Visual systems Flashcards
Which cells in the eye are used in periods of bright light ?
Cone cells
What does cone cells do ?
Identify colors
How many
cone cells & Rod cells
are there in relation to neuron cells ?
1:1 cone cells
10:1 - 10.000:1 rod cells
Which cells are used in periods of low light and darkness ?
Rod cells
What’s the eyes two blind spots called and how many degrees do they encompass ?
Day blind spot: 5.5-7.5º
Night blind sport: 5-10º
What component of the eye contains the photoreceptors “rods & cones” ?
The retina
What’s the chemical that allows us to see black, white and grey colors at night ?
Rhodopsin
What’s the function of the pupil when looking at an object ?
The pupil allows light to enter the eye and stimulate the retina
Name the 4 visual deficiencies
Astigmatism
Myopia
Hyperopia
Presbyopia
What happens to a person if they have Astigmatism
Blurry vision
Can’t focus on vertical and horizontal features at the same time
What’s myopia and how is it experienced ?
Nearsightedness
blurry vision when viewing image at a distance
focal point is infront of retina
What’s Hyperopia and how is it experienced ?
Farsightedness
blurry vision when viewing image that are nearby
focal point is behind retina
What’s presbyopia ?
Aging og the eye - hardening of the lense
Hard to focus on things nearby
Can result in glare disability (contrast sensitivity)
Which 3 corneal refractive surgeries are allowable in the army aviatio ?
PRK, LASIK, LASEK
(Has to consult flight surgeon beforehand)
Name the 3 types of vision + what they are for?
- Photopic vision
Daylight/bright light
- Mesopic vision
Dawn, dusk (bright nights - full moon)
- Scotopic vision
Night vision
Which of the 3 vision types brings the most challenges to crewmembers ?
not sure
Mesopic vision
(night vision - twillight)
What is considered the most important cue (GRAM) to depth perception ?
Motion parallax
Driving a moving car - Things closer to you appears to move faster then things further away - Use to determine how close things are to you, based on how fast objects are moving
Name the binocular cue
Retinal disparity
Different view of an image between each eye
Name the monocular cues
GRAM
Geometric perspective
Retinal image size
Aerial perspective
Motion parallax
What is the avarage time required for dark adaptation ?
30-45 minutes
Name 4 visual illutions
FFSS
Fication
False horizon
Structural illusion
Size distance illusion
Name some limitations of night vision
- Depth perception
- Night blind spots
- Color perception
- Dark adaptiation time
- Visual cues
- Visual acuity ( obstacle identification )
Which of the self-imposed stresses (DEATH) can result in hypemic hypoxia ?
Tobacco use
Which surgical procedure is less likely to cause permanent vision change (due to thinness of the flap) ?
LASEK
