Precision Matters

Prescription and various terms

A prescription can be written in various ways, but the basic components remains universally the same. The various prescription components are:

  • Sphere
  • Cylinder always written with axis direction
  • Add - if you need a separate magnification to see things close, for example to read, then you may find an 'ADD' prescribed. The focal distance is within 45cms from the front surface of your eye.
  • Near Add - same as 'ADD'
  • Inter add - reduction in near 'ADD' to accommodate an intermediate distance, usually within 55-75cms.
  • Prism - for muscle imbalances a prism might be prescribed.
  • RE - right eye
  • OD - ocular dexter
  • LE - left eye
  • OS - ocular sinister
  • PD - pupillary distance or distance between your pupils.

At specsonweb, all you need to do, is to upload the photo of your prescription and select the appropriate lens package. We will match the prescription to your request and requirements.

Pupil distance measurement (PD)

This is simply the 'distance between your pupils'. Your prescription may or may not have this measurements.

Prescription & pupillary distance

Two methods of taking your PD measurement

Method 1: Using the ruler

  • It is a good idea if this measurement is taken by someone else on you
  • You will need a mm or cm ruler for this measurement
  • Make sure you and the person taking the measurement are at the same eye level and at arms length distance facing each other
  • While taking the measurement, your eyes need to be focused directly at the eyes of the person taking the measurement for you.
  • Measure the reading
  • Please take 3 readings and take and note down the most common reading
  • Enter the readings only in mm
  • The average reading for an adult women is 62mm and adult male is 64mm

Method 2: Dotting the glasses

  • You wear your glasses.
  • Ask the person who is taking the measurements to stand in front of you at arms-length distance.
  • Please make sure you have a marker pen
  • Simple dot both sides of the lens directly in front of your pupil centers.
  • Take the glasses and measure the distance between the dots.
  • Erase the dot and take an average of 3 readings

Tip: It would be good if you can take this measurement, using both method 1 and 2. It only takes 3 minutes to complete this.