Treatment Effect and Corneal Light Scattering With 2 Corneal Cross-linking Protocols: A Randomized Clinical Trial

JAMA Ophthalmol. 2015 Nov;133(11):1254-60. doi: 10.1001/jamaophthalmol.2015.2852.

Abstract

Importance: We describe and evaluate a complementary method to indirectly quantify the treatment effect of corneal cross-linking (CXL). Additional methods to indirectly quantify the treatment effect of CXL are needed.

Objective: To assess the spatial distribution and the time course of the increased corneal densitometry (corneal light backscatter) seen after CXL with riboflavin and UV-A irradiation.

Design, setting, and participants: Open-label randomized clinical trial of 43 patients (60 eyes) who were 18 to 28 years of age and had progressive keratoconus and a plan to be treated with CXL at Umeå University Hospital, Umeå, Sweden. The patients were randomized to receive conventional CXL (n = 30) using the Dresden protocol or CXL with mechanical compression of the cornea using a flat rigid contact lens sutured to the cornea during the treatment (CRXL) (n = 30). All participants were followed up during a 6-month period from October 13, 2009, through May 31, 2012.

Interventions: Corneal cross-linking according to the Dresden protocol or CRXL.

Main outcomes and measures: Change in corneal densitometry after CXL and CRXL for keratoconus.

Results: Of the original 60 eyes included, 4 had incomplete data. A densitometry increase was seen after both treatments that was deeper and more pronounced in the CXL group (difference between the groups at 1 month in the center layer, zone 0-2 mm, 5.02 grayscale units [GSU], 95% CI, 2.92-7.12 GSU; P < .001). This increase diminished with time but was still noticeable at 6 months (difference between the groups at 6 months in the center layer, zone 0-2 mm, 3.47 GSU; 95% CI, 1.72-5.23 GSU; P < .001) and was proportional to the reduction in corneal steepness (R = -0.45 and -0.56 for CXL and CRXL, respectively).

Conclusions and relevance: The degree of corneal light backscatter relates to the reduction in corneal steepness after cross-linking and may become a relevant complement to other methods in evaluating the cross-linking effect, for example, when comparing different treatment regimens.

Trial registration: clinicaltrials.gov Identifier: NCT02425150.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Collagen / metabolism
  • Cornea / physiology*
  • Corneal Stroma / metabolism*
  • Cross-Linking Reagents*
  • Densitometry
  • Female
  • Humans
  • Keratoconus / drug therapy*
  • Keratoconus / metabolism
  • Light
  • Male
  • Photochemotherapy / methods*
  • Photosensitizing Agents / therapeutic use
  • Riboflavin / therapeutic use
  • Scattering, Radiation*
  • Treatment Outcome
  • Ultraviolet Rays
  • Young Adult

Substances

  • Cross-Linking Reagents
  • Photosensitizing Agents
  • Collagen
  • Riboflavin

Associated data

  • ClinicalTrials.gov/NCT02425150