Having said that the risk is real. Every time eyelid surgery is performed there is a risk of visual loss. For this reason, it is important that your assessment prior to eyelid surgery include an examination of your eyes including an assessment of your vision. Experience has some bearing on the rate of visual loss and certain procedures may have a higher risk of bleeding behind the eye which is the most common cause of blindness after eyelid surgery. Certainly your eyelid surgeon needs to be able to identify and know how to manage bleeding behind the eye, also known as retrobulbar hemorrhage.
When a surgeon states that they have never experienced a retrobulbar hemorrhage in a patient, they have not been in practice long enough. A retrobulbar hemorrhage, which may occur perhaps one case in a 1000, does not necessarily lead to blindness. Immediate recognition of the problem with evidence of pushing forward of the eye, pain, reduced vision, and impairment of the pupillary function, and assessment of elevated intraocular pressure and rapid intervention by the surgery can preserve vision.
What is the actual risk of visual loss? It is only estimated. Approximately 250,000 cosmetic eyelid surgery were performed last year in the United States. If the rate was one in 30,000 cases, this would mean that about 8 patients lost vision in one of their eyes as a result of eyelid surgery. This could be about right.
Bottom line is that yes, it is possible to loose vision as a result of an eyelid surgery. You can reduce your risks by disclosing to your surgeon all medications and herbal products and to follow all directions regarding preparing yourself for surgery. Your surgeon should personal examine your eyes and check your vision prior to eyelid surgery. The risk of visual loss is small but not zero. If you are concerned about this risk, discuss the issue with your eyelid surgeon and seek surgeons who is qualified to handle any eye emergencies that might arise in association with your eyelid surgery.