Lens choices for EyeglassesWhen it involves selecting lens lenses, it's now not an easy selection of "glass or plastic?" Let's examine your several choices in lens lenses in detail:
Want dilutant, Lighter Lenses? opt for a High Index Lens MaterialNearly everybody will enjoy dilutant, lighter lenses. High index lenses will be up to five hundredth dilutant than regular glass or plastic lenses, and they are typically a lot of lighter, too.
Though these lenses area unit is particularly helpful if you have got a powerful eyeglasses prescription, they will build a clear distinction within the look of just about any combination of glasses. High index lenses bend light-weight additional with efficiency than regular glass or plastic lenses, thus less lens material is needed to correct your vision.
Various high index lenses area unit accessible nowadays in numerous worth points supported what proportion dilutant they're compared with regular plastic lenses. The lenses area unit classified by their "index of refraction" (or "refractive index").
Generally, lenses with a better index of refraction are going to be dilutant (and typically additional expensive) than lenses with a lower index. The index of refraction of normal plastic lenses is one.50. The ratio of high index plastic lenses ranges from one.53 to 1.74. Those within the vary of one.53 to 1.59 area unit concerning two hundredth dilutant than regular plastic lenses, whereas 1.74 high index lenses area unit concerning the thickness of normal plastic lenses.
Most popular lens styles (single vision, bifocal, progressive, photochromic, etc.) are available in high index materials, and your doctor or lens maker can recognize which of them area unit accessible in your prescription. central and trifocal high index lenses also are accessible, although the choice is additionally restricted.
Note: High index lenses mirror additional light-weight than regular glass or plastic lenses, thus anti-reflective (AR) coating is extremely counseled for these lenses (see below).