In the hands of a well-trained, experienced, and seasoned refractive surgeon, LASIK is a very good procedure with excellent results. IntraLASIK, the same procedure that uses a laser to even out the flap. An often overlooked complication of the procedure is the effect the oil glands have on the final results.
Meibomian (oil) glands, or tarsal glands as they are sometimes called, are sebaceous glands located in the tarsal plate of the eyelids. These are located near the edge of the eyelids and are responsible for the production of sebum, an oily material. This very important part of the tear film prevents tear evaporation by maintaining tear/corneal contact evenly over the entire surface. As it thickens tears, it also works to prevent tears from running down the eyelids. The final effect of the sebum is to create a tight lid-lid seal that keeps the eyes moist at night.
The upper eyelid has about 50 glands and the lower 25. These very important organs were first mentioned in the late 1600s by the German physician Heinrich Meibom. So how and why do these glands affect LASIK?
Meibomian glands produce the sebum 24 hours a day and secrete it into the eye at every blink of an eye. Squeezing the eyelids pushes out more sebum, making the eyes oilier.
The cornea is completely transparent and must remain so in order to see clearly. The most important point to always maintain during LASIK is to ensure that when the flap is put back in place, it returns exactly as before and that the area underneath is free of debris. Unfortunately, if the patient squeezes his/her eyes during surgery, the meibomian glands will secrete more sebum into the eye and coat the exposed surface. If this happens while the flap is lifted, the sebum will coat the inside of the cornea and cause distorted vision. When the flap is put back in place, this excess sebum is trapped under the flap. While there is no health risk from this trapped sebum, it does leave an oily residue in the center of the cornea.
The final result is an imperfect cornea. When examining these post-operative patients, one can see oily, hazy areas. The effect on a person’s vision will range from mild to severe blurriness, photophobia (glare and light sensitivity), and decreased vision. If the oil slick is off the visual axis, glare is the only visual side effect. If it is in the line of sight, most patients complain of impaired vision. In severe cases, the surgeon must operate again, lift the flap and clean the area.
The best way to avoid this surgical complication is to listen to the doctor during surgery and not blink or squirm during the procedure. That is often much easier said than done.
A LASIK complication – oil gland secretions
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