Purpose:

To describe the natural history of corneal haze over 1 year after collagen crosslinking (CXL) alone, CXL and simultaneous intrastromal corneal ring segment (CXL-ICR), and CXL and simultaneous topography-guided photorefractive keratectomy (CXL-TG-PRK) for keratoconus, pellucid marginal degeneration (PMD) and LASIK-induced ectasia.

Methods:

Prospective single center non-randomized interventional cohort study including 532 patients (n=924) eyes with progressive keratoconus, PMD or laser-in-situ-keratomileusis (LASIK)-induced ectasia. Six hundred seventy six eyes underwent CXL alone, 126 eyes underwent CXL-ICR, and 122 eyes underwent CXL-TG-PRK. Subjects underwent preoperative and postoperative assessments at 1, 3, 6, and 12 months that included best spectacle corrected visual acuity (BSCVA), slitlamp biomicroscopy, and corneal topography and tomography. Postoperative haze grading at any location on the cornea was scored using the Hanna grading scale.

Results:

For CXL alone, mean corneal haze peaked (0.7±0.5) at 1 month after surgery and continued to decrease thereafter. Significant haze (grade ≥3) was not seen at 6 or 12 months. For CXL-ICR and CXL-TG-PRK, mean corneal haze peaked 6 months postoperatively (1.5±0.8 and 1.2±0.8, respectively). For both interventions, 6% had significant haze at 6 months. At 1 year, CXL-ICR and CXL-TG-PRK had 2% and 1% significant haze, respectively. No significant correlation was found between corneal haze grade and BSCVA (pearson correlation, r=-0.098).

Conclusions:

Significant haze was not seen past 3 months for CXL. At 1 year, CXL-ICR and CXL-TG-PRK had minimal significant haze. In all groups, even at 1 year, patients with a grade 3 haze or more still had significant improvements in BSCVA. This can provide useful information to counsel patients who require these interventions.