Natural history of corneal haze after collagen crosslinking for keratoconus and corneal ectasia: Scheimpflug and biomicroscopic analysis

J Cataract Refract Surg. 2010 Dec;36(12):2105-14. doi: 10.1016/j.jcrs.2010.06.067.

Abstract

Purpose: To determine the natural history of collagen crosslinking (CXL)-associated corneal haze measured by Scheimpflug imagery and slitlamp biomicroscopy in patients with keratoconus or ectasia after laser in situ keratomileusis.

Setting: Cornea and refractive surgery subpecialty practice, United States.

Design: Prospective randomized controlled clinical trial.

Methods: The treatment group received ultraviolet-A/riboflavin CXL therapy. The control group received riboflavin alone without epithelial debridement. To objectively measure CXL-associated corneal haze, corneal densitometry using Scheimpflug imagery was measured and the changes in haze were analyzed over time. A similar analysis was performed using clinician-determined slitlamp haze. Correlation of CXL-associated corneal haze with postoperative outcomes was analyzed.

Results: The mean preoperative corneal densitometry was 14.9 ± 1.93 (SD) (Pentacam Scheimpflug densitometry units). Densitometry peaked at 1 month (mean 23.4 ± 4.40; P<.001), with little change at 3 months (mean 22.4 ± 4.79; P = .06) and decreased between 3 months and 6 months (19.4 ± 4.48; P<.001) and between 6 months and 12 months. By 12 months, densitometry had not completely returned to baseline in the entire cohort (mean 17.0 ± 3.82; P<.001) and the keratoconus subgroup; however, it returned to baseline in the ectasia group (16.1 ± 2.41; P = .15). The postoperative course of slitlamp haze was similar to objective densitometry measurements. Increased haze, measured by densitometry, did not correlate with postoperative clinical outcomes.

Conclusions: The time course of corneal haze after CXL was objectively quantified; it was greatest at 1 month, plateaued at 3 months, and was significantly decreased between 3 months and 12 months. Changes in haze did not correlate with postoperative clinical outcomes.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Collagen / metabolism*
  • Corneal Opacity / diagnosis*
  • Corneal Opacity / physiopathology
  • Corneal Stroma / metabolism*
  • Corneal Stroma / pathology
  • Corneal Topography
  • Cross-Linking Reagents / therapeutic use*
  • Diagnostic Techniques, Ophthalmological
  • Dilatation, Pathologic / drug therapy
  • Dilatation, Pathologic / metabolism
  • Female
  • Follow-Up Studies
  • Humans
  • Keratoconus / drug therapy*
  • Keratoconus / metabolism
  • Male
  • Microscopy, Acoustic
  • Middle Aged
  • Photography
  • Photosensitizing Agents / therapeutic use
  • Postoperative Complications*
  • Prospective Studies
  • Riboflavin / therapeutic use
  • Time Factors
  • Ultraviolet Rays
  • Visual Acuity
  • Young Adult

Substances

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