What is the difference between cosmetic and functional Eyelid surgery?

The surgical techniques are actually quite similar. Even in functional cases where the goal is to lift a heavy eyelid to improve vision, I usually try to create a very nice aesthetic result. Cosmetic blepharoplasty is aimed at strictly improve the shape of the eyelid and improving aged or tired appearing eyes. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

Cosmetic surgery of the upper eyelids is done to improve the appearance of the eyes and eyelids when there is no problem with the function of the eyelids.  Functional eyelid surgery is done to correct or improve a problem with the way the eyelids work.  

Functional eyelid surgery is something that defines as medically necessary. Excessive drooping of the upper eyelid may affect peripheral vision and your ability to see on the side. Excess skin is normal from the upper lids and will improve appearance with a more youthful look.

Essentially cosmetic is to enhance your existing eyelid features and so deals with beauty or aesthetic alone. Functional eyelid surgery is to improve the function of the eyelids, to protect the eyes better or to help you see out better, so is medical. Functional should also be aesthetic as all surgeons will want to do the most beautiful surgery they can for the patient, even if for medical reasons. The area where it is more fifficult to say whether it is functional is where the eyelid surgery is being done for strong psychological reasons, to boost confidence such as in a congenital deformity, correct an asymmetry which is noticeable and affects the persons ability to be social or get work, yet is not interfering with sight. In many cases that can also be temed functional if it meets certain criteria in the UK.  The surgeon will follow strict rules in assessing you, ask specific questions and do tests such as visual fields, to see if the eyelid surgery is to improve function, called medical indicaiton. 

The surgeries are very similar, but for insurance to cover the procedure strict criteria must be met.  These can include demonstrable visual field loss by testing, photographs demonstrating partial obstruction of the pupil, and issues with visual activities such as driving interference/concerns due to the overhanging tissues.  Cosmetic eyelid surgery can include additional procedures such as fat sculpting, repositioning, chemical/laser peeling of the skin, brow sutures to avoid the eyebrows being pulled downward etc.

Functional eyelid surgery is usually removing excess skin that is creating  vision loss on the upper lids. To submit for insurance, visual field obstruction test must be performed, along with pictures and medical necessity documented at the time of examination which are then submitted to insurance for preauthorization. A cosmetic blepharoplasty involves improving the look of the eyelids with a blepharoplasty procedure which involves removal of excess skin a small amount of fat and occasionally a small strip of muscle. For many examples, please see the link below

A cosmetic repair of the eyelids implies that the main focus on the surgery is to achieve a more aesthetically pleasing shape to the patient's eye. Functional eyelid surgery is aimed at correcting problems, not appearance, with the eyelid. For example, a patient experiencing diminished vision due to eyelid ptosis (sagging) may require surgery in order to improve their range of sight.