Keratorefractive Lenticule Extraction – KLEx

Abstract

The clinical use of femtosecond lasers has led to significant progress in a number of surgical procedures in ophthalmology. In the field of corneal refractive surgery, a one-step intrastromal laser procedure without a flap has been established for the first time. This review follows the development of this surgical procedure.

Keywords

Refractive Surgery - femtosecond laser - lenticule extraction - KLEx

Publication History

Received: 09 March 2025

Accepted: 06 June 2025

Article published online:
21 August 2025

• References/Literatur

• 1 Barraquer JI. The history and evolution of keratomileusis. Int Ophthalmol Clin 1996; 36: 1-7
• 2 Ibrahim O, Waring GO, Salah T. et al. Automated in situ Keratomileusis for myopia. J Refract Surg 1995; 11: 431-441
• 3 Wiegand W, Krusenberg B, Kroll P. Keratomileusis in situ bei hochgradiger Myopie. Erste Ergebnisse. Ophthalmologe 1995; 92: 402-409
• 4 Trokel SL, Srinivasan R, Braren B. Excimer laser surgery of the cornea. Am J Ophthalmol 1983; 96: 710-715
• 5 Ito M, Quantock AJ, Malhan S. et al. Picosecond laser in situ keratomileusis with a 1053-nm Nd : YFL laser. J Refract Surg 1996; 12: 721-728
• 6 Krueger RR, Juhasz T, Gualano A. et al. The picosecond laser for nonmechanical laser in situ keratomileusis. J Refract Surg 1998; 14: 467-469
• 7 Kurtz RM, Horvath C, Liu HH. et al. Lamellar refractive surgery with scanned intrastromal picoseconds and femtosecond laser pulses in animal eyes. J Refract Surg 1998; 14: 541-548
• 8 Heisterkamp A, Mamon T, Kermani O. et al. Intrastromal refractive surgery with ultrashort laser pulses: in vivo study on the rabbit eye. Graefes Arch Clin Exp Ophthalmol 2003; 241: 511-517
• 9 Ratka-Traub I, Ferincz IE, Juhasz T. et al. First clinical results with the femtosecond neodymium-glass laser in refractive surgery. J Refract Surg 2003; 19: 94-103
• 10 Nordan LT, Slade SG, Baker RN. Femtosecond laser flap creation for laser in situ keratomileusis: six-months follow-up of the initial US clinical series. J Refract Surg 2003; 19: 8-14
• 11 Kezirian GM, Stonecipher KG. Comparison of the IntraLase femtosecond laser and mechanical microkeratome for laser in situ Keratomileusis. J Cataract Refract Surg 2004; 30: 26-32
• 12 Durrie DS, Kezirian GM. Femtosecond laser versus mechanical keratome flaps in wavefront-guided laser in situ keratomileusis: prospective contralateral eye study. J Cataract Refract Surg 2005; 31: 120-126
• 13 Tran DB, Sarayba MA, Bor Z. et al. Randomized prospective clinical study comparing induced aberrations with IntraLase and Hansatome flap creation in fellow eyes: potential impact on wavefront-guided laser in situ keratomileusis. J Cataract Refract Surg 2005; 31: 97-105
• 14 Vetter JM, Holzer MP, Teping C. et al. Intraocular pressure during corneal flap preparation: comparison among four femtosecond lasers in porcine eyes. J Refract Surg 2011; 27: 427-433
• 15 Vetter JM, Faust M, Gericke A. et al. Intraocular pressure measurements during flap preparation using 2 femtosecond lasers and 1 microkeratome in human donor eyes. J Cataract Refract Surg 2012; 38: 2011-2018
• 16 Blum M, Kunert K, Gille A. et al. First experience in Femtosecond LASIK with the Zeiss VISUMAX^® Laser. J Refract Surg 2009; 25: 350-356
• 17 Sekundo W, Kunert K, Russmann C. et al. First efficacy and safety study of femtosecond lenticule extraction for the correction of myopia. J Cataract Refract Surg 2008; 34: 1513-1520
• 18 Blum M, Kunert K, Schröder M. et al. Femtosecond Lenticule Extraction (FLEX) for the correction of myopia: 6 months results. Graefes Arch Clin Exp Ophthalmol 2010; 248: 1019-1027
• 19 Blum M, Flach A, Kunert KS. et al. Five-year results of Refractive Lenticule Extraction. J Cataract Refract Surg 2014; 40: 1425-1429
• 20 Blum M, Kunert KS, Schulze M. et al. 10-year results of FLEx Refractive Surgery. J Refract Surg 2019; 35: 707-711
• 21 Sekundo W, Kunert K, Blum M. Small Incision Femtosecond Lenticule Extraction (SMILE) for the correction of Myopia and Myopic Astigmatism: Results of a 6 month prospective study. Br J Ophthalmol 2011; 95: 335-339
• 22 Shah R, Shah S, Segupta S. Results of small incision lenticule extraction: All-in-one femtosecond laser refractive surgery. J Cataract Refract Surg 2011; 37: 127-137
• 23 Shah R, Shah S. Effect of scanning patterns on the results of femtosecond laser lenticule extraction refractive surgery. J Cataract Refract Surg 2011; 37: 1636-1647
• 24 Hjortdal JO, Vestergaard AH, Ivarsen A. et al. Predictors for the outcome of small incision lenticule extraction for Myopia. J Refract Surg 2012; 28: 865-871
• 25 Reinstein DZ, Archer TJ, Gobbe M. Accuracy and reproducibility of cap thickness in small incision lenticule extraction. J Refract Surg 2013; 29: 810-815
• 26 Ozgurhan EB, Agca A, Bozkurt E. et al. Accuracy and precision of cap thickness in small incision lenticule extraction. Clin Ophthalmol 2013; 7: 923-926
• 27 Sekundo W, Gertnere J, Bertelmann T. et al. One-year refractive results, contrast sensitivity, high-order aberrations and complications after myopic small-incision lenticule extraction (ReLEx SMILE). Graefes Arch Clin Exp Ophthalmol 2014; 252: 837-843
• 28 Ivarsen A, Asp S, Hjortdal J. Safety and complications of more than 1500 small incision lenticule extraction procedures. Ophthalmology 2014; 121: 822-828
• 29 Kamiya K, Shimizu K, Igarashi A. et al. Visual and refractive outcomes of femtosecond lenticule extraction and small incision lenticule extraction for myopia. Am J Ophthalmol 2014; 157: 128-134
• 30 Blum M, Täubig K, Gruhn C. et al. Five-year results of Small Incision Lenticule Extraction (ReLEx^® SMILE). Br J Ophthalmol 2015; 100: 1192-1195
• 31 Blum M, Lauer AS, Kunert KS. et al. 10-year results of Small Incision Lenticule Extraction. J Refract Surg 2019; 35: 618-623
• 32 Aygün BT, Cankaya KI, Agca A. et al. Five-year outcomes of small incision lenticule extraction vs. femtosecond laser assisted laser in situ keratomileusis: a contralateral eye study. J Cataract Refract Surg 2020; 46: 403-409
• 33 Spiru B, Kling S, Hafezi F. et al. Biomechanical Properties of Human Cornea Tested by Two-Dimensional Extensiometry Ex Vivo in Fellow Eyes: Femtosecond Laser-Assisted LASIK Versus SMILE. J Refract Surg 2018; 34: 419-423
• 34 Shen Z, Zhu Y, Song X. et al. Dry Eye after Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted in Situ Keratomileusis (FS-LASIK) for Myopia: A Meta-Analysis. PLoS One 2016; 11: e0168081
• 35 Sekundo W, Chang JSM, Ganesh S. et al. Keratorefractive Lenticule Extraction for Myopia and Myopic Astigmatism with the VISUMAX 800: 6-Month Outcomes of a Prospective Multi-center Post-market Clinical Follow-up Study. J Refract Surg 2025; 41: e264-e271
• 36 Ganesh S, Brar S, Swamy DT. Comparison of Clinical Outcomes and Patient Satisfaction following SMILE Performed with the VisuMax 800 in One Eye and VisuMax 500 in the Contralateral Eye. J Refract Surg 2025; 41 (01) e14-e21
• 37 Siedlecki J, Siedlecki M, Luft N. et al. Surface ablation versus Circle für myopic enhancement after SMILE: A matched comparative study. J Refract Surg 2019; 35: 294-300
• 38 Dupps WJ, Randleman JB, Kohnen T. et al. Scientific nomenclature for keratorefractive lenticule extraction (KLEx) procedures: a joint editorial statement. J Cataract Refract Surg 2023; 49: 1085
• 39 Nanavaty MA, Naveed H, Ashena Z. et al. Ex-vivo study on the surface quality of corneal lenticule and stroma after low energy femtosecond laser lenticule extraction. Sci Rep 2022; 12: 10034
• 40 Izquierdo L, Sossa D, Ben-Shaul O. et al. Corneal lenticule extraction assisted by low-energy femtosecond laser. J Cataract Refract Surg 2020; 46: 1217-1221
• 41 Lwowski C, Voigt A, van Keer K. et al. Corneal Lenticule Creation Using a New Solid-State Femtosecond Laser Measured by Spectral Domain OCT in a Porcine Eye Model. Transl Vis Sci Technol 2022; 11: 20
• 42 Pradhan KR, Mosquera SA. Three-month outcomes of myopic astigmatism correction with small incision guided human cornea treatment. J Refract Surg 2021; 37: 304-311
• 43 Pradhan KR, Mosquera SA. Twelve-month outcomes of a new refractive lenticular extraction procedure. J Optom 2023; 16: 30-41
• 44 Gabric I, Bohac M, Gabric K. et al. First European results of a new refractive lenticular extraction procedure – SmartSight by SCHWIND eye-tech-solutions. Eye (Lond) 2023; 37: 3768-3775
• 45 Chen L, Khamar P, Wang Y. et al. Evaluation of Higher-Order Aberrations After the Smooth Incision Lenticular Keratomileusis (SILK^™) Procedure Using the ELITA^™ Femtosecond Platform for Correction of Myopic and Astigmatic Refractive Errors. Clin Ophthalmol 2024; 18: 2155-2166
• 46 Sachdev MS, Shetty R, Khamar P. et al. Safety and Effectiveness of Smooth Incision Lenticular Keratomileusis (SILK^™) Using the ELITA^(TM) Femtosecond Laser System for Correction of Myopic and Astigmatic Refractive Errors. Clin Ophthalmol 2023; 17: 3761-3773
• 47 De Medeiros FW. Effect of femtosecond laser energy level on corneal stromal cell death and inflammation. J Refract Surg 2009; 25: 869-874
• 48 Hammer CM, Petsch C, Klenke J. et al. Corneal tissue interactions of a new 345 nm ultraviolet femtosecond laser. J Cataract Refract Surg 2015; 41: 1279-1288
• 49 Hammer CM, Petsch C, Klenke J. et al. Wound healing in rabbit corneas after flapless refractive lenticule extraction with a 345 ultraviolet femtosecond laser. J Cataract Refract Surg 2017; 43: 1335-1342
• 50 Blum M, Kunert KS, Vossmerbaeumer U. et al. Femtosecond-Lenticule-Extraction (ReLEx^®) for correction of hyperopia – first results. Graefes Arch Clin Exp Ophthalmol 2013; 251: 349-355
• 51 Sekundo W, Reinstein DZ, Blum M. Improved lenticule shape for hyperopic femtosecond lenticule extraction (ReLEx FLEx): a pilot study. Lasers Med Sci 2016; 31: 659-664
• 52 Sekundo W, Messerschmidt-Roth A, Reinstein DZ. et al. Femtosecond Lenticule Extraction (FLEx) für spherocylindrical hyperopia using new profiles. J Refract Surg 2018; 34: 6-10
• 53 Reinstein DZ, Pradhan KR, Carp GI. et al. Small incision lenticule extraction (SMILE) for hyperopia: optical zone centration. J Refract Surg 2017; 33: 150-156
• 54 Reinstein DZ, Pradhan KR, Carp GI. et al. Small incision lenticule extraction (SMILE) for hyperopia: optical zone diameter and spherical aberration induction. J Refract Surg 2017; 33: 370-376
• 55 Pradhan KR, Reinstein DZ, Carp GI. et al. Small incision lenticule extraction (SMILE) for hyperopia: 12-month refractive and visual outcomes. J Refract Surg 2019; 35: 442-450
• 56 Reinstein DZ, Sekundo W, Archer TJ. et al. SMILE for Hyperopia with and without Astigmatism: Results of a prospective multicenter 12-month study. J Refract Surg 2022; 38: 760-769
• 57 Barraquer JI. Queratomileusis y queratofakia. Instituto Barraquer de America; 1980: 342
• 58 Jankov M, Mrochen M, Seiler T. Laser intrastromal keratoplasty – case report. J Refract Surg 2004; 20: 79-84
• 59 Pradhan KR, Reinstein DZ, Carp GI. et al. Femtosecond laser-assisted keyhole endokeratophakia: correction of hyperopia by implantation of an allogenic lenticule obtained by SMILE from a myopic donor. J Refract Surg 2013; 29: 777-782
• 60 Lazaridis A, Messerschmidt-Roth A, Sekundo W. et al. Refractive Lenticule Implantation for correction of ametropia: Case report and Literature review. Klin Monbl Augenheilkd 2017; 234: 77-89
• 61 Brar S, Ganesh S, Sriganesh SS. et al. Long-term outcomes of Bowmannʼs Membrane Relaxation for Enhancement of Femtosecond Intrastromal Lenticule Implantation Performed for the Management of High Hyperopia. J Refract Surg 2022; 38: 134-141
• 62 Sun L, Yao P, Li M. et al. The safety and predictability of implanting autologous lenticule obtained by SMILE for hyperopia. J Refract Surg 2015; 31: 374-379
• 63 Liu S, Wei R, Choi J. et al. Visual Outcomes After Implantation of Allogenic Lenticule in a 100 µm Pocket for Moderate to High Hyperopia: 2-year Results. J Refract Surg 2021; 37: 734-740
• 64 Damgaard IB, Ivarsen A, Hjortdal J. Biological lenticule implantation for correction of hyperopia: an ex vivo study in human corneas. J Refract Surg 2018; 34: 245-252
• 65 Stodulka P, Randárová E, Slovák M. et al. Corneal Stromal Lenticule Rotation for High Astigmatism Correction. J Refract Surg 2025; 41 (01) e5-e13
• 66 Shang J, Wang X, Xu H. et al. Correction of High Astigmatism by Autologous Astigmatic Lenticule Reshaping and Rotation. J Refract Surg 2024; 40: e554-e561
• 67 Sekundo W, Messerschmidt-Roth A. Präzision im Fokus: Simultane Lentikel-Rotation und Femto-LASIK bei komplexen Fehlsichtigkeiten mit 2-jährigem Follow-up. Vortrag beim 39. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinden Implantation (DGII), Erlangen, 15.02.2025.
• 68 Jacob S, Kumar DA, Agrawal A. et al. Preliminary evidence of successful near vision enhancement with a new technique; PrEsbyopic Allogenic Refractive Lenticule (PEARL) corneal inlay using a SMILE lenticule. J Refract Surg 2017; 33: 224-229