Which Lens And Why?

Lenses are categorised by many variables. The most important of these variables is the “Refractive Index”. The other variables such as the V-Value are for scientific/laboratory reasons.

The higher the refractive index number is, the thinner the lens will be. Refractive means bending of light and index is the standardised numerical value to explain the extent of this bending of light. Therefore, if you have a high refractive index number, this would mean the light is bended more than lower refractive index. Thereby less of the lens mass is needed for that high prescription which would normally require more of a lens mass to bend the light rays to correct the eyesight.

Lens Types:

Plastic 1.53 (standard lens): The industry standard plastic lens is a 1.53 refractive index. This lens is ideal for most types of prescriptions. Anything from + or – 0 to 3.00 would look fine, i.e.: lens would not look thick. But, anything above 3.00 would then mean your lenses would look thick with this standard plastic lens.

Plastic 1.6: This lens is thinner than the standard lens above. Up to 25% thinner and lighter than standard lenses. Suitable for up to +6.00 and - 5.00. Anything out of this range would still make the lenses look thick, even with this 1.6 refractive index lens.

Plastic 1.67: Up to 35% thinner than standard plastic lenses. Ideal for lenses up to +7.00 and –7.00. Prescriptions above this range will still look thick.

Plastic 1.74: The thinnest plastic lens available on the market today. Up to 45% thinner than standard plastic lenses. Suitable for mid to high prescriptions.

Glass 1.7: Very thin lens. Suitable for high minus powers. High lens density and therefore, to keep the weight down this lens is best suited to not a large frame.

Glass 1.8: Extremely thin lens. Suitable for very high minus powers. High lens density and therefore, to keep the weight down this lens is best suited to not a large frame.

Glass 1.9: Thinnest lens in the world. Only used in extremely high minus powers. High lens density and therefore, to keep the weight down this lens is best suited to not a large frame.