LASIK Surgery Article

LASIK SURGERY . . .

WHEN THINGS GO WRONG

By B. Kent Buckingham, O.D., J.D.

Reprinted from TRIAL Magazine

THROW AWAY YOUR GLASSES!

This invitation has a strong allure, particularly to those folks who have been saddled with thick glasses in order to see clearly. In 1999, more than 500,000 Americans responded to this solicitation and underwent refractive surgery to correct their vision. This number is expected to double every year for the next several years. Millions of people will be turning to refractive surgery to cure their vision problems, but at what cost?

Since the onset of refractive surgery in the U.S. in the late-70s, there have been a number of documented surgical complications, ranging in severity from simply bothersome to devastating. This article will discuss the three primary refractive surgery modalities and the possible complications that can accompany this sought-after surgical repair.

THE ANATOMY AND PHYSIOLOGY OF THE EYE

In order to understand the mechanism of refractive surgery and its complications, it is necessary to be familiar with the anatomy and physiology of the ocular system, with a particular emphasis on the cornea as it is the sole part of the eye operated upon by refractive surgeons.

The human eye is similar to a camera where a system of lenses focuses a picture onto a light-sensitive film. The eyeball itself is essentially an opaque globe, encapsulated with a tough, protective white sheath, the sclera, and filled with a gel-like fluid called the vitreous. In the front of the eyeball, the sclera gives way to a transparent dome known as the cornea.

The cornea is similar to the crystal of a wristwatch and vaults over the anterior chamber of the eye, much as the crystal vaults over the watch-face. The cornea is a clear membrane which has the dual purpose of protecting the eye and focusing light as it enters the eye. It is maintained in a perfectly transparent state with a constant curvature. After light passes through the cornea, it then passes through the pupil, an opening in the iris (the colored part of the eye).

Functioning much like the aperture of a camera, the pupil opening can be adjusted by the iris working as a diaphragm, either dilating or contracting depending upon how much light is needed in the eye. In bright-light conditions, the iris contracts, thereby reducing the size of the pupil and limiting the amount of light which enters the eye. Conversely, in dim-light situations, the iris dilates and increases the pupillary opening to maximize the amount of light which enters the eye.

Once through the pupil, light then passes through the crystalline lens, which along with the cornea is responsible for the focusing of the eye. However, unlike the cornea, the lens of the eye is able to change its shape and thus serves to fine-tune the vision process. The lens is controlled by the ciliary muscles which relax and contract in order to change the shape of the lens. By carefully adjusting its shape, the lens assists the cornea in the critical task of producing a focused image on the back of the eyeball.

Light then passes through the gel-like vitreous and falls upon the retina, the light-sensitive tissue at the back of the eyeball (functioning much like the film in a camera) that converts the light into electrical signals. The retina contains cells, called rods and cones, which serve the task of detecting the intensity and the frequency of the incoming light. The rods and cones then send nerve impulses through the optic nerve to the brain, where translation of the impulses into vision takes place.

THE CORNEA

The cornea is approximately 500 microns thick (.5 millimeter) and is responsible for 80% of the focusing (refracting) of the light entering the eye. The cornea consists of five cell layers, which moving from the front of the eye inward are the Epithelium, Bowman's Membrane, Stroma, Descemet's Membrane, and Endothelium. The most important of these for purposes of this article are the Epithelium, the Stroma, and the Endothelium.

The Epithelium is the outermost layer of the cornea and is the eye's first barrier to infectious organisms. Riding on the very outside of the epithelium is a very thin film of water and other chemicals (salt, antibiotics, etc.) known as the tear film. The tear film lubricates the cornea and keeps it moist. A problem with the tear film causes the sensation of dry eye.

The epithelial layer is approximately 20 microns deep. Its cells are short-lived and highly regenerative. The inner cells generate the outer layer cells by splitting continuously. The cells then migrate to the top, where they die and are sloughed off during the process of blinking. Coursing through the epithelium are a tremendous number of nerve cells with bare ends. If these nerve endings become exposed to the air by the slightest defect in the epithelial surface, a corneal abrasion is created which is usually accompanied by exquisite pain.

The stroma is the thickest part of the cornea, and is about 450 microns thick. When damaged, the stroma does regenerate to some extent, however, the regeneration does not have the same architecture as the original stroma and may cause a reduction in the overall transparency of the cornea.

The cornea's innermost layer is the Endothelium and while it is only one cell layer thick (about 5 - 10 microns), it provides one of the most vital functions necessary to maintain corneal transparency - regulation of the water content of the stroma. It achieves this by actively pumping water in or out of the stroma, depending on the cellular needs. If the Endothelial layer is disrupted, the cornea becomes cloudy, greatly impairing its ability to pass light into the eye.

REFRACTIVE ERRORS

In order for our eyes to be able to see, light rays must be bent or "refracted" so they can precisely focus upon the retina. A refractive error means that the optics of the eye do not refract the light properly, so that the image formed on the retina is blurred. While refractive errors are called eye disorders, they are not diseases. There are three primary refractive errors which are addressed by refractive surgery: myopia, hyperopia, and astigmatism. Myopia is by far the most prevalent of the refractive errors and comprises the bulk of the refractive surgeon's patient base.

Myopia (nearsightedness) is where the distance vision is blurred at all times while near vision is often excellent within a certain range. In the myopic eye, the image ultimately comes to a focus at a point in front of, rather than directly on, the retina. Myopia is due to an excessively long eyeball and/or a cornea that is too steeply curved, creating an excessive amount of focusing. It is this corneal curvature which is altered in the various refractive surgery techniques to be discussed.

Conversely, hyperopia (farsightedness) is the refractive condition where near objects may appear blurred while distant objects typically appear clear. As with myopia, there are two explanations for this optical condition. The eyeball may be too short, causing the image to be virtually focused past or behind the retina. Or, more likely, the curvature of the cornea is too flat, causing the light entering the eye to not be adequately refracted enough to come to a point focus directly upon the retina. Although the hyperopic eye is deficient in focal power, it can sometimes correct for this situation by requiring the internal crystalline lens to add the additional needed power. In small amounts of hyperopia, the eye can compensate for the refractive error. As the amount of hyperopia increases, the ability of the ocular system to deal with it declines and near objects cannot be brought into focus. At higher levels, even distant objects become blurry.

The third refractive error dealt with through refractive surgery is astigmatism. Astigmatism occurs because the cornea's curvature is not uniform, the effect is that vision is distorted or blurred for both distance and near. In an astigmatic eye, the cornea is shaped like a somewhat flattened football, with the flatter curvature usually along the horizontal. Observable distortion occurs when the cornea has excessive flattening (or steepening) in one meridian more so than another. Astigmatism can occur alone as the sole optical error; however, it more often occurs combined with myopia or hyperopia.

Refractive errors are measured in Diopters. Myopia is measured in terms of minus "-" diopters, hyperopia in "+" diopters. Nearsightedness requiring up to -3.00 Diopters of corrective power would be considered mild myopia, requiring -3.00 to -6.00 moderate, and above -6.00 Diopters is high myopia. Hyperopia tracks the same nomenclature with "+" Diopters.

REFRACTIVE SURGERY MODALITIES

The intent of refractive surgery is to change the natural curvature of the cornea in order to alter the eye's focusing power ... to make a myopic cornea flatter or a hyperopic cornea steeper. There are three primary surgical techniques in the refractive surgeon's arsenal to accomplish this goal: Radial Keratotomy (RK), PhotoRefractive Keratectomy (PRK), and Laser ASsisted In-situ Keratomileusis (LASIK).

Radial Keratotomy (RK) was pioneered in the early 1970s by Vyataslov Fyodorov, a Russian eye surgeon. By the end of the 70s, a number of U.S. eye surgeons had traveled to Russia to learn the procedure and import it back to their U.S. practices. It is the simplest to perform of the three techniques and is used primarily to "cure" low to moderate amounts of myopia. As it requires no special medical device, i.e., a laser, its performance is not monitored by the FDA.

All of the techniques begin with applying topical anesthesia to the eyeball. These eye drops numb the cornea to any sensation. With the RK procedure, some surgeons in the past have used a local injection of anesthesia behind the eye. However, as will be discussed, this occasionally led to devastating vision loss and has been largely abandoned to the safer and easier application of eye drops.

Once the cornea is sufficiently numb, the lids are then retracted and the cornea is marked with a special ink. This is to delineate the diameter of a clear zone directly in front of the pupil. Unlike PRK and LASIK (where the central cornea is the area of operation), RK is performed solely on the corneal periphery. The reason being that the incisions form scar tissue when healed. If incisions were made in the central cornea, the resulting scar tissue would distort the light rays entering into the pupil, causing severe visual disturbances.

Using an operating microscope, a diamond-edge scalpel is then used to cut a number of radial incisions (up to 90% of the corneal depth) in the periphery of the cornea, similar to cutting a pie. The number of incisions and their depth is dependant upon the amount of flattening of the cornea that is required to obtain a proper focus on the retina. The greater the amount of myopia to be treated, the higher the number of incisions and the deeper they are made. The incisions slightly weaken the peripheral cornea, causing it to bulge. This peripheral bulging in turns flattens the center of the cornea, weakening the focus power, and causing the focal point of light entering the eye to move backwards onto the desired retinal surface.

In the early 80s, eye surgeons became aware of the Excimer laser, then being used in the computer chip industry. While most surgical laser beams affect tissue by producing heat, the Excimer laser uses a charged mixture of argon and fluorine gases to produce a cool beam of ultraviolet light. The beam breaks the molecular bonds between cells and vaporizes tissue, one microscopic layer at a time. The Excimer laser was formally approved for use in PRK in 1995, although many eye surgeons were flying their patients to Mexico or Canada prior to that to circumvent the FDA prohibition.

In PRK, the Excimer laser is used to reshape the cornea in an effort to effect a change in the refractive characteristics of the eye and thereby correct or lessen myopia, hyperopia, and/or astigmatism. Before the laser is applied, the epithelial layer of the cornea is removed by either mechanical means (simply scraped away) or chemical (application of alcohol solution). The laser is then used to photoablate (vaporize) several microns of tissue from the central and mid cornea. Usually from 3% to 15% of the central corneal tissue is utilized for corneal reshaping for myopic corrections from -1.00 to -7.00.

The epithelium usually regrows over the treated area within several days. To reduce the amount of myopia in the eye, the cornea is flattened by removing more tissue from the center of the cornea than from the midzone cornea. The resultant central corneal flattening moves the focus point farther back toward its desired spot on the retina. To reduce hyperopia, more tissue is removed from the midzone cornea, thereby steepening the central cornea.

The LASIK procedure is similar to PRK (photorefractive keratectomy) but does not treat or alter the very front surface of the cornea (epithelium). In the LASIK procedure, a liquid anesthetic is dropped into the patient's eye, numbing it for surgery. The surgeon then props the eyelids open and marks the cornea with water soluble ink to guide in the later repositioning of the flap. A suction ring is placed on the eye to secure the eye and maintain pressure within the eye while the cornea is drawn outward.

Simultaneously, a microkeratome (similar to a carpenter's plane, but automated) is placed in the track of the suction ring. The blade of the microkeratome then moves across the cornea, creating a flap of corneal tissue some 30-40% of the total corneal thickness. This layer (down into the corneal stroma) is not cut away completely, but remains attached at one side and is then opened like a door on a hinge to reveal the stroma beneath.

Once the upper corneal flap has been folded back, the excimer laser is then employed to ablate (vaporize) the amount of underlying corneal tissue necessary to reshape the corneal curvature to the desired degree. To correct myopia, the laser trims the cornea's center, making it flatter. For hyperopia, a doughnut-shaped ring of tissue is removed. The laser is programmed to ablate the necessary amount with a modified version of the patient's glasses or contact lens prescription. The corneal flap is then repositioned to its original position on the stromal bed where it adheres over the next several months. As in the other procedures, the eye is then treated with antibiotics, covered with a shield, and the patient is sent home to recover.

COMPLICATIONS

In Refractive Surgery, there are a number of complications that should be anticipated by the surgeon and explained to the patient. The nature of these complications range from problems that, at best, are quite bothersome to those who suffer from them to the worst case scenario . . . the loss of an eye. As the procedures of refractive surgery have been refined over the last two decades, the incidence of the worst case scenario has decreased to almost being nonexistent; however, the lesser problems continue to plague some unfortunate patients who experience a less than perfect outcome.

In RK, the corneal incisions are very effective at changing the shape of the eye, however, complications are substantially more common, and potentially more devastating, with RK than with laser refractive surgery. This is due to the procedure itself as the corneal incisions go almost all the way through the cornea.

During the RK incision procedure, it is quite easy have perforations of the cornea where the fluid between the cornea and the iris (the aqueous) leaks out.⁽¹⁾ This allows an easy access for bacteria to enter into the eye itself. Once bacteria are able to breach the natural corneal barrier, a severe infection called endophthalmitis can take place in which the entire eyeball is infected, many times leading to total blindness.⁽²⁾ There are also reported cases of corneal ulcerations occurring post-RK. Ulcerations can be not only difficult to heal, but due to the resultant scarring, may ultimately require a corneal transplant (penetrating keratoplasty) in order to obtain clear vision.⁽³⁾

Another complication arising out of RK surgery is that of cataract formation. Cataracts form in the crystalline lens of the eye (discussed above) and cause the lens, usually totally transparent to become so cloudy that light no longer can pass through to reach the cornea. The reason for this complication is not clearly understood, but is thought to be related to the possible corneal perforations that can occur using the diamond-blade scalpel. Perhaps there is some mechanical injury to the lens at the point of corneal perforation. While a cataract can be removed and a lens implant performed, this requires additional open eye surgery with the attendant risks of infection, etc.⁽⁴⁾

In the past, some surgeons used a retrobulbar (behind the eyeball) injection of anesthesia to numb the whole eye prior to performing RK. Not only is this overkill (as it is only the cornea which requires anesthesia), but it led to acute optic atrophy in a number of cases. This results in complete loss of vision in that eye.⁽⁵⁾

While RK may still be recommended for certain selected situations, it is rapidly being supplanted by laser surgery (PRK and LASIK) for most vision correction applications. Laser surgery is somewhat safer and more predictable than RK, and to a large extent, reduces the rare but more serious complications of RK surgery described above. However, laser surgery is not without its attendant risks and it has been noted that the "[S]tandards for the safety and predictability of ...PRK must be high, because these are elective procedures to correct myopia, a nonblinding, optically correctable disorder."⁽⁶⁾

The primary complication of PRK, particularly with correction of high amounts of myopia, is that of scarring of the central cornea where the laser ablation takes place. This scarring acts as a diffuser of the light passing through the central cornea and, due to creation of haze, causes a reduction in vision.⁽⁷⁾ This light diffusion also greatly contributes to patients' complaints of glare and halos.⁽⁸⁾

Interestingly, these complaints are sometimes extremely disabling to a patient, to the point of preventing night driving and creating poor visual function at low light levels. Yet, they are rarely considered by the surgeons in determining their statistical successes. Most of the medical literature on refractive surgery complications speaks solely to achieving a visual acuity of 20/20 as a success; however, many patients who can read the 20/20 line postoperatively are not able to function well in the "real" world due to problems with glare, halos, and double vision. This is part of the growing frustration among patients who, while being told they are a success by their refractive surgeon, feel otherwise when they can't drive at night or go to the movies.

LASIK, while not creating the amount of central corneal scarring as PRK, brings its own set of complications due to the necessity of creating the corneal flap. "Flap abnormalities are the most feared of LASIK complications and have the potential for serious visual loss. They range from catastrophic to insignificant."⁽⁹⁾ One of the most serious risks has been identified as human error in the placing the plate controlling the depth of cut into the microkeratome. When this occurs, the cornea can be completely perforated while the contents of the eye are under high intraocular pressure (due to the prior placement of the suction ring to assist in cutting the flap). The resultant blow-out can cause extensive damage to the inner structures of the eye.⁽¹⁰⁾ The potential for this risk has been alleviated to some extent with the development of newly designed microkeratomes; however, the older models may still be in use in some surgical centers (see Strategies below).

A more common problem with the flap is loss of suction during the microkeratome cut. This may cause an incomplete cut or a thin flap. If this occurs, most surgeons will replace the flap and abort the procedure for the time being. The surgery can be attempted again in approximately three months with no reduction of expected success.

Another flap problem is the formation of wrinkles or flap misalignment.⁽¹¹⁾ This may result in reduction in acuity due to the creation of irregular astigmatism. It would be similar to looking through a wrinkled piece of Saran Wrap. Flap wrinkles are usually detected at the end of the LASIK procedure after the flap in put back into place. If wrinkles are detected, they are usually eliminated by repositioning and smoothing of the flap. In some cases of extreme wrinkling, it may be impossible to eliminate through flap adjustment and will require the wearing of a gas-permeable contact lens in an attempt to restore good vision.⁽¹²⁾

One final complication of LASIK is that of epithelial growth into the cornea stroma which can produce significant vision problems.⁽¹³⁾

This occurs when the epithelium lining the front of the cornea begins to grow into and invade the stroma area. If this ingrowth remains on the periphery of the flap, it is of little subsequence. However, if it continues to grow on across the visual axis (the central part of the cornea), it can begin to interfere with light passing through to the pupil. It may also cause a lifting of the cornea thereby creating irregular astigmatism with subsequent vision problems. Epithelial ingrowth is usually dealt with by a re-operation where the flap is removed once again and the ingrowth is scraped away. If that fails, laser ablation is applied to the affected area.

CASE STRATEGIES

One area to pursue in discovery is all advertisements done by the surgeon, any members of the co-management team, or the laser center where the surgery is performed. Many times, the advertisements are created by marketing consultants and will provide fruitful cross-examination material with such claims as "Throw your glasses away" or claims that the procedure is "safe and effective."

Another issue will be the possible defendants to the suit. Most laser surgeries are handled by a team of eye doctors as "co-managers," which consists of the ophthalmologist who actually performs the procedure and the referring optometrist who provides the pre- and post-operative care.

An optometrist has the degree Doctor of Optometry (O.D.) and is a primary vision care specialist. Following college, they complete a four-year doctorate program. The course of study includes basic medical anatomy and pharmacology and specific courses relating to the diagnosis and treatment of disorders and diseases of the eyes and vision system. An optometrist will examine the eyes and related structures for health and vision disorders and treats vision problems with glasses and contact lenses. In most of the states, optometrists can treat certain eye diseases. The scope of their practice and the type of eye diseases they may medically treat varies from state to state.

The ophthalmologist has either an M.D. or an D.O. (Doctor of Osteopathy) and is a primary and secondary, medical/surgical eye care provider. Following college, they then complete four years of medical school and a residency training relating to the diagnosis and treatment, including surgery, of eye diseases. Ophthalmologists perform surgical procedures including cataract removal and various repairs and therapies utilizing lasers. In some states, they also provide vision examinations and may dispense contact lenses and eyeglasses.

The larger laser surgical centers typically strive to set up a network of referring optometrists to feed the surgical requirements of the centers. The typical fee for refractive surgery per eye is $2,200. This fee is then distributed as follows: $250 to the laser manufacturer as a use of patent fee, $750 to the referring optometrist as payment for pre- and post- care, $400 to the surgeon, and $800 to the surgery center. A laser surgeon affiliated with the right surgery center can easily perform thirty or more procedures a week.

Due to the surgeon's volume approach, there is little time for patient interaction. Most, if not all of the patient education, is provided by the referring optometrist. This gives rise to at least two defendants, the surgeon and the optometrist, in a case based on lack of "informed consent." Many prospective patients, due to media reports and input from friends, approach refractive surgery with a rather caviler attitude. It is incumbent on the co-management team to clearly explain to the patient the risks that are involved and assure that the patient truly appreciates the procedure they are about to undertake.

There are also liability considerations as to the possibility of negligent referral on the part of the optometrist if he fails to adequately investigate the surgeon to whom he refers his refractive surgery patients. Question the referring optometrist as to what type of investigation he performed prior to making the referral. Did he determine if the surgeon was board-certified? Did he ascertain if the surgeon was going to use state-of-the-art surgical equipment? How many of the specific surgeries had the surgeon performed (was he still in a learning curve for the procedure)? What was his rate of complications or adverse outcomes? Find out if there is a possibility that the main reason for the referral to a particular surgeon is obtaining his "cut" of the refractory surgery charge that perhaps a better-qualified surgeon in the area does not return to the referring optometrist.

Other possible defendants are the surgery center and the equipment manufacturers. Many times, a problem that arises during refractive surgery has do to with the equipment provided by the center. Is there a failure of the microkeratome due to a "bad" blade or a loss of vacuum suction on the eye at a critical point? Was there a failure on the center's part to change out the microkeratome's blade before each procedure? Was there a human failure when the center's technician calibrated the surgical equipment? If they reuse the equipment, is there a failure to adequately sterilize between patients and thus create a source of infection?

RESOURCES

There is a wealth of information available on the Internet. In addition to the usual medical literature sources, there are a number of sites created by various associations interested in the area of refractive surgery that can provide relevant information, i.e. http://www.usaeyes.org/ and http://www.eyenet.org/. In addition, there are sites set up by folks who had less than ideal outcomes from refractive surgery and are eager to warn others of the dangers of refractive surgery. Examples of this type of webpage can be found at http://www.surgicaleyes.org and http://members.aol.com/eyeknowwhy/.

Also consider using illustrations from various webpages as trial exhibits which, with the help of your experts, will allow the jury to visually understand what your client sees. Several sites use digitally altered photographs to depict the visual problems seen by patients with bad surgery outcomes, i.e. http://www.surgicaleyes.org, http://home.pacbell.net/kensian1/moon.htm, and http://hem.passagen.se/rhn/eyes/.

CONCLUSION

With the anticipated explosion in refractive surgeries predicted to occur, we will all be seeing someone who had a less than satisfactory result. They turn to us to be their champions. As with every case we handle, it is incumbent upon us as trial lawyers to thoroughly understand and evaluate our clients' cause and fight the good fight.

B. Kent Buckingham, formerly an eye doctor, now practices medical malpractice law with The Buckingham Law Firm in Midland, Texas. His e-mail address is kentb@medmal-law.com.

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