How safe and effective is blepharoplasty? how high are the chances of noticeable scarring, deformities and other risks?

Depends!: As with any surgical procedure, there are risks. How extensive a repair matters, as does the skill of the surgeon, your health, & your willingness to follow aftercare instructions. If done by an experienced surgeon, excellent results are possible with minimal scarring which improves over time. Get a couple of opinions and look at photos of past cases the doc has done. Ask a lot of questions 1st!