“hallucinations – seeing shapes, people or animals that aren’t really there “
http://www.nhs.uk/Conditions/macular-degeneration/Pages/Symptoms.aspx
The brain can be weird. When it loses central vision but peripheral vision is still there, it may try to ‘replace’ that missing space. It’s trying to paint continuity of what is being seen around the edges if that makes sense. Not hard if there’s only a very small degree of MD, but much harder as the central blind spot becomes larger. It helps if you explain to the person what is happening, so they don’t think they’re going crazy - their brain is just running through it’s bag of tricks to try to compensate and sometimes those tricks can involve shadows or shapes and waviness that appears to be motion.
The brain can be weird. When it loses central vision but peripheral vision is still there, it may try to ‘replace’ that missing space.
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And healthy brains do that with the blind spot we all have.