Definition
A scotoma is a localized area of reduced or absent vision within an otherwise normal visual field. In the context of high-altitude flight and decompression sickness, scotomas can appear as blind spots or blurred patches caused by nitrogen bubbles affecting the central nervous system or the visual pathways.
Plain English
A blind spot or blurry patch in your vision, surrounded by areas where you can still see normally.
Context Anchor
Seen in aeromedical discussions of altitude-related illness, including decompression sickness, when describing possible vision changes after exposure to reduced pressure.
Derivation
From the Greek 'skotoma,' meaning 'darkness' or 'dizziness,' itself from 'skotos' (darkness). The original sense of a dark spot in vision carries directly into the medical meaning still used today.
Why Pilots Care
A scotoma signals possible decompression sickness and requires immediate descent and medical evaluation to avoid further impairment.
Analogy
It is like having a small smudge in your vision, except the problem is in what you are seeing, not on your glasses or windshield.
Intuition Check
A scotoma does not usually mean total blindness. It means one area of vision is missing, dim, or distorted while other areas may still look normal.
Example Sentence 1
After a rapid decompression, the pilot reported a small scotoma in his left visual field and immediately began a descent to a lower altitude.
Example Sentence 2
After descending to a lower altitude the scotoma gradually disappeared.