightforward. OD means right eye, OS means left eye, OU means both eyes; these are just the abbreviations for the Latin oculus Dexter (right) and oculus sinister (left). The Spherical correction is for near or far sightedness, while the cylindrical and axis is for astigmatism. The Add part is for reading/near correction which is necessary for bifocal and progressive lenses.

The Prescription is a series of numbers with a plus (+) or minus (-) sign.
Minus (-) means you are short sighted (Myopia) i.e. you can see close up, but objects viewed in the distance appear blurred. And plus (+) means you are long sighted (Hyperopic) i.e. objects viewed close up may be out of focus.

Here are a few examples of what prescription record cards can look like:


Sample 1

In this example the person is short sighted (indicated by the minus sign) with a spherical (SPH) power of -5.50, a cylindrical (CYL) power of -1.25 and an (AXIS) of 180 degree; while on the on the right eye below its -6.50; -1.25 and 145 respectively. Note the Add of +1.00 on both left and right eye (above & below) - this is added for the reading value used in Bifocals and progressives

Dist -5.50 -1.25 180 Add +1.00


Dist -6.50 -1.25 145 Add +1.00


Left & right

The same values but written for both Right and Left eye.
OD -6.50 -1.25 145   1.00
OS -5.50 -1.25 180   1.00
Sample 3
Different values written for both Right and Left eye but also with near values
Distance OD 0.75 -0.5 010  
  OS 1.50      
Near OD 0.75 -0.5 010  
  OS 1.00      
Tip: It is common to have no values for any one of these, in which case you might see nothing in the boxes or see the letters “PL” or “Plano” which means zero.

Note: particularly your astigmatism cylinder correction. Some doctors write their prescriptions in plus (+) cylinder and some in minus (-) cylinder. They are not the same. Take special note of this when entering your prescription online. If you don't see anything there, leave it blank. see the example below

Always contact us if in doubt!

Here are some examples of presriptions and what they mean:

Example 1

(R) Right eye: SPH is +0.75, no CYL, No Axis, (left blank)  ADD is 2.25

(L) Left eye:   SPH is +0.75, no CYL, No Axis, (left blank)  ADD is 2.25

Near PD is 61

Far   PD is 63

Note: Your eyes come together (squint) when a object is close so your near PD is smaller.

This prescription can be used for for single vision (distance, reading), and also can be used for Multi focal lenses( bi focal and progressives)

Example 2

Right eye: Plano (no correction) CYL - 3.00 Axis 180  (addition is blank)

Left eye:  -0.25  CYL - 2.50 Axis 10 (addition is blank)

Note: there is no add, so this is a single vision prescription only

Always contact us if in doubt!

Distance Vision (dist.) is usually abbreviated D.V.

Reading Vision (near) is usually abbreviated N.V. or NVO

Reading-only eyeglasses: Some prescriptions are written separately for just reading (as "NEAR", "N.V." or "N.V.O.").

Bifocals and progressives:

If you have a prescription for multi-focal glasses but want to order a single vision distance, just leave off the “add” part, which is for the near or reading correction.


papillary distance PD information

This measurement is necessary to ensure the correct positioning of your lenses within the frame you have chosen so make sure to fill in the value for your PD or papillary distance, it should be on your prescription but if not, as a lot of optometrists are lazy about this, this is the distance in millimetres between the centres of your two pupils.

Adult's PD never changes. Women’s average PD is 60mm and men’s is 64mm and Most kids' PD's are between 42-54

Sometimes your optician may write the PD as “65/62”. This means that your PD for distance vision (or DPD) is 65, and for near vision (or NPD, for reading eyeglasses or multifocal lenses) it is 62. Your near vision PD is almost always 3mm less than your distance vision PD. ( your pupils move in when focusing on a near object)


To measure you’re PD, simply:

Place a millimetre ruler on your nose bridge.
Ask a friend to face you about arms length away.
Ask your friend to measure the distance between the centres of your pupils.

If you don’t have any friends, you can measure this yourself in the mirror using a ruler but you may find it difficult, especially if you need to wear glasses to read the measurements.

If you have prisms in your prescriptions you must provide a accurate PD

It is as simple as that.

Unusual or extra strong prescriptions that are beyond spherical +4 or -12, and/or greater than cylindrical +/-2 will take an extra few days delivery and of course have extra cost.

Please take extra care to make sure your prescription data entries are correct and DOUBLE CHECK all entries before "Adding to Cart".

We cannot exchange your glasses if you give us the incorrect information because each pair is custom made.

Always contact us if in doubt!
help topics for lenses and prescription reading

If you don't see numbers in some of the boxes (if there is no CYL or AXIS or ADD), leave those values blank when ordering. If you only see one number for each eye, it's normally the "SPHERE" power; so leave all the other fields blank. It is also common for the doctor to sometimes leave out the decimal points. – (Their abbreviations) so a number like -50 or +175, is understood to mean -0.50 or +1.75, respectively. Also, an axis of 5 (or 05) is the same as 005; 90 is the same as 090. See further examples in this help topic.

Your doctor may have used a blank Rx pad , not a pre-printed Rx pad for your eyeglasses prescription. If this is the case, draw imaginary grid-lines to separate the numbers. This will separate the different values more easily for you. The top power is always the right eye & the bottom power is always the left.

If you have no astigmatism in one or both eyes, your doctor may just write the sphere power alone, or may use placeholders like SPH ("sphere") or D.S. ("dioptres sphere") instead.

If your prescription for bifocals has only one ADD power, it's understood that you have the same ADD for both eyes. If you don't see an ADD power, leave it blank.

Always contact us if in doubt!

Some common prescription abbreviations:

SPH SPHERE power; the "overall" power of the lens
DS dioptres sphere (means you have sphere power only)
CYL CYLINDER power; the amount of astigmatism
X axis; X 80 means AXIS 080
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/plo PLANO; that means the number zero
O.D. right eye
O.S. left eye
O.U. both eyes
NV/NVO near-vision or near-vision-only; your doctor is recommending "reading-only" glasses
P.D./PD pupillary distance (the distance in between your right pupil and your left pupil), in millimetres (mm)

Examples of how numbers are often written

-50     =  -0.50
+100  = +1.00
-75     =  -0.75
+125  = +1.25


Always contact us if in doubt!

This is where the curvature of the front surface of the eye is not perfectly round. Your vision will be blurred at most distance if the astigmatism is significant.

A correction for astigmatism will be recorded in the 'Cylinder' and 'Axis' part of the prescription. Axis is simply an angle, at which the cylindrical power of your lens sits. This angle is measured in degrees (1 degree to 180 degrees)


This is where the lens inside your eyes loses its flexibility so that focusing on objects close up becomes difficult. As part of natural ageing process of the eye, this usually affects people in their mid 40s. A correction for Presbyopia will be recorded in the 'Near' and 'intermediate' part of the prescription.


Fitting Height (FH) This term is used in Multi focal lenses and is the distance from the lowest edge of the frame to the centre of your pupil.  You will need to know the Fitting Height for the frame you choose or you will need a fitting, from an optician who can determine the “Fitting height” for the type of frame. This prescription measurement is a must if you want a perfect fit for your prescription progressive glasses.

Seg Height (Seg Ht) – This term is used in multi-focal or progressive lenses and is the distance from the lowest portion of the frame to the top horizontal line of the Segment. In Bifocals it would be the top line (flat top) of the near lens


Add Powers - In multi focal lenses, it is the part of the lens that corrects for near vision. Distance prescription and Reading prescription are sometimes 2 separate prescriptions, but the optometrist’s sometimes combine these two (distance and reading) into one prescription by ‘Adding’ the reading part to the distance part. This simply means that additional power is added to the distance power (SPH) of the prescription. If there is only one ADD power on your prescription for bifocals, this means that the same ADD power is used for both eyes. If there is no ADD power given, leave this section blank when ordering. The value is always the same for both your right eye and left eye.


 Multi focal Lens – Is a lens with more than one optical centre e.g., a bifocal has 2 optical centres; a trifocal has three, a progressive lens has many.

Transition Zone - The area of progressive lenses where the distance vision curve gradually changes to the intermediate zone then into the near-vision zone of the lens – its gradual unlike Bifocals which ‘jump’

SPH = SPHERE - The amount of long or short sightedness. It always has a plus (+) or a minus (-) sign in front or above it. There will always be a value for SPH, even if it is just zero (written as 0.00, Plano, Pl…) If the vision in one eye is very poor, the word 'balance' or 'bal' may be written.

CYL = CYLINDER (Astigmatism). This is the measure for astigmatism. Again, there is always a plus (+) or minus (-) sign present in front or above it. There may not be a value of cylinder in your prescription if you DO NOT have astigmatism.

A prescription with a Cylinder value higher than +2 cylinders or -2 cylinders is more expensive due to the complexity of the lens.

AXIS - This will only appear if there is a value for cylinder, as it relates to the cylindrical lens and denotes a reference point that indicates the direction of the power of the cylindrical lens. It will be a number between 1 and 180. It may or may not be written with a degree 'o' symbol after the number. In some prescriptions, the axis value is indicated on a semi- circular scale. This should be read to the nearest 5 degrees.

PRISM is a box on the Rx prescription form that is not normally filled in. Occasionally, when the two eyes are not properly aligned and looking directly at the same thing, PRISM can be ground into the lenses in order to re-align them. This can occur with strabismus (ie - an eye turn) or in situations where the eyes are properly aligned but are under a tremendous amount of strain in order to keep them aligned. The value under the 'prism' heading denotes the strength of the prism.

BASE - rotation of the prism that is simply specified as 'base in' or 'base out' (where 'in' means towards the nose) or 'base up' or 'base down'. Only these four positions exist, however, orientations between these four positions can be specified by using combinations of horizontal and vertical prisms in the same lens.

Always contact us if in doubt!

what is a eye doctor?
Eye Doctors what are they called and what do they do?
Ophthalmologists :

Ophthalmologists are licensed physicians and surgeons and have an extensive level of education - typically twelve to fifteen years of undergraduate work, medical school and advanced training. They can perform ophthalmologic examinations, prescribe vision correction (glasses or contacts) and medications, and diagnose and treat diseases and disorders of the eye. In addition, ophthalmologists can diagnose general diseases of the body and treat ocular manifestations of systemic diseases.

Optometrists :
Optometrists are licensed healthcare providers who have completed four years of undergraduate work and four years of optometry school. They can perform eye exams, prescribe and dispense eyeglasses and contact lenses, and diagnose vision disorders and eye disease. Optometrists can prescribe medications to treat certain eye diseases.
Opticians :

Opticians are technicians who have graduated from a two-year program at a community or technical college. They are qualified to make, fit, and dispense eyeglasses and contact lenses, either in an optical laboratory or for retail sale to the public. Opticians do not perform patient examinations or write prescriptions for eye correction or medication.


If you still do not understand ANY part of your prescription, please email us to ensure everything is entered correctly. Don't be shy; we are here to help, and we want your glasses to be made exactly to your doctor's specifications.

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