Vision Lab Flashcards
Function of cornea
transmits and bends light
Function of lens
focuses light onto retina, adaptation of distance
Function of retina
contains light sensitive receptors
What is refraction?
light rays are bent as they pass from the air to an area of greater density
Path of light through the eyes
Visual field to cornea to aqueous humor to lens to vitrious humor then focused on the retina
Accomodation
the ability of the eye to focus the images of objects at different distances from the lens
Accommodation (distance)
- ciliary muscle is relaxed, suspensory ligaments pulls on the lens
- lens is more flat
Accommodation (near)
- ciliary muscle contracts, suspensory ligament is relaxed
- lens is more round (convex)
Hypertrophia
- eyeball is too short or lens cannot become round enough
- difficult seeing close objects
- glasses with convex lenses help correct
Myopia
- eyeball is too long or lens cannot be flat enough
- difficult seeing distant objects
- glasses with concave lenses help correct
presbyopia
- lens is unable to return to a rounded shape
- cannot focus on near objects
Astigmatism
- blurry vision due to irregularly shaped cornea or lens
- refraction of light rays in the horizontal plane is different from the light in the vertical plane
Nystagmus
weak or damaged muscles. the eye will drift slowly in one direction and then rapidly back to the correct position
pupillary constriction
-parasympathetic
pupillary dilation
-sympathetic
