vision

Hearing and vision are important to everyone, including active duty service members. They must be alert at all times to their surroundings and potential dangers.
Eyes may be the window to the soul, as William Shakespeare reportedly said, but in the military, eyesight is essential to remain fit for duty.
At first, flashes of light or floating debris-like shapes appear in a person’s field of vision. If the condition progresses, a curtain of darkness can be seen as the field of vision narrows.