06 Eye And Vision

Question 1

Empty field Myopia

Answer 1

No visual reference point.

Eye automatically focuses 1-2m in front.

Blurs objects such as other aircraft.

Continually ‘scan’ outside the aircraft

Question 2

Myopia

Answer 2

Short sightedness.

Eye is too long.
Focal point is in front of the retina.

Corrected with diverging / concave lenses.

Question 3

Hypermetropia

Answer 3

Long sightedness.

Eye is to short.

Focal point is behind the retina.

Corrected with converging / convex lenses

Question 4

Presbyopia

Answer 4

Loss of elasticity in the ciliary muscles.
Lens losses ability to focus.

Comes on with Age (45 - 50)

Form of longsightedness (Hypermetropia)

Question 5

Astigmatism

Answer 5

Uneven shaped cornea or lens.

Causes Myopia or Hypermetropia.

Corrected with cylindrical lenses.

Question 6

Cataracts

Answer 6

Clouding of the lens.

Less light is allowed through so reduces sight.

In extreme cases the lens is removed to correct.

Forms with Age.

Question 7

Glaucoma

Answer 7

High interocular pressure.

Drainage canal becomes blocked so pressure in vitrious humour increases.

Insidious onset with concealed progression.

Starts with blurred vision -> tunnel vision -> blindness

Over time can damage optic nerve.

Question 8

Colour blindness

Answer 8

Damage to one or more of the cones
(Red, Blue, Green)

Genetic issue.

More common in men.

7% of men to 0.1% women.

Does not effect visual acurity.

Question 9

Requirements for Sunglasses

Answer 9

1. Impact resistant
2. Strong metal frame
3. High optic quality
4. Coated in poly-carbonate for strength
5. Luminance transmittance of no more than 10 - 15%
6. Appropriate filtration characteristics
7. Transition/photo-chromatic lenses are prohibited
8. Polarised lenses are discouraged - distort instruments and windscreens

Question 10

What factors effect Visual Acuity?

Answer 10

• Hypoxia
• Smoking
• Alcohol
• Some medications
• Angle from the Fovea
• Myopia and Hypermetropia