OPTICAL LENSES INDEX , THICKNESS
and suitable focal corrections
Standard 1.499 Index CR-39
SPH +/- 2.25 and below CYL +/- 1.50 and below
these traditional plastic lenses made fromhard resin are great for almost any prescription
and much lighter and less breakable than glass lenses.
Medium thickness RX 1.56 index
SPH +/- 2.50 to + 4.00 CYL +/- 1.50 to +/- 2.00
Up to 20% thinner than Standard Plastic CR-39 lenses which provide the ultimate in thin size,
optically superior lense
Thinner Polycarbonate RX1.59 index
Up to 20% thinner and stronger than plastic. Impact resistant, safety lens material.
Polycarbonate was the first plastic high index lens originally used primarily for industrial
safety glasses, now used for children and sports wearers.
Super thin Hi-Index RX 1.61 Index
SPH +/- 4.25 to +/- 6.75 CYL +/- 2.25 to +/- 3.00
Up to 30% thinner than Standard Plastic CR-39 lenses.
Ultra thin Hi-Index RX 1.67 index
SPH +/- 7.00 to +/- 9.00 CYL +/- 3.25 to +/- 4.00
Up to 42% thinner than Standard Plastic CR-39 lenses
Free Form (highest up-to-date progressive lens technology)
These ultimate technology lens are also know as "Individually Customized lenses." Whereas traditional lens are tailored for a broad categories of wearers, Free Form advanced technology enables customizing the lens design for individual prescriptions using computer ray tracing and lens-eye modeling state-of-the-art computer generated algorithms.
They are not only made at the wearer's specific prescripion but also to his frame measurements. Free-Form technology has the capacity to produce lenses with accuracy down to .05 diopters, a considerable improvement over current technology which is accurate to +/- 0.12 diopters. They are also known as “Distorsion Reducers” or “Rear Surface” lenses being hem programmed on their back surface, nearer to the eye.