Right eye and left eye
OD or RE means your right eye. OS or LE means your left eye. OU means both eyes. Match the eye labels on your prescription to the form; do not rely on the order in which the numbers appear.
SPH — sphere
SPH is the main lens power, measured in dioptres. Keep the plus or minus sign exactly as written. Plano or PL means zero sphere power; it does not necessarily mean the entire prescription has no correction.
CYL and AXIS — astigmatism correction
CYL is the amount of astigmatism correction and can be positive or negative. AXIS describes its direction in degrees. Enter both exactly as prescribed when cylinder correction is present. If no cylinder is prescribed, use the form’s no-astigmatism option.
Do not change signs or convert the prescription yourself. If a value is unclear or cannot be entered, ask your eye care professional or contact us before continuing.
ADD — near addition
ADD is additional power for near vision. Use it when requested for your chosen lens purpose. A near prescription may already include the reading power, so do not add ADD to SPH yourself.
Prism and special instructions
Prism and base describe an additional correction. If your prescription includes prism, different ADD values or special fitting instructions that the form cannot represent, contact us before placing an order. Do not omit those details to make the form accept the order.
What is PD?
Pupillary distance (PD) is the distance between the centres of your pupils, measured in millimetres. It is used to position the optical centres of your lenses.
Single PD and dual PD
Single PD is one total measurement. Dual, or monocular, PD records a separate measurement for each eye.
Enter dual measurements according to their right-eye and left-eye labels. For example, a prescription explicitly labelled Right 31 mm and Left 32 mm should be entered in those respective fields. Do not guess the eye order from a slash-separated pair of numbers.
Do not divide a total PD into equal halves to invent monocular measurements. The two sides can differ. If the form requires separate values and you only have a total, ask your eye care professional for the required measurements.
Distance PD and near PD
Distance and near PD are measurements for different viewing distances. Two numbers may indicate right and left measurements, or distance and near measurements. Their size alone does not establish their meaning.
Use the labels on your prescription and the PD type requested for your lens purpose. If the labels are absent or unclear, confirm them with your eye care professional before ordering.
If your PD is missing
Ask your optometrist or optician for the PD measurements needed for your chosen lenses, especially for progressive lenses. Do not use an average or a guessed value.
If you have measured PD yourself and are unsure of the result, have it checked professionally before confirming your prescription.
Before you confirm
This guide explains ordering fields; it does not replace an eye examination or individual clinical advice.
- Use a current glasses prescription from your eye care professional. Glasses and contact lens prescriptions are not interchangeable.
- Check right and left, signs, decimals, cylinder, axis, ADD and PD against the original.
- If anything is missing or ambiguous, ask the prescriber to clarify it.