[Deck 1 - The Eye] Flashcards
How much focusing does the cornea do?
~ 80%
~ opens up eye + allows vision with less light
How much focusing does the lens do?
~ 20%
Accommodation
The eye can alter the shape and curvature of the lens to adjust the degree of refraction
~ ciliary muscles relax = lens stretches = focus on things FAR AWAY
Astigmatism
~ surface of cornea/lens are unequal curved
~ image not focused as one point = blurry
Myopia
NEAR SIGHTED
~ distant objects blurry
~ lens too strong OR eye too long
~ focus before retina
Hyperopia
LONG SIGHTED
~ near objects blurry
~ lens too weak OR eye too short
~ focus after retina
What’s different about the eyes of underwater creatures?
NO CORNEA –> big lens instead
~ no air-water trade off so cornea wouldn’t work
Glaucoma
~ build up of aqueous fluid
~ increased pressure damages optic nerve
~ main cause of blindness
What is the sclera and what is it for?
~ the white of the eye
~ social species –> others can see where we look
What is the tapetum?
~ mirror at back of the eye
~ gives eye 2nd chance to catch info
~ dogs have it
How do you reduce the volume of light that enters the eye? (3)
~ increase light’s directionality
~ increases depth of field
~ pupils does this
What are rectangular pupils good for?
increase range of sight (herbivores)
What are circular pupils good for?
good for hunting
What are vertical pupils good for?
camouflage
How does the level of melatonin effect your eyes?
brown eyes = lots of melatonin = shades eyes from sun
blue eyes = lack of melatonin
~ lack of colour makes things seem blue
