Lens Distance From Eye
The overall size of the lens is controlled by how far the lens is positioned away from the eyes. A closer distance allows for a smaller lens, but there is a limit on how close eyeglass lenses in a frame can be to the eye, imposed by the eyelashes and eyelid.
Contact lenses placed directly on the cornea are physically larger than the pupillary region, and have a ring of extra unused material around the outer perimeter that simply helps to center the lens on the cornea.
Eyeglass lenses need to be larger the further away they are from the eye. Very large lenses in a double-bridge frame do not necessarily provide greater peripheral vision, due to the nose rest holding the lenses slightly further away from the eyes than with smaller lens frames.
Read more about this topic: Corrective Lens
Famous quotes containing the words distance and/or eye:
“1946: I go to graduate school at Tulane in order to get distance from a possessive mother. I see a lot of a red-haired girl named Maude-Ellen. My mother asks one day: Does Maude-Ellen have warts? Every girl Ive known named Maude-Ellen has had warts. Right: Maude-Ellen had warts.”
—Bill Bouke (20th century)
“The hero is a feeling, a man seen
As if the eye was an emotion,
As if in seeing we saw our feeling
In the object seen and saved that mystic
Against the sight, the penetrating,
Pure eye.”
—Wallace Stevens (18791955)