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THE VISUAL SYSTEM IN FLIGHT

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THE VISUAL SYSTEM IN FLIGHT TERMINAL LEARNING OBJECTIVE Action: Manage the effects of visual limitations during flight Conditions: While performing as an aircrew member Standards : IAW FM 3-04.301, FM 8-50, AR 40-501, and AR 40-8 ANATOMY OF THE HUMAN EYE

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terminal learning objective
TERMINAL LEARNING OBJECTIVE
  • Action: Manage the effects of visual limitations during flight
  • Conditions: While performing as an aircrew member
  • Standards : IAW FM 3-04.301, FM 8-50, AR 40-501, and AR 40-8
anatomy of the human eye
ANATOMY OF THE HUMAN EYE
  • CORNEA: The clear outer portion of the eye through which light passes.
  • IRIS: The colored portion of the eye which controls the diameter of the pupil.
  • Pupil: The dark center of the eye which allows light to pass through to the lens.
anatomy of the human eye7
ANATOMY OF THE HUMAN EYE
  • LENS: Located behind the pupil it focuses light on the retina.
  • RETINA: Composed of many tiny photosensitive cells called rods and cones.
  • FOVEA CENTRALIS: Contains a very high concentration of cone cells but no rod cells.
slide10
ANATOMY OF THE HUMAN EYE

FOVEA

CENTRALIS

anatomy of the human eye11
ANATOMY OF THE HUMAN EYE

RODS & CONES

  • Named because of their shape
  • Rods are used for night and low-intensity light vision (Scotopic Vision)
  • Cones are used for day or high-intensity light vision (Photopic Vision)
  • Both used at Dusk or Dawn (Mesopic Vision)
anatomy of the human eye12
ANATOMY OF THE HUMAN EYE

RODS

  • Contains rhodopsin also known as vision purple
  • Rhodopsin bleached out by light making rod cells inactive
  • Extremely light sensitive (Scotopic Vision)
  • 30 to 45 minutes required to build up Rhodopsin (Dark Adapt)
slide13
ANATOMY OF THE HUMAN EYE

CONES

  • Contains iodopsin
  • Identifies colors
  • Sharp visual acuity and color sense (Photopic Vision)
  • 7 million in fovea and parafovea regions
  • 1:1 ratio of cone cells to neuron cells
anatomy of the human eye14
ANATOMY OF THE HUMAN EYE
  • OPTIC DISK: The day blind spot. No rods or cones are present as the optic nerve enters the eye at this point.
  • PARAFOVEAL REGIONS: Mixture of rods and cones
  • PERIPHERAL REGIONS: Mostly composed of rods for night vision
slide16
ANATOMY OF THE HUMAN EYE

PARAFOVEAL REGIONS

slide17
ANATOMY OF THE HUMAN EYE

PERIPHERAL REGIONS

visual deficiencies
VISUAL DEFICIENCIES
  • ASTIGMATISM
  • MYOPIA
  • HYPEROPIA
  • PRESBYOPIA
  • RETINAL RIVALRY
astigmatism
ASTIGMATISM
  • This condition is caused by an unequal curvature of the cornea or lens of the eye
  • Astigmatism is defined as the inability to focus different meridians simultaneously.
  • If, for example, astigmatics focus on power poles (vertical), the wires (horizontal) will be out of focus for most of them, as shown on the next slide.
visual deficiencies21
VISUAL DEFICIENCIES

Myopia: Nearsightedness

Hyperopia: Farsightedness

Presbyopia: (aging)Hardening of lens, loss of elasticity

retinal rivalry
RETINAL RIVALRY
  • This condition is caused when the eyes attempt to simultaneously perceive two dissimilar objects independent of each other.
  • Quite often the dominant eye will override the nondominant eye, possibly causing information to be missed.
  • This phenomenon may occur when pilots are viewing objects through the heads-up displays found in the optical systems of the AH-64.
corrective surgery
CORRECTIVE SURGERY
  • RADIAL KERATOTOMY
  • LASER IRIDOTOMY
  • PHOTO REFRACTIVE KERATECTOMY
  • LASER IN SITU KERATOMILEUSIS
radial keratotomy
RADIAL KERATOTOMY
  • Flattening of the cornea by the creation of spoke like incisions
  • Performed to correct abnormal curvature of the cornea
laser iridotomy
LASER IRIDOTOMY
  • A lazed opening of the iris to open ocular fluid passageways
  • Performed for the treatment of glaucoma
  • Creates artificial pupil (Lost peripheral vision non-correctable)
slide28
PHOTOPICVISION
  • Daylight or bright light
  • Central vision
  • Color sense and image sharpness
  • Visual acuity 20/20
  • Involves cones only
mesopic vision
MESOPIC VISIONMESOPIC VISION
  • Occurs at dawn, dusk and in full moonlight
  • Reduces color vision and decreases visual acuity
  • Involves both rods and cones
  • Greater emphasis should be placed on off-center vision as cones become less effective
scotopic vision
SCOTOPIC VISIONSCOTOPIC VISION
  • Occurs on dimly lit nights
  • Decreases visual acuity 20/200 or less
  • Causes loss of color perception
  • Causes night blind spot
  • Requires use of peripheral vision and recognition of objects by silhouettes
  • Involves the rods only
binocular cues
BINOCULAR CUES
  • Valuable only when object is close
  • Each eye has a slightly different view
  • Operates subconsciously
monocular cues gram
MONOCULAR CUES(GRAM)
  • Object seen as one picture
  • Are derived from experience
  • Subject to interpretation
geometri c perspective

GEOMETRIC PERSPECTIVE

OBJECTS have different shapes when viewed at varying distances and altitudes

geometric perspectives
GEOMETRIC PERSPECTIVES

Linear

perspectives

Apparent

foreshortening

Vertical position

in the field

retinal image size
RETINAL IMAGE SIZE
  • Known size of objects
  • Increasing or decreasing size of objects
  • Terrestrial association
  • Overlapping contours
slide36
5 Degrees

30 Ft

10 Degrees

KNOWN SIZE OF OBJECTS

1000 FT

30 Ft

500 FT

slide37
DECREASE IN SIZE

INCREASE IN SIZE

aerial perspective
AERIAL PERSPECTIVE
  • Distant information gained by clarity of object viewed or by the shadow it casts
slide44
MOTION PARALLAX
  • Very important cue to depth perception
    • Stationary objects
  • Rate depends on the distance of the object
flight hazards
FLIGHT HAZARDS
  • SOLAR GLARE
  • BIRD STRIKES
  • LASERS
  • NERVE AGENTS
laser
LASER
  • LASER

Light

Amplification by a

Stimulated

Emission of

Radiation

laser49
LASER
  • Intense, narrow beam of light, less than 1 inch in diameter
  • Widens with distance: 2km-diameter is 2 meter

2Meters

2 Km

laser injuries
LASER INJURIES
  • Lens: Focuses and concentrates light rays entering the eye
  • Concentration of energy through the lens is intensified 100,000 times greater than the normal light entering the eye
laser injuries51
LASER INJURIES
  • Amount of damage depends on laser type, exposure time, and distance from the laser
  • Types of injuries:
    • Tiny lesions on the back of the eye
    • Flash blindness
    • Impaired night vision
    • Severe burns effecting vast body portions
slide52
Hemorrhage

in to the vitreous

Multiple retinal laser burns

slide53
Corneal burns

Subretinal hemorrhage

laser protective measures
Passive:

Take cover

NVD’S

Squinting

Protective goggles

Active:

Counter measures taught or directed

Evasive action

Scanning with one eye or monocular optics

LASER PROTECTIVE MEASURES
nerve agents
NERVE AGENTS
  • Threat present both day and night at low level flight
  • Direct or minute exposure will cause miosis (pupil constriction)
  • Severity of miosis depends on agent concentration and cumulative effects of repeated exposure
nerve agent symptoms
NERVE AGENT SYMPTOMS
  • Range from minimal to severe (dosage to eye?)
  • Severe miosis may persist for 48 hrs
  • Complete recovery may take up to 20 days
  • Consult flight surgeon immediately
self imposed stresses
SELF-IMPOSED STRESSES
  • Drugs
  • Exhaustion
  • Alcohol
  • Tobacco
  • Hypoglycemia
slide58
QUIZ

Click on the link below to access the

VISION IN AVIATION Quiz

http://ang.quizstarpro.com

Log-in and Click “Search” Tab

Class Name = VISION IN AVIATION

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