Why has my one eyelid suddenly started drooping? (Photo)

Thank you for the question. You do have a ptotic left upper eyelid. Since you had it for a long time, it is probably nothing. On the other hand, since it is getting worse suddenly, you need to see an oculoplastic surgeon for evaluation. It could be related to a systemic medical condition (although unlikely). Surgery is covered by insurance if it can be demonstrated that you have lost some vision do to the droopy eyelid. Good luck.

There are many causes of unilateral (one sided) eyelid ptosis (drooping).  They are probably best understood as neurological vs physical in terms of categories.  To differentiate the two and identify the exact cause it would be bet to see a neurologist, ophthalmologist, or plastic surgeon to have your medical history and physical exam details noted.  This is usually sufficient but radiographic evaluation may also be needed to exclude vascular or other soft tissue issues.All the best,Dr Remus Repta