Treatment of neurotrophic keratopathy with minimally invasive corneal neurotisation: long-term clinical outcomes and evidence of corneal reinnervation

Abstract

AimTo report clinical outcomes and evidence of corneal innervation in patients with neurotrophic keratopathy (NK) treated with minimally invasive corneal neurotisation (MICN) using a sural nerve graft and donor sensory nerves from the face.MethodsPatients undergoing MICN at The Hospital for Sick Children, Toronto, Canada were prospectively recruited. Data on central corneal sensation (CCS, measured with Cochet-Bonnet aesthesiometer), best-corrected visual acuity (BCVA) and corneal epithelial integrity were collected. In four patients who subsequently underwent keratoplasty, immunohistochemical analysis was performed on the corneal explants. One patient underwent magnetoencephalography (MEG) after MICN to characterise the neurophysiological pathways involved.ResultsBetween November 2012 and February 2017, 19 eyes of 16 patients underwent MICN. Mean follow-up was 24.0±16.1 months (range, 6–53). Mean CCS significantly improved from 0.8±2.5 mm to 49.7±15.5 mm at final follow-up (p<0.001). Mean BCVA remained stable, and the number of episodes of corneal epithelial defects after MICN was significantly reduced compared with the year leading up to the procedure (21% vs 89%, respectively; p<0.0001). In the four eyes that underwent keratoplasties after MICN, all transplants fully re-epithelialised and regained sensation subsequently. Immunohistochemistry of the corneal explants demonstrated evidence of corneal reinnervation. In one patient who was 8 months after MICN, novel neuroactivity was detected on MEG in the ipsilateral somatosensory cortex on mechanical stimulation of the reinnervated cornea.ConclusionsBy providing an alternative source of innervation, MICN improves corneal sensation and stabilises the corneal epithelium, permitting optical keratoplasty for patients with NK-related corneal opacity.

Corneal Neurotization and Novel Medical Therapies for Neurotrophic Keratopathy

“…This portion of the SN provides sensation to the distal lower leg and dorsum of the foot and can be harvested with minimal morbidity. A review of 19 eyes of young patients with mostly grade 2-3 NK that underwent CN with this technique showed significant improvements in the number of episodes of epithelial defects and improved central corneal sensation by CB esthesiometry at a mean follow-up of 24 months [22]. Although the BCVA remained stable, immunochemical staining and magnetoencephalography confirmed the reinnervation of the cornea [22].…”

“…A review of 19 eyes of young patients with mostly grade 2-3 NK that underwent CN with this technique showed significant improvements in the number of episodes of epithelial defects and improved central corneal sensation by CB esthesiometry at a mean follow-up of 24 months [22]. Although the BCVA remained stable, immunochemical staining and magnetoencephalography confirmed the reinnervation of the cornea [22]. The SN graft has the ability to provide over 20 cm in length, which expands the donor nerve options to include the maxillary and mandibular branches of the trigeminal nerve [33].…”

“…CN has shown success at restoring corneal sensation by reinnervating the stromal and sub-basal layers of the cornea, with a metareview of 54 eyes showing significant improvement in both best-corrected visual acuity (BCVA) and corneal sensation following neurotization [20••, 21]. This surgical approach has been demonstrated in both humans and animal models to effectively protect the cornea from ulceration and perforation and to promote faster epithelial healing compared to nonneurotized neurotrophic corneas [3,5,10,11,[22][23][24]. Since CN was first introduced by Terzis et al in 2009 [10], a series of adaptations and new techniques have evolved.…”

“…At the corneoscleral limbus, some surgeons secure the nerve fascicles to the perilimbal episcleral space using absorbable or non-absorbable 8-0 to 10-0 sutures [25,35]. Other surgeons choose to secure the fascicles to the corneoscleral limbus using fibrin glue alone or a combination of the two [22]. Another option is to place the fascicles in perilimbal scleral tunnels, which bring the nerve fascicles into closer contact with the cornea but are technically challenging to execute and can lead to nerve fascicle damage and weaken the cornea's structure [3,22,31,32].…”

Antiinflammatory therapy of neurotrophic corneal diseases

“…Для диагностики и подбора эффективной терапии при НК часто требуются консультации других специалистов (например, невролога, отоларинголога, эндокринолога). Лечение НК определяется клинической формой и тяжестью течения заболевания, а также наличием сопутствующей патологии [13].…”