Correlation of Scheimpflug densitometry changes with clinical outcomes after corneal crosslinking

Purpose: To characterize changes in densitometry after corneal crosslinking (CXL) and correlate it with visual outcomes. Setting: Tertiary referral academic medical center, New York, New York, USA. Design: Retrospective case series. Methods: Patients with progressive keratoconus or post-laser in situ keratomileusis ectasia had CXL following the Dresden protocol. The corrected distance visual acuity (CDVA) and Pentacam imaging were obtained at baseline and follow-up visits. Results: Fifty-seven patients were followed for a mean of 15 months (range 1 to 24 months) after CXL. The CDVA improved significantly from baseline to 6, 12, 18, and 24 months postoperatively. The change in densitometry of the mid-stromal layer, 2.0 to 6.0 mm annulus, at 6 months was correlated with the improvement in CDVA at 6, 12, and 24 months (all P <.10). The increase in densitometry of the mid-stromal layer, centermost 0.0 to 2.0 mm annulus, at 6 months was significantly associated with the decrease in maximum keratometry (K) at 6 and 12 months (both P <.05). Last, the change in densitometry at 6 months was significantly correlated with the decrease in specific higher-order aberrations (HOAs) (P <.05). Conclusions: Although the greatest and most durable post-CXL densitometry change was in the anterior layer, the degree of increased densitometry haze in the mid-stromal layer was most associated with and possibly predictive of improvement in CDVA, maximum K, and HOAs. The persistence of corneal haze at 6 months, measured by increased densitometry, might be a prognostic marker for CXL effectiveness.