Demarcation line depth after contact lens–assisted corneal crosslinking for progressive keratoconus: Comparison of dextran-based and hydroxypropyl methylcellulose–based riboflavin solutions

Abstract

To compare the demarcation line depth after contact lens-assisted corneal crosslinking (CXL) for progressive keratoconus using dextran-based and hydroxypropyl methylcellulose (HPMC)-based riboflavin solutions. Advanced Eye Centre, Postgraduate Institute of Medical Education and Research, Chandigarh, India. Retrospective case series. Patients with preoperative epithelium-on (epi-on) minimum corneal thickness between 350μm and 450μm having contact lens-assisted CXL for progressive keratoconus were crosslinked with isoosmolar 0.1% riboflavin in 20% dextran 500 or HPMC 1.1%. The primary outcome measure was the mean demarcation line depth measured 1month postoperatively on anterior-segment optical coherence tomography. The secondary outcome measure was change in endothelial cell density (ECD) 6months from baseline. The study comprised 21 patients (21 eyes, 9 in the HPMC group and 12 in the dextran group). The mean demarcation line depth was deeper in the HPMC group (308.22μm±84.19 [SD]) than in the dextran group (235.33±64.87μm)(P<.04). This difference remained significant (P=.02) even after controllingfor the preoperative lesser epi-on minimum corneal thickness in the HPMC group (385.56±13.81μm) versus the dextran group(413.08±29.58μm)(P<.02). The ECD 6months aftercontact lens-assisted CXL was comparable to the baselinelevels in both groups (P=.19 and P=.09, respectively). During contact lens-assisted CXL, HPMC-based riboflavin seemed to be associated with a deeper demarcation line than dextran-based riboflavin, although both solutions were safe for the endothelium at 6months.