Factors that affect

The thickness of an eyeglass lenses is an increasingly important factor that is considered by eyeglass wearers. How thick the edge of a lens will directly affect the appearance of the eyes. In the past, only lenses with quite thick edges were available for individuals having a high prescription. Nowadays, lens advances have enabled corrective eyeglass wearers to go with thinner lenses. In most cases, thinner lenses cost more money.

Although there are available extra thin and ultrathin lenses, the edge thickness of them actually depends on several factors. The first one is the lens prescription. In general, a high prescription requires a thicker lens. But there is still a slight difference between negative spherical power lenses and positive power lenses. While a lens with high positive power is thicker in the center than at the edge, a high negative prescription makes a lens thicker on the edge than in the center.

A second factor is the lens material. A basic point is that denser materials can strengthen the light-bending ability of a lens. A good example is that higher index lenses are thinner than lower index lenses when they have the same capability of bending light. While the standard index is 1.5, glasses lenses can be made of an index up to 1.9.

The edge thickness of a lens can also be affected by the eyesize of the frame which represents the horizontal distance between a lens in a frame, the bridge size of the frame, as well as the wearer’s pupillary distance (PD). When it comes to negative spherical prescriptions, thicker edges occur in larger eyesizes.  The sum of the bridge and eyesize and the PD should be equal, only in this case the lens thickness at the nasal side is the same as that at the temple side.

Purchasing a new pair of eyeglasses, customers will reasonably choose thin lenses. It is necessary to consult a professional about right ways to assess those factors associated with lens thickness.

you will get some help about eye care clinics and eye doctors in following optical eyeglasses stores of  Lewes :  Atlantic Eye   Grifasi Holloway Eye Care