Sebaceous glands and sinuses are going to be problems for as long as humans vaguely resemble other apes. Those are the sorts of problems you're up against, combined with the basic optics problems. Don't you think that if there was an easier way to put the required visual field in front of the eye closer, with a lighter lens, that wouldn't have been already done? There's some basic optics problems that fix the solution space in ways that are not great the particular sack of meat that biology produced.