Deep-stromal implantation of a double-crosslinked bioengineered porcine collagen implant (BPCDX) in advanced keratoconus: a 12-month study of corneal remodeling and visual outcomes

To evaluate the efficacy of the Bioengineered Porcine Collagen, Double-Crosslinked (BPCDX) Implant in patients with advanced keratoconus (KCN). This study included 17 eyes of 17 patients (mean age = 32.29 ± 9.21 years) with stage 3–4 KCN. A BPCDX implant (type I collagen derived from porcine skin; thickness 280–440 μm, 8.00 mm diameter) was inserted into the deep corneal stromal pocket created at 60–70% of the preoperative thinnest corneal thickness, preserving approximately 100 μm of posterior cornea. The pocket and a 3.5-mm temporal incision were created using a femtosecond laser (VisuMax platform, Carl Zeiss Meditec AG, Germany). Assessments including uncorrected (UCVA) and best-corrected visual acuity (BCVA), refractive error, corneal thickness and curvature, and anterior chamber depth (ACD) were performed preoperatively, and at 1 and 12 months postoperatively. At 12 months, central corneal thickness increased from 417 μm to 698 μm, and thinnest pachymetry rose from 370 μm to 661 μm. Sphere improved from − 6.54 ± 5.89 to − 3.73 ± 3.99 D (p = 0.003), and spherical equivalent from − 9.85 ± 6.52 to − 6.19 ± 3.37 D (p = 0.008). During this time, UCVA improved from 1.24 ± 0.27 to 0.92 ± 0.27 logMAR (p = 0.023); BCVA also improved from 0.54 ± 0.26 to 0.42 ± 0.20 logMAR (p = 0.07). One year after BPCDX implantation, the mean changes in anterior flat and steep keratometry were − 6.75 ± 4.29 and − 6.02 ± 6.18, respectively (both p < 0.05). Besides, Anterior maximum keratometry decreased from 70.62 ± 8.32 to 61.65 ± 5.38 D (p = 0.004). ACD also decreased slightly from 3.62 ± 0.49 to 3.33 ± 0.53 mm (p = 0.006). No serious intraoperative or postoperative complications occurred over 12 months. Stromal implantation of BPCDX effectively reconstructs corneal shape and improves visual and refractive outcomes in advanced KCN, with a favorable safety profile. These results support its potential as a minimally invasive alternative to penetrating keratoplasty, warranting further investigation in larger, controlled trials.