I don't know about his vision but in the top photo I can see his second eye-lids are accross his eyes. If they are like this most of the time it suggests he is not well and you would be best to take him to a vet as soon as you can.
It is very difficult to test a cat for vision, esp young kittens as they use so many other senses together with their sight (which is not nearly as important to them as it is to humans).