Effect of Topographic Cone Location on Outcomes of Corneal Collagen Cross-linking for Keratoconus and Corneal Ectasia
Abstract
PURPOSE:
To assess the effect of preoperative topographic cone location on 1-year outcomes of corneal collagen cross-linking (CXL).
METHODS:
In this prospective, randomized, controlled clinical trial, 99 eyes (66 keratoconus, 33 ectasia) from 76 patients underwent CXL. Cone location was defined by the coordinates of preoperative maximum keratometry (maximum K) using the anterior sagittal curvature topography map (Pentacam, Oculus Optikgeräte GmbH). Patients were divided into three groups: those with a maximum K located within the central 3-mm (central cone group), 3- to 5-mm (paracentral cone group), and outside the 5-mm (peripheral cone group) optical zones. Topography and visual acuity data were obtained preoperatively and at 1 year.
RESULTS:
In the combined cohort, maximum K and uncorrected and corrected distance visual acuity significantly improved by −1.60±3.40 diopters (D) (P<.001), −0.08±0.25 logMAR (P=.001), and −0.10±0.18 log-MAR (P<.001), respectively. Comparing cone groups, maximum K decreased by 2.60±4.50 D (P<.001) in the central cone group, 1.10±2.50 D (P=.02) in the paracentral cone group, and 0.40±1.20 D (P=.08) in the peripheral cone group. Differences among groups were statistically significant (P<.001). Uncorrected distance visual acuity improved by −0.07±0.3 logMAR (P=.1) (central cone group), −0.1±0.17 logMAR (P=.004) (paracentral cone group), and −0.1±0.25 logMAR (P=.04) (peripheral cone group). Corrected distance visual acuity improved by −0.14±0.21 logMAR (P<.001) (central cone group), −0.08±0.17 logMAR (P=.01) (paracentral cone group), and −0.08±0.12 logMAR (P=.002) (peripheral cone group). For both UDVA and CDVA outcomes, these differences among groups were not statistically significant.
CONCLUSIONS:
After CXL, more topographic flattening occurs in eyes with centrally located cones and the least flattening effect occurs when the cone is located peripherally. This cone-location effect is found in eyes with both keratoconus and ectasia.
- 1.Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen cross-linking for the treatment of keratoconus. Am J Ophthalmol. 2003; 135(5):620–627.
10.1016/S0002-9394(02)02220-1 Crossref MedlineGoogle Scholar - 2.Vinciguerra P, Camesasca FI, Albè E, Trazza S. Corneal collagen cross-linking for ectasia after excimer laser refractive surgery: 1-year results. J Refract Surg. 2010; 26(7):486–497.
10.3928/1081597X-20090910-02 LinkGoogle Scholar - 3.Hafezi F, Kanellopoulos J, Wiltfang R, Seiler T. Corneal collagen cross-linking with riboflavin and ultraviolet A to treat induced keratectasia after laser in situ keratomileusis. J Cataract Refract Surg. 2007; 33(12):2035–2040.
10.1016/j.jcrs.2007.07.028 Crossref MedlineGoogle Scholar - 4.Wollensak G, Spoerl E, Seiler T. Stress-strain measurements of human and porcine corneas after riboflavin-ultraviolet-A-induced cross-linking. J Cataract Refract Surg. 2003; 29(9):1780–1785.
10.1016/S0886-3350(03)00407-3 Crossref MedlineGoogle Scholar - 5.Ahearne M, Yang Y, Then KY, Liu KK. Non-destructive mechanical characterisation of UVA/riboflavin crosslinked collagen hydrogels. Br J Ophthalmol. 2008; 92(2):268–271.
10.1136/bjo.2007.130104 Crossref MedlineGoogle Scholar - 6.He X, Spoerl E, Tang J, Liu J. Measurement of corneal changes after collagen cross-linking using a noninvasive ultrasound system. J Cataract Refract Surg. 2010; 36(7):1207–1212.
10.1016/j.jcrs.2009.12.047 Crossref MedlineGoogle Scholar - 7.Vinciguerra P, Albè E, Trazza S, Refractive, topographic, tomographic, and aberrometric analysis of keratoconic eyes undergoing corneal cross-linking. Ophthalmology. 2009; 116(3):369–378.
10.1016/j.ophtha.2008.09.048 Crossref MedlineGoogle Scholar - 8.Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen cross-linking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. 2008; 34(5):796–801.
10.1016/j.jcrs.2007.12.039 Crossref MedlineGoogle Scholar - 9.Hersh PS, Greenstein SA, Fry KL. Corneal collagen cross-linking for keratoconus and corneal ectasia: one year results of a prospective randomized study. J Cataract Refract Surg. 2011; 37(1):149–160.
10.1016/j.jcrs.2010.07.030 Crossref MedlineGoogle Scholar - 10.Grewal DS, Brar GS, Jain R, Sood V, Singla M, Grewal SP. Corneal collagen cross-linking using riboflavin and ultraviolet-A light for keratoconus: one-year analysis using Scheimpflug imaging. J Cataract Refract Surg. 2009; 35(3):425–432.
10.1016/j.jcrs.2008.11.046 Crossref MedlineGoogle Scholar - 11.Caporossi A, Mazzotta C, Baiocchi S, Caporossi T. 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.
10.1016/j.ajo.2009.10.021 Crossref MedlineGoogle Scholar - 12.Caporossi A, Baiocchi S, Mazzotta C, Traversi C, Caporossi T. Parasurgical 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.
10.1016/j.jcrs.2006.01.091 Crossref MedlineGoogle Scholar - 13.Greenstein SA, Fry KL, Bhatt J, Hersh PS. Natural history of corneal haze after collagen cross-linking for keratoconus and corneal ectasia: Scheimpflug and biomicroscopic analysis. J Cataract Refract Surg. 2010; 36(12):2105–2114.
10.1016/j.jcrs.2010.06.067 Crossref MedlineGoogle Scholar - 14.Greenstein SA, Shah VP, Fry KL, Hersh PS. Corneal thickness changes after corneal collagen cross-linking for keratoconus and corneal ectasia: 1 year results. J Cataract Refract Surg. 2011; 37(4):691–700.
10.1016/j.jcrs.2010.10.052 Crossref MedlineGoogle Scholar - 15.Koller T, Mrochen M, Seiler T. Complication and failure rates after corneal cross-linking. J Cataract Refract Surg. 2009; 35(8):1358–1362.
10.1016/j.jcrs.2009.03.035 Crossref MedlineGoogle Scholar - 16.Spoerl E, Mrochen M, Sliney D, Trokel S, Seiler T. Safety of UVA-riboflavin cross-linking of the cornea. Cornea. 2007; 26(4):385–389.
10.1097/ICO.0b013e3180334f78 Crossref MedlineGoogle Scholar - 17.Salgado JP, Khoramnia R, Lohmann CP, Winkler von Mohrenfels C. Corneal collagen cross-linking in post-LASIK keratectasia. Br J Ophthalmol. 2011; 95(4):493–497.
10.1136/bjo.2010.179424 Crossref MedlineGoogle Scholar - 18.Koller T, Pajic B, Vinciguerra P, Seiler T. Flattening of the cornea after collagen cross-linking for keratoconus. J Cataract Refract Surg. 2011; 37(8):1488–1492.
10.1016/j.jcrs.2011.03.041 Crossref MedlineGoogle Scholar - 19.Greenstein S, Hersh PS. A multifactorial treatment analysis and algorithm for corneal collagen cross-linking. http://www.arvo.org. Association for Research in Vision and Ophthalmology Web site. Accessed May 2012. Google Scholar
- 20.Greenstein SA, Fry KL, Hersh PS. Corneal topography indices after corneal collagen cross-linking for keratoconus and corneal ectasia: one-year results. J Cataract Refract Surg. 2011; 37(7):1282–1290.
10.1016/j.jcrs.2011.01.029 Crossref MedlineGoogle Scholar - 21.Greenstein S, Fry K, Hersh P. Higher-order aberrations after corneal collagen crosslinking for keratoconus and corneal ectasia. J Cataract Refract Surg. 2012; 38(2):292–302.
10.1016/j.jcrs.2011.08.041 Crossref MedlineGoogle Scholar - 22.Mrochen M, Bueeler M, Donitzky C, Seiler T. Optical ray tracing for the calculation of optimized corneal ablation profiles in refractive treatment planning. J Refract Surg. 2008; 24(4):S446–S451. MedlineGoogle Scholar
- 23.Hersh PS, Fry K, Blaker JW. Spherical aberration after laser in situ keratomileusis and photorefractive keratectomy. Clinical results and theoretical models of etiology. J Cataract Refract Surg. 2003; 29(11):2096–2104.
10.1016/j.jcrs.2003.09.008 Crossref MedlineGoogle Scholar - 24.Wollensak G, Spoerl E, Reber F, Seiler T. Keratocyte cytotoxicity of riboflavin/UVA-treatment in vitro. Eye (Lond). 2004; 18(7):718–722.
10.1038/sj.eye.6700751 Crossref MedlineGoogle Scholar - 25.Hersh PS, Fry KL, Chandrashekhar R, Fikaris DS. Conductive keratoplasty to treat complications of LASIK and photorefractive keratectomy. Ophthalmology. 2005; 112(11):1941–1947.
10.1016/j.ophtha.2005.05.017 Crossref MedlineGoogle Scholar
