Refractive Eye Surgery: Helping Patients Make Informed Decisions About LASIK JOHN M. WILKINSON, MD; ELIZABETH W. COZINE, MD; and AMIR R. KHAN, MD, Mayo Clinic College of Medicine, Rochester, Minnesota A variety of refractive surgery techniques, which reshape the corneal stroma using laser energy, have been marketed as simple and safe alternatives to glasses or contact lenses. Laser-assisted in-situ keratomileusis (LASIK) is the most common of these procedures. Although there are few high-quality prospective studies of long-term outcomes, com- plications, or stability for refractive surgery procedures, there is at least general agreement that more than 90% of appropriately selected patients achieve excellent uncorrected distance vision. In addition to well-recognized contra- indications (e.g., unstable refraction, pregnancy and lactation, chronic eye disease, systemic illness, corneal abnor- malities), there are other conditions that warrant caution (e.g., excessively dry eyes, contact lens intolerance, chronic pain syndromes). Postoperative dry eye, which may in part represent a corneal neuropathy, usually resolves after six to 12 months but persists in up to 20% of patients. Up to 20% of patients may have new visual disturbances, particu- larly with night driving. Vision-threatening complications are rare. Intraocular lenses, implanted following cataract extraction, may be an alternative to LASIK in older patients. Although the overall dependence on corrective lenses is markedly reduced, many patients still require glasses or contact lenses after LASIK, particularly in low-light condi- tions and as they age. Most patients report satisfaction with the results. Family physicians can help patients make informed decisions by exploring their values, preferences, expectations, and tolerance of uncertainty and risk. (Am Fam Physician. 2017;95(10):637-644. Copyright © 2017 American Academy of Family Physicians.) CME This clinical content ver the past two decades, a vari- various persistent adverse effects, certain conforms to AAFP criteria ety of refractive surgery tech- individuals should approach these proce- for continuing medical education (CME). See niques have been developed dures with caution. In addition, younger CME Quiz Questions on and marketed as simple and patients may not fully consider the possibil- page 622. Osafe alternatives to glasses or contact lenses. ity of long-term issues, such as changes in Author disclosure: No rel- Laser-assisted in-situ keratomileusis (LASIK) visual stability. evant financial affiliations. is the best-known and most widely per- Although most patients are satisfied with ▲ Patient information: formed technique. the outcomes following LASIK surgery, a A handout on this topic is Approximately 600,000 individuals, usu- small number are not.3,4 The determinants available at http://www. ally in their 30s with discretionary income, of both satisfaction and dissatisfaction are aafp.org/afp/2017/0515/ undergo LASIK or similar procedures each highly subjective and unpredictable. Most p637-s1.html. year in the United States. Its popularity in studies reporting on subjective complaints this country has decreased from a peak of lack objective data concerning persistently 1,400,000 procedures in 2006 for reasons bothersome symptoms, and cannot dis- that are not entirely clear, although millions tinguish between refractive error remain- of persons worldwide, particularly in Asia, ing after surgery and adverse effects of the still choose refractive surgery.1,2 surgery itself.3 This article updates a prior There are few high-quality prospec- review5 and provides a framework to help tive studies of refractive surgery. Existing patients make informed decisions. evidence is limited by small series, short follow-up, lack of standardized outcomes Refractive Error and Options measures, lack of pre- and postoperative for Correction visual symptom comparisons, and continu- Most refractive errors are caused by a mis- ally changing technology. Overall, there is match between the optics of the cornea and general agreement that refractive surgery lens and the length of the globe. This results is safe and effective.3 However, because of in images that are focused in front of the MayDownloaded 15, 2017 from ◆ Volumethe American 95, NumberFamily Physician 10 website at www.aafp.org/afp.www.aafp.org/afp Copyright © 2017 American Academy of FamilyAmerican Physicians. Family For the Physician private, noncom 637- mercial use of one individual user of the website. All other rights reserved. Contact [email protected] for copyright questions and/or permission requests. Refractive Eye Surgery Retina Lens Retina Lens Cornea Cornea Focal Focal point point behind the retina 2008 MAYO 2008 MAYO © © COPYRIGHT COPYRIGHT COPYRIGHT COPYRIGHT Figure 1. Emmetropia. With emmetropia, the optics of the Figure 3. Hyperopia. With hyperopia (farsightedness), the cornea and lens are perfectly matched to the length of eye is too short, and images are focused at a point behind the globe, and images are focused directly on the retina. the retina. Used with permission from Mayo Foundation for Medical Education and Used with permission from Mayo Foundation for Medical Education and Research. All rights reserved. Research. All rights reserved. Lens Retina Lens Retina Cornea Cornea Focal point No sharp focal point achieved 2008 MAYO 2008 MAYO © © COPYRIGHT COPYRIGHT COPYRIGHT COPYRIGHT Figure 2. Myopia. With myopia (nearsightedness), the eye Figure 4. Astigmatism. With astigmatism, distortions on is too long and images are focused at a point in front of the corneal surface make it impossible for images to be the retina. sharply focused anywhere. Used with permission from Mayo Foundation for Medical Education and Used with permission from Mayo Foundation for Medical Education and Research. All rights reserved. Research. All rights reserved. retina, causing myopia or nearsightedness, or focused results). Astigmatism (Figure 4) is caused by distortions behind the retina, causing hyperopia or farsightedness on the corneal surface. It is corrected by removing vari- (Figures 1 through 3). able amounts of tissue at different points. The surface epithelium of the cornea is only a few cells In all types of refractive surgery, the thicker, struc- thick and is continually regenerating; it maintains the tural, corneal stroma is reshaped, most commonly using tear film and provides a smooth refractive surface. The a pulsatile (excimer) laser to remove a preprogrammed inner endothelium maintains the relative dehydration of the cornea, which is essential for clarity. The central stroma is made up of layers of collagen and accounts for WHAT IS NEW ON THIS TOPIC: REFRACTIVE EYE 90% of overall corneal thickness. It also provides most of SURGERY the structural integrity of the cornea. Refractive surgery reshapes the cornea itself. Decreas- In the Patient-Reported Outcomes with LASIK (PROWL) ing the curvature of the cornea by removing tissue from studies, excellent visual acuity was routinely achieved, with few highly bothersome, persistent symptoms and the center corrects for myopia. Increasing the curvature very rare vision-threatening complications. However, data of the cornea by removing tissue from the periphery are limited about the long-term stability of correction. corrects for hyperopia (with somewhat less predictable 638 American Family Physician www.aafp.org/afp Volume 95, Number 10 ◆ May 15, 2017 Refractive Eye Surgery Table 1. Types of Refractive Surgery Surface ablation PRK amount of tissue from the anterior surface. Epithelium is pushed or scraped aside and must regrow; moderately Variations in how the epithelium is man- significant pain, tearing, photophobia, and blurred vision for the first aged distinguish the different procedures three to four days (Table 1).5-11 Epithelial LASIK With LASIK (Figure 5), a flap about the Epithelium is removed in a thin flap using a blade (epikeratome) and size of a contact lens and consisting of epi- may be replaced or discarded; more corneal stroma to work with than LASIK; less pain than PRK thelium supported by a thin layer of under- LASEK lying stroma is formed using a special type of Epithelium is removed using alcohol; more corneal stroma to work with cutting laser (femtosecond laser). The flap is than LASIK; less pain than PRK folded back into place and reattaches to the Stromal flap corneal surface spontaneously. LASIK With photorefractive keratectomy, instead Epithelium supported by a thin layer of underlying stroma is removed of forming a flap, the epithelium is scraped in a flap (originally with a microkeratome) produced by a cutting laser away to access the stroma. Essentially a (femtosecond); less pain than PRK large corneal abrasion is created; therefore, Lenticule extraction patients will have moderate pain and blurred FLEx vision for three to four days until it heals. Femtosecond laser cuts a lens-shaped segment (lenticule) within the Compared with surface ablation proce- corneal stroma, removed through a LASIK-like flap dures, LASIK results in less pain, less haze, SMILE and faster recovery and stabilization of Similar to FLEx, but the lenticule is extracted through a small laser-cut vision, and is a better option for correct- incision on the edge of the cornea 6 ing high myopia. Because no flap is raised FLEx = femtosecond laser extraction; LASEK = laser-assisted subepithelial keratomile- with photorefractive keratectomy, it is theo- usis; LASIK = laser-assisted in-situ keratomileusis; PRK = photorefractive