Here are some options: the earth; the body; the head; the eye-brain system; a specific set of neurons; the ‘self’ a straight line running through the eye; an average of these. Let’s take each in turn:
- The Earth/The Earth’s Orbit/The Solar System/The Heliosphere/The Galaxy/The -[insert large embedding spatial entity here]
I can’t make sense of the idea that ‘in front’ for my eye is relative to the earth or any other larger body — to which, for all intents and purposes, we are at rest and in which we are located or embedded. Instead of going through all cases (orbit, heliosphere, etc.), let’s just take the Earth. ‘Directions’ on earth are typically defined in terms of latitude/longitude and North/South/East/West. Let’s ignore for the sake of argument the conventionality of these terms (for example, I think we could as much define directions by the rolling of the Earth on its axis about the sun: say, Descent-wise (in the direction in which the Earth turns toward the sun) and Ascent-wise (the direction in which the Earth turns away from the sun).
To say that directions on the Earth define ‘in front for my eyes’ is to say that something in front of my eye because it is either North/South, etc., of my eye. This means that, no matter how I turn my eyes or head, or body, something remains in front of my eye so long as it is the same relative to the directions defined by the Earth. I take it that this is just flat-out wrong, and will ignore it. But I also think that most other directions, though commonly closer matches to the eye’s direction, e.g., the body, head, etc., are equally as problematic. They have the same general problem: what we call ‘in front of’ for the eye can vary from whatever we might call any direction as defined by them.