Homeostasis and Response - THE EYE - Accomodation Flashcards
When an object is near the light rays are…
at a wider angle so need to be refracted more.
When an object is near the _______ muscles… and the ______________ ligaments
ciliary
contract and the suspensory ligaments slacken.
When the ciliary muscles contract and the suspensory ligaments slacken the lens becomes…
fat/thicker and light is refracted strongly.
When an object is far away the light rays are almost parallel and light rays only need to be…
refracted slightly.
When an object is distant the ciliary muscles… and the _________ ligaments
relax an the suspensory ligaments are taut.
When the ciliary muscles are relaxed and the suspensory ligaments are tight the lens is…
thin thus light is refracted slightly.
Myopia
Short-sightedness
Short sighteness is caused by one of the following…
The lens is too thick and curved - so that light is focused in front of the retina.
The eyeball being elongated - so that the distance between the lens and the retina is too great.
Myopia can be treated by a _______ lens as…
concave
It diverges light rays entering the eye so they focus a little further back, landing directly on the retina instead of in front of it.
Hyperopia
long-sightedness
Hyperopia is caused by the following…
the eyeball being too short - so the distance between the lens and retina is too small.
a loss of elasticity in the lens - meaning it cannot become thick enough to focus (which is often age-related).
Hyperopia can be fixed by a…
convex lens as By beginning the refraction process prior to light reaching the eye, the image of nearby objects is once again focused upon the retinal surface.
