Ophthalmology

Question 1

Visual functions

Answer 1

Spatial resolution
Temporal resolution
Wavelength discrimination
Depth perception

Question 2

What is spatial resolution reliant on

Answer 2

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

Distance and up close
Contrast and reduced contrast as well

Question 3

Temporal resolution relays involves?

Answer 3

Motion perception
Peripheral field

Function on peripheral retina

Question 4

Wavelength discrimination

Answer 4

Colour vision

Question 5

Depth perception

Answer 5

Binocular Stereopsis

Question 6

The factors in aviation that can affect vision function

Answer 6

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

Question 7

How do we test for spatial resolution

Answer 7

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

Question 8

When testing visual fields what pathways with present with which defects

Answer 8

Anterior visual pathways

• altitudinal defect
• retina or macular pathology
• optic neuropathy

Posterior visual pathways

• vertically delineated defect
• chasm pathology
• occipital lobe pathology

Question 9

Anomalies of the visual system

Answer 9

Refractive errors
Fields
Colour disorders
Diseases

Question 10

Types of refraction errors

Answer 10

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

Question 11

Effect of spectacles in the aviation environment

Answer 11

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

Question 12

Effections of aviation on contact lenses

Answer 12

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

Question 13

Discuss difference between PRK and LASIK

Answer 13

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

Question 14

Explained significant of monovision

Answer 14

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

Question 15

Monochromats

Answer 15

Monochromats - very rare

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

Question 16

Different types of colour vision defects

Answer 16

Monochormats
Dicromats
Trichromats

Question 17

Dichromats

Answer 17

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

Question 18

Trichromats

Answer 18

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

Question 19

name the acquired colour deficiencies

Answer 19

Macular disease - CSR
optic neuritis
drugs

Question 20

Pterygium

Answer 20

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

Question 21

Keratoconus

Answer 21

Corneal ectasia
causes progressive myopia and astigmatism
TMUFF
3 month recovery