See if he responds to movement, to one side and then the other. Use far away movement and gradually come in closer. Try this on your other piggie first so that you know what a good response looks like.
Carmina's sight has been going for some time. Characteristics are - a tendancy to lift her chin right up, open her mouth and inhale in order to smell better. A tendancy to run away if startled - I now have to announce my presence verbally and have to be careful not to abruptly loom. A tendancy to become startled at something that I wouldn't have expected like a reflection (sometimes nothing at all). She homes in on the other piggies, relying on smell and hearing and simply whatever they are doing to find interesting stuff such as greens. She has also become more demanding rather than less, and tends to totally relax only once she feels completely secure.
It could be shortsightedness rather than blindness. Peering with the head forwards is characteristic in shortsighted humans, as is squinting. If it is shortsightedness then he is more likely to run from a looming strange shape from about two metres away....he won't be able to focus on you and work out it's just you. But he won't run and will respond normally when you move in close. Be aware that if you talk to him he would respond normally anyhow, he will know it's you! So it has to be a silent test.
I hope he is ok, but there is no real difficulty with most sight problems. Carmina is absolutely fine!
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