The Effect of Corneal Collagen Cross-Linking on Higher Order Aberrations in Keratoconus

Main Article Content

Ahmed M. Moharam
Mohammad M. Khater
Hisham A. Saad
Khaled A. Nagy

Abstract

Purpose: To assess the changes in ocular high order aberrations after collagen cross linking for keratoconus.

Patients and Methods: This study included 30 eyes with confirmed KCN. Baseline evaluation focused on: UDVA and BSCVA using logMAR notation, MRSE, corneal topography using Orbscan IIZ and wave-front aberrometry using Zywave II. CXL was performed per ‘Dresden protocol’ through a 30-minutes exposure to 370 nm UVA with an irradiance of 3 mW/cm 2. Patients had comprehensive ophthalmic evaluation after 6 months with special attention to: UDVA, BSCVA, MRSE, corneal topography and wave-front aberrometry changes. 

Results: The mean age was 25.5±5.84 (20:31) years. After 6 months, there was a significant decrease in corneal thickness from 493.2± 24.17µ to 486.7±24.26µ (P<0.05) and a significant decrease in K max from 47.4±1.17D to 46.1±1.17D (P<0.05). BSCVA improved from preoperative value (0.00:0.5 logMAR (median 0.3)) to 6 months’ value (0.1:1.00 logMAR (median 0.2) (P <0.05). Preoperative MRSE was -7.25: -0.5D (median -2.85D) and at 6 months was -6.25: -0.5D (median - 2.125D) (P<0.05). A significant correlation was found at 6 months between changes in both BSCVA and: K max (P<0.001), corneal thickness (P<0.05), vertical coma (P<0.001) and trefoil (P<0.001). 

Conclusions: Improvement in HOA was detected after CXL for KCN. The changes in total, vertical coma and vertical trefoil aberrations were significantly correlated with postoperative improvement in BSCVA. Thus, improvement in HOA profile after CXL is one of the explanations of improvement in visual function after CXL in KCN.

Keywords:
Corneal Collagen, Keratoconus, visual acuity

Article Details

How to Cite
Moharam, A. M., Khater, M. M., Saad, H. A., & Nagy, K. A. (2021). The Effect of Corneal Collagen Cross-Linking on Higher Order Aberrations in Keratoconus. Ophthalmology Research: An International Journal, 14(2), 1-8. https://doi.org/10.9734/or/2021/v14i230187
Section
Case study

References

Gomes JA, Tan D, Rapuano CJ, Belin MW, Ambrósio R Jr, Guell JL et al. Group of panelists for the global delphi panel of keratoconus and ectatic diseases. Global consensus on keratoconus and ectatic diseases. Cornea. 2015;34(4):359-69.

Hasby EA, Saad HA. Immunohistochemical expression of Fas ligand (FasL) and neprilysin (neutral endopeptidase/CD10) in keratoconus. Int Ophthalmol. 2013;33(2):125-31.

Orucoglu F, Toker E. Comparative analysis of anterior segment parameters in normal and keratoconus eyes generated by scheimpflug tomography. J Ophthalmol. 2015;2015:925414.

Jhanji V, Sharma N, Vajpayee RB. Management of keratoconus: Current scenario. Br J Ophthalmol. 2011;25(8): 1044–1050.

Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003;135 (5):620–627.

Caporossi A, Mazzotta C, Baiocchi S. Long-term results of riboflavin ultraviolet a corneal collagen cross-linking for keratoconus in Italy: the Siena eye cross study. Am J Ophthalmol. 2010;149(4):585–593.

Iqbal M, Elmassry A, Tawfik A, Elgharieb M, Nagy K, Soliman A, Saad H, Tawfik T, Ali O, Gad A, El Saman I, Radwan A, Elzembely H, Abou Ali A, Fawzy O. Standard cross-linking versus photorefractive keratectomy combined with accelerated cross-linking for keratoconus management: a comparative study. Acta Ophthalmol. 2019;97(4):e623-e631.

Pantanelli S, MacRae S, Jeong TM, Yoon G. Characterizing the wave aberration in eyes with keratoconus or penetrating keratoplasty using a high-dynamic range wavefront sensor. Ophthalmology. 2007;114(11):2013-21.

Bühren J, Kühne C, Kohnen T. Defining subclinical keratoconus using corneal first-surface higher-order aberrations. Am J Ophthalmol. 2007;143(3):381-389.

Applegate RA, Marsack JD, Ramos R. Interaction between aberrations to improve or reduce visual performance. J Cataract Refract Surg. 2003;29(8):1487–1495.

Meiri Z, Keren S, Rosenblatt A, Sarig T, Shenhav L, Varssano D. Efficacy of corneal collagen cross-linking for the treatment of keratoconus: a systematic review and meta-analysis. Cornea. 2016; 35(3):417-28.

Derakhshan A, Heravian Shandiz J, Ahadi M. Short-term outcomes of collagen crosslinking for early keratoconus. J Ophthalmic Vis Res. 2011;6(3):155–159.

Vinciguerra P, Albè E, Trazza S, Rosetta P, Vinciguerra R, Seiler T, Epstein D. Refractive, topographic, tomographic, and aberrometric analysis of keratoconic eyes undergoing corneal cross-linking. Ophthalmology. 2009;116(3):369-78.

Chang CY, Hersh PS. Corneal collagen cross-linking: a review of 1-year outcomes. Eye Contact Lens. 2014;40(6): 345-352.

Raiskup-Wolf F, Hoyer A, Spozerl E. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. 2008;34(5):796–801.

Caporossi A, Baiocchi S, Mazzotta C. Para-surgical therapy for keratoconus by riboflavin ultraviolet type A rays induced cross-linking of corneal collagen: preliminary refractive results in an Italian study. J Cataract Refract Surg. 2006; 32(5):837–845.

Razmjoo H, Nasrollahi AP, Salam H, Karbasi N, Najarzadegan MR. Topographic corneal changes after collagen cross-linking in patients with corneal keratoconus. J Res Med Sci. 2013;18(10): 882–886.

Legare ME, Iovieno A, Yeung SN, Kim P, Lichtinger A, Hollands S, Slomovic AR, Rootman DS. Corneal collagen cross-linking using riboflavin and ultraviolet A for the treatment of mild to moderate keratoconus: 2-year follow-up. Can J Ophthalmol. 2013;48(1):63-8.

Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. 2008;34(5):796-801.

Greenstein SA, Fry KL, Hersh MJ. Higher-order aberrations after corneal collagen crosslinking for keratoconus and corneal ectasia. J Cataract Refract Surg. 2012; 38(2):292–302.

Applegate RA, Sarver EJ, Khemsara V. Are all aberrations equal? J Refract Surg. 2002;18(5):S556–S562.

Miháltz K, Kovács I, Kránitz K, Erdei G, Németh J, Nagy ZZ. Mechanism of aberration balance and the effect on retinal image quality in keratoconus: optical and visual characteristics of keratoconus. J Cataract Refract Surg. 2011;37(5):914-22.

Naderan M, Jahanrad A. Higher-order aberration 4 years after corneal collagen cross-linking. Indian Journal of Ophthalmology. 2017;65(9):808-812.

El-Massry AA, Dowidar AM, Massoud TH, Tadros BG. Evaluation of the effect of corneal collagen cross-linking for keratoconus on the ocular higher-order aberrations. Clin Ophthalmol. 2017;11: 1461-1469.