Physiologically, during a redout the blood vessels inside the eyes expand, creating hazy, reddish vision. If they expand far enough, they can rupture. The patient can develop retinal damage and free-flowing blood inside the head may also lead to hemorrhagic stroke, where brain cells start to die because of pressure buildups inside the skull. During a redout, the patient may lose consciousness or become confused and sluggish as tissues inside the brain start to experience damage.