Iatrogene Keratektasie nach refraktiver Chirurgie – Ursachen, Prophylaxe, Therapie

Felix Mathias Wagner; Walter Sekundo

doi:10.1055/a-2073-8478

Klinische Monatsblätter für Augenheilkunde, Inhaltsverzeichnis

Klin Monbl Augenheilkd 2023; 240(06): 783-794
DOI: 10.1055/a-2073-8478

Übersicht/Review

Iatrogenic Keratectasia after Refractive Surgery – Causes, Prophylaxis, Therapy

Artikel in mehreren Sprachen: deutsch | English

Felix Mathias Wagner

¹Universitätsaugenklinik Mainz, Mainz, Deutschland

²Universitätsaugenklinik Marburg, Marburg, Deutschland

,

Walter Sekundo

²Universitätsaugenklinik Marburg, Marburg, Deutschland

› Institutsangaben

Abstract

Iatrogenic keratectasia is induced thinning and protrusion of the cornea after laser refractive surgery. Known risk factors include an excessively thin postoperative residual stromal bed, a thicker flap, or preoperatively undetected evidence of preexisting subclinical keratoconus. The rate of post-refractive ectasia in eyes without identifiable preoperative risk factors is 20 per 100 000 eyes for photorefractive keratectomy, 90 per 100 000 eyes for laser in situ keratomileusis, and 11 per 100 000 eyes for small incision lenticule extraction. Traditional screening tools for preoperative risk include the ectasia risk score system and percentage of tissue alteration. More recent methods include corneal elastography and epithelial mapping, in addition to Artificial Intelligence methods for data analysis. Therapy includes contact lenses, cross-linking, implantation of intracorneal ring segments, penetrating or lamellar keratoplasty, and, in early studies, implantation of corneal lenticules.

Key words

cornea - refractive surgery - ectasia

Volltext

Referenzen

References/Literatur
1 Binder PS. Ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2003; 29: 2419-2429
2 Gokul A, Patel DV, Watters GA. et al. The natural history of corneal topographic progression of keratoconus after age 30 years in non-contact lens wearers. Br J Ophthalmol 2017; 101: 839-844
3 Santodomingo-Rubido J, Carracedo G, Suzaki A. et al. Keratoconus: An updated review. Cont Lens Anterior Eye 2022; 45: 101559
4 Espandar L, Meyer J. Keratoconus: overview and update on treatment. Middle East Afr J Ophthalmol 2010; 17: 15-20
5 Jhanji V, Sharma N, Vajpayee RB. Management of keratoconus: current scenario. Br J Ophthalmol 2011; 95: 1044-1050
6 Piñero DP, Nieto JC, Lopez-Miguel A. Characterization of corneal structure in keratoconus. J Cataract Refract Surg 2012; 38: 2167-2183
7 Torres Netto EA, Al-Otaibi WM, Hafezi NL. et al. Prevalence of keratoconus in paediatric patients in Riyadh, Saudi Arabia. Br J Ophthalmol 2018; 102: 1436-1441
8 Weed KH, Macewen CJ, McGhee CN. The Dundee University Scottish Keratoconus Study II: a prospective study of optical and surgical correction. Ophthalmic Physiol Opt 2007; 27: 561-567
9 Gordon MO, Steger-May K, Szczotka-Flynn L. et al. Baseline factors predictive of incident penetrating keratoplasty in keratoconus. Am J Ophthalmol 2006; 142: 923-930
10 McGhee CN, Kim BZ, Wilson PJ. Contemporary Treatment Paradigms in Keratoconus. Cornea 2015; 34 (Suppl. 10) S16-S23
11 Bykhovskaya Y, Margines B, Rabinowitz YS. Genetics in Keratoconus: where are we?. Eye Vis (Lond) 2016; 3: 16
12 Binder PS. Analysis of ectasia after laser in situ keratomileusis: risk factors. J Cataract Refract Surg 2007; 33: 1530-1538
13 Moshirfar M, Albarracin JC, Desautels JD. et al. Ectasia following small-incision lenticule extraction (SMILE): a review of the literature. Clin Ophthalmol 2017; 11: 1683-1688
14 Ambrósio jr. R, Lopes BT, Faria-Correia F. et al. Integration of Scheimpflug-Based Corneal Tomography and Biomechanical Assessments for Enhancing Ectasia Detection. J Refract Surg 2017; 33: 434-443
15 Ambrósio jr. R, Randleman JB. Screening for ectasia risk: what are we screening for and how should we screen for it?. J Refract Surg 2013; 29: 230-232
16 Ambrósio jr. R. Post-LASIK Ectasia: Twenty Years of a Conundrum. Semin Ophthalmol 2019; 34: 66-68
17 Binder PS, Lindstrom RL, Stulting RD. et al. Keratoconus and corneal ectasia after LASIK. J Cataract Refract Surg 2005; 31: 2035-2038
18 Seiler T, Quurke AW. Iatrogenic keratectasia after LASIK in a case of forme fruste keratoconus. J Cataract Refract Surg 1998; 24: 1007-1009
19 Ambrósio jr. R, Valbon BF, Faria-Correia F. et al. Scheimpflug imaging for laser refractive surgery. Curr Opin Ophthalmol 2013; 24: 310-320
20 Mannis MJ. Keratoconus: why and when do we turn to surgical therapy?. Am J Ophthalmol 2006; 142: 1044-1045
21 Ambrósio jr. R. Violet June: The Global Keratoconus Awareness Campaign. Ophthalmol Ther 2020; 9: 685-688
22 McMonnies CW. Mechanisms of rubbing-related corneal trauma in keratoconus. Cornea 2009; 28: 607-615
23 Edwards M, McGhee CN, Dean S. The genetics of keratoconus. Clin Exp Ophthalmol 2001; 29: 345-351
24 Jani D, McKelvie J, Misra SL. Progressive corneal ectatic disease in pregnancy. Clin Exp Optom 2021; 104: 815-825
25 Sugar J, Macsai MS. What causes keratoconus?. Cornea 2012; 31: 716-719
26 Randleman JB, Trattler WB, Stulting RD. Validation of the Ectasia Risk Score System for preoperative laser in situ keratomileusis screening. Am J Ophthalmol 2008; 145: 813-818
27 Binder PS, Trattler WB. Evaluation of a risk factor scoring system for corneal ectasia after LASIK in eyes with normal topography. J Refract Surg 2010; 26: 241-250
28 Gatinel D. Eye Rubbing, a Sine Qua Non for Keratoconus?. Int J Kerat Ect Cor Dis 2016; 5: 6-12
29 Moran S, Gomez L, Zuber K. et al. A Case-Control Study of Keratoconus Risk Factors. Cornea 2020; 39: 697-701
30 Torres-Netto EA, Abdshahzadeh H, Abrishamchi R. et al. The Impact of Repetitive and Prolonged Eye Rubbing on Corneal Biomechanics. J Refract Surg 2022; 38: 610-616
31 Dou S, Wang Q, Zhang B. et al. Single-cell atlas of keratoconus corneas revealed aberrant transcriptional signatures and implicated mechanical stretch as a trigger for keratoconus pathogenesis. Cell Discov 2022; 8: 66
32 Moshirfar M, Tukan AN, Bundogji N. et al. Ectasia After Corneal Refractive Surgery: A Systematic Review. Ophthalmol Ther 2021; 10: 753-776
33 Brar S, Roopashree CR, Ganesh S. Incidence of Ectasia After SMILE From a High-Volume Refractive Surgery Center in India. J Refract Surg 2021; 37: 800-808
34 Aghamohammadzadeh H, Newton RH, Meek KM. X-ray scattering used to map the preferred collagen orientation in the human cornea and limbus. Structure 2004; 12: 249-256
35 Bergmanson JP, Horne J, Doughty MJ. et al. Assessment of the number of lamellae in the central region of the normal human corneal stroma at the resolution of the transmission electron microscope. Eye Contact Lens 2005; 31: 281-287
36 Randleman JB, Dawson DG, Grossniklaus HE. et al. Depth-dependent cohesive tensile strength in human donor corneas: implications for refractive surgery. J Refract Surg 2008; 24: S85-89
37 Knox Cartwright NE, Tyrer JR, Jaycock PD. et al. Effects of variation in depth and side cut angulations in LASIK and thin-flap LASIK using a femtosecond laser: a biomechanical study. J Refract Surg 2012; 28: 419-425
38 Reinstein DZ, Archer TJ, Randleman JB. Mathematical model to compare the relative tensile strength of the cornea after PRK, LASIK, and small incision lenticule extraction. J Refract Surg 2013; 29: 454-460
39 Sinha Roy A, Dupps jr. WJ, Roberts CJ. Comparison of biomechanical effects of small-incision lenticule extraction and laser in situ keratomileusis: finite-element analysis. J Cataract Refract Surg 2014; 40: 971-980
40 Spiru B, Torres-Netto EA, Kling S. et al. Biomechanical Properties of Human Cornea Tested by Two-Dimensional Extensiometry Ex Vivo in Fellow Eyes: PRK Versus SMILE. J Refract Surg 2019; 35: 501-505
41 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
42 Critchfield JW, Calandra AJ, Nesburn AB. et al. Keratoconus: I. Biochemical studies. Exp Eye Res 1988; 46: 953-963
43 Atilano SR, Coskun P, Chwa M. et al. Accumulation of mitochondrial DNA damage in keratoconus corneas. Invest Ophthalmol Vis Sci 2005; 46: 1256-1263
44 Arnal E, Peris-Martínez C, Menezo JL. et al. Oxidative stress in keratoconus?. Invest Ophthalmol Vis Sci 2011; 52: 8592-8597
45 Balasubramanian SA, Pye DC, Willcox MD. Are proteinases the reason for keratoconus?. Curr Eye Res 2010; 35: 185-191
46 Chwa M, Atilano SR, Hertzog D. et al. Hypersensitive response to oxidative stress in keratoconus corneal fibroblasts. Invest Ophthalmol Vis Sci 2008; 49: 4361-4369
47 Kenney MC, Chwa M, Atilano SR. et al. Increased levels of catalase and cathepsin V/L2 but decreased TIMP-1 in keratoconus corneas: evidence that oxidative stress plays a role in this disorder. Invest Ophthalmol Vis Sci 2005; 46: 823-832
48 Smith VA, Matthews FJ, Majid MA. et al. Keratoconus: matrix metalloproteinase-2 activation and TIMP modulation. Biochim Biophys Acta 2006; 1762: 431-439
49 Lema I, Durán JA. Inflammatory molecules in the tears of patients with keratoconus. Ophthalmology 2005; 112: 654-659
50 Lema I, Sobrino T, Durán JA. et al. Subclinical keratoconus and inflammatory molecules from tears. Br J Ophthalmol 2009; 93: 820-824
51 Matthews FJ, Cook SD, Majid MA. et al. Changes in the balance of the tissue inhibitor of matrix metalloproteinases (TIMPs)-1 and -3 may promote keratocyte apoptosis in keratoconus. Exp Eye Res 2007; 84: 1125-1134
52 Elmohamady MN, Abdelghaffar W, Salem TI. Tear Martix Metalloproteinase-9 and Tissue Inhibitor of Metalloproteinase-1 in Post-Lasik Ectasia. Int Ophthalmol 2019; 39: 631-637
53 Pahuja NK, Shetty R, Deshmukh R. et al. In vivo confocal microscopy and tear cytokine analysis in post-LASIK ectasia. Br J Ophthalmol 2017; 101: 1604-1610
54 Shetty R, Kumar NR, Khamar P. et al. Bilaterally Asymmetric Corneal Ectasia Following SMILE With Asymmetrically Reduced Stromal Molecular Markers. J Refract Surg 2019; 35: 6-14
55 Salomão MQ, Hofling-Lima AL, Faria-Correia F. et al. Dynamic corneal deformation response and integrated corneal tomography. Indian J Ophthalmol 2018; 66: 373-382
56 Belin MW, Ambrósio R. Scheimpflug imaging for keratoconus and ectatic disease. Indian J Ophthalmol 2013; 61: 401-406
57 Li Y, Meisler DM, Tang M. et al. Keratoconus diagnosis with optical coherence tomography pachymetry mapping. Ophthalmology 2008; 115: 2159-2166
58 Ambrósio jr. R, Caiado AL, Guerra FP. et al. Novel pachymetric parameters based on corneal tomography for diagnosing keratoconus. J Refract Surg 2011; 27: 753-758
59 Li Y, Tan O, Brass R. et al. Corneal epithelial thickness mapping by Fourier-domain optical coherence tomography in normal and keratoconic eyes. Ophthalmology 2012; 119: 2425-2433
60 Li Y, Chamberlain W, Tan O. et al. Subclinical keratoconus detection by pattern analysis of corneal and epithelial thickness maps with optical coherence tomography. J Cataract Refract Surg 2016; 42: 284-295
61 Reinstein DZ, Archer TJ, Urs R. et al. Detection of Keratoconus in Clinically and Algorithmically Topographically Normal Fellow Eyes Using Epithelial Thickness Analysis. J Refract Surg 2015; 31: 736-744
62 Herber R, Ramm L, Spoerl E. et al. Assessment of corneal biomechanical parameters in healthy and keratoconic eyes using dynamic bidirectional applanation device and dynamic Scheimpflug analyzer. J Cataract Refract Surg 2019; 45: 778-788
63 Herber R, Hasanli A, Lenk J. et al. Evaluation of Corneal Biomechanical Indices in Distinguishing Between Normal, Very Asymmetric, and Bilateral Keratoconic Eyes. J Refract Surg 2022; 38: 364-372
64 Sedaghat MR, Momeni-Moghaddam H, Heravian J. et al. Detection ability of corneal biomechanical parameters for early diagnosis of ectasia. Eye (Lond) 2022;
65 Rabinowitz YS. Videokeratographic indices to aid in screening for keratoconus. J Refract Surg 1995; 11: 371-379
66 Randleman JB, Woodward M, Lynn MJ. et al. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology 2008; 115: 37-50
67 Santhiago MR, Smadja D, Gomes BF. et al. Association between the percent tissue altered and post-laser in situ keratomileusis ectasia in eyes with normal preoperative topography. Am J Ophthalmol 2014; 158: 87-95.1
68 Santhiago MR. Percent tissue altered and corneal ectasia. Curr Opin Ophthalmol 2016; 27: 311-315
69 Santhiago MR, Wilson SE, Smadja D. et al. Validation of the Percent Tissue Altered as a Risk Factor for Ectasia after LASIK. Ophthalmology 2019; 126: 908-909
70 Kataria P, Padmanabhan P, Gopalakrishnan A. et al. Accuracy of Scheimpflug-derived corneal biomechanical and tomographic indices for detecting subclinical and mild keratectasia in a South Asian population. J Cataract Refract Surg 2019; 45: 328-336
71 Ferreira-Mendes J, Lopes BT, Faria-Correia F. et al. Enhanced Ectasia Detection Using Corneal Tomography and Biomechanics. Am J Ophthalmol 2019; 197: 7-16
72 Chan TCY, Wang YM, Yu M. et al. Comparison of Corneal Tomography and a New Combined Tomographic Biomechanical Index in Subclinical Keratoconus. J Refract Surg 2018; 34: 616-621
73 Vinciguerra R, Ambrósio jr. R, Elsheikh A. et al. Detection of postlaser vision correction ectasia with a new combined biomechanical index. J Cataract Refract Surg 2021; 47: 1314-1318
74 Sinha Roy A, Shetty R, Kummelil MK. Keratoconus: a biomechanical perspective on loss of corneal stiffness. Indian J Ophthalmol 2013; 61: 392-393
75 Scarcelli G, Besner S, Pineda R. et al. Biomechanical characterization of keratoconus corneas ex vivo with Brillouin microscopy. Invest Ophthalmol Vis Sci 2014; 55: 4490-4495
76 Qian X, Ma T, Shih CC. et al. Ultrasonic Microelastography to Assess Biomechanical Properties of the Cornea. IEEE Trans Biomed Eng 2019; 66: 647-655
77 De Stefano VS, Ford MR, Seven I. et al. Live human assessment of depth-dependent corneal displacements with swept-source optical coherence elastography. PLoS One 2018; 13: e0209480
78 Scarcelli G, Yun SH. In vivo Brillouin optical microscopy of the human eye. Opt Express 2012; 20: 9197-9202
79 Seiler TG, Shao P, Eltony A. et al. Brillouin Spectroscopy of Normal and Keratoconus Corneas. Am J Ophthalmol 2019; 202: 118-125
80 Downie LE, Lindsay RG. Contact lens management of keratoconus. Clin Exp Optom 2015; 98: 299-311
81 Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-A–induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol 2003; 135: 620-627
82 Spoerl E, Huhle M, Seiler T. Induction of cross-links in corneal tissue. Exp Eye Res 1998; 66: 97-103
83 Chunyu T, Xiujun P, Zhengjun F. et al. Corneal collagen cross-linking in keratoconus: a systematic review and meta-analysis. Sci Rep 2014; 4: 1-8
84 Hafezi F, Kanellopoulos J, Wiltfang R. et al. Corneal collagen crosslinking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ keratomileusis. J Cataract Refract Surg 2007; 33: 2035-2040
85 Yildirim A, Cakir H, Kara N. et al. Corneal collagen crosslinking for ectasia after laser in situ keratomileusis: long-term results. J Cataract Refract Surg 2014; 40: 1591-1596
86 Vinciguerra P, Camesasca FI, Albè E. et al. Corneal collagen cross-linking for ectasia after excimer laser refractive surgery: 1-year results. J Cataract Refract Surg 2010; 26: 486-497
87 Salgado JP, Khoramnia R, Lohmann CP. et al. Corneal collagen crosslinking in post-LASIK keratectasia. Br J Ophthalmol 2011; 95: 493-497
88 Richoz O, Mavrakanas N, Pajic B. et al. Corneal collagen cross-linking for ectasia after LASIK and photorefractive keratectomy: long-term results. Ophthalmology 2013; 120: 1354-1359
89 Marino GK, Torricelli AA, Giacomin N. et al. Accelerated corneal collagen cross-linking for postoperative LASIK ectasia: two-year outcomes. J Refract Surg 2015; 31: 380-384
90 Li G, Fan ZJ, Peng XJ. Corneal collagen crosslinking for corneal ectasia of post-LASIK: one-year results. Int J Ophthalmol 2012; 5: 190
91 Hersh PS, Stulting RD, Muller D. et al. U.S. Multicenter Clinical Trial of Corneal Collagen Crosslinking for Treatment of Corneal Ectasia after Refractive Surgery. Ophthalmology 2017; 124: 1475-1484
92 Raiskup F, Spoerl E. Corneal cross-linking with hypo-osmolar riboflavin solution in thin keratoconic corneas. Am J Ophthalmol 2011; 152: 28-32.e1
93 Cifariello F, Minicucci M, Di Renzo F. et al. Epi-Off versus Epi-On Corneal Collagen Cross-Linking in Keratoconus Patients: A Comparative Study through 2-Year Follow-Up. J Ophthalmol 2018; 2018: 4947983
94 Randleman JB, Khandelwal SS, Hafezi F. Corneal cross-linking. Surv Ophthalmol 2015; 60: 509-523
95 Subasinghe SK, Ogbuehi KC, Dias GJ. Current perspectives on corneal collagen crosslinking (CXL). Graefes Arch Clin Exp Ophthalmol 2018; 256: 1363-1384
96 Kanellopoulos AJ, Binder PS. Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the Athens protocol. J Refract Surg 2011; 27: 323-331
97 Yildirim A, Uslu H, Kara N. et al. Same-day intrastromal corneal ring segment and collagen cross-linking for ectasia after laser in situ keratomileusis: long-term results. Am J Ophthalmol 2014; 157: 1070-1076
98 Nosé W, Neves RA, Burris TE. et al. Intrastromal corneal ring: 12-month sighted myopic eyes. J Refract Surg 1996; 12: 20-28
99 Colin J, Cochener B, Savary G. et al. Correcting keratoconus with intracorneal rings. J Cataract Refract Surg 2000; 26: 1117-1122
100 Ertan A, Colin J. Intracorneal rings for keratoconus and keratectasia. J Cataract Refract Surg 2007; 33: 1303-1314
101 Izquierdo jr. L, Mannis MJ, Mejías Smith JA. et al. Effectiveness of Intrastromal Corneal Ring Implantation in the Treatment of Adult Patients With Keratoconus: A Systematic Review. J Refract Surg 2019; 35: 191-200
102 Janani L, Tanha K, Najafi F. et al. Efficacy of complete rings (MyoRing) in treatment of Keratoconus: a systematic review and meta-analysis. Int Ophthalmol 2019; 39: 2929-2946
103 Israel M, Yousif MO, Osman NA. et al. Keratoconus correction using a new model of intrastromal corneal ring segments. J Cataract Refract Surg 2016; 42: 444-454
104 Siganos D, Ferrara P, Chatzinikolas K. et al. Ferrara intrastromal corneal rings for the correction of keratoconus. J Cataract Refract Surg 2002; 28: 1947-1951
105 Emerah SH, Sabry MM, Saad HA. et al. Visual and refractive outcomes of posterior chamber phakic IOL in stable keratoconus. Int J Ophthalmol 2019; 12: 840-843
106 Jonas J. Intrastromal lamellar femtosecond laser keratoplasty with superficial flap. Br J Ophthalmol 2003; 87: 1195
107 Angunawela RI, Riau AK, Chaurasia SS. et al. Refractive lenticule re-implantation after myopic ReLEx: a feasibility study of stromal restoration after refractive surgery in a rabbit model. Invest Ophthalmol Vis Sci 2012; 53: 4975-4985
108 Zhao J, Shen Y, Tian M. et al. Corneal lenticule allotransplantation after femtosecond laser small incision lenticule extraction in rabbits. Cornea 2016; 36: 222-228
109 Liu R, Zhao J, Xu Y. et al. Femtosecond laser-assisted corneal small incision allogenic intrastromal lenticule implantation in monkeys: a pilot study. Invest Ophthalmol Vis Sci 2015; 56: 3715-3720
110 Jin H, Liu L, Ding H. et al. Comparison of femtosecond laser-assisted corneal intrastromal xenotransplantation and the allotransplantation in rhesus monkeys. BMC Ophthalmol 2017; 17: 1-10
111 He M, Jin H, He H. et al. Femtosecond laser-assisted small incision endokeratophakia using a xenogeneic lenticule in rhesus monkeys. Cornea 2018; 37: 354-361
112 Alio del Barrio JL, Chiesa M, Garagorri N. et al. Acellular human corneal matrix sheets seeded with human adipose-derived mesenchymal stem cells integrate functionally in an experimental animal model. Exp Eye Res 2015; 132: 91-100
113 Williams GP, Wu B, Liu YC. et al. Hyperopic refractive correction by LASIK, SMILE or lenticule reimplantation in a non-human primate model. PLoS One 2018; 13: e0194209
114 Barraquer JI. Queratomileusis y queratofaquia. Bogota, Colombia: Instituto Barraquer de América; 1980: 340-342 405–406
115 Sekundo W, Kunert K, Russmann C. et al. First efficacy and safety study of femtosecond lenticule extraction for the correction of myopia: six-month results. J Cataract Refract Surg 2008; 34: 1513-1520
116 Pradhan KR, Reinstein DZ, Carp GI. et al. Femtosecond laser-assisted keyhole endokeratophakia: correction of hyperopia by implantation of an allogeneic lenticule obtained by SMILE from a myopic donor. J Refract Surg 2013; 29: 777-782
117 Jadidi K, Hasanpour H. Unilateral Keratectasia Treated with Femtosecond Fashioned Intrastromal Corneal Inlay. J Ophthalmic Vis Res 2017; 12: 333-337
118 Mastropasqua L, Nubile M, Salgari N. et al. Femtosecond Laser-Assisted Stromal Lenticule Addition Keratoplasty for the Treatment of Advanced Keratoconus: A Preliminary Study. J Refract Surg 2018; 34: 36-44
119 Jadidi K, Mosavi SA. Keratoconus treatment using femtosecond-assisted intrastromal corneal graft (FAISCG) surgery: a case series. Int Med Case Rep J 2018; 11: 9-15
120 Jin H, He M, Liu H. et al. Small-Incision Femtosecond Laser-Assisted Intracorneal Concave Lenticule Implantation in Patients With Keratoconus. Cornea 2019; 38: 446-453
121 Henein C, Nanavaty MA. Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus. Cont Lens Anterior Eye 2017; 40: 3-14
122 Keane M, Coster D, Ziaei M. et al. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for treating keratoconus. Cochrane Database Syst Rev 2014; (07) CD009700
123 Davidson AE, Hayes S, Hardcastle AJ. et al. The pathogenesis of keratoconus. Eye (Lond) 2014; 28: 189-195