With the increasing number of online stores dealing in prescription glasses and varifocal glasses, they have become the preferred destination for many buyers. Not only do they offer a wide range but the rates are way below than their high-street counterparts. But buying online entails a necessary pre-requisite. One has to provide the prescription plus the pupillary distance measurement online, to get a comfortable pair of glasses. This pupillary distance can be measured by a trained optician, or you can follow the simple steps and work it out yourself. This pupillary distance is really important for getting a pair of glasses which has lenses with correct corrective vision.
If you want to purchase a regular pair of prescription glasses then all you have to do is to use a ruler and stand in front of a mirror. Generally, the measurement has to be taken twice. The first time the measurement is taken with you focusing at a distance. The second measurement is related to your near vision. This second measurement is particularly necessary if you are buying a reading glass. A popular rule of thumb prevails which says, if your “far PD” is more than 60 mm, then your “near PD” will be 4 millimetres less than the “far PD”. And when “far PD” is less than 60 millimetres, then “near PD” will be 3 mm less than it.
In case of measuring the pupillary distance for kids, who are less likely to stay still, it is always better to take the measurements through professional optician. Usually they measure from the distance from the medical canthus to the lateral canthus.
The measurement of pupillary distance becomes even more important when you want to buy varifocal glasses. This measurement is really important to an optician who needs to fit your lenses, because of the fact that the optical centre of the lenses should be directly in front of the pupils. The level of correct vision is decided by the optical centre. In case a presbyopic patient is planning to buy a pair of varifocal glasses, then it is always a wise practice to measure the pupillary distance in advance. Most of these online shops have a detailed system which helps you to measure the correct pupillary distance. This is a critical task and must be done with utmost care.
The pupillary distance plays a major part in deciding how correct will be your vision and how comfortable will be your eyewear experience and so proper care must be taken while measuring it.