International Journal of Keratoconus and Ectatic Corneal Diseases

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VOLUME 7 , ISSUE 1 ( 2018 ) > List of Articles

ORIGINAL AND RESEARCH ARTICLE

The Potential Impact of Cone Eccentricity on Visual Outcomes in Inferior and Central Keratoconus Patients following Keraring Implantation: A Pilot Preliminary Study

Iraklis Vastardis, Aye Khine, Mohamed Elalfy, Samer Hamada, Georgios Perdikakis, Markus Kohlhaas, Zisis Gatzioufas

Keywords : Kerarings, Keratoconus.,Eccentricity

Citation Information : Vastardis I, Khine A, Elalfy M, Hamada S, Perdikakis G, Kohlhaas M, Gatzioufas Z. The Potential Impact of Cone Eccentricity on Visual Outcomes in Inferior and Central Keratoconus Patients following Keraring Implantation: A Pilot Preliminary Study. Int J Kerat Ect Cor Dis 2018; 7 (1):12-18.

DOI: 10.5005/jp-journals-10025-1154

License: CC BY-SA 3.0

Published Online: 00-06-2018

Copyright Statement:  Copyright © 2018; Jaypee Brothers Medical Publishers (P) Ltd.


Abstract

Aim: To evaluate possible correlation of cone eccentricity and visual acuity in inferior and central keratoconus patients following Keraring implantation for keratoconus. Materials and methods: A total of 19 eyes from an equal number of patients were analyzed in this preliminary pilot retrospective study. Two groups were formed, group I for inferior (n = 11) and group II for central keratoconus (n = 9). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometric readings, central corneal thickness, maximum keratometric distance from corneal apex (DKmax), and corneal thinnest point from corneal apex (DTh) were evaluated preoperatively and 6 months after the Keraring implantation. The DKmax and DTh were measured and from corneal apex to evaluate the eccentricity of the cone. Results: The CDVA and refractive cylinder reduction improved at 6 months postoperatively in both groups (t-test, p = 0.002, p < 0.0001 and p = 0.0007, p = 0.0017 respectively). Topography keratometric findings (Kmax difference) and spherical equivalent improved for group II but not for group I (t-test, p = 0.002, p = 0.005 and p = 0.85, p = 0.12 respectively). There was a high correlation between CDVA and corneal astigmatic reduction (p = 0.0283, correlation coefficient r = -0.7) and a negative relation in regression analysis (p = 0.0240, y = 0.2616 + - 0.1354 × + 0,03750 × 2, coefficient of determination R2 = 0.7115) for the central keratoconus but not for the inferior one. There was no correlation between the topography landmarks DKmax or DTh and CDVA and no statistical difference was found between them in t-test at 6 months. Conclusion: Both groups profited from a Keraring implantation in terms of CDVA, but a relation between corneal astigmatic reduction and CDVA after Keraring implantation at 6 months was found only in patients with central keratoconus. Clinical significance: This finding suggests that a visual acuity improvement in keratoconus patients is not only topographic and keratometric-related but also higher order aberration reduction-dependent. Bigger prospective studies that also evaluate corneal aberration reduction findings are needed to support our results.


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  1. Burris TE. Intrastromal corneal ring technology: results and indications. Curr Opin Ophthalmol 1998 Aug;9(4):9-14.
  2. Colin J, Cochener B, Savary G, Malet F. Correcting keratoconus with intracorneal rings. J Cataract Refract Surg 2000 Aug;26(8):1117-1122.
  3. Silvestrini TA, Mathis ML, Loomas BE, Burris TE. A geometric model to predict the change in corneal curvature from the intrastromal corneal ring (ICR). Invest Ophthalmol Vis Sci 1994;35:2023.
  4. Burris TE, Baker PC, Ayer CT, Loomas BE, Mathis ML, Silvestrini TA. Flattening of central corneal curvature with intrastromal corneal rings of increasing thickness: an eye-bank eye study. J Cataract Refract Surg 1993;19(Suppl 1):182-187.
  5. Daxer A, Fratzl P. Collagen orientation in the human corneal stroma and its implication in keratoconus. Invest Ophthalmol Vis Sci 1997 Jan;38(1):121-129.
  6. Albertazzi, R. Tratamiento del queratocono con segmentos intracorneales. In: Albertazzi R, editor. Queratocono: pautas para su diagnóstico y tratamiento. Buenos Aires: Ediciones cientificas argentina para la keratoconus society; 2010. pp. 205-268.
  7. Coskunseven E, Kymionis GD, Tsiklis NS, Atun S, Arslan E, Jankov MR, Pallikaris IG. One-year results of intrastromal corneal ring segment implantation (KeraRing) using femtosecond laser in patients with keratoconus. Am J Ophthalmol 2008 May;145(5):775-779.
  8. Piñero DP, Alió JL. Intracorneal ring segments in ectatic corneal disease: a review. Clin Exp Ophthalmol 2010 Mar;38(2):154-167.
  9. Vega-Estrada A, Alió JL, Brenner LF, Javaloy J, Plaza Puche AB, Barraquer RI, Teus MA, Murta J, Henriques J, Uceda- Montanes A. Outcome analysis of intracorneal ring segments for the treatment of keratoconus based on visual, refractive, and aberrometric impairment. Am J Ophthalmol 2013 Mar;155(3):575.e1-584.e1.
  10. Kaya V, Utine CA, Karakus SH, Kavadarli I, Yilmaz OF. Refractive and visual outcomes after Intacs vs Ferrara intrastromal corneal ring segment implantation for keratoconus: a comparative study. J Refract Surg 2011 Dec;27(12):907-912.
  11. Giacomin NT, Mello GR, Medeiros CS, Kiliç A, Serpe CC, Almeida HG, Kara-Junior N, Santhiago MR. Intracorneal ring segments implantation for corneal ectasia. J Refract Surg 2016 Dec;32(12):829-839.
  12. Torquetti L, Ferrara G, Almeida F, Cunha L, Araujo LP, Machado A, Marcelo Lyra J, Merayo-Lloves J, Ferrara P. Intrastromal corneal ring segments implantation in patients with keratoconus: 10 year follow-up. J Refract Surg 2014 Jan;30(1):22-26.
  13. Vega-Estrada A, Alió JL, Brenner LF, Burguera N. Outcomes of intrastromal corneal ring segments for treatment of keratoconus: five-year follow-up analysis. J Cataract Refract Surg 2013 Aug;39(8):1234-1240.
  14. Yeung SN, Lichtinger A, Ku JY, Kim P, Low SA, Rootman DS. Intracorneal ring segment explantation after intracorneal ring segment implantation combined with same-day corneal collagen crosslinking in keratoconus. Cornea 2013 Dec;32(12): 1617-1620.
  15. Shabayek MH, Alió JL. Intrastromal corneal ring segment implantation by femtosecond laser for keratoconus correction. Ophthalmology 2007 Sep;114(9):1643-1652.
  16. Coskunseven E, Kymionis GD, Tsiklis NS, Atun S, Arslan E, Siganos CS, Jankov M, Pallikaris IG. Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus. Acta Ophthalmol 2011 Feb;89(1):54-57.
  17. Sharma M, Boxer Wachler BS. Comparison of single segment and double-segment Intacs for keratoconus and post-LASIK ectasia. Am J Ophthalmol 2006 May;141(5):891-895.
  18. Alió JL, Artola A, Hassanein A, Haroun H, Galal A. One or 2 Intacs segments for the correction of keratoconus. J Cataract Refract Surg 2005 May;31(5):943-953.
  19. Miranda D, Sartori M, Francesconi C, Allemann N, Ferrara P, Campos M. Ferrara intrastromal corneal ring segments for severe keratoconus. J Refract Surg 2003 Nov-Dec;19(6): 645-653.
  20. Kwitko S, Severo NS. Ferrara intracorneal ring segments for keratoconus. J Cataract Refract Surg 2004 Apr;30(4): 812-820.
  21. Siganos D, Ferrara P, Chatzinikolas K, Bessis N, Papastergiou G. Ferrara intrastromal corneal rings for the correction of keratoconus. J Cataract Refract Surg 2002 Nov;28(11): 1947-1951.
  22. Coskunseven E, Kymionis GD, Tsiklis NS, Atun S, Arslan E, Siganos CS, Jankov M, Pallikaris IG. Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus. Acta Ophthalmol 2011 Feb;89(1):54-57.
  23. Vega-Estrada A, Alió JL. The use of intracorneal ring segments in keratoconus. Eye Vis (Lond) 2016 Mar;3:8.
  24. Ertan A, Colin J. Intracorneal rings for keratoconus and keratectasia. J Cataract Refract Surg 2007 Jul;33(7):1303-1314.
  25. Alió JL, Shabayek MH, Artola A. Intracorneal ring segments for keratoconus correction: long-term follow-up. J Cataract Refract Surg 2006 Jun;32(6):978-985.
  26. Shetty R, Kurian M, Anand D, Mhaske P, Narayana KM, Shetty BK. Intacs in advanced keratoconus. Cornea 2008 Oct;27(9):1022-1029.
  27. Peña-García P, Alió JL, Vega-Estrada A, Barraquer RI. Internal, corneal, and refractive astigmatism as prognostic factors for intrastromal corneal ring segment implantation in mild to moderate keratoconus. J Cataract Refract Surg 2014 Oct;40(10):1633-1644.
  28. Zare MA, Hashemi H, Salari MR. Intracorneal ring segment implantation for the management of keratoconus: safety and efficacy. J Cataract Refract Surg 2007 Nov;33(11): 1886-1891.
  29. Prakash G, Srivastava D, Choudhuri S, Thirumalai SM, Bacero R. Differences in central and non-central keratoconus, and their effect on the objective screening thresholds for keratoconus. Acta Ophthalmol 2016 Mar;94(2): e118-e129.
  30. Shetty R, Nuijts RM, Nicholson M, Sargod K, Jayadev C, Veluri H, Sinha Roy A. Cone location-dependent outcomes after combined topography-guided photorefractive keratectomy and collagen cross-linking. Am J Ophthalmol 2015 Mar;159(3):419.e2-425.e2.
  31. Gatzioufas Z, Panos GD, Elalfy M, Khine A, Hamada S, Lake D, Kozeis N, Balidis M. Effect of conus eccentricity on visual outcomes after intracorneal ring segments implantation in keratoconus. J Refract Surg 2018 Mar;34(3):196-200.
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