Hypo-osmolar accelerated corneal crosslinking on resultant sub-400 µm topography-guided excimer regularized keratoconus corneas.

ABSTRACT

PURPOSE: To investigate the efficacy and safety of phototherapeutic keratectomy (PTK) with topography-guided photorefractive keratectomy (T-PRK) corneal regularization followed by sequential hypo-osmolar riboflavin accelerated corneal crosslinking (CXL) in keratoconic (KC) eyes with <400 µm stromal bed thickness after excimer ablation. SETTING: Multisurgeon multicenter standardized protocol practice. DESIGN: Retrospective multicenter case series. METHODS: This study included progressive KC eyes that underwent PTK and T-PRK combined with accelerated CXL and had a corneal stromal bed thickness of <400 µm after excimer ablation before administration of hypo-osmolar riboflavin. Demographics and clinical measures were reviewed at baseline and every follow-up visit. RESULTS: 61 consecutive eyes had a mean corneal stromal bed thickness of 367 ± 21 µm after excimer laser normalization. Postoperatively, uncorrected distance visual acuity (UDVA) improved by 0.29 logMAR ( P < .0001), corrected distance visual acuity (CDVA) improved by 0.07 logMAR ( P = .0012), and maximum keratometry (Kmax) decreased by 4.67 diopters ( P < .0001). The safety index was favorable (1.29 ± 0.56), with stable manifest astigmatism, Kmax, and pachymetry at 12 months. 2 eyes (3%) showed evidence of keratometric progression on topography. CONCLUSIONS: In KC corneas thinner than 400 µm after excimer ablation, PTK epithelial removal followed by T-PRK and hypo-osmolar accelerated CXL decreases manifest astigmatism and Kmax, improves UDVA and CDVA, and halted disease progression in 97% of eyes at 12 months. These outcomes are comparable with thicker ablated corneas not requiring hypo-osmolar stromal swelling.