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Keratectomy is a surgical procedure that involves the partial or complete removal of the cornea. Conducted when corneal tissue is diseased or damaged, cornea removal is medical procedure usually performed on an outpatient basis. There are a number of applications associated with cornea removal, from corneal transplantation to vision correction. As with any medical procedure, there are risks associated with keratectomy and these should be discussed with an ophthalmologist prior to surgery.
Corneal transplantation is the most common application of corneal removal. During the transplantation process, a portion of the corneal tissue is excised with a laser and is replaced with that from a donor. Depending on the severity of the cornea's condition, either a partial or complete transplantation can be performed. Corneal transplant is utilized for improving vision, alleviating pain, and improving corneal appearance. Risks associated with transplantation include corneal rejection, infection, and corneal swelling.
Initially, corneal excision was conducted manually with a knife. Astigmatic keratectomy (AK) was among the first successful keratectomies performed and is still performed today. During AK, two incisions are made along marked areas of the cornea to alter and correct its shape. Though the astigmatism is alleviated, AK has been associated with an increased risk of infection, light sensitivity, and glare. Modern approaches to cornea removal are utilized for more than just astigmatism correction.
The mid-1990s ushered in a new generation of keratectomy, which was performed with a laser. Laser-assisted in situ keratomileusis, or LASIK, combined the use of an oscillating blade and a precision laser to excise corneal tissue. During LASIK, a corneal flap is created through which a small portion of the cornea is removed and a laser is used to reshape the remaining tissue. The cornea flap heals on its own without the aid of stitches. Risks associated with LASIK include infection, flap wrinkles, and corneal ecstasia, or a bulging of the cornea.
Corneal reshaping is another procedure associated with keratectomy's many functions. Though it can be conducted in a non-surgical capacity, corneal reshaping plays a pivotal role in the successful application of photorefractive keratectomy (PRK). Utilizing an ultraviolet laser, PRK is performed to reduce a patient's dependence on glasses or contact lenses.
To correct nearsightedness, an ultraviolet laser removes tissue from the center of the cornea to make the corneal surface more even. In the case of farsightedness, the opposite occurs in that the cornea is built up by the removal of corneal tissue from the external edges of the cornea. Astigmatisms are corrected by the reshaping of the cornea to a more round shape. Complications associated with PRK include corneal haze, prolonged healing time, and infection.
PRK is often combined with a corneal therapy treatment known as phototherapeutic keratectomy (PTK), which is used to treat superficial corneal scars and disease. During PTK, the outermost layer of the cornea is removed in order to form a more even corneal surface. Common conditions associated with PTK treatment include corneal dystrophies, where vision is impaired due to corneal haze; opacities, or loss of corneal transparency; and scarring. Side effects associated with PTK include visual effects, such as light sensitivity and glare, which usually diminish with time.
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