The cornea is the transparent eye tissue found in the outermost layer of the eye. It works to protect the eyes from dirt and germs, as well as filtering out the small sounds of ultraviolet light.
Thin corneas are when the thickness falls below 500 microns (half a millimeter) as the average normal thickness of a cornea is about 540 microns.
They can lead to a variety of vision symptoms that can have both short-term and long-term effects. Additionally, it may disqualify you from certain eye surgeries.
The cornea is altered when LASIK is performed, as it is responsible for how light enters the eye, which influences the range of vision. During a LASIK procedure, the surgeon cuts a flap in the cornea, disarticulates it, and then uses a laser to cut tissue and reshape it. The more myopic you are, the more tissue the doctor will have to remove. After this procedure is complete, the flap is replaced and given time to heal.
However, with some patients, the corneas are not thick enough to withstand cutting. Cutting the corneas of these patients could lead to a substantially weakened eye, something no one wants. Other problems can also develop, including ectasia, where the cornea becomes so weak that it begins to bulge outward and can even lead to permanent blindness. A notable condition of corneal ectasia is keratoconus, where the cornea bulges outward, which can worsen vision.
For this reason, the recommended procedure for patients with thin corneas is epicrystalline lens surgery, which is placed between the lens and the iris.
El Dr. José Alberto Muiños, medical director of Innova Ocular Muiños Clinic, explains in 30 seconds the other options that patients with very thin corneas have to eliminate graduation defects.