Comparison Of The Depth Of The Stromal Demarcation Line In Corneal Crosslinking Treatment With Hpmc-Based And Vitamin E-Tpgs-Based Riboflavin Solutions

This study aims to compare the visual and topographic results and the depth of demarcation line (DL) in patients who underwent epithelial-off-cross-linking with riboflavin solutions containing D alpha-tocopheryl polyethylene-glycol 1000 succinate (VE-TPGS) and 1.1% hydroxypropyl methylcellulose (HPMC). 

Department of Ophthalmology, University of Health Sciences, Yuksek Ihtisas Training and Research Hospital, Bursa, Türkiye

Patients with progressive keratoconus, 27 of whom were treated with HPMC (Group 1) and 34 of whom were treated with VE-TPGS (Group 2), were evaluated retrospectively. Best corrected visual acuity (BCVA), spherical equivalent (SE), refractive cylinder, and corneal topography indices (keratometry of flat and steep meridians (K1 and K2), maximum keratometry (Kmax), central, thinnest, and apical corneal thickness) at baseline and postoperative follow-up visits were compared (1, 3, 6, and 12 months). Corneal stromal DL depth was measured centrally, nasally, and temporally by anterior segment optical coherence tomography at 1 month postoperatively, and changes in endothelial cell density (ECD) at 6 months were compared between the two groups.

There was no difference between the two groups in terms of age and gender. The mean demarcation line depth was deeper in group 1 (335,22µm ± 83,4) than in group 2 (267,02 µm ± 55,7) (p<0.001). In the 3rd month K1, K2, and Kmax changes, while a decrease was observed in Group 1 compared to the baseline, an increase was observed in Group 2 (all p-value <0.05). At the end of the 12th month, K1, K2, and Kmax decreased in both groups. There was no difference in ECD change between baseline and 6 months in both riboflavin solutions (p=0.12).

HPMC-based riboflavin appears to be associated with a deeper demarcation line than VE-TPGS-based riboflavin. While a decrease in K values was observed in the earlier period in HPMC, no difference was observed between VE-TPGS and HPMC in the 12th month in terms of efficacy. Both riboflavin solutions were safe for the endothelium.