What are the risks of upper eyelid surgery?

Dear Alexa
Please don't let anyone rush you into eyelid surgery because it is simple and straight forward. My colleagues have done a good job describing the textbook issues that can arise after upper eyelid surgery.
However, by far the most common and most important potential complication is a failure of communication between you and your surgeon. You go to the doctor and you might even ask for an upper eyelid blepharoplasty. However this may or may not be what you need. The doctor might even agree to preform eyelid surgery, after all the surgeon may consider this a very simple procedure.
Here is the issue: is this what you need? Most people assume that they need eyelid surgery when the upper eyelid fold hangs onto the eyelid platform or eyelashes. Due to how the brain is wired, the upper eyelid fold is supported by activity in the forehead lifting muscles that raise the eyebrow. When upper blepharoplasty is performed, the skin resting on the eyelid is removed and so is the signal for the forehead muscle to activate. The forehead relaxes and the eyebrows fall. This can make the eyes look smaller after upper eyelid surgery. In this circumstance, the correct surgery is not upper eyelid surgery but rather an endoscopic forehead lift.
Another area for disappointment is loss of the upper eyelid fold itself. Many surgeons will resect all the available upper eyelid fold while still permitting the eyes to close. This is generally a big surprise to the patient. The upper eyelid fold is a very important aesthetic feature of the face. The unexpected loss of this important feature can lead to long term disappointment with the surgery. The surgeon often does not understand why the patient is unhappy with surgery because to their thinking, this is what eyelid surgery is supposed to accomplish. However, the answer here is that most people would preserve the fold but have it cleaned up if they had been given the choice. It is possible to do very elegant eyelid surgery and yet leave the upper eyelid fold.
Other areas of disappointment include the placement of the upper eyelid crease too high. The plastic surgery textbooks routine describe making the lowest upper eyelid incision 10 mm above the eye lashes. However, this is much too high. Normally in women, the natural upper eyelid crease is actually located at about 8 mm. However, when an incision is made, the final location of the incision will be 1 to 2 mm higher than intended due to how the eyelid heals. So the 10 mm incision heals to a 12 mm height. This is a very bad thing. It is much safer to place the incision at 6 or 7 mm.
Also, it is important to put the eyelid platform skin on slight stretch. This tension helps support the upper eyelid lashes so they perk up after surgery rather than point down. This maneuver is called anchor blepharoplasty. To perform it, the eyelid platform skin needs to be attached to the tendon that raises the upper eyelid. This requires a specialized knowledge of eyelid anatomy that most eyelid surgeons lack.
So the biggest risks of the surgery come from a lack of a detailed and systematic approach to performing eyelid surgery, through consultation and communication. If you spend less than 5 minutes with your potential eyelid surgeon, this should be a big red flag.

The risk of eyelid surgery is similar to risk of any surgery, minor or major, every surgery always has the risk of bleeding, infection, injury to surrounding tissue or the need for revision. But eyelid surgery when properly done in experienced hands is usually a procedure that requires minimal risk and need for revision. During surgery if the incision is near the eyeball, often a protective shield will be used. So in general very safe surgery.

Bleeding and infection are early problems.  Dryness of the eye is common but only lasts a few days or weeks.  Upper lid bleoharoplasty is a very easy procedure to go through and heal from.