What does it mean when a cat's eyes become round?

External light can affect the size of a cat's pupils. When the eyes are exposed to strong light, the pupils will gradually shrink to the size of a grain of rice to prevent a large amount of light from entering and damaging the eyes.

In low light at night, cats dilate their pupils to allow light into their eyes so they can see clearly. This makes their eyes appear rounder.

When a cat enters hunting mode, its eyes focus on its prey, causing its pupils to dilate. This indicates that it is about to attack.