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

Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus, Teaneck, New Jersey, USA.
Journal of Cataract and Refractive Surgery (Impact Factor: 2.72). 12/2010; 36(12):2105-14. DOI: 10.1016/j.jcrs.2010.06.067
Source: PubMed


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.
Cornea and refractive surgery subpecialty practice, United States.
Prospective randomized controlled clinical trial.
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.
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.
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.

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Available from: Peter S Hersh, Apr 01, 2015
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    • "Consequently, the development of haze may be attributed not to CXL itself but to the stage of keratoconus. Objective quantification of the time course of CXL-induced haze suggests that it peaks at 1 month, plateaus at 3 months, and then gradually decreases thereafter [112]. "
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    ABSTRACT: Collagen cross-linking (CXL) using UVA light and riboflavin (vitamin B2) was introduced as a clinical application to stabilize the cornea by inducing cross-links within and between collagen fibers. CXL has been investigated extensively and has been shown clinically to arrest the progression of keratoconic or post-LASIK ectasia. With its minimal cost, simplicity, and proven positive clinical outcome, CXL can be regarded as a useful approach to reduce the number of penetrating keratoplasties performed. Small case series have also indicated that CXL is beneficial in corneal edema by reducing stromal swelling behavior and in keratitis by inhibiting pathogen growth. Despite these encouraging results, CXL remains a relatively new method that is potentially associated with complications. Aspects such as side effects and recurrence rates have still to be elucidated. In light of the growing interest in CXL, our paper summarizes present knowledge about this promising approach. We have intentionally endeavored to include the more relevant studies from the recent literature to provide an overview of the current status of CXL.
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    • "Greenstein et al. [30] studied the natural course after CXL and found a significant postoperative increase in haze measured by both Scheimpflug densitometry and slit lamp assessment. The increase peaked at 1 month and plateaued between 1 month and 3 months. "
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