The cornea is the strongest refracting surface of the eye. It is, essentially, the window of the eye. It is made of several layers of tissue. The epithelial layer is the outermost layer. It has 5-7 cell layers and averages approximately 50 microns thick. The next layer is Bowman’s layer. It is the basement membrane of the epithelial layer. It serves as the “glue” that holds the epithelial layer in place. Because it is so important to our visual acuity, the cornea must remain clear at all times.
Unfortunately, there are certain conditions that can result in inflammation and permanent scarring of the cornea. This can result in permanent visual dysfunction including blurred vision and irregular astigmatism. Luckily, there is a surgical procedure that can remove any scarring or inflammation in the superficial cornea and clear the way to brighter vision. It is called Superficial Keratectomy or SK.
Because we have some of the best corneal specialists in the state here at Milan Eye Center, we perform superficial keratectomy procedures, with excellent results, on a daily basis. Some of the conditions resulting in the need for SK include:
Occasionally, if the corneal defect is minor, the procedure can be performed at the slit lamp in the examination room. However, in most cases, the procedure is performed in the operating room under topical anesthesia. Topical anesthetic is applied to numb the eye. The eye is held open by an instrument known as a lid speculum. To remove the defect, either a blunt instrument known as a corneal hoe or a sharper instrument known as beaver blade is used to gently scrape away the defective cells and scarring or inflammation if it is present. After the defective epithelial cells are removed, the underlying layers of the cornea, Bowman’s membrane, are sometimes polished with a diamond burr. Then, a bandage contact lens is used to aid in healing and for comfort. Just as its name describes, this contact lens acts like a bandage and allows the natural healing process of the cornea cells to occur. The patient is given a topical antibiotic drop to prevent infection, a topical steroid drop to decrease the inflammation, preservative free tear drops for lubrication and an oral pain medication.
The day after the procedure, the patient returns to the office for removal of the bandage contact lens and insertion of a lens made of amniotic membrane tissue, the Prokera Slim.
|The Prokera Slim is a cryo-preserved amniotic membrane tissue encased in an ophthalmic conformer.|
This tissue promotes quicker healing by decreasing inflammation and minimizes the chance of scarring. The lens is kept in place for 5 days. It can be slightly uncomfortable but, with the topical drops and oral pain medication, it is tolerated very well. After removal of the amniotic membrane, the steroid drops are used for two weeks. This limits the amount of inflammation present and will allow the cells to heal clearly. Recovery will usually take a couple weeks. During this time, the cornea will heal further and the vision continues to clear.
Superficial keratectomy is a surgical procedure that is helpful in clearing inflammation, scarring and other superficial, visually significant, defects of the corneal epithelium. It can be performed prior to cataract surgery and is a minor procedure that leads to much improved visual outcomes. With the aid of amniotic membrane therapy, the healing process is much faster, the epithelial cells are stronger, and the cornea remains clearer throughout the patient’s follow up.
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