Turns out that he (4-5yro Netherland dwarf) is most probably blind in both eyes. This following a trip to the vet, after mini-ao noticing that he had developed cloudy eyes. No real pupillary response, and vet couldn't see the optic disc. Apparently it could have been due to a parasitic infection he had in the summer, sounded like e.cuniculi (having googled it). On the plus side - it probably shouldn't impact too much on him.