How long does it take for severe damage to last if you have macular degeneration?

Very variable: Macular degeneration can come rapidly within days or it can take years to affect vision. There is a dry macular degeneration that takes years to affect vision but is more common. The more infrequent condition is wet macular degeneration that cause vision damage literally overnight and needs immediate attention.

Any time: Macular degeneration is a "spectrum" disease: it can be very mild for a very long time, or can become severe rather quickly. Once damage sets in, it tends to progress. The "dry" form is slower to progress but has no good treatments available. The "wet" form is more devastating but there are some good therapies that can control it if caught early.