An in-depth look into the various types of corneal surgery and who they benefit the most. Read on to see if you are a good candidate.
Corneal surgery generally refers to two types of surgeries: corneal transplantation and refractive surgery. In corneal transplantation (also called keratoplasty), the cloudy or diseased part of your cornea is replaced with corneal tissue from a donor. In refractive surgery, the curve of your cornea is reshaped to correct vision problems such as nearsightedness (myopia), farsightedness (hyperopia), astigmatism, and presbyopia. The most widely performed type of refractive surgery is LASIK (laser-assisted in situ keratomileusis). Both types of corneal surgery can restore vision; corneal transplantation can also improve the appearance of a damaged cornea and reduce eye pain as well as other symptoms of corneal disease.
A variety of conditions can affect the function of the cornea—the clear, dome-shaped surface of your eye that largely determines how your eye focuses. The reason for your corneal surgery will often determine whether your medical insurance will cover the cost. In general, corneal transplantation is usually covered, and refractive surgery is considered an elective procedure and is not covered.
According to the Eye Bank Association of America, 46,196 corneal transplantations were performed in the United States in 2011 and more than 95 percent of all corneal transplantations successfully restore the corneal recipient’s vision. The number of refractive surgeries performed in the United States each year is much higher, and has ranged from 1.4 million in 2007 (American Academy of Optometry) to 750,000 in 2011 (ASDReports).
Corneal surgery is typically done on an outpatient basis. Although most patients who undergo corneal surgery are satisfied with the results, complications can occur. In some cases, these can be corrected with further surgery.
Candidates for Corneal Surgery
Your ophthalmologist may recommend a corneal implant if you have poor vision, eye pain, or other symptoms caused by a corneal condition that cannot be managed by other measures, such as medical treatment and wearing glasses or contact lenses.
Corneal transplantation can be used to treat a number of conditions, including:
- Keratoconus, in which the cornea bulges outward
- Cloudy cornea
- Corneal thinning
- Corneal scarring caused by trauma or infection
- Corneal ulcers, including those caused by infection
- Complications caused by previous eye surgery
Most people who choose to have refractive surgery want to reduce their dependence on glasses or contact lenses. Refractive surgery may be a good option for you if you are free of eye disease and have a moderate level of myopia or hyperopia. With any elective surgery, you must accept the inherent risks and potential adverse effects of the procedure. Depending on your visual acuity before surgery, you may still need glasses or contacts after the procedure to achieve your best vision. If you cannot stare at a fixed object for at least 60 seconds, you may not be a good candidate for this surgery.
How to Prepare for Corneal Surgery
Before your surgery, you will need to do the following:
See your eye doctor to determine whether you are a good candidate for surgery. Your eye doctor will perform a baseline evaluation. Contact lens wearers will need to stop wearing their lenses for a while before the evaluation can be performed.
Tell your doctor about your past and present medical and eye conditions and provide a list of all the prescription and over-the-counter medications and supplements you are taking and any medications you may be allergic to.
Stop using eye creams, lotions, and makeup. These products may increase the risk of infection. Thoroughly scrubbing your eyelashes to get rid of any residue is important.
Arrange for transportation to and from your surgery and your first follow-up visit. On the day of surgery, your doctor may give you medicine that helps you relax, but which also impairs your vision and your ability to drive. Your vision may be blurry for a few days after surgery.
If you are undergoing corneal transplantation, your eye doctor will measure your eye to determine what size donor cornea you need. He or she will also identify and treat any conditions that may cause complications after surgery.
If you are considering refractive surgery, carefully consider the pros and cons. You should not feel pressured by your family, friends, or anyone else to make a decision about having surgery.
Corneal Surgery Procedures
In most corneal surgeries, you will be given a sedative to help you relax and a local anesthetic to numb your eye. These will prevent you from feeling any pain but will not put you to sleep.
Corneal transplantation techniques include:
This is the most common type of corneal transplantation procedure. It involves cutting into the entire thickness of the damaged cornea to remove a small button-sized disc of corneal tissue. Your surgeon will use a trephine, a tool that works like a cookie cutter, to make the cut in your cornea and then cut the donor cornea to fit the opening. He or she will then carefully sew the donor cornea into place using sutures that are thinner than a human hair. The sutures are removed after the new cornea has healed properly.
Anterior Lamellar Keratoplasty
Although there are several ways to perform this surgery, the basic procedure consists of these two steps:
The anterior corneal surface is cut with a suction trephine set to a depth of about two-thirds of the corneal thickness. Then the stromal layers are dissected with a rounded blade, angled parallel to Descemet’s membrane. Fluid or air is then injected using either a 27- or 30-gauge cannula in between the deep stroma and Descemet’s membrane to separate those layers.
Your surgeon prepares the donor cornea and removes Descemet’s membrane and endothelium by gently swabbing the posterior corneal surface of the donor corneoscleral rims with dry cellulose sponges. Forceps also may be used to remove the posterior corneal layers. Then a corneal button is punched out from the tissue. Your surgeon will choose one of several suturing techniques (interrupted, running, or combined interrupted-running 10.0 nylon sutures) to close the opening. After suturing, a soft contact lens is placed on the cornea as a bandage.
Also known as posterior lamellar keratoplasty, endothelial keratoplasty is often used for patients with Fuchs endothelial dystrophy. The procedure is performed through a small incision or two small incisions, to remove and replace the inner cell layer of the cornea without damaging the other cell layers. The diseased endothelium is gently stripped off, leaving the remaining cornea intact. Your surgeon will thinly slice the donor cornea, fold the back portion in half, and insert it through the small incision. Air bubbles are injected into the chamber to unfold and position the donor tissue on your cornea. Within a few minutes the donor tissue attaches without the use of any sutures.
Refractive surgeries can be divided into two types:
- Keratorefractive, in which the physical architecture of the cornea is altered. Common keratorefractive surgeries are Photorefractive Keratectomy and LASIK. For detailed descriptions of these procedures—what happens during and after surgery and risks of surgery—visit the pages for these procedures on this web site.
- Intraocular, in which a synthetic lens is added, with or without removal of the patient’s natural crystalline lens. Intraocular surgeries, Phakic Intraocular Lenses and Clear Lens Extraction, are more invasive than Photorefractive Keratectomy and LASIK and are used less frequently; however, they may be appropriate for certain patients.
After Corneal Surgery
Immediately after a corneal transplantation, you will receive eye drops to help your eye heal and prevent infection and rejection. You may receive other oral medications, such as corticosteroids and antibiotics, during your recovery to help control infection, swelling, and pain.
For the first few days after surgery, your doctor may ask you to wear a protective eye patch. This is to help protect your eye from injury and because the cornea tends to heal slowly. You will need to take care not to disturb the healing process, which means taking it easy for about a month after surgery and slowly resuming your normal activities.
Within the first two weeks and months of surgery, you will need to see your doctor for follow-up. During these follow-up examinations, your doctor will remove any sutures and look for complications. The frequency of your visits will depend on your situation.
For the rest of your life, you’ll need to take extra precautions to avoid hurting your eye. When participating in sports or other activities in which there is a risk of eye injury, you should consider wearing safety glasses or eye protectors.
Risks of Corneal Surgery
The major risks of refractive surgery are overcorrection and undercorrection of your vision problem. Undercorrection can be treated with further surgery. You should report any new or worsening symptoms to your doctor.
The risk of complications from corneal transplantation varies depending on how many layers of the cornea are transplanted. Your body is less likely to reject the transplant if only the outer layers are used, rather than using all the layers or the deepest layer. Rejection has been reported to occur in about 20 percent of cases, and may occur years after surgery.
Contact your doctor if you have any of the following symptoms after surgery:
- Leakage of fluid from the transplant incision
- Sensitivity to light
- Decreased, cloudy, or foggy vision
- Other vision problems
These symptoms could indicate infection, cataract formation, retinal detachment, damage to other parts of the eye, or rejection.
Talking to Your Eye Doctor
- Here are some questions to ask your eye care professional about corneal surgery:
- How will you determine which corneal procedure is best for me?
- Where will my donor cornea come from?
- How much time should I plan to take off work following surgery?
- What symptoms indicate corneal transplant rejection?
- What are the possible risks and benefits involved?
- How often is a second procedure after corneal transplantation required?
- Eye Bank Association of America, “Frequently Asked Questions, http://www.restoresight.org/about-us/frequently-asked-questions/
- American Academy of Optometry, “Position Paper on Refractive Surgery: Section on Cornea, Contact Lenses, and Refractive Technologies, Information for Eye Care Practitioners,” February, 2009, http://www.aaopt.org/Media/Default/Docs/Position Papers/AAO CCLRT Refractive Surgery.pdf
- ASDReports, “The Global Refractive Surgery Devices Market is Forecast to Exceed $800m in 2017,” February 29, 2012, https://www.asdreports.com/news.asp?pr_id=274