In the hands of a well-trained, experienced, and experienced refractive surgeon, LASIK is a very good procedure with excellent results. IntraLASIK which is the same procedure that uses a laser to create the flap is uniform. An often overlooked complication of the procedure is the effect that the sebaceous glands have on the final results.
Meibomian (oil) glands, or tarsal glands as they are sometimes known, are sebaceous glands located in the tarsal plate of the eyelids. These are found near the edge of the eyelids and are responsible for the production of sebum, which is an oily material. This very important component of the tear film prevents tear evaporation by maintaining uniform contact between the tear and the cornea over the entire surface. Since it thickens tears, it also works to prevent tears from spilling onto the eyelids. The ultimate effect of sebum is to create a tight seal between the eyelids that keeps the eyes moist at night.
The upper eyelid has approximately 50 glands and the lower 25. These important organs were first named in the late 17th century by the German physician Heinrich Meibom. So how and why do these glands affect LASIK?
The meibomian glands produce sebum 24 hours a day and secrete it into the eye with each blink. Squeezing your eyelids tightly will cause more sebum to come out, which will make your eyes oilier.
The cornea is completely transparent and must remain that way in order to see clearly. The most important point to always maintain during LASIK is to make sure that when the flap is put back in place, it goes back exactly how it was before, and that the area underneath is free of any debris. Unfortunately, if the patient squeezes their eyes during surgery, the Meibomian glands will secrete more sebum into the eye and cover the exposed surface. If this occurs while the flap is being lifted, the sebum will coat the inner area of the cornea and cause distorted vision. When the flap snaps back into place, it traps this excess sebum under the flap. Although this trapped sebum does not pose a health risk, it does leave an oily residue in the middle of the cornea.
The end result is an imperfect cornea. When examining these postoperative patients, oily and cloudy areas may be seen. The effect on vision will range from mild to severe clouding, photophobia (glare and sensitivity to light), and decreased vision. If the oil slick is off the visual axis, glare will be the only visual side effect. If it is in the line of sight, most patients complain of decreased vision. In severe cases, the surgeon must go back to surgery, lift the flap, and clean the area.
The best way to prevent this surgical complication is to listen to your doctor during surgery and not blink or squirm during the procedure. This is often much easier said than done.
