Eyes first evolved about half a billion years ago, and in that time, the Permian extinction is probably the worst thing they’ve seen. A large eruption of lava in what is now Siberia injected huge amounts of CO2 into the atmosphere, causing temperatures to spike. The oceans deoxygenated and acidified. Clouds of poison gas rolled across the land. Most plant life was wiped from the continents, leaving Earth a sandy desolate wasteland. Almost everything died.
