>>1432821Brains are basically hard wired to protect extremely vital areas such as the face and eyes at all costs. Losing vision means death and eyes are right there out in the open, while the internal organs are not. Causing obvious (from the perspective of the animal) irritation or mutilation to eyes basically tells the brain to direct all attention to sorting out whatever is happening to cause the damage and ignore anything else that does not otherwise cause a stronger signal to act (life threatening threat). Eyes are a particularly good target because almost all mammal brains are specifically hardwired through evolution to react extremely strongly to genital and eye damage/pain. (In the bears case, nose damage as well)
In short: you might be able to disable the bear quickly with a gun, but the bear cares much more about getting sprayed than shot. Even people who have gotten shot report that it doesn’t immediately hurt, yet people who get sprayed universally report immediate intense pain that is impossible to ignore.