Ophthalmology Flashcards

1
Q

Visual functions

A

Spatial resolution
Temporal resolution
Wavelength discrimination
Depth perception

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2
Q

What is spatial resolution reliant on

A

Optical properties of cornea and lens
Cone density at fovea
Neural processing

Distance and up close
Contrast and reduced contrast as well

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3
Q

Temporal resolution relays involves?

A

Motion perception
Peripheral field

Function on peripheral retina

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4
Q

Wavelength discrimination

A

Colour vision

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5
Q

Depth perception

A

Binocular Stereopsis

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6
Q

The factors in aviation that can affect vision function

A
Extreme environment
- hypoxia
- high G
- low humidity
- glare sources
- very low light
Heads up displays/visor display
NVG
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7
Q

How do we test for spatial resolution

A
VA
- Snellen chart 
- LogMAR
Temporal resolution - peripheral vision
Wavelength discrimination 
-  ishihara plates - congenital red-green deficiencies
- Farnsworth lantern 
—- Binocular test
—- Mesopic condition
—- distinguish white-red-green
Accommodation - Foster’s rule
Convergence - foster’s rule
- tested using Maddox Rod test
—- measure the angle of deviation
Strabismus - cover test
Visual fields 
- testing to determine anterior vs posterior 
Depth perception
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8
Q

When testing visual fields what pathways with present with which defects

A

Anterior visual pathways

  • altitudinal defect
  • retina or macular pathology
  • optic neuropathy

Posterior visual pathways

  • vertically delineated defect
  • chasm pathology
  • occipital lobe pathology
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9
Q

Anomalies of the visual system

A

Refractive errors
Fields
Colour disorders
Diseases

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10
Q

Types of refraction errors

A

Myopia - Near-sightedness. Close is clear and fas is not. Eye too long
Hypermetropia - close is blurry. Common in adults. Also known as far-sightedness. Eye too short.
Astigmatism - abnormal curve of eye or lens.
Presbyopia - aging disorder. Failure to change from far to near

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11
Q

Effect of spectacles in the aviation environment

A
Good central vision
Frame scotoma
Peripheral aberrations
Reflections
Fogging of lenses
No complication
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12
Q

Effections of aviation on contact lenses

A
Good quality vision
Good field
Movement on eye
Affected by hydration and altitude
Allergy to lens and solutions
Hygiene
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13
Q

Discuss difference between PRK and LASIK

A

PRK

  • laser eye
  • weeks to months to recovery

LASIK

  • Flap with laser underneath
  • rapid recovery
  • return to flying quicker

Used to treat myopia, hyperopia or astigmatism

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14
Q

Explained significant of monovision

A

Occurs for treatment of presbyopia
Gives one eye close vision and one eye as far vision
Leads to issues with depth perception
Contraindicated for aviations

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15
Q

Monochromats

A

Monochromats - very rare

  • only see in black and white
  • can see through camophage
  • Cone = good VA but Rod = poor VA
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16
Q

Different types of colour vision defects

A

Monochormats
Dicromats
Trichromats

17
Q

Dichromats

A

Dichromats

  • possess 2 functional types of cones
  • Protanopes - lack red cones 1:1000, loss of brightness
  • deuteranopes - lack of red and green 1:65 000,
  • Tritanopes - lack of blue cones
18
Q

Trichromats

A

possess all three cones but one set functions sub optimally
can distinguish between fully saturated colours
difficulty arises with
- low saturation - pastels
- low luminance - dark colours

19
Q

name the acquired colour deficiencies

A

Macular disease - CSR
optic neuritis
drugs

20
Q

Pterygium

A
visual problems
Surgical removal if symptomatic 
2weeks garrison duties
6 weeks TMUFF
3 month deploy
21
Q

Keratoconus

A

Corneal ectasia
causes progressive myopia and astigmatism
TMUFF
3 month recovery