Is surgery required to achieve a double eyelid for only one eye? (Photos)

You actually have left upper eyelid ptosis with brow compensatory elevation. The amount of skin is the same on both sides. You remind me of an Asian patient with almost exact features. See following link for her before/after photos. She had left upper eyelid ptosis surgery and bilateral Asian blepharoplasty.

Ultimately surgery is needed to make the double eyelid permanent.  I that case, I recommend an open double fold surgery rather than DST method which can often breakdown.

so see a surgeon and hopefully your results will be symmetric as having some differences should be expected.  And know what the revision policy is in case you do not get what was anticipated.

Hello allysaki!
I don't know if you had previous surgery but doing a nonincisional asian led crease formation would be a good choice for you. Its fast, predictable and quick recovery. No incisions are made. Only sutures are passed to recreate that fold. You would do great.  Seek an oculoplastic surgeon for an expert consult.
Cheers!

Surgery to permanently establish the crease on the right is the best solution. A lid crease incision on the right with fixation of the crease to match the left is the best alternative. See an oculoplastic surgeon for evaluation and treatment. Best wishes.