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:
“The mystery of the evening-star brilliant in silence and distance between the downward-surging plunge of the sun and the vast, hollow seething of inpouring night. The magnificence of the watchful morning-star, that watches between the night and the day, the gleaming clue to the two opposites.”
—D.H. (David Herbert)
“Those who wander in the world avowedly and purposely in pursuit of happiness, who view every scene of present joy with an eye to what may succeed, certainly are more liable to disappointment, misfortune and unhappiness, than those who give up their fate to chance and take the goods and evils of fortune as they come, without making happiness their study, or misery their foresight.”
—Frances Burney (1752–1840)