Similar to the eye-brain, we might say that a self-eye system defines ‘front’ for the eye. What is behind the eye is whatever lies on the same side of the eye as the self; what is in front of the eye is whatever lies on the other side.
However, where is the self so that you can even say what lies some distance or direction from it? I have no idea.
One general idea of physically-minded theorists is that, if it exists at all, the ‘self’ is in the brain. So what we’re saying is: a part of the brain + eye. See above for problems with that.
All appeals to the brain have a general problem, one brought up by Dennett in his early work.
Looking at Your Brain In Its Jar
In Dennett’s Brainstorms, Dennett tells a story about a situation where his body and brain are remotely linked, such that his brain is kept in a room while his body roams around out in the world; his sense-organs go with his body. In this story, where Dennett — himself — is seems to be where his body is. Yet, it is if anywhere, where his brain is. In the story, he is shown his brain. He stands there looking at the brain — him — in the jar. Is he standing in front of himself? If so, then, what is in front of his eyes?
If we take the self to be in the brain, and ‘in front’ for the eyes to be defined by whatever lies on the other side of the self, we get this: Dennett’s skull, and what Dennett does not see, is in front of his eyes. While what he sees — e.g., the room, the walls of the jar before his body — this is behind his eyes. If he says ‘what lies before my eyes is my brain in a jar’ he is strictly speaking wrong. This lies behind his eyes as is a lot of what he sees.
All of these solutions share a similar feature: they involve evoking something other than the eye alone. The eye inherits its direction from either something else — the earth, the body — or from something else along with the eye. Perhaps this is too complicated. We can take the eye on its own. We can say that the eye has an intrinsic direction.