HIGH INDEX LENSES
EYE HEALTHCARE – DO YOU REQUIRE THINNER LENSES ?
The term ‘hi-index’ is a reference given to the ‘index of refraction’ (the capability to bend or refract light) of a particular lens material. A standard plastic lens, for example, has an index rating of approx 1.5, which is used for, the majority of spectacle lens (up to +/-2.50 dioptres). As the prescription increases, short sighted lenses get progressively thicker at the edges (centre remains thin), where long sighted prescriptions become thicker centrally (with thin edges), hence warranting a slimmer and lighter lens made of this ‘denser’ hi index material.
With an anti-reflective coat as standard on all hi-index lenses, your eyecare professional will guide you through the choices with complete ease.
Noel McCrystal
BSc.(Hons.)MCOptom.Dip.Sc.V MASv.P