Direct versus indirect corneal neurotization for the treatment of neurotrophic keratitis: a multicenter prospective comparative study

PURPOSE: To analyze the comparative safety and efficacy of two techniques of corneal neurotization (direct corneal neurotization [DCN] vs indirect corneal neurotization [ICN] for the treatment of patients with neurotrophic keratitis (NK). DESIGN: Multicenter Interventional Prospective Comparative Study. METHODS: Setting: ASST Santi Paolo e Carlo University Hospital, Milan; S.OrsolaMalpighi University Hospital, Bologna; Santa Maria alle Scotte University Hospital, Siena. Study Population: Consecutive patients with NK undergoing corneal neurotization between November 2014 and October 2019; Intervention Procedures: DCN was performed by transferring contralateral supraorbital and supratrochlear nerves; ICN was performed using sural nerve graft. Main Outcome Measures: NK healing rate; corneal sensitivity; corneal nerve fiber length (CNFL) measured by in vivo confocal microscopy (IVCM); complication rate. RESULTS: 26 eyes of 25 patients were included: 16 were treated with DCN and 10 with ICN. After surgery, NK healed in all patients after a mean period of 3.91.5 months without differences between patients undergone DCN and ICN. Overall, mean corneal sensitivity improved significantly 1 year after surgery (from 3.07 to 22.11 mm; p<0.001) without differences between the two groups. Corneal sub-basal nerve plexus that was absent before surgery in all patients except 3 become detectable in all cases (mean CNFL 14.677.92 mm/mm2 1 year postoperatively). No major complications were recorded in both groups. CONCLUSIONS: Corneal neurotization allowed the healing of NK and the improvement of corneal sensitivity in all patients thanks to nerve regeneration documented by IVCM. One year postoperatively, DCN and ICN showed comparable outcomes.