Plano lenses are simply an optical lens which provide no corrective spherical power.
You’ll know if you require plano lenses if you see the term “plano”, “PL” or “0.00” in your Sphere box (SPH) on your prescription paper. Instead of leaving this initial box blank, it’s common practice for your optometrist to confirm that you require no dioptric correction in that eye.
Here are three examples;
SPH: PL | CYL: 0.00 | AXIS: 000
SPH: ∞ | CYL: -1.25 | AXIS: 105
SPH: 0.00 | CYL: +0.75 | AXIS: 025
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What does plano mean?
Plano derives from the Latin word “planus” for flat or level. In the context of optical lenses, a planoconvex lens refers to a lens which is flat and provides neither positive or negative dioptric power.
What are demo lenses?
For demonstrative purposes, spectacle frames are fitted with demo lenses.
Demo lenses simulate corrective lenses, simply to give you an idea of what the frame will look like in a more realistic aesthetic. They also help to keep the frame in the correct shape before prescription lenses are fitted.
Despite providing no corrective power, demo lenses are not the same as plano lenses. For display purposes only, demo lenses are cheaply made from thin acrylic and don’t provide any UV or blue light protection for your eyes.
If you prescription requires you to use a plano lens, your glasses will always be fitted with matching quality of lens such as CR39 or polycarbonate. This means your lenses will look and perform the same if you choose to have any additional coatings such as anti-glare, anti-scratch and/or blue light blocking.
Demo lenses are only used for retail purposes to simulate real lenses.
Reasons to use plano lenses
More often than not, one of your eyes will be weaker than the other.
Ocular asymmetry is extremely common therefore you may only require correction in just one eye. This is most common for very mild or single vision prescriptions. However, there are other reasons why plano lenses can be used.
- No SPH power required
- Blindness in left or right eye
- Computer, blue light blocking glasses
- Stage/acting purposes
- Fashion purposes
The difference between plano and demo lenses
Plano lenses are usually made of a polymer resin called CR39. They are comparably thicker than demo lenses and will usually have additional lens coatings such as anti-glare and anti-scratch. These coatings yield purple and/or green hues when light is reflected from the lens.
Demo lenses are usually made of thin acrylic which is comparably more flexible to the touch. They don’t have any additional lens coatings which produce a plain white reflection. Furthermore, demo lenses are commonly labelled or pad printed with brand name or company information.
Left: Plano lenses with purple and green reflections | Right: demo lenses
Can you wear demo lenses?
Other than retail showroom scenarios, demo lenses aren’t suitable for daily use. They are flimsy, unreliable and provide no ultraviolet or blue light protection for your eyes.
Plano lenses however, are suitable for wearing as they'll be fitted in correspondence with your prescription by a qualified optometrist.
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