Hi Index Lenses

So you might be asking yourself, 'why should I choose to have hi-index lenses in my new frame?', well it's simple; Hi-index lenses are much more attractive and light-weight than any standard prescription lens. They are also much more comfortable than standard lenses, due the reduction in weight.

Most of the todays modern frames are made from plastic or metal that are thinner than the lenses, so they tend to expose a lot more of the lens thickness. This means that the edge of the lens is more visible and doesn't look cosmetically pleasing when you put a lens of high prescription into the frame. In fact, sometimes a standard lens can completely spoil the overall appearance of your glasses.

Hi-index (1.6) - A 1.60 refractive index lens is up to 20% thinner than standard plastic lenses. These prescription lenses are generally recommended for prescriptions above plus or minus 2.50. These lenses are currently the worlds most popular Hi index lenses on the optical market as they offer the wearer a good cosmetic result at an affordable price.   Hi-index (1.67) - A 1.67 refractive index lens is up to 30% thinner than standard plastic lenses. Thinner 1.67 Aspheric Lenses are one of the thinnest and lightest plastic lenses available in the Lens range making it suitable for most of the majority of today's popular frames. These lenses are generally recommended for prescriptions above plus or minus 3.00. Suitable for rimmed, half rimmed and rimless frames. Hi-index (1.74) - A 1.74 refractive index lens is up to 45% thinner than standard plastic lenses - these hi hindex lenses are currently the worlds thinnest plastic lens material. These lenses are generally recommended for prescriptions above plus or minus 5.00. Here at online glasses direct we are able to offer these very thin lenses to our customers at a fraction of what most high street retailers sell them for.

Hi index lenses can reflect up to 50% more light than a standard lens which only reflects around 10% but if you apply an anti reflection coating to the lens then it can transmit around 99.5% of reflections and thus allow more light to enter your eye.

The different types of hi index lenses available are classified by how well each lens is able to bend light, otherwise known as 'index of refraction' or 'refractive index'. This ratio compares the speed of light when it travels through air with the speed of light when it passes through the lens - if the lens is able to bend the light more then the speed it travels at will be slowed down so the higher the refractive index, the thinner the lens.