Grosso® Implant For Corneal Reshaping In Advanced Keratoconus: First Translational Results

To evaluate the safety and feasibility of the GROSSO® corneal nitinol implant for restoring corneal curvature when deformed or weakened. Here we report preclinical results after implantation in the rabbit cornea and first clinical feasibility results.

Faculty of Medicine, Linköping University, Sweden and Instituto de Microcirugia Ocular, Barcelona, Spain

A 9.5mm diameter corneal midstromal pocket was created by femtosecond laser in 20 New Zealand white albino rabbits, into which a GROSSO® shape-memory implant was inserted in 12 rabbits, with 8 serving as controls. Intraocular pressure, tomography, topography and biomechanics were evaluated before operation and at 1 week and month 1, 2, 3 and 6. In vivo confocal microscopy and histology were used to assess safety and integration. A single patient with advanced keratoconus received the GROSSO® implant and was followed up for 2 months.

All surgeries were successfully completed with postoperative keratitis and peripheral neovascularization noted in several rabbit eyes (implants and controls), which were treated. Surgeries and GROSSO® implantation did not alter intraocular pressure or corneal thickness, and significantly reduced the flat, steep and average keratometry relative to controls with flattening being stable at 1 month. GROSSO® implanted corneas had enhanced biomechanical strength without signs of inflammation or fibrosis. The first patient to receive the GROSSO implant did not experience corneal thinning or pressure change or exhibit adverse reaction up to 2 months postoperatively, with reduced flat keratometry (K1) and maintained steep keratometry (K2).

The GROSSO® implant could be safely implanted in the cornea using a laser-assisted surgery in both rabbits and in humans. Postoperative keratitis and minor neovascularization in some rabbit eyes was not encountered in the patient. The implant did not impact IOP in rabbits or in the patient. A stable long-term flattening and biomechanical strengthening effect was noted in rabbits, while first safety and biocompatibility in a human subject was demonstrated. More patients and longer follow-up times are needed.