Regular glass or plastic lenses for high amounts of nearsightedness or farsightedness can be quite thick and heavy. Fortunately, chemists have created a variety of new “high-index” plastic lens materials that bend light more efficiently.
This means less material can be used in high-index lenses to correct the same amount of refractive error, which makes high-index plastic lenses both thinner and lighter than conventional glass or plastic lenses.
But not too much light weight, because the general super-thin lenses formula with a certain amount of rare elements, so the proportion of the material is larger
The size of the general refractive index is proportional to the specific gravity of the material
when are high index lenses necessary?
Lenses with high refractive index are not recommended if the degree is not high So below 300 degrees with ordinary lenses is better.
Ernst Abbe was obviously a German mathematician and physicist who found that lenses created from different materials have varying numbers of chromatic aberration. This is what’s called the Abbe value: the greater the Abbe value, minimal volume of distortion while looking through the lens. Standard glass lenses have a great Abbe value, but high index lenses have a lower Abbe value. Cosmetically high index lenses could possibly be more appealing, nonetheless they do not correct vision and also standard lenses.
Conventional lenses reflect 8 percent of light, while high index lenses reflect nearly 50 % of light. This large number can result in eye fatigue to make night driving difficult. With an antireflective coating, it is possible to solve this problem. Take into account that anti-reflective coatings can deteriorate with everyday deterioration.