A superficial keratectomy is a cornea procedure used to treat anterior basement membrane dystrophy (ABMD).
What Is Anterior Basement Membrane Dystrophy And How Is It Treated?
Anterior basement membrane corneal dystrophy is a condition of abnormal maturation of the epithelial cells and basement membrane that forms the outermost surface of the cornea, the clear watch crystal on the front of the eye. These abnormal cells create an irregular corneal surface which can be comprised of parallel lines, white putty-like deposits, fine haze or scarring, and even elevated nodules
What methods are employed to remove the corneal lesions?
Excising or shaving off the areas of the cornea involved with anterior basement membrane corneal dystrophy and corneal nodules can include the use of a sharp metal blade, fine diamond burr, and sometimes even the excimer laser in a procedure called PTK (phototherapeutic keratectomy). The cornea can be scraped if the lesions are superficial, or a deeper excision called a superficial keratectomy may be indicated. Depending on the extent of the keratectomy, the procedure may take place in the clinic, in the ambulatory surgical center, or at the laser center.
What are treatment alternatives?
This is an elective procedure. Patients with anterior basement membrane dystrophy often do not need to have corneal excision or superficial keratectomy surgeries. In many cases no treatment is needed. Sometimes eye drops, ointments, oral doxycycline pills, and even contact lenses may be used to smooth out the surface of the cornea thereby improving vision and reducing the incidence of painful corneal erosions. If these growths threaten sight or cause persistent discomfort, they can be removed. Another common reason to pursue this treatment is for preparation for cataract surgery in order to obtain accurate preoperative measurements.
What type of anesthesia is used?
Typically, a surgeon utilizes topical anesthetic eye drops or gels to anesthetize the eye in order to perform corneal excision or superficial keratectomy surgery. Topical anesthetics can cause ocular irritation, itching, redness, eyelid swelling, and delayed healing of the optical surface. When the procedure is done in the ambulatory surgical center, additional IV sedation can be given to help relax the patient.
What is the post-operative care?
Following excision of these growths, a bandage contact lens is often placed on the eye to reduce discomfort and assist in the healing of the corneal surface. Patients are usually treated with antibiotic eye drops to reduce the risk of infection, and steroid or non-steroidal anti-inflammatory drops to reduce post-operative pain and inflammation. Sometimes oral pain medications are needed. Patients will need to be followed closely until the corneal surface heals.
What are the main risks of corneal excision and superficial keratectomy?
The most common risk of the procedure is a shift in the refractive error of the eye. This shift usually takes 4-6 weeks to stabilize and during this time patients often note glare, halos around lights and can have double visision. Vision threatening risks are usually due to delayed healing and can involve infection and ulceration of the cornea. Severe cases of infection and ulceration can lead to loss of corneal clarity or scarring. In rare cases, uncontrolled infection can lead to melting or perforation of the cornea. In any case, the abnormal tissue from anterior basement corneal dystrophy including the nodules may grow back. Often underlying dry eye must be addressed.