def extract_eyeid_diameters(pupil_datum):
    """Extract data for a given pupil datum
    
    Returns: tuple(eye_id, confidence, diameter_2d, and diameter_3d)
    """
    return (
        pupil_datum["id"],
        pupil_datum["confidence"],
        pupil_datum["diameter"],
        pupil_datum.get("diameter_3d", 0.0),
    )