Original Article

Effect of Topographic Cone Location on Outcomes of Corneal Collagen Cross-linking for Keratoconus and Corneal Ectasia

Steven A. Greenstein, MD; Kristen L. Fry, OD, MS; Peter S. Hersh, MD

  • Journal of Refractive Surgery
  • June 2012 - Volume 28 · Issue 6: 397-405
  • DOI: 10.3928/1081597X-20120518-02
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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.

AUTHORS

From Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus (Hersh, Greenstein, Fry), Teaneck; and the Department of Ophthalmology, UMDNJ-New Jersey Medical School (Hersh, Greenstein), Newark, New Jersey.

Dr Hersh is a medical monitor for Avedro Inc. The remaining authors have no financial or proprietary interest in the materials presented herein.

Supported in part by Peschke Meditrade GmbH, Zurich, Switzerland; and an unrestricted grant to the Department of Ophthalmology from Research to Prevent Blindness Inc, New York, New York.

Correspondence: Peter S. Hersh, MD, Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus, 300 Frank W Burr Blvd, Teaneck, NJ 07666. Tel: 201.883.0505; E-mail: PHersh@vision-institute.com

Received: September 06, 2011
Accepted: March 27, 2012

doi: 10.3928/1081597X-20120518-02

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