Refractive Surgery for Active Patients
Weighing the Pros and Cons
Bruce H. Schwartz, MD; Bruce M. Zagelbaum, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 10 - OCTOBER 1, 1999
In Brief: Athletes who need corrective lenses may ask about refractive surgery. Radial keratotomy, photorefractive keratectomy, and laser in situ keratomileusis surgically alter the shape of the cornea. All three methods generally result in vision sufficient to pass a driver's test without corrective lenses. A thorough patient evaluation and education about risks must be undertaken before an active patient undergoes any type of refractive surgery.
In spite of the major role of visual acuity in athletic performance, active patients may find glasses or contact lenses a hindrance to peak performance. In the late 1920s, for example, George Torporcer of the St Louis Cardinals, the first infielder to play professional baseball while wearing glasses, had them broken five times by the ball (1). Even though they may need them, many athletes refuse to wear corrective lenses while playing. The athletic patient looking for any legitimate competitive advantage may therefore be enticed by the idea of surgery that alleviates dependence on corrective lenses.
Refractive surgery may eliminate the need for corrective lenses in some—but not all—patients, but it may carry special risks in some sports. A satisfactory outcome requires that healthcare practitioners ensure a firm understanding of the benefits, risks, limitations, and alternatives before their patients undergo any refractive procedure.
Principles of Vision
Vision in which images are focused sharply onto the retina without corrective lenses is called emmetropia; possible refractive errors are myopia (near-sightedness), hyperopia (farsightedness), and astigmatism (uneven vision). Figure 1 (not shown) illustrates these conditions.
The cornea provides about two thirds of the eye's refracting power, and the remainder is provided by the lens. Since it is not possible to alter the length of the eye and not currently practical to change the shape of the lens, refractive surgery alters the curvature of the cornea so that a sharp image is transmitted onto the retina.
Any patient who desires refractive surgery, regardless of his or her activity level, must meet certain requirements. The patient should discuss the topic carefully with an eye-care provider and should be encouraged to ask questions. The surgeon is responsible for making sure the patient fully understands possible complications and limitations.
Requirements. A candidate for refractive surgery must be at least 18 years of age, not pregnant or nursing, and able to demonstrate a stable corrective lens prescription for at least 1 year. Because contact lenses may alter the curvature of the cornea, prospective patients should discontinue soft lenses for 1 week and rigid lenses 3 to 4 weeks before undergoing a preoperative examination.
Contraindications. Patients should be free of any ocular or medical conditions that would contraindicate refractive surgery as determined by the surgeon. Ocular contraindications include keratoconus, severe dry eye, corneal scarring (from herpes simplex, herpes zoster, chemical burn, etc), severe uveitis (intraocular inflammation), and severe untreated blepharitis. Medical contraindications include collagen vascular diseases, keloid formation, poorly controlled diabetes mellitus, and an immunocompromised state (a relative contraindication).
Risks. Refractive surgery should not be thought of as risk-free. Current procedures have in common the potential—though low—risk of a loss of best-corrected visual acuity, under- or overcorrection, and surgically induced astigmatism. In addition, higher levels of myopia may not be completely corrected, necessitating enhancement surgery. Based on clinical observation, sight-threatening complications, while possible, are rare. Although rare, infection has also been noted. Complications specific to each surgical technique are discussed below.
Limitations. Despite the precision of the most recent surgical methods, the healing response can be unpredictable, and unless the surgeon informs the patient of potential limitations to the surgery, the outcome may be disappointing to both patient and surgeon.
Nearsighted patients who can read without corrective lenses should be informed that, if they have surgery, when they reach their 40s or 50s they may need glasses to read. For patients who currently require reading glasses, refractive surgery can correct distance vision but not close vision, for which glasses may still be required. The best candidates for refractive surgery are those who accept the possibility that they may need to wear glasses some of the time after surgery.
The three most common refractive surgeries currently performed in the United States are radial keratotomy (RK), photorefractive keratectomy (PRK), and laser in situ keratomileusis (LASIK). RK is the oldest and most studied of the modern refractive surgeries, but PRK and LASIK have rapidly become the safest and most frequently performed. The choice of procedure depends on the extent of the refractive error and the surgeon's comfort level with a particular procedure. Procedures are continually being refined (see "Future Surgical Directions," below).
Because these procedures are most commonly used to treat myopia, most of the following discussion will involve management of this refractive error.
With origins dating back to the 1930s, RK was introduced in the United States in 1978, and its popularity grew in the late 1980s and early 1990s. RK is best suited for patients with a correction up to approximately -6.00 diopters of myopia. At greater levels, the procedure is less predictable.
Technique. While technique has evolved, the basic principles have remained. After anesthetic eye drops (topical anesthesia) are given, a thin diamond surgical blade is used to make a series of radial incisions into the cornea to a maximum depth of 90% to 95% (figure 2). These incisions induce peripheral steepening of the cornea, which in turn causes flattening of the central cornea. This results in images coming into focus on the retina.
The amount of correction can be altered with the length and depth of the incisions. Variations in RK have also been developed that include the use of hexagonal cuts for treating hyperopia and arcuate cuts for treating astigmatism; in addition, radial incisions can be combined with arcuate cuts to treat myopia accompanied by astigmatism.
Outcome. Visual recovery is rapid, with little discomfort. RK patients with satisfactory postoperative visual acuity, however, may still be bothered by fluctuating vision, glare, decreased contrast sensitivity, or photophobia. Other complications can include the appearance of circular or star-shaped halos around lights, hyperopic shift, monocular diplopia (double vision in one eye), light sensitivity, traumatic rupture of scars, corneal edema, epithelial ingrowth, erosions, and nonhealing epithelial defects.
In 1980, the prospective evaluation of radial keratotomy (PERK) study (2) was initiated, which evaluated the effectiveness of RK for the treatment of myopia of -2.00 to -8.75 diopters. The results of this study have been the standard for evaluating RK results. The 10-year results (3) showed that 53% of patients had 20/20 or better uncorrected visual acuity and 85% had 20/40 or better (20/40 is necessary to pass a standard driver's license eye test). Approximately 3% of patients experienced a decrease in best-corrected visual acuity. An important finding was that the procedure did not appear to provide long-term stability of refraction, and a hyperopic shift was found in 43% of eyes between the subjects' 6-month and 12-year follow-ups. It is not known whether this trend will continue as patients are evaluated at 15- and 20-year follow-ups.
Although perhaps the refractive procedure of choice for most surgeons years ago, RK has largely and justifiably been supplanted by the more recent laser procedures, PRK and LASIK.
The excimer laser used in PRK delivers pulsed ultraviolet light to penetrate only a small distance into corneal tissue and works by breaking chemical bonds instead of destroying tissue with heat. In 1995, this instrument was approved by the US Food and Drug Administration (FDA) for treatment of mild to moderate myopia. Recently, FDA approval was obtained for its use in treating astigmatism and low to moderate levels of hyperopia.
Technique. Although PRK does not involve use of a surgical blade to make corneal incisions, it is still considered a surgical procedure. Like RK, the procedure is performed using topical anesthesia. Following removal of the corneal epithelium (the superficial layer of the cornea) over the pupil area, the excimer laser is used to remove precise amounts of corneal tissue, thus reshaping the anterior corneal surface (figure 3).
After surgery, the patient uses antibiotic eyedrops along with a therapeutic contact lens placed over the eye for 2 to 3 days for protection while the surface heals. Corticosteroid eyedrops are used postoperatively for months.
Outcome. With PRK, vision recovery takes slightly longer than with other refractive procedures and may be associated with discomfort because surface healing of the cornea is involved. Visual acuity is usually diminished for several days because of the resultant temporary epithelial defect created over the laser-treated ablation zone. The patient, however, can function well during this time.
Patients may experience glare and halos after PRK, though usually less frequently than RK patients. Patients also may develop haze from stromal scarring that usually diminishes with time and is occasionally associated with a decrease in visual acuity. Haze tends to be more significant with treatment of higher levels of myopia. Results by 6 weeks following the procedure are similar to the more recently developed LASIK, described below (4). Regression (loss of treatment effect) and central islands may also be associated with PRK. In addition, PRK patients may rarely develop cataracts or glaucoma as a reaction to postoperative corticosteroids.
In the low-to-moderate range of myopia (-1.00 to -6.00 diopters), PRK appears to offer predictable and stable visual acuity (5-7). Recently, a 2-year follow-up study (8) was obtained in the phase III clinical trial of PRK for patients with -1.50 to -6.00 diopters of myopia. Results showed that 66.5% of treated eyes had 20/20 or better uncorrected visual acuity and 92.5% of patients had 20/40 or better uncorrected vision. From 18 to 24 months postoperatively, 96.3% of patients had a stable refraction within 1 diopter of emmetropia.
The authors found that in most eyes, acuity is maximized at 3 months, but some may need 6 to 12 months. With higher degrees of myopia (-8.00 diopters or more), results with PRK are less predictable, and patients' final refractive outcomes may take longer to stabilize (9,10).
After their vision has stabilized, patients whose vision is undercorrected can undergo an additional enhancement, if indicated.
Laser in Situ Keratomileusis
LASIK involves the use of a surgical microkeratome, or thin surgical blade, to create a corneal flap that is hinged (figure 4). Patient selection for LASIK is similar to PRK but with an approximate refractive error of -4.00 to -24.00 diopters being considered. Some surgeons, though, are performing LASIK on eyes with as little as -0.50 diopters of myopia.
Technique. Like RK and PRK, LASIK is performed using topical anesthesia. With LASIK, as with PRK, the underlying corneal bed is treated with the excimer laser. With LASIK, however, the surface tissue is left partially attached and repositioned after laser treatment, allowing a more rapid and less painful recovery than with PRK. The patient then usually uses antibiotic-corticosteroid eye drops for 4 days after the procedure.
Outcome. Because LASIK requires a greater learning curve and level of surgical skill as well as perfect functioning of the microkeratome, the potential exists for more frequent and more serious intraoperative complications than with RK or PRK. Inadequate suction or problems with gears, blades, or calibration of the microkeratome can result in a lost, thin, uneven, partial, free, or loose flap. Such complications occur in about 2% of LASIK cases, although resulting significant vision loss or vision below 20/40 is rare (11). Moreover, most complications do not result in permanent sequlae.
Other flap complications can include epithelialization or retained debris beneath the flap, an inflammatory reaction, dislocation, rotation, and/or folds. Refractive complications can include regression and scar formation.
LASIK has been shown to be effective for treating low levels of myopia (less than -6.00 diopters) (4,12-15). While seemingly a safe and effective procedure for all ranges of myopia, LASIK is still a newer procedure, and long-term follow-up on patients is only starting to be reported. Early reports (4,12-15) indicate that this procedure appears to offer stability equal to or greater than that with PRK. Vision-related outcomes with low levels of myopia are similar to PRK, with roughly 56% to 68% of patients obtaining 20/20 uncorrected vision and 89% to 100% obtaining 20/40 vision or better (13-15).
Implications for Active Patients
Athletes' expectations need to be understood before any surgery, and each athlete's suitability as a candidate examined.
Does the athlete expect that surgery will improve his or her performance? No guarantees of that nature can be made. Currently there is no central system for reporting the benefits and risks of refractive surgery as they apply to athletes, and our literature search yielded no data on the performance of athletes following refractive surgery. It is uncertain whether the baseball player's ability to catch a fly ball under the lights or looking into the sun will be affected. Glare and decreased contrast sensitivity have been noted but are frequently of short duration, and their implications in real-world situations have yet to be evaluated. Haze is more common with PRK than with LASIK.
The individual's acuity requirement should be considered. In baseball, a batter, for example, likely has a higher visual requirement than does a pitcher.
In addition, practitioner and patient need to discuss sport-specific risks of ocular injury. Because RK involves incisions, the structural integrity of the eye is permanently weakened. Prospective patients who are at increased risk of blunt trauma to their eyes should therefore be discouraged from RK because they may be at an increased risk of globe rupture (16). Both PRK and LASIK appear to offer better refractive stability and do not structurally weaken the eye. However, the corneal flap in LASIK can become dislodged with blunt trauma, so athletes participating in contact sports need to be made aware of this risk.
Athletes who decide to have refractive surgery should consider protective eyewear, especially if their activity puts them at risk for eye trauma. Refractive surgery should not be thought of as an excuse to go without this protection; in fact, it should encourage its use.
Ensure Clear Perceptions
Refractive surgery can be a viable alternative for active patients, but potential pitfalls of the procedure must be understood and realistic expectations ensured. Above all, whether eye surgery is performed or not, appropriate eye protection cannot be overlooked.
Future Surgical Directions
As technology evolves, results of current methods of refractive surgery continue to improve. With the advent of enhanced lasers and refined microkeratomes, PRK and LASIK may become more accurate and predictable in the management of all forms of refractive errors.
In addition, new procedures are being developed. One of these involves implantation of an intrastromal corneal ring, which allows correction of myopia without the high cost of modern lasers. This procedure is now available to the public for treating low levels of myopia. The use of intraocular lenses (lens implants) in patients who still have their natural lenses is also being studied.
Dr Schwartz is an ophthalmologist in private practice in South Bend, Indiana. Dr Zagelbaum is an ophthalmologist in private practice in Manhasset, New York, the team ophthalmologist for the New York Mets and the New York Islanders, a consultant to the National Football League, a fellow of the American College of Surgeons, and an editorial board member of The Physician and Sportsmedicine. Address correspondence to Bruce M. Zagelbaum, MD, 333 East Shore Rd, Suite 202, Manhasset, NY 11030; e-mail to [email protected].