I was wondering what is the best treatment to get rid of this 30 degree slanting line under my eyes? (photo)

I have had it since I am 19 now 27 after my eye bags swelled up due to a reaction from a pet. But they have since swelled down but i still have the line. The photo provide is my face at resting position. I have never seen this on another person I also wonder anatomically speaking what has happened to cause these lines.

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