Dark adaptation, night vision protection, and central night blind spot

Question 1

Definition:

Answer 1

Dark adaptation is the process by which the eyes become more sensitive to low levels of illumination.

Question 2

______ (visual purple) is the substance in the rods responsible for light sensitivity.

Answer 2

Rhodopsin

Question 3

Characteristics

Answer 3

● The lower the starting illumination level, the less time required for adaptation
● Optimal night vision acuity approaches its max level in about 30-45 min
● If exposed to bright light after adaptation, sensitivity is temporarily impaired: degree of impairment depends on the intensity and duration of the exposure (several min to 45 min)
● Exposure to bright sunlight has a cumulative and adverse effect

Question 4

Night vision protection:

Answer 4

● Sunglasses: When exposed to bright sunlight for prolonged periods (ND-15 equivalent)
● Red-lens goggles: retinal rods least affected by wavelengths of deep red light
● Supplemental Oxygen: Adverse effects on night vision begin at 4,000’ PA, so use if available above this altitude.

Question 5

Reference:

Answer 5

Reference: TC 3-04.4 Ch. 8