Don't worry about it. It's probably albino. If it has white fur, its eyes are changing to red. The light is making the irises look violet. Either that, or your bunny has something called Alexandria's Genesis, which is a disorder that causes its eyes to turn violet. For humans, the disorder causes women not to grow any hair besides on they head, their eyebrows, and their eyelashes, and women do not get their menstrual cycle but are still fertile. Unfortunately, Alexandria's Genesis has not proven to be real, and Albinism (being albino) causes the same effects. To my point: Your rabbit is albino and you have nothing to worry about.
Yeah, eyes change color sometimes. Mine are hazel, so sometimes they look green and sometimes they look yellow. Other people in my family have irises that are two different colors at the same time, one half is gray, the other brown.