Corneal Neurotization A Meta-analysis of Outcomes and Patient Selection Factors

Background Corneal neurotization describes reinnervation of the anesthetic or severely hypoesthetic cornea with a healthy local nerve or graft. Preliminary evidence has shown corneal neurotization to improve corneal sensation, visual acuity, and ocular surface health. Factors that improve patient selection and lead to better neurotization outcomes have yet to be elucidated, limiting ability to optimize perioperative decision-making guidelines. Methods A systematic review with meta-analysis was performed of the MEDLINE and Embase databases using variations of "corneal," "nerve transfer," "neurotization," and "neurotization." The primary outcomes of interest were corrected visual acuity, NK Mackie stage, and central corneal sensation. Regression analyses were performed to identify the effects of surgical technique, duration of denervation, patient age, and etiology of corneal pathology on neurotization outcomes. Results Seventeen studies were included. Corneal neurotization resulted in significant improvement in NK Mackie stage (0.84 vs 2.46, P < 0.001), visual acuity (logarithm of minimum angle of resolution scale: 0.98 vs 1.36, P < 0.001), and corneal sensation (44.5 vs 0.7, P < 0.001). Nerve grafting was associated with greater corneal sensation improvement than nerve transfer (47.7 +/- 16.0 vs 35.4 +/- 18.76, P = 0.03). Denervation duration was predictive of preneurotization visual acuity (logarithm of minimum angle of resolution scale; R-2 = 0.25, P = 0.001), and older age (ss = 0.30, P = 0.03) and acquired etiology (ss = 0.30, P = 0.03) were predictive of improved visual acuity. Conclusions Corneal neurotization provides significant clinical improvement in visual acuity, NK Mackie staging, and corneal sensation in patients who experience NK. Both nerve grafting and nerve transfer are likely to yield similar levels of benefit and ideally should be performed early to limit denervation time.