Hypoosmolar riboflavin for corneal swelling in thin keratoconic corneas prior to crosslinking: An exploratory study
Clark Y. Chang, Subba R. Gollamudi, Daniel G. Fuller, Chawan RasheedBackground
Corneal crosslinking (CXL) treats progressive keratoconus (KCN), but thin corneas may fall below 400 µm after epithelial removal and riboflavin induction, risking endothelial damage. Hypoosmolar riboflavin ophthalmic solution (HORF) can swell corneas intraoperatively, though factors contributing to achieving adequate corneal swelling using HORF that allows for safe CXL remain undefined.
Objective
To explore the associations between preoperative and post-induction minimum corneal thickness (MCT) and the corneal swelling response to HORF in patients with thin keratoconic corneas undergoing CXL.
Design
Retrospective, single-center consecutive case series.
Methods
Keratoconic eyes that dehydrated to <400 µm after isoosmolar riboflavin with 20% dextran and required HORF swelling prior to CXL were included. HORF 0.146% (157–181 mOsm/kg) was used until MCT was ≥400 µm. Corneal swelling was correlated with keratometric indices using Spearman correlation analysis. Visual acuity and keratometry were assessed preoperatively and at last follow-up.
Results
52 eyes (50 patients) were included. Mean preoperative MCT was 438.6±42.4 µm, which decreased to 364.6±19.6 µm after epithelial removal and isoosmolar riboflavin saturation. While mean corneal swelling was 66.5±40.7 µm (n=45), a subcohort of eyes with post-induction MCT <350 µm exhibited a mean swelling of 105.4±28.3 µm (n=7). Overall, 47 eyes (90.4%) achieved an MCT of ≥400 µm. Mean postoperative follow-up was 13.1±11.1 months. Among eight eyes with paired preop and postop UDVA measurements, seven (87.5%) showed improvement. No significant changes were observed in corrected distance visual acuity or keratometric indices. Post-induction MCT showed a moderate correlation with preoperative MCT but not with preoperative keratometric indices.
Conclusion
In this exploratory study, most eyes with pachymetry <400 µm after induction with isoosmolar riboflavin achieved adequate corneal swelling with HORF, with no significant changes in CDVA or keratometry observed over follow-up. These preliminary findings warrant prospective evaluation of HORF-assisted corneal swelling in thin keratoconic corneas, with further studies needed to establish evidence-based patient-selection criteria.