Human Eye Flashcards
Parts of eye
Ciliary body, sclera, retina, fovea centralis, optic disk(blind spot), optic nerve, suspensory ligament, lens, cornea, pupil, iris
What is the sclera
Tough outer layer of eye
What is the iris
Has muscles controlling the size of the pupil
Controls amount of light entering eye
What is the cornea
Transparent outer layer of front of eye
What is the pupil
Space/ hole in the middle of the eye which allows light to enter
What is the lens
Focuses light onto the retina
What is the retina
Light sensitive cells(receptors) in back of eye
What happens when there is dim light
Pupil dilation
Radial muscles contract
What happens when there is bright light
Pupil constrict
Circular muscles contract
What is accommodation?
How we focus on objects close/ far away from you
What happens when we look at an object which is close to us
When you are looking at an object which is close to us the ciliary muscles contract and suspensory ligaments relax causing lens to become rounder and thicker, refracting light to the retina in order to focus on the ovkect
What happens when we look at an object far away
When you are looking at something far away the ciliary muscles relax and the suspensory ligaments pull against the lens causing the lens to become flatter therefore refracting light to the retina, focusing on the object far away from you
What is long sighted
Longsighted = hyperopia
Unable to focus on near objects
Image focused behind retinas
Cant refract light enough (eyeball too short)
Convex lens
What is short sighted
Shortsighted = myopia
Unable to see distant objects
Image focused in front of retina
Lens refracts lens too much ( eyeball too long)
Concave lens
Treatments
Contact lenses:
- made of plastic and i s placed on eye, works similar to glasses
- risks of getting stuck or eye infection
- helps do physical activities
Laser eye surgery:
- vaporises part of the cornea to correct vision
- laser can go wrong and worsen vision
- really expensive
- perfect vision
Replacement lens surgery:
- Replace eye lens with artificial lens
- permanent fix
- opening of eye, eye infection
