05. The Eye and Vision Flashcards
Anatomy of the Visual System
What 3 elements does the visual system comprise of?
- EYES
- OPTIC NERVE
- VISUAL CORTEX
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Anatomy of the Visual System
What does the optic nerve connect the eyes to
VISUAL CORTEX
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Anatomy of the Visual System
What is the visual cortex
AREA AT BACK OF BRAIN
Responsible for processing information received by the eyes
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Anatomy of the Visual System
The outside eye is covered in a smooth, very tough layer of white tissued called what
SCLERA
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Anatomy of the Visual System
The ____ allows light to enter the eye and fall onto the lens
TRANSLUCENT CORNEA
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Anatomy of the Visual System
The hole in the iris is known as what
PUPIL
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Anatomy of the Visual System
The ___ contracts and expands in response to light levels
IRIS
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Anatomy of the Visual System
The cornea helps focus light onto which part of the eye
RETINA
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Anatomy of the Visual System
The focusing process, in which the contraction and relaxation of the ciliary muscle takes place, thus changing the focal length of the lens, is known as what
ACCOMMODATION
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Anatomy of the Visual System
The back of the eye is densely packed with what 2 things
hint
1. which reacts to light and colour
2. which reacts to stimuli
- PHOTORECEPTORS (cones and rods)
- NEURONS
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Anatomy of the Visual System
What are the 2 types of photoreceptors
- RODS - sensitive to light
- CONES - colour detection
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Anatomy of the Visual System
RODS or CONES are the most sensitive receptor to light
RODS
REMEMBER
Cones = Colour
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Anatomy of the Visual System
RODS or CONES are the most sensitive receptor to colour
CONES
REMEMBER
Cones = Colour
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Anatomy of the Visual System
What are the 2 fluids that help maintain the spherical shape of the eye
- AQUEOUS HUMOUR
- VITREOUS HUMOUR
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Anatomy of the Visual System
What liquid occupies the space in front of the lens
AQUEOUS HUMOUR
REMEMBER
Advanced; meaning forward = Aqueous
Volume; meaning larger space = Vitreous
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Anatomy of the Visual System
What liquid occupies the space behind of the lens
VITREOUS HUMOUR
REMEMBER
Advanced; meaning forward = Aqueous
Volume; meaning larger space = Vitreous
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Anatomy of the Visual System
What component of the eye washes the surface with a mildly antibiotic solution
TEAR DUCT
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Anatomy of the Visual System
Why is it important for the cornea to be kept moist at all times
HELPS DIFFUSE OXYGEN
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Anatomy of the Visual System
What is the purpose of the 2 photoreceptors rods and cones
DETECT LIGHT and COLOUR
Rods - black and white, highly sensitive to light
Cones - colour, less sensitive to light, not used at night
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Anatomy of the Visual System
The axons of the cells to which the rods and cones are connected to, exit the eye at what point
OPTIC DISC
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Anatomy of the Visual System
The optic disc has no (i) ____, and as a result, cannot detect (ii) ____.
This is therefore known as the (iii)____
- PHOTORECEPTORS
- LIGHT
- BLIND SPOT
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Anatomy of the Visual System
CONES or RODS are the principle means of vision during the day
CONES
REMEMBER
Ice cream cones by the beach on a sunny day
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Anatomy of the Visual System
CONES or RODS are the principle means of vision during the night
RODS
REMEMBER
Ice cream cones by the beach on a sunny day
Rods are highly sensitive to light, which there is little of in the dark
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Anatomy of the Visual System
The central area of the retina, which is densely packed with cones, is known as what
FOVEA
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Anatomy of the Visual System
The area immediately surrounding the fovea is densely packed with what
RODS and CONES
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Anatomy of the Visual System
The number of cones INCREASE or DECREASE as you move progressively outwards from the fovea
DECREASE
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Anatomy of the Visual System
Which part of the retina is able to resolve letters and numbers, and why
- FOVEA
- DENSELY PACKED WITH RODS AND CONES
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Anatomy of the Visual System
Which part of the eye is most sensitive to detecting objects at night and why
- PERIPHERAL VISION
- Cones DECREASE outwards from the fovea (center of retina), rods are more sensitive to light
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Anatomy of the Visual System
The entire area of space which can be seen at any one time is known as what
VISUAL FIELD
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Anatomy of the Visual System
The sudden and jerky movement of the eye is known as what
SACCADE
THINK
Side-to-side = Saccade
where AC and CA are side by side
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Anatomy of the Visual System
Which part of the visual system is specifically tuned to respond to relative movement
VISUAL CORTEX
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Anatomy of the Visual System
The process of our eyes smoothly tracking a moving object is known as what sort of movement
PURSUIT MOVEMENT
THINK
Following is in pursuit
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Anatomy of the Visual System
Objects passing through the field of vision are tracked. This allows them to be ____ upon, which allows them to be tracked again.
This is an alternating pattern of ____ and ____ movement of the eye
- FIXATED
- PURSUIT
- SACCADE
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Anatomy of the Visual System
A group of how many muscles make eye movements
What part of the eye are the muscles attached to
- 6
- SCLERA
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Vision
The process of taking signals from the eyes an interpreting them in the brain is known as what
VISION
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Vision
Why is some visual acuity lost in the dark
CONES NOT CONTRIBUTING
Cones, which require high levels of flight to function, are not contributing to object detection
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Vision
What are 2 biological reasons for a loss of visual acutiy
- AGE
- DISEASE
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Vision
What are 5 physiological factors for reducing visual acuity
REMEMBER
You are mash less
M
A
S
H
LsSs
- MEDICATIONS
- ALCOHOL
- SMOKING - excessive CO2
- SHORT/LONG SIGHTEDNESS
- HYPOXIA - cabin altitude > 5,000 ft
REMEMBER MASShH (MASH)
Medications
Alcohol
Smoking
Hypoxia
Long sightedness
Short sightedness
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Vision
Visual fields of each eye overlap, which creates what sort of vision.
This is necessary for what
- BINOCULAR / STEREOSCOPIC
- DEPTH PERCEPTION (short distance)
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Vision
What range is stereoscopic depth perception effective up to
60 m (200 ft)
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Vision
Another term for binocular vision is what
STEREOSCOPIC VISION
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Vision
What are the 4 visual cues used beyond stereoscopic vision to infer depth
- COLOUR
- CONTRAST
- SIZE
- RATE OF MOVEMENT
- COLOUR - Paler objects considered more distance
- CONTRAST - decreasing contrast seen as increasing distance
- SIZE - large objects seen as small object inferred as distant
- RATE OF MOVEMENT - angular displacement far away is reduced. Rapid movement therefore inferred to be closer
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Vision
What sort of vision results in the loss of all depth perception
MONOCULAR (one eyed)
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Dark and light adaptation
The process of increasing retinal sensitivity to reducing light is known as what
DARK ADAPTATION
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Dark and light adaptation
It takes 7-9 minutes for CONES or RODS to become adapted to dark
It takes 30 minutes for CONES or RODS to become adapted to dark
- CONES
- RODS
REMEMBER
C before R
C for cones comes before R for rods in the alphabet
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Dark and light adaptation
How long does it take for the eye to adapt from darkness to bright light conditions
10 seconds
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Dark and light adaptation
Bleaching of the retina from sudden exposure to bright light is known as what
FLASH BLINDNESS
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Dark and light adaptation
Why is it recommended to turn up the lights in the cockpit at night during a thunderstorm
AVOID FLASH BLINDNESS
happens when the eyes are bleached from the sudden flash of lightening
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Dark and light adaptation
Rods and cones are very sensitive to the effects of what condition that typically could occur at high altitudes
HYPOXIA
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Dark and light adaptation
What operational maintenance process is a prime culprit to eye damage in the aviation industry over time
ARC WELDING
Repairing the fuselage using welding torches
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Dark and light adaptation
At what end of the spectrum does the highest level of light energy occur (what colour).
What level is the highest risk (light range)
Where do these light energies typically occur (altitude)
- BLUE
- ULTRAVIOLET
- HIGH ALTITUDES
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Dark and light adaptation
When selecting sunglasses for the cockpit, what 4 qualities should you try to ensure they meet
- ____ : brand
- ____ : made from
- ____ : frames
- ____ : regulation
- HIGH QUALITY
- POLYCARBONATE MATERIAL
- THIN / NO RIMS
- CONFORMS with EN 1836:1997
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Dark and light adaptation
What 2 types of sunglasses are not permitted in the flight cockpit
- PHOTOCHROMIC
- POLARISED
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Physiological limitations
Why is it important to frequently change your focus of attention when looking out of the cockpit window
BLIND SPOT
avoid potential threat coinciding with the blind spot
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Physiological limitations
When the eye has no objects to attract its attention, this causes issues with the ability to focus on distant objects. This is known as what
EMPTY FIELD MYOPIA
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Physiological limitations
When suffering from empty field myopia, the eyes will result to default focus, which is a range of approximately how far
1 - 2 METRES
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Physiological limitations
What are 2 key issues related to focusing and vision in the dark
- PUPILS DILATED
- ONLY RODS USED - few located near fovea
Dilated pupils removes the beneficial effect a constricted pupil brings for focusing.
There are few rods located near the fovea.
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Physiological limitations
People with what sort of eyesight have issues focusing in the dark
POOR EYESIGHT
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Physiological limitations
At night, it is sometimes necessary to look at objects using peripheral vision, meaning you are looking at the object ____.
Why is this required
- OFF-CENTRE
- ONLY RODS USED
Few rods in the fovea. Since only rods are used at night, and these are used more specifically in the peripheral vision, it is better to look off-centre to help with object detection.
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Physiological limitations
When scanning the sky, how much should each stop overlap with the last search field
10°
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Defective vision
Cones detect colour vision. This is known as what
PHOTOPIC VISION
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Defective vision
Rods detect various shades of light and dark. This is known as what
SCOTOPIC VISION
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Defective vision
The most common type of eye defect is what
REFRACTIVE ERROR
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Defective vision
Myopia is what sort of eye defect
SHORT SIGHTEDNESS
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Defective vision
What is short sigtedness known as
MYOPIA
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Defective vision
Hyperopia (hypermetropia) is what sort of eye defect
LONG SIGHTEDNESS
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Defective vision
Long sightedness is known as
HYPEROPIA
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Defective vision
What sort of lens will be used to correct vision for someone suffering from myopia
CONCAVE
Short sightedness, concave (inwards sloping) lens
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Defective vision
What sort of lens will be used to correct vision for someone suffering from hyperopia
CONVEX
Long sightedness, convex (outwards bowing) lens
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Defective vision
Long sightedness / hyperopia is the inability to focus on what
Short sightedness / myopia is the inability to focus on what
- NEAR OBJECTS
- FAR AWAY OBJECTS
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Defective vision
What is astigmatism
SLIGHT IMPERFECTIONS in CORNEA or LENS
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Defective vision
Slight imperfections in the cornea or lens that causes slight variations in optical power between areas of the cornea is known as what
ASTIGMATISM
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Defective vision
What are the conditions that must be met by a pilot in order to retain their pilot licence/medical if using corrective lenses;
- Not worse than ____/____ vision in either eye
- Not worse than ____/____ vision in both eyes
- Read small print up to ____cm (same as which line in snellen chart)
- 6/9
- 6/6
- 30cm
- Next to bottom
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Defective vision
Wherever corrective glasses are used, what must a pilot carry at all times when exercising their pilots licence
SPARE PAIR
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Defective vision
When using corrective glasses, bifocal lenses ARE or ARE NOT permitted
ARE PERMITTED
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Defective vision
When using corrective contact lenses, bifocal lenses ARE or ARE NOT permitted
ARE NOT PERMITTED
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Defective vision
What is presbyopia
LONG SIGHTEDNESS
reduction in the elasticity of the lens
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Defective vision
Long sightedness caused by a reduction in the elasticity of the lens, typically age related is known as what
PRESBYOPIA
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Defective vision
What is cataracts
CLOUDING OF LENSES OF EYES
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Defective vision
A clouding of the lenses of the eyes is known as what condition
CATARACTS
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Defective vision
Cataracts is a progressive disease that results in increasingly what sort of lenses
OPAQUE
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Defective vision
Internal (intraocular) pressure of the eye increases. This condition is know as what
GLAUCOMA
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Defective vision
What is glaucoma
INTERNAL (INTRAOCULAR) PRESSURE OF THE EYE INCREASES
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Defective vision
What is an early symptom of glaucoma
LOSS OF VISUAL ACUITY
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