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Shams M, Sharifi A, Akbari Z, Maghsoudlou A, Reza Tajali M. Penetrating Keratoplasty versus Deep Anterior Lamellar Keratoplasty for Keratoconus: A Systematic Review and Meta-analysis. JOVR [Internet]. 2022Jan.21 [cited 2024Apr.25];17(1):89–107. Available from: https://knepublishing.com/index.php/JOVR/article/view/10174
https://doi.org/10.18502/jovr.v17i1.10174
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authors
-
Majid Shams
Majid Shams
Department of Ophthalmology, Shafa Hospital, Kerman University of Medical Sciences, Kerman, Iran
-
Ali Sharifi
Ali Sharifi
Department of Ophthalmology, Shafa Hospital, Kerman University of Medical Sciences, Kerman, Iran
-
Zahra Akbari
Zahra Akbari
Student Research Committee, Kerman University of Medical Sciences, Kerman, Iran
-
Ali Maghsoudlou
Ali Maghsoudlou
Noor Eye Hospital, Tehran, Iran
-
Mohammad Reza Tajali
Mohammad Reza Tajali
Student Research Committee, Kerman University of Medical Sciences, Kerman, Iran
Published Date
- Jan 21, 2022
Penetrating Keratoplasty versus Deep Anterior Lamellar Keratoplasty for Keratoconus: A Systematic Review and Meta-analysis
Abstract
Keratoconus is the most common form of primary corneal thinning. Different methods have been suggested to deal with the condition, including glasses, contact lenses, and surgical interventions, like penetrating keratoplasty (PKP) and deep anterior lamellar keratoplasty (DALK), well-known methods of the latter. This study was conducted to compare the outcomes and side effects of the two mentioned keratoplasty techniques. First, we systematically reviewed all original articles studies on PubMed, Scopus, Web of Science, and Embase. Then, the extracted data were pooled and meta-analyzed on each of the intended outcomes. A total of 30 studies were included in which PKP was more commonly performed compared to DALK. We found that adverse outcomes consisting of cataracts, graft rejection, graft failure, High-IOP, and corneal infection, were all more common findings in the PKP groups compared to the DALK groups. However, only for the high-IOP, cataracts, and graft rejection, the analysis of the extracted results demonstrated statistical significance. Overall, the DALK groups demonstrated significantly better results when considering the improvement levels by measuring the Endothelial Cell Count (ECC) and Spherical Equivalent (SE). In addition, though statistically insignificant, the Central Corneal Thickness(CCT), Best Corrected Visual Acuity(BCVA), Topographic Cylinder(TC), Refractive Cylinder values were greater in the PKP groups. Based on our study and with its limitations in mind, we can conclude that DALK can be a relatively safer and more effective procedure. Though, a larger number of high-standard randomized clinical trials still need to be conveyed for more definite conclusions.
Keywords:
Corneal Transplant, Deep Anterior Lamellar Keratoplasty, Keratoconus, Penetrating Keratoplasty
References
1. Zadnik K, Barr JT, Gordon MO, Edrington TB. Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group. Cornea 1996;15:139–146.
2. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study of keratoconus. Am J Ophthalmol 1986;101:267–273.
3. Zadnik K, Steger-May K, Fink BA, Joslin CE, Nichols JJ, Rosenstiel CE, et al. Between-eye asymmetry in keratoconus. Cornea 2002;21:671–679.
4. Chopra I, Jain AK. Between eye asymmetry in keratoconus in an Indian population. Clin Exp Optom 2005;88:146–152.
5. Rabinowitz YS. Keratoconus. Surv Ophthalmol 1998;42:297–319.
6. Bilgin LK, Yılmaz S, Araz B, Yüksel SB, Sezen T. 30 years of contact lens prescribing for keratoconic patients in Turkey. Cont Lens Anterior Eye 2009;32:16–21.
7. Gordon MO, Steger-May K, Szczotka-Flynn L, Riley C, Joslin CE, Weissman BA, et al. Baseline factors predictive of incident penetrating keratoplasty in keratoconus. Am J Ophthalmol 2006;142:923–930.
8. Fallahi Motlagh B, Javadi MA, Jafari Nasab MR, Rabbanikhah Z, Anisian A, Souri H. Corneal transplantation in patients with keratoconus. Iran J Ophthalmol 2003;16:9–19. [In Persian]
9. Javadi MA, Mohammadi MJ, Mirdehghan SA, Sajjadi SH. A comparison between donor-recipient corneal size and its effect on the ultimate refractive error induced in keratoconus. Cornea 1993;12:401–405.
10. Brierly SC, Izquierdo Jr L, Mannis MJ. Penetrating keratoplasty for keratoconus. Cornea 2000;19:329–332.
11. Kirkness CM, Ficker LA, Steele AD, Rice NS. The success of penetrating keratoplasty for keratoconus. Eye 1990;4:673– 688.
12. Lim L, Pesudovs K, Coster DJ. Penetrating keratoplasty for keratoconus: visual outcome and success. Ophthalmology 2000;107:1125–1131.
13. Colin J, Velou S. Current surgical options for keratoconus. J Cataract Refract Surg 2003;29:379–386.
14. Agarwal Rk. Deep lamellar keratoplasty, an alternative to penetrating keratoplasty. Br J Ophthalmol 1997;81:178–179.
15. Croasdale CR, Barney E, Warner EJ. Eye bank tissue utilization between endothelial keratoplasty and penetrating keratoplasty. Cornea 2013;32:280–284.
16. Cassidy D, Beltz J, Jhanji V, Loughnan MS. Recent advances in corneal transplantation for keratoconus. Clin Exp Optom 2013;96:165–172.
17. Weed KH, McGhee CN, MacEwen CJ. Atypical unilateral superior keratoconus in young males. Cont Lens Anterior Eye 2005;28:177–179.
18. MacIntyre R, Chow SP, Chan E, Poon A. Long-term outcomes of deep anterior lamellar keratoplasty versus penetrating keratoplasty in Australian keratoconus patients. Cornea 2014;33:6–9.
19. Van Dooren B, Mulder PG, Nieuwendaal CP, Beekhuis WH, Melles GR. Endothelial cell density after posterior lamellar keratoplasty (Melles techniques): 3 years follow-up. Am J Ophthalmol 2004;138:211–217.
20. Shimazaki J, Shimmura S, Ishioka M, Tsubota K. Randomized clinical trial of deep lamellar keratoplasty vs penetrating keratoplasty. Am J Ophthalmol 2002;134:159– 165.
21. Moher D, Liberati A, Tetzlaff J, Altman DG, Prisma Group. Preferred reporting items for systematic reviews 2009;6:e1000097.
22. Joanna Briggs Institute. The Joanna Briggs Institute Critical Appraisal tools for use in JBI systematic reviews checklist for prevalence studies [Internet]. Adelaide, Australia: Joanna Briggs Institute; 2017. Available from: http://joannabriggs.org/research/criticalappraisaltools.html
23. Abdelaal AM, Alqassimi AH, Malak M, Hijazi HT, Hadrawi M, Khan MA. Indications of keratoplasty and outcomes of deep anterior lamellar keratoplasty compared to penetrating keratoplasty. Cureus 2021;13:e13825.
24. Busool Abu Eta Y, Tomkins-Netzer O, Mimouni M, Hamed Azzam S, Shehadeh Mashour R. Predicting factors of ocular hypertension following keratoplasty: Indications versus the procedure. Eur J Ophthalmol 2021;31:1749– 1753.
25. Akdemir MO, Kandemir B, Sayman IB, Selvi C, Dogan OK. Comparison of contrast sensitivity and visual acuity between deep anterior lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus. Int J Ophthalmol 2012;5:737–741.
26. Alzahrani K, Dardin SF, Carley F, Brahma A, Morley D, Hillarby MC. Corneal clarity measurements in patients with keratoconus undergoing either penetrating or deep anterior lamellar keratoplasty. Clin Ophthalmol 2018;12:577–585.
27. Amayem AF, Hamdi IM, Hamdi MM. Refractive and visual outcomes of penetrating keratoplasty versus deep anterior lamellar keratoplasty with hydrodissection for treatment of keratoconus. Cornea 2013;32:e2–e5.
28. Bahar I, Kaiserman I, Srinivasan S, Ya-Ping J, Slomovic AR, Rootman DS. Comparison of three different techniques of corneal transplantation for keratoconus. Am J Ophthalmol 2008;146:905–912.e1.
29. Cohen AW, Goins KM, Sutphin JE, Wandling GR, Wagoner MD. Penetrating keratoplasty versus deep anterior lamellar keratoplasty for the treatment of keratoconus. Int Ophthalmol 2010;30:675–681.
30. Donoso R, Díaz C, Villavicencio P. Comparative study of keratoconus between Anwar’s deep anterior lamellar keratoplasty versus converted penetrating keratoplasty. Arch Soc Esp Oftalmol 2015;90:257–263.
31. Funnell CL, Ball J, Noble BA. Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus. Eye 2006;20:527–532.
32. Godefrooij DA, Gans R, Imhof SM, Wisse RP. Trends in penetrating and anterior lamellar corneal grafting techniques for keratoconus: a national registry study. Acta Ophthalmol 2016;94:489–493.
33. Hamdi IM, Hamdi MM. Quality of vision after deep anterior lamellar keratoplasty (fluid dissection) compared to penetrating keratoplasty for the treatment of keratoconus. J Ophthalmol 2017;2017:4507989.
34. Huang T, Hu Y, Gui M, Hou C, Zhang H. Comparison of refractive outcomes in three corneal transplantation techniques for keratoconus. Graefes Arch Clin Exp Ophthalmol 2015;253:1947–1953.
35. Jafarinasab MR, Feizi S, Javadi MA, Hashemloo A. Graft biomechanical properties after penetrating keratoplasty versus deep anterior lamellar keratoplasty. Curr Eye Res 2011;36:417–421.
36. Janiszewska-Bil D, Czarnota-Nowakowska B, Krysik K, Lyssek-Boron A, Dobrowolski D, Grabarek BO, et al. Comparison of long-term outcomes of the lamellar and penetrating keratoplasty approaches in patients with keratoconus. J Clin Med 2021;10:2421.
37. Javadi MA, Feizi S, Yazdani S, Mirbabaee F. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for keratoconus: a clinical trial. Cornea 2010;29:365–371.
38. Jones MN, Armitage WJ, Ayliffe W, Larkin DF, Kaye SB. Penetrating and deep anterior lamellar keratoplasty for keratoconus: a comparison of graft outcomes in the United kingdom. Invest Ophthalmol Vis Sci 2009;50:5625–5629.
39. Kasbekar SA, Jones MN, Ahmad S, Larkin DF, Kaye SB. Corneal transplant surgery for keratoconus and the effect of surgeon experience on deep anterior lamellar keratoplasty outcomes. Am J Ophthalmol 2014;158:1239–1246.
40. Khattak A, Nakhli FR, Al-Arfaj KM, Cheema AA. Comparison of outcomes and complications of deep anterior lamellar keratoplasty and penetrating keratoplasty performed in a large group of patients with keratoconus. Int Ophthalmol 2018;38:985–992.
41. Kim KH, Choi SH, Ahn K, Chung ES, Chung TY. Comparison of refractive changes after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus. Jpn J Ophthalmol 2011;55:93–97.
42. Koytak A, Kubaloglu A, Sari ES, Atakan M, Culfa S, Ozerturk Y. Changes in central macular thickness after uncomplicated corneal transplantation for keratoconus: penetrating keratoplasty versus deep anterior lamellar keratoplasty. Cornea 2011;30:1318–1321.
43. Kubaloglu A, Coskun E, Sari ES, Gunes AS, Cinar Y, Piñero DP, et al. Comparison of astigmatic keratotomy results in deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus. Am J Ophthalmol 2011;151:637–643.e1.
44. Macintyre R, Chow SP, Chan E, Poon A. Long-term outcomes of deep anterior lamellar keratoplasty versus penetrating keratoplasty in Australian keratoconus patients. Cornea 2014;33:6–9.
45. Motlagh BF, Sedghipoor MR, Abroon G, Sadigh AL. Outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus in a university teaching hospital. Iran J Ophthalmol 2012;24:52–56.
46. Oh BL, Kim MK, Wee WR. Comparison of clinical outcomes of same-size grafting between deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus. Korean J Ophthalmol 2013;27:322–330.
47. Pedrotti E, Passilongo M, Fasolo A, Ficial S, Ferrari S, Marchini G. Refractive outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes for keratoconus. Int Ophthalmol 2017;37:911–919.
48. Sögütlü Sari E, Kubaloglu A, Ünal M, Piñero Llorens D, Koytak A, Ofluoglu AN, et al. Penetrating keratoplasty versus deep anterior lamellar keratoplasty: comparison of optical and visual quality outcomes. Br J Ophthalmol 2012;96:1063–1067.
49. Watson SL, Ramsay A, Dart JK, Bunce C, Craig E. Comparison of deep lamellar keratoplasty and penetrating 2004;111:1676–1682.
50. Yüksel B, Kandemir B, Uzunel UD, Çelik O, Ceylan S, Küsbeci T. Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus. Int J Ophthalmol 2017;10:385–390.
51. Zhang YM, Wu SQ, Yao YF. Long-term comparison of fullbed deep anterior lamellar keratoplasty and penetrating keratoplasty in treating keratoconus. J Zhejiang Univ Sci B 2013;14:438–450.
52. Ziaei M, Vellara HR, Gokul A, Ali NQ, McGhee CNJ, Patel DV. Comparison of corneal biomechanical properties following penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus. Clin Exp Ophthalmol 2020;48:174–182.
53. Liu H, Chen Y, Wang P, Li B, Wang W, Su Y, et al. Efficacy and safety of deep anterior lamellar keratoplasty vs. penetrating keratoplasty for keratoconus: a meta-analysis. PLoS ONE 2015;10:e0113332.
54. 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.
55. Song Y, Zhang J, Pan Z. Systematic review and meta-analysis of clinical outcomes of penetrating keratoplasty versus deep anterior lamellar keratoplasty for keratoconus. Exp Clin Transplant 2020;18:417–428.
2. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study of keratoconus. Am J Ophthalmol 1986;101:267–273.
3. Zadnik K, Steger-May K, Fink BA, Joslin CE, Nichols JJ, Rosenstiel CE, et al. Between-eye asymmetry in keratoconus. Cornea 2002;21:671–679.
4. Chopra I, Jain AK. Between eye asymmetry in keratoconus in an Indian population. Clin Exp Optom 2005;88:146–152.
5. Rabinowitz YS. Keratoconus. Surv Ophthalmol 1998;42:297–319.
6. Bilgin LK, Yılmaz S, Araz B, Yüksel SB, Sezen T. 30 years of contact lens prescribing for keratoconic patients in Turkey. Cont Lens Anterior Eye 2009;32:16–21.
7. Gordon MO, Steger-May K, Szczotka-Flynn L, Riley C, Joslin CE, Weissman BA, et al. Baseline factors predictive of incident penetrating keratoplasty in keratoconus. Am J Ophthalmol 2006;142:923–930.
8. Fallahi Motlagh B, Javadi MA, Jafari Nasab MR, Rabbanikhah Z, Anisian A, Souri H. Corneal transplantation in patients with keratoconus. Iran J Ophthalmol 2003;16:9–19. [In Persian]
9. Javadi MA, Mohammadi MJ, Mirdehghan SA, Sajjadi SH. A comparison between donor-recipient corneal size and its effect on the ultimate refractive error induced in keratoconus. Cornea 1993;12:401–405.
10. Brierly SC, Izquierdo Jr L, Mannis MJ. Penetrating keratoplasty for keratoconus. Cornea 2000;19:329–332.
11. Kirkness CM, Ficker LA, Steele AD, Rice NS. The success of penetrating keratoplasty for keratoconus. Eye 1990;4:673– 688.
12. Lim L, Pesudovs K, Coster DJ. Penetrating keratoplasty for keratoconus: visual outcome and success. Ophthalmology 2000;107:1125–1131.
13. Colin J, Velou S. Current surgical options for keratoconus. J Cataract Refract Surg 2003;29:379–386.
14. Agarwal Rk. Deep lamellar keratoplasty, an alternative to penetrating keratoplasty. Br J Ophthalmol 1997;81:178–179.
15. Croasdale CR, Barney E, Warner EJ. Eye bank tissue utilization between endothelial keratoplasty and penetrating keratoplasty. Cornea 2013;32:280–284.
16. Cassidy D, Beltz J, Jhanji V, Loughnan MS. Recent advances in corneal transplantation for keratoconus. Clin Exp Optom 2013;96:165–172.
17. Weed KH, McGhee CN, MacEwen CJ. Atypical unilateral superior keratoconus in young males. Cont Lens Anterior Eye 2005;28:177–179.
18. MacIntyre R, Chow SP, Chan E, Poon A. Long-term outcomes of deep anterior lamellar keratoplasty versus penetrating keratoplasty in Australian keratoconus patients. Cornea 2014;33:6–9.
19. Van Dooren B, Mulder PG, Nieuwendaal CP, Beekhuis WH, Melles GR. Endothelial cell density after posterior lamellar keratoplasty (Melles techniques): 3 years follow-up. Am J Ophthalmol 2004;138:211–217.
20. Shimazaki J, Shimmura S, Ishioka M, Tsubota K. Randomized clinical trial of deep lamellar keratoplasty vs penetrating keratoplasty. Am J Ophthalmol 2002;134:159– 165.
21. Moher D, Liberati A, Tetzlaff J, Altman DG, Prisma Group. Preferred reporting items for systematic reviews 2009;6:e1000097.
22. Joanna Briggs Institute. The Joanna Briggs Institute Critical Appraisal tools for use in JBI systematic reviews checklist for prevalence studies [Internet]. Adelaide, Australia: Joanna Briggs Institute; 2017. Available from: http://joannabriggs.org/research/criticalappraisaltools.html
23. Abdelaal AM, Alqassimi AH, Malak M, Hijazi HT, Hadrawi M, Khan MA. Indications of keratoplasty and outcomes of deep anterior lamellar keratoplasty compared to penetrating keratoplasty. Cureus 2021;13:e13825.
24. Busool Abu Eta Y, Tomkins-Netzer O, Mimouni M, Hamed Azzam S, Shehadeh Mashour R. Predicting factors of ocular hypertension following keratoplasty: Indications versus the procedure. Eur J Ophthalmol 2021;31:1749– 1753.
25. Akdemir MO, Kandemir B, Sayman IB, Selvi C, Dogan OK. Comparison of contrast sensitivity and visual acuity between deep anterior lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus. Int J Ophthalmol 2012;5:737–741.
26. Alzahrani K, Dardin SF, Carley F, Brahma A, Morley D, Hillarby MC. Corneal clarity measurements in patients with keratoconus undergoing either penetrating or deep anterior lamellar keratoplasty. Clin Ophthalmol 2018;12:577–585.
27. Amayem AF, Hamdi IM, Hamdi MM. Refractive and visual outcomes of penetrating keratoplasty versus deep anterior lamellar keratoplasty with hydrodissection for treatment of keratoconus. Cornea 2013;32:e2–e5.
28. Bahar I, Kaiserman I, Srinivasan S, Ya-Ping J, Slomovic AR, Rootman DS. Comparison of three different techniques of corneal transplantation for keratoconus. Am J Ophthalmol 2008;146:905–912.e1.
29. Cohen AW, Goins KM, Sutphin JE, Wandling GR, Wagoner MD. Penetrating keratoplasty versus deep anterior lamellar keratoplasty for the treatment of keratoconus. Int Ophthalmol 2010;30:675–681.
30. Donoso R, Díaz C, Villavicencio P. Comparative study of keratoconus between Anwar’s deep anterior lamellar keratoplasty versus converted penetrating keratoplasty. Arch Soc Esp Oftalmol 2015;90:257–263.
31. Funnell CL, Ball J, Noble BA. Comparative cohort study of the outcomes of deep lamellar keratoplasty and penetrating keratoplasty for keratoconus. Eye 2006;20:527–532.
32. Godefrooij DA, Gans R, Imhof SM, Wisse RP. Trends in penetrating and anterior lamellar corneal grafting techniques for keratoconus: a national registry study. Acta Ophthalmol 2016;94:489–493.
33. Hamdi IM, Hamdi MM. Quality of vision after deep anterior lamellar keratoplasty (fluid dissection) compared to penetrating keratoplasty for the treatment of keratoconus. J Ophthalmol 2017;2017:4507989.
34. Huang T, Hu Y, Gui M, Hou C, Zhang H. Comparison of refractive outcomes in three corneal transplantation techniques for keratoconus. Graefes Arch Clin Exp Ophthalmol 2015;253:1947–1953.
35. Jafarinasab MR, Feizi S, Javadi MA, Hashemloo A. Graft biomechanical properties after penetrating keratoplasty versus deep anterior lamellar keratoplasty. Curr Eye Res 2011;36:417–421.
36. Janiszewska-Bil D, Czarnota-Nowakowska B, Krysik K, Lyssek-Boron A, Dobrowolski D, Grabarek BO, et al. Comparison of long-term outcomes of the lamellar and penetrating keratoplasty approaches in patients with keratoconus. J Clin Med 2021;10:2421.
37. Javadi MA, Feizi S, Yazdani S, Mirbabaee F. Deep anterior lamellar keratoplasty versus penetrating keratoplasty for keratoconus: a clinical trial. Cornea 2010;29:365–371.
38. Jones MN, Armitage WJ, Ayliffe W, Larkin DF, Kaye SB. Penetrating and deep anterior lamellar keratoplasty for keratoconus: a comparison of graft outcomes in the United kingdom. Invest Ophthalmol Vis Sci 2009;50:5625–5629.
39. Kasbekar SA, Jones MN, Ahmad S, Larkin DF, Kaye SB. Corneal transplant surgery for keratoconus and the effect of surgeon experience on deep anterior lamellar keratoplasty outcomes. Am J Ophthalmol 2014;158:1239–1246.
40. Khattak A, Nakhli FR, Al-Arfaj KM, Cheema AA. Comparison of outcomes and complications of deep anterior lamellar keratoplasty and penetrating keratoplasty performed in a large group of patients with keratoconus. Int Ophthalmol 2018;38:985–992.
41. Kim KH, Choi SH, Ahn K, Chung ES, Chung TY. Comparison of refractive changes after deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus. Jpn J Ophthalmol 2011;55:93–97.
42. Koytak A, Kubaloglu A, Sari ES, Atakan M, Culfa S, Ozerturk Y. Changes in central macular thickness after uncomplicated corneal transplantation for keratoconus: penetrating keratoplasty versus deep anterior lamellar keratoplasty. Cornea 2011;30:1318–1321.
43. Kubaloglu A, Coskun E, Sari ES, Gunes AS, Cinar Y, Piñero DP, et al. Comparison of astigmatic keratotomy results in deep anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus. Am J Ophthalmol 2011;151:637–643.e1.
44. Macintyre R, Chow SP, Chan E, Poon A. Long-term outcomes of deep anterior lamellar keratoplasty versus penetrating keratoplasty in Australian keratoconus patients. Cornea 2014;33:6–9.
45. Motlagh BF, Sedghipoor MR, Abroon G, Sadigh AL. Outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus in a university teaching hospital. Iran J Ophthalmol 2012;24:52–56.
46. Oh BL, Kim MK, Wee WR. Comparison of clinical outcomes of same-size grafting between deep anterior lamellar keratoplasty and penetrating keratoplasty for keratoconus. Korean J Ophthalmol 2013;27:322–330.
47. Pedrotti E, Passilongo M, Fasolo A, Ficial S, Ferrari S, Marchini G. Refractive outcomes of penetrating keratoplasty and deep anterior lamellar keratoplasty in fellow eyes for keratoconus. Int Ophthalmol 2017;37:911–919.
48. Sögütlü Sari E, Kubaloglu A, Ünal M, Piñero Llorens D, Koytak A, Ofluoglu AN, et al. Penetrating keratoplasty versus deep anterior lamellar keratoplasty: comparison of optical and visual quality outcomes. Br J Ophthalmol 2012;96:1063–1067.
49. Watson SL, Ramsay A, Dart JK, Bunce C, Craig E. Comparison of deep lamellar keratoplasty and penetrating 2004;111:1676–1682.
50. Yüksel B, Kandemir B, Uzunel UD, Çelik O, Ceylan S, Küsbeci T. Comparison of visual and topographic outcomes of deep-anterior lamellar keratoplasty and penetrating keratoplasty in keratoconus. Int J Ophthalmol 2017;10:385–390.
51. Zhang YM, Wu SQ, Yao YF. Long-term comparison of fullbed deep anterior lamellar keratoplasty and penetrating keratoplasty in treating keratoconus. J Zhejiang Univ Sci B 2013;14:438–450.
52. Ziaei M, Vellara HR, Gokul A, Ali NQ, McGhee CNJ, Patel DV. Comparison of corneal biomechanical properties following penetrating keratoplasty and deep anterior lamellar keratoplasty for keratoconus. Clin Exp Ophthalmol 2020;48:174–182.
53. Liu H, Chen Y, Wang P, Li B, Wang W, Su Y, et al. Efficacy and safety of deep anterior lamellar keratoplasty vs. penetrating keratoplasty for keratoconus: a meta-analysis. PLoS ONE 2015;10:e0113332.
54. 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.
55. Song Y, Zhang J, Pan Z. Systematic review and meta-analysis of clinical outcomes of penetrating keratoplasty versus deep anterior lamellar keratoplasty for keratoconus. Exp Clin Transplant 2020;18:417–428.