Chapter 6 - The Eye Flashcards
x3 parts that create vision
Eye
Optical Nerve
Primary visual cortex
Eye movement controlled by
x6 Extraocular Muscles
What is Saccade
Series of jerks the eye moves. 1 every 1/3 of a second
Accommodation is done by?
The lens 20 - 30 %
Visual field is the combination of
central & peripheral
Rods
Do black & white / scoptic
Contains a protein called Rhodospin (Visual Purple)
Can be destroyed by high levels of light/ bleeched
Surround the fova approx 10 degrees from the centre
Good for Peripheral vision / picking up movement
Night vision how to counter it?
Look 10 degrees to the side (helps the rods)
- stop using red light because it distorts charts and instruments
To see far away the lens is?
Flatter / Concave
Visual Acuity is? how is it displayed?
The measure of efficiency on central vision
20/15 20 = what the average person see’s at 20 feet
200 = what you see the same at 15 feet
Accommodation is done by?
The lens
2 main factors effecting accommodation?
Age and fatigue
How do cones + rods react to dark to bright, how long
Cones and rods in the same time, about 10 seconds
What effects night vision
Altitude, smoking, alcohol, blue light, mild hypoxia
Cones
Do coloured / photopic vision. made up of red, blue and green - require bright light to work. Concentrated in the fova, 150,000 cones per mm.
How do cones + rods react to light to dark, how long
Cones take 7 mins
Rods takes 30 mins
