When a patient undergoes cataract surgery, a circular opening is initially caused in the front capsule of the lens and then the nucleus is removed from the inside of the lens. The remaining capsule housing supports the new artificial lens, which is typically injected through the opening in the capsule. Over time the capsule shrinks and wraps around the new lens, such as a shrunken wrapper or membrane.
As the capsule contains living cells, a layer of new cells can develop an opacification on the back surface of the lens. This is called posterior capsular opacification (PCO) or secondary cataracts and can occur in up to 25% of patients after cataract surgery.
YAG is the laser used to clear the blur behind the surface of the intraocular lens. Treatment with YAG laser is painless and is completed in a few minutes with the patient in a seated position; during treatment, the doctor may use a contact magnifying glass to target the YAG laser on the hazy layer; during treatment, patients will see flashes of light and hear a click sound; the pupil dilatation before the laser is performed to allow visibility on the rear surface of the lens.
Most patients will notice improved clarity and vision within a day. YAG laser treatment is usually performed only once.
Another application of YAG laser is to perform a microscopic hole in the iris in cases of acute closed-angle glaucoma (iridotomy)