Eye color changes are related to DNA, and brain health. You may have activated a delayed DNA change from childhood, blue is the basic color in caucasian babies. It may be a natural part of your DNA being able to function and express itself more naturally, and it might be a sign of improved brain metabolisim.
Hair color, hair texture, etc, are expressed the same way. My sister's hair went from saucy brown with soft curls to afro-curls after hitting 21, and she's heavily taking anti-anxiety meds.