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Laser refractive surgery

Kraig S Bower, MD
Section Editor
Jonathan Trobe, MD
Deputy Editor
Janet L Wilterdink, MD


Laser refractive surgery is becoming increasingly popular as people are turning to alternatives to traditional spectacles and contact lenses for vision correction. This review will briefly discuss the anatomy and principles behind visual problems and correction, and will provide an overview of laser refractive surgery.


The transparent cornea is about one-half millimeter thick and has five distinct layers. The epithelium is the most exterior layer providing the smooth refractive surface and barrier against infection. The function of Bowman's membrane, which lies beneath the epithelium and its basement membrane, is unclear. The stroma, made up of intertwining lamellae of collagen fibrils, provides structure and accounts for 90 percent of the corneal thickness. The endothelium and its basement membrane (Descemet's membrane) form the innermost layers. Endothelial cells, via an active sodium-potassium-ATPase pump, are responsible for the natural corneal dehydration necessary for corneal clarity.


Refraction is the bending of light rays as they pass from one transparent medium to another medium of a different density. Refraction is measured in diopters (D). The refractive power of a lens is the reciprocal of its focal length in meters. (See "Visual impairment in adults: Refractive disorders and presbyopia".)

In emmetropia (an eye with normal vision), the focusing power of the cornea and lens is perfectly matched to the length of the eye. Parallel light rays from a distant object are brought into focus precisely on the retina and a clear image is perceived (figure 1).

Refractive errors occur when light rays entering the eye do not focus properly on the retina:


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Literature review current through: Sep 2016. | This topic last updated: Apr 27, 2016.
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  1. Netto MV, Dupps W Jr, Wilson SE. Wavefront-guided ablation: evidence for efficacy compared to traditional ablation. Am J Ophthalmol 2006; 141:360.
  2. Krueger RR. Introduction to commercially approved wavefront-guided customization: third year in review. J Refract Surg 2005; 21:S767.
  3. Kaiserman I, Hazarbassanov R, Varssano D, Grinbaum A. Contrast sensitivity after wave front-guided LASIK. Ophthalmology 2004; 111:454.
  4. Alessio G, Boscia F, La Tegola MG, Sborgia C. Topography-driven photorefractive keratectomy: results of corneal interactive programmed topographic ablation software. Ophthalmology 2000; 107:1578.
  5. McDonald MB, Deitz MR, Frantz JM, et al. Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser. Ophthalmology 1999; 106:1481.
  6. El-Maghraby A, Salah T, Waring GO 3rd, et al. Randomized bilateral comparison of excimer laser in situ keratomileusis and photorefractive keratectomy for 2.50 to 8.00 diopters of myopia. Ophthalmology 1999; 106:447.
  7. Dulaney DD, Barnet RW, Perkins SA, Kezirian GM. Laser in situ keratomileusis for myopia and astigmatism: 6 month results. J Cataract Refract Surg 1998; 24:758.
  8. Buzard KA, Fundingsland BR. Excimer laser assisted in situ keratomileusis for hyperopia. J Cataract Refract Surg 1999; 25:197.
  9. Yoo SH, Azar DT. Laser in situ keratomileusis for the treatment of myopia. Int Ophthalmol Clin 1999; 39:37.
  10. Salah T, Waring GO 3rd, el Maghraby A, et al. Excimer laser in situ keratomileusis under a corneal flap for myopia of 2 to 20 diopters. Am J Ophthalmol 1996; 121:143.
  11. Zadok D, Maskaleris G, Montes M, et al. Hyperopic laser in situ keratomileusis with the Nidek EC-5000 excimer laser. Ophthalmology 2000; 107:1132.
  12. Lindstrom RL, Linebarger EJ, Hardten DR, et al. Early results of hyperopic and astigmatic laser in situ keratomileusis in eyes with secondary hyperopia. Ophthalmology 2000; 107:1858.
  13. Gimbel HV, Penno EE, van Westenbrugge JA, et al. Incidence and management of intraoperative and early postoperative complications in 1000 consecutive laser in situ keratomileusis cases. Ophthalmology 1998; 105:1839.
  14. Gimbel HV, van Westenbrugge JA, Penno EE, et al. Simultaneous bilateral laser in situ keratomileusis: safety and efficacy. Ophthalmology 1999; 106:1461.
  15. Durrie DS, Vande Garde TL. LASIK enhancements. Int Ophthalmol Clin 2000; 40:103.
  16. Alió JL, Ortiz D, Muftuoglu O, Garcia MJ. Ten years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for moderate to high myopia (control-matched study). Br J Ophthalmol 2009; 93:1313.
  17. Durrie DS, Slade SG, Marshall J. Wavefront-guided excimer laser ablation using photorefractive keratectomy and sub-Bowman's keratomileusis: a contralateral eye study. J Refract Surg 2008; 24:S77.
  18. Slade SG, Durrie DS, Binder PS. A prospective, contralateral eye study comparing thin-flap LASIK (sub-Bowman keratomileusis) with photorefractive keratectomy. Ophthalmology 2009; 116:1075.
  19. de Benito-Llopis L, Teus MA, Gil-Cazorla R, Drake P. Comparison between femtosecond laser-assisted sub-Bowman keratomileusis vs laser subepithelial keratectomy to correct myopia. Am J Ophthalmol 2009; 148:830.
  20. Dawson DG, Grossniklaus HE, McCarey BE, Edelhauser HF. Biomechanical and wound healing characteristics of corneas after excimer laser keratorefractive surgery: is there a difference between advanced surface ablation and sub-Bowman's keratomileusis? J Refract Surg 2008; 24:S90.
  21. Hersh PS, Brint SF, Maloney RK, et al. Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study. Ophthalmology 1998; 105:1512.
  22. Pop M, Payette Y. Photorefractive keratectomy versus laser in situ keratomileusis: a control-matched study. Ophthalmology 2000; 107:251.
  23. Shah S, Chatterjee A, Smith RJ. Predictability of spherical photorefractive keratectomy for myopia. Ophthalmology 1998; 105:2178.
  24. Corones F, Gobbi PG, Vigo L, Brancato R. Photorefractive keratectomy for hyperopia: long-term nonlinear and vector analysis of refractive outcome. Ophthalmology 1999; 106:1976.
  25. Seiler T, McDonnell PJ. Excimer laser photorefractive keratectomy. Surv Ophthalmol 1995; 40:89.
  26. Rouweyha RM, Chuang AZ, Mitra S, et al. Laser epithelial keratomileusis for myopia with the autonomous laser. J Refract Surg 2002; 18:217.
  27. Zhao LQ, Wei RL, Cheng JW, et al. Meta-analysis: clinical outcomes of laser-assisted subepithelial keratectomy and photorefractive keratectomy in myopia. Ophthalmology 2010; 117:1912.
  28. Li SM, Zhan S, Li SY, et al. Laser-assisted subepithelial keratectomy (LASEK) versus photorefractive keratectomy (PRK) for correction of myopia. Cochrane Database Syst Rev 2016; 2:CD009799.
  29. Seiler T, Koufala K, Richter G. Iatrogenic keratectasia after laser in situ keratomileusis. J Refract Surg 1998; 14:312.
  30. Stulting RD, Carr JD, Thompson KP, et al. Complications of laser in situ keratomileusis for the correction of myopia. Ophthalmology 1999; 106:13.
  31. Teus MA, de Benito-Llopis L, García-González M. Comparison of visual results between laser-assisted subepithelial keratectomy and epipolis laser in situ keratomileusis to correct myopia and myopic astigmatism. Am J Ophthalmol 2008; 146:357.
  32. Pallikaris IG, Kalyvianaki MI, Katsanevaki VJ, Ginis HS. Epi-LASIK: preliminary clinical results of an alternative surface ablation procedure. J Cataract Refract Surg 2005; 31:879.
  33. Pallikaris IG, Katsanevaki VJ, Kalyvianaki MI, Naoumidi II. Advances in subepithelial excimer refractive surgery techniques: Epi-LASIK. Curr Opin Ophthalmol 2003; 14:207.
  34. Lee DH, Chung HS, Jeon YC, et al. Photorefractive keratectomy with intraoperative mitomycin-C application. J Cataract Refract Surg 2005; 31:2293.
  35. Gambato C, Ghirlando A, Moretto E, et al. Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes. Ophthalmology 2005; 112:208.
  36. Lovisolo CF, Reinstein DZ. Phakic intraocular lenses. Surv Ophthalmol 2005; 50:549.
  37. Olson RJ, Werner L, Mamalis N, Cionni R. New intraocular lens technology. Am J Ophthalmol 2005; 140:709.
  38. Chang DH, Davis EA. Phakic intraocular lenses. Curr Opin Ophthalmol 2006; 17:99.
  39. Barsam A, Allan BD. Excimer laser refractive surgery versus phakic intraocular lenses for the correction of moderate to high myopia. Cochrane Database Syst Rev 2014; :CD007679.
  40. Igarashi A, Kamiya K, Shimizu K, Komatsu M. Visual performance after implantable collamer lens implantation and wavefront-guided laser in situ keratomileusis for high myopia. Am J Ophthalmol 2009; 148:164.
  41. Ghanem RC, de la Cruz J, Tobaigy FM, et al. LASIK in the presbyopic age group: safety, efficacy, and predictability in 40- to 69-year-old patients. Ophthalmology 2007; 114:1303.
  42. Simpson RG, Moshirfar M, Edmonds JN, Christiansen SM. Laser in-situ keratomileusis in patients with diabetes mellitus: a review of the literature. Clin Ophthalmol 2012; 6:1665.
  43. Wilson SE, Lin DT, Klyce SD, et al. Topographic changes in contact lens-induced corneal warpage. Ophthalmology 1990; 97:734.
  44. Hersh PS, Steinert RF, Brint SF. Photorefractive keratectomy versus laser in situ keratomileusis: comparison of optical side effects. Summit PRK-LASIK Study Group. Ophthalmology 2000; 107:925.
  45. Bullimore MA, Olson MD, Maloney RK. Visual performance after photorefractive keratectomy with a 6-mm ablation zone. Am J Ophthalmol 1999; 128:1.
  46. Holladay JT, Dudeja DR, Chang J. Functional vision and corneal changes after laser in situ keratomileusis determined by contrast sensitivity, glare testing, and corneal topography. J Cataract Refract Surg 1999; 25:663.
  47. Battat L, Macri A, Dursun D, Pflugfelder SC. Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface. Ophthalmology 2001; 108:1230.
  48. Melki SA, Azar DT. LASIK complications: etiology, management, and prevention. Surv Ophthalmol 2001; 46:95.
  49. McDonald MB, Carr JD, Frantz JM, et al. Laser in situ keratomileusis for myopia up to -11 diopters with up to -5 diopters of astigmatism with the summit autonomous LADARVision excimer laser system. Ophthalmology 2001; 108:309.
  50. Chayet AS, Assil KK, Montes M, et al. Regression and its mechanisms after laser in situ keratomileusis in moderate and high myopia. Ophthalmology 1998; 105:1194.
  51. Kawesch GM, Kezirian GM. Laser in situ keratomileusis for high myopia with the VISX star laser. Ophthalmology 2000; 107:653.
  52. Watson SL, Bunce C, Allan BD. Improved safety in contemporary LASIK. Ophthalmology 2005; 112:1375.
  53. Hori Y, Wantanabe H, Maeda N, et al. Medical treatment of operative corneal perforation caused by laser in situ keratomileusis. Arch Ophthalmol 1999; 117:1422.
  54. Tsuneyoshi Y, Negishi K, Saiki M, et al. Apparent progression of presbyopia after laser in situ keratomileusis in patients with early presbyopia. Am J Ophthalmol 2014; 158:286.
  55. Garcia-Gonzalez M, Teus MA, Hernandez-Verdejo JL. Visual outcomes of LASIK-induced monovision in myopic patients with presbyopia. Am J Ophthalmol 2010; 150:381.
  56. Braun EH, Lee J, Steinert RF. Monovision in LASIK. Ophthalmology 2008; 115:1196.
  57. Benitez-del-Castillo JM, del Rio T, Iradier T, et al. Decrease in tear secretion and corneal sensitivity after laser in situ keratomileusis. Cornea 2001; 20:30.
  58. Wilson SE. Laser in situ keratomileusis-induced (presumed) neurotrophic epitheliopathy. Ophthalmology 2001; 108:1082.
  59. Krueger RR, Saedy NF, McDonnell PJ. Clinical analysis of steep central islands after excimer laser photorefractive keratectomy. Arch Ophthalmol 1996; 114:377.
  60. Tamayo Fernandez GE, Serrano MG. Early clinical experience using custom excimer laser ablations to treat irregular astigmatism. J Cataract Refract Surg 2000; 26:1442.
  61. www.fda.gov/medwatch/safety/2007/safety07.htm#LADAR6000 (Accessed on June 18, 2007).
  62. Rajan MS, Jaycock P, O'Brart D, et al. A long-term study of photorefractive keratectomy; 12-year follow-up. Ophthalmology 2004; 111:1813.
  63. Endl MJ, Martinez CE, Klyce SD, et al. Effect of larger ablation zone and transition zone on corneal optical aberrations after photorefractive keratectomy. Arch Ophthalmol 2001; 119:1159.
  64. Pérez-Santonja JJ, Sakla HF, Alió JL. Contrast sensitivity after laser in situ keratomileusis. J Cataract Refract Surg 1998; 24:183.
  65. Mutyala S, McDonald MB, Scheinblum KA, et al. Contrast sensitivity evaluation after laser in situ keratomileusis. Ophthalmology 2000; 107:1864.
  66. Alió JL, Artola A, Claramonte PJ, et al. Complications of photorefractive keratectomy for myopia: two year follow-up of 3000 cases. J Cataract Refract Surg 1998; 24:619.
  67. Karp CL, Tuli SS, Yoo SH, et al. Infectious keratitis after LASIK. Ophthalmology 2003; 110:503.
  68. Tham VM, Maloney RK. Microkeratome complications of laser in situ keratomileusis. Ophthalmology 2000; 107:920.
  69. Lin RT, Maloney RK. Flap complications associated with lamellar refractive surgery. Am J Ophthalmol 1999; 127:129.
  70. Leung AT, Rao SK, Cheng AC, et al. Pathogenesis and management of laser in situ keratomileusis flap buttonhole. J Cataract Refract Surg 2000; 26:358.
  71. Walker MB, Wilson SE. Incidence and prevention of epithelial growth within the interface after laser in situ keratomileusis. Cornea 2000; 19:170.
  72. Wang MY, Maloney RK. Epithelial ingrowth after laser in situ keratomileusis. Am J Ophthalmol 2000; 129:746.
  73. Linebarger EJ, Hardten DR, Lindstrom RL. Diffuse lamellar keratitis: diagnosis and management. J Cataract Refract Surg 2000; 26:1072.
  74. Sonmez B, Maloney RK. Central toxic keratopathy: description of a syndrome in laser refractive surgery. Am J Ophthalmol 2007; 143:420.
  75. Solomon KD, Fernández de Castro LE, Sandoval HP, et al. LASIK world literature review: quality of life and patient satisfaction. Ophthalmology 2009; 116:691.
  76. el Danasoury MA, el Maghraby A, Klyce SD, Mehrez K. Comparison of photorefractive keratectomy with excimer laser in situ keratomileusis in correcting low myopia (from -2.00 to -5.50 diopters). A randomized study. Ophthalmology 1999; 106:411.
  77. Sakimoto T, Rosenblatt MI, Azar DT. Laser eye surgery for refractive errors. Lancet 2006; 367:1432.
  78. Chiang PK, Hersh PS. Comparing predictability between eyes after bilateral laser in situ keratomileusis: a theoretical analysis of simultaneous versus sequential procedures. Ophthalmology 1999; 106:1684.
  79. Van Gelder RN, Steger-May K, Pepose JS. Correlation of visual and refractive outcomes between eyes after same-session bilateral laser in situ keratomileusis surgery. Am J Ophthalmol 2003; 135:577.
  80. Tabbara KF, El-Sheikh HF, Islam SM. Laser in situ keratomileusis for the correction of hyperopia from +0.50 to +11.50 diopters with the Keracor 117C laser. J Refract Surg 2001; 17:123.
  81. Shortt AJ, Allan BD. Photorefractive keratectomy (PRK) versus laser-assisted in-situ keratomileusis (LASIK) for myopia. Cochrane Database Syst Rev 2006; :CD005135.
  82. Settas G, Settas C, Minos E, Yeung IY. Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction. Cochrane Database Syst Rev 2012; :CD007112.
  83. Alió JL, Muftuoglu O, Ortiz D, et al. Ten-year follow-up of photorefractive keratectomy for myopia of less than -6 diopters. Am J Ophthalmol 2008; 145:29.
  84. Alió JL, Muftuoglu O, Ortiz D, et al. Ten-year follow-up of laser in situ keratomileusis for myopia of up to -10 diopters. Am J Ophthalmol 2008; 145:46.
  85. Alió JL, Muftuoglu O, Ortiz D, et al. Ten-year follow-up of photorefractive keratectomy for myopia of more than -6 diopters. Am J Ophthalmol 2008; 145:37.
  86. Alió JL, Muftuoglu O, Ortiz D, et al. Ten-year follow-up of laser in situ keratomileusis for high myopia. Am J Ophthalmol 2008; 145:55.
  87. Kato N, Toda I, Hori-Komai Y, et al. Five-year outcome of LASIK for myopia. Ophthalmology 2008; 115:839.
  88. O'Brart DP, Shalchi Z, McDonald RJ, et al. Twenty-year follow-up of a randomized prospective clinical trial of excimer laser photorefractive keratectomy. Am J Ophthalmol 2014; 158:651.