To understand the potential complications of eyelid surgery, you first need to understand the important physiologic function of the eyelid. The eyelid serves an important protective function for the eye, and a defective eyelid can lead to corneal damage, infection, which can lead to corneal perforation and even loss of the eye. However, most cosmetic eyelid surgeries do not result in eyelid defects, although they may diminish the protective function of the eyelid. The eyelids primarily protect the cornea, the corneal epithelium to be exact. The eyelids certainly protect the cornea when the eyes are closed, but what protects the exposed portion of the cornea when the eyes are open? It is the tear film. The health of this tear film is critical to protecting the cornea! It must ensure that the cornea is moist in our open eye state and the tear film must remain intact. This is called the tear film break up time (TBUT), which is normally 10 seconds. Why? The above diagram shows the tear film, which is supposed to be an intact tear film that completely protects the cornea from drying out. This is because a normal person blinks more than 6 times per minute, about 10 times. The purpose is to lubricate the surface of the cornea and coat the tears by blinking. Therefore, the tear film must remain intact when not blinking. If the TBUT is less than 10 seconds, the cornea is not fully protected when not blinking, and dry eye can develop, which in turn can lead to corneal damage. The main reason for a shortened TBUT is known to be a lack of tears, or a decrease in their quality, including a decrease in the production of oils in the surface layer, which leads to faster evaporation, or a decrease in the production of mucin in the inner layer, which does not allow for an even tear adhesion. However, changes in the tear film caused by cosmetic eyelid surgery are not taken seriously. The image above shows tear film abnormalities caused by various dry eye conditions. So what changes does eyelid surgery cause? Most commonly, it causes the lower eyelid to shift downward in position and the lid fissure to passively open up. This forces the tear film area to expand in the open eye state. Since the size of the lid fissure and the eyeball are matched in each individual, if the lid fissure is caused to open up later in life, the eyelid closure is slightly out of place when blinking, the tear river is affected, and the surface tension of the tear film is not enough to maintain the enlarged area. This leads to a shortening of the tear film rupture time TBUT, which in turn leads to a number of symptoms such as dry eye and others. The same is true for eye opening surgery. It is possible for these symptoms to either compensate or return over time, or they may persist. Therefore, this type of surgery must take these changes in the patient into account. As shown above, after lower eyelid blepharoplasty, the lower lid margins move significantly downward, resulting in ocular surface overexposure, and the tear film breakup time is then shortened, and varying degrees of dry eye can occur. For blepharoplasty there are two effects. First, the lack of blepharoplasty can cause the tear film to evaporate too quickly. Secondly, it can cause a change in the strength of lid apposition, leading to lid margin friction syndrome. Above is a schematic of some eyelid surgeries that may damage the levator glands and thus affect secretion. Eyelid surgery can also lead to a blepharitis-like presentation with impaired secretion from the levator glands. However, what is more likely to be overlooked is that eyelid surgery can lead to changes in eyelid tension, mostly by making the eyelid more tightly attached to the surface of the eye. This leads to increased friction between the lid margin and the surface of the eye, resulting in varying degrees of lid-wiper epitheliopathy (LWE). Some of the potential, easily overlooked complications mentioned above can cause much of the patient’s postoperative discomfort. They should be closely monitored after surgery and artificial tears without preservatives should be used more often. If you feel uncomfortable after surgery, or even experience symptoms of stinging and tearing, you should follow up promptly.