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A contact lens (also known simply as a contact) is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye. Modern soft contact lenses were invented by the Czech chemist Otto Wichterle and his assistant Drahoslav Lím , who also invented the first gel used for their production.
The spaces of the eye are filled with the aqueous humour anteriorly, between the cornea and lens, and the vitreous body, a jelly-like substance, behind the lens, filling the entire posterior cavity. The aqueous humour is a clear watery fluid that is contained in two areas: the anterior chamber between the cornea and the iris, and the posterior ...
An intraocular lens (IOL) is a lens implanted in the eye usually as part of a treatment for cataracts or for correcting other vision problems such as near-sightedness (myopia) and far-sightedness (hyperopia); a form of refractive surgery.
The refracting superposition eye has a gap between the lens and the rhabdom, and no side wall. Each lens takes light at an angle to its axis and reflects it to the same angle on the other side. The result is an image at half the radius of the eye, which is where the tips of the rhabdoms are.
People who have a multifocal intraocular lens after their cataract is removed may be less likely to need additional glasses compared with people who have standard monofocal lenses. [2] People receiving multifocal lenses may experience more visual problems, such as glare or haloes (rings around lights), than with monofocal lenses.
The lens is located towards the front part of the vertebrate eye, called the anterior segment, which includes the cornea and iris positioned in front of the lens. The lens is held in place by the suspensory ligaments (Zonule of Zinn), [1] attaching the lens at its equator to the rest of the eye [2] [3] through the ciliary body.
Monocular cues provide depth information when viewing a scene with one eye. Accommodation – This is an oculomotor cue for depth perception. When we try to focus on distant objects, the ciliary muscles relax allowing the eye lens to flatten, making it thinner.
The lens is implanted in the eye's lens capsule, where the contractions of the ciliary body, which would focus the eye with the natural lens, are used to focus the implant, instead. [2] [38] IOLs used in correcting astigmatism have different curvature on two orthogonal axes, as on the surface of a torus: for this reason, they are called toric ...