Yep, looks like a nuclear cataract to me too. The time it takes to develop depends on the cause - a lot of cataracts develop slowly on old rabbits, but you don't necessarily notice until it's very visible, but one can develop after an impact. It can be caused by e cuniculi, but I think it's doubtful here as their is no visible rupture of the lens.
It's something you'll need to monitor with a vet, cataract can be treated by surgery and e cuniculi calls for a one month treatment, but rabbits with poor vision or even no vision at all generally adapt quickly and live very well - Aki has lost her vision one year and a half ago (the optical nerve stopped working, as she was getting old and has violet eyes coming from her albino mother... from what I've read REW rabbits often have poor vision and often become blind as they age) and you would never guess watching her... I've never even seen her bump into anything.
