Changes in straylight and densitometry values after corneal collagen crosslinking.

Purpose: To evaluate the change in backward-directed and forward-directed corneal straylight in eyes after corneal collagen crosslinking (CXL) and its correlation with corrected distance visual acuity (CDVA) and changes in corneal topography.

Setting: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

Design: Retrospective cohort study.

Methods: Following the Dresden protocol, corneal CXL was performed in eyes with progressive keratoconus. Corneal light scattering was evaluated using densitometry measurements from different corneal layers and zones obtained using Scheimpflug tomography (Pentacam HR). Retinal straylight values were measured using the C-Quant device. The CDVA was recorded during each follow-up examination. Changes in corneal topography were measured using Scheimpflug tomography.

Results: The study evaluated 31 eyes of 31 patients. The mean densitometry of different corneal layers and in 3 different zones increased 3 months postoperatively and decreased thereafter. The mean densitometry in the 0.0 to 2.0 mm zone remained statistically significantly elevated after 12 months (P < .05). The mean preoperative retinal straylight was 1.14 log(s) ± 0.28 (SD). The mean straylight peaked after 1 month and then decreased continuously but remained elevated after 1 year at 1.26 ± 0.21 log(s). There was an increase in CDVA and flattening of the steepest keratometry (K) value (maximum K). Eyes with the greatest maximum K reduction also had the highest densitometry values.

Conclusions: Crosslinking-induced stromal changes resulted in an increase in densitometry, especially in the anterior stroma of the central (0.0 to 2.0 mm) zone. These changes correlated with an increase in retinal straylight but not with the postoperative CDVA values.