Role of Corneal Collagen Cross-Linking in Pseudophakic Bullous Keratopathy A Clinicopathological Study

Objective: To evaluate the clinical and histopathologic changes induced by collagen cross-linking (CXL) in pseudophakic bullous keratopathy (PBK). Design: Randomized, prospective, interventional study. Participants: Twenty-four patients with PBK were included in the study. Methods: Twenty-four patients with PBK underwent CXL followed by keratoplasty at 1 or 3 months. Twelve patients underwent penetrating keratoplasty 1 month after CXL (group A) and the remaining 12 patients underwent penetrating keratoplasty 3 months after CXL (group B). The main outcome measures were assessed at 1 week and 1 month for all patients and at 3 months for 12 patients only. The corneal buttons underwent histopathologic and immunofluorescence evaluation. Main Outcome Measures: Visual acuity, ocular discomfort (tearing, redness, pain), corneal haze, central corneal thickness, histopathologic evaluation, and immunofluorescent microscopy. Results: Mean visual acuity showed a significant improvement after CXL, from 1.925 +/- 0.173 before surgery to 1.75 +/- 0.296 at 1 month after surgery (P = 0.010), but deteriorated to 1.81 +/- 0.23 at 3 months. Symptomatic relief after CXL was at a maximum at 1 month, with a worsening trend at 3 months. Eighteen patients showed a reduction in corneal haze 1 month after CXL. The effect was maintained in 9 of 12 patients at 3 months. The mean central corneal thickness decreased significantly from 846.46 +/- 88.741 to 781.0 +/- 98.788 mu m at 1 month (P<0.01) after CXL, but increased to 805.08 +/- 136.06 mu m at 3 months. Immunofluorescence microscopy revealed anterior stromal compaction in 7 of 12 patients (58.3%) in group A and in 5 of 12 patients (41.6%) in group B. Staining of keratocyte nuclei with 4',6-diaminido-2-phenylindole dihydrochloride (Molecular Probes, Carlsband, CA) revealed a relative uniform distribution throughout the stroma. Conclusions: Collagen cross-linking causes symptomatic relief and a decrease in central corneal thickness and anterior stromal compaction in PBK. However, the effect decreases with time and depends on disease severity. (C) 2013 by the American Academy of Ophthalmology.