Prescription Lens Guide
The lens index refers to the refractive index of lens material for eyewear. It is a relative measurement number that describes how efficiently the material bends light. Light refraction will depend on how quick light itself passes through the lens.
But we are not going to any Physics here. This is a simple but quick guideline to make your decision a little bit easier. Although the lens thickness can be greatly influenced by factors such as frame size, lens diameter etc. other than the prescription, this table may help you understand a bit about the prescription strength and lens thickness relationship and to choose the perfect one for you.
|Prescription Range||Recommended Index|
|Upto +/-2.00 SPH or upto +/-2.00 CYL||1.5 index|
|Upto +/-2.50 SPH or upto +/-2.00 CYL||1.56 index|
|For Kids, Safety Glasses, Sports Eyewear, Rimless frames||1.59 Polycarbonate|
|Rx between +/-2.50- +/-4.00 SPH or CYL up to -3.00||1.61 index|
|Rx between +/-4.00- +/-7.00 SPH or CYL up to -4.00||1.67 index|
|Rx above +/-7.00 SPH or CYL between +/-4.00- +/-6.00||1.74 index|