One eye smaller than the other. Any ideas on what it could be? (Photo)

Thank you for your question,When I check you photos carefully I can see that your eyebrows are in different levels. Right side is in a lower position than the left one. Most of the people has an asymmetry between the sides and it is obvious in your face. It is not about the eyes or eyelids. My recommendation will be an endoscopic forehead lift to make them more similar. You should not forget that they will not be 100% symmetric.