Medical uses<unk> es may be used to improve vision and reduce pain and light sensitivity for people suffering from a growing number of disorders or injuries to the eye, such as severe dry eye syndrome, microphthalmia, keratoconus, corneal ectasia, Stevens–Johnson syndrome, Sjögren's syndrome, aniridia, neurotrophic keratitis (anesthetic corneas), complications post-LASIK, higher-order aberrations of the eye, complications post-corneal transplant and pellucid degeneration. Injuries to the eye such as surgical complications, distorted corneal implants, as well as chemical and burn injuries also may be treated by the use of<unk> es.<unk> s may also be used in people with eyes that are too sensitive for other smaller corneal-type<unk> es, but require a more rigid<unk>  for vision correction conditions such as astigmatism. Special effects<unk> es are not to be confused with "sclera"<unk> es, which are soft<unk> es and do not contain a fluid reservoir. "Sclera" contacts are used in movies such as the whited-out eyes of the monsters in Evil Dead, or blacked-out eyes in Underworld and Underworld: Evolution, or the Star Trek episode Where No Man Has Gone Before. These<unk> es can become uncomfortable when worn for long periods of time and can sometimes impede the actors' vision, but the visual effects produced can be striking. These<unk> es can be custom-painted, although most companies only sell<unk> es with a pre-designed look which are extremely popular for halloween and cosplay fancy dress costumes. Eye movement measurement In experiments in ophthalmology or cognitive science,<unk> es with embedded mirrors or with embedded magnetic field sensors in form of wire coils (called<unk>  coils) are commonly used for measuring eye movements.
Scleral lens
Corneal button
Optic cup 
Intraocular lens
Optic pit
Corneal limbus
Optic vesicle
Lacrimal sac