Corneal neurotization
Authors: Isabelle Brunette 1, Michèle Mabon1, Akram Rahal2, Isabelle Hardy1, Alex Camacho1, Lamia Ammarkhodja3, Nora Cherifi3, Jean Meunier4. 1Centre Universitaire d’Ophtalmologie de l’Université de Montréal à l’Hôpital Maisonneuve-Rosemont, Montreal, QC, Canada, 2Division of Otolaryngology-Head and Neck Surgery, Université de Montréal, Maisonneuve-Rosemont Hospital, Montreal, QC, Canada, 3Maisonneuve-Rosemont Hospital Research Center, Montreal, QC, Canada, 4Department of computer science and operations research, Université de Montréal, Montreal, QC, Canada.
Author Disclosures: I. Brunette: None. M. Mabon: None. A. Rahal: None. I. Hardy: None. A. Camacho: None. L. Ammarkhodja: None. N. Cherifi: None. J. Meunier: None.
Abstract Body:
Purpose: Neurotrophic keratopathy is a devastating condition consisting of corneal denervation, loss of corneal sensation, loss of the corneal epithelium trophic function, epithelial breakdown, stromal ulceration, and eventually perforation and loss of the eye. There is currently no generally accepted curative treatment for this condition and conservative support aiming at protecting the corneal surface, promoting tear film rehabilitation, and trying to control inflammation is used, but with limited success. Surgical corneal neurotization has recently stimulated strong interest and several direct or indirect approaches have been explored. While overall promising, however, these studies globally lack a standardized methodology. Specific objectives: (1) To develop tools to better understand the underlying mechanisms of corneal reinnervation in order to optimize anatomical and functional rehabilitation following corneal neurotization in patients with neurotrophic keratopathy. (2) To report our results.
Study Design: Prospective cohort study.
Methods: (i) Our team custom built a modified version of an Non-Contact Corneal Aesthesiometer (NCCA) initially described by Murphy et al. The NCCA is a slit lamp mounted air puff module that measures central corneal sensitivity. It was validated and compared with the Cochet Bonnet aesthesiometer which remains the current clinical validated standard. (ii) Corneal re-innervation is assessed by confocal microscopy (RCM-HRT III) and a corneal nerve fiber analysis software adapted for corneal reinnervation is used for image processing. (iii) A standardized clinical protocol was developed to assess functional nerve regeneration following corneal neurotization.
Results: Clinical results will be presented. Six patients have now undergone corneal neurotization for neurotrophic keratopathy at the Maisonneuve-Rosemont Hospital Department of ophthalmology, with a mean postoperative follow-up of 7.5 months (3 to 14 months). Preoperative diagnoses included sequelae from Kawasaki, Herpes Zoster virus V1 (2 cases), brain tumor, and trigeminal neuralgia surgery. Two of these patients underwent repeat amniotic membrane transplantation and penetrating keratoplasty (PK) 4 to 10 months after corneal neurotization and all of the others present corneal scarring that may or not necessitate PK or DALK. Preoperative BCVA were 20/80, 20/100, 20/150, CF, CF, and HM, respectively improving at 20/70, 20/30, 20/50, 20/40, CF, 20/80 with time. Preoperatively, Cochet Bonnet esthesiometry mean values were 2.3 - 0 - 3.5 - 0 - 0.6 - 0 cm, improving respectively to 6 - 4 - 3 - 2 - n/a - 6 cm focal measurements after neurotization. Improvement of esthesiometry values were corroborated by progressive reinnervation of the sub-basal plexus and mid-stroma, as characterized by corneal nerve fiber (CNF) density (n/mm2); CNF total length (mm/mm2); CNF branch density (n/mm 2); NF average nerve fiber width (mm/mm2); CNF tortuosity; and CNF beading.
Conclusions: Corneal neurotization has changed the prognosis of neurotrophic keratopathy. We think that comprehensive evaluation is the optimal way to derive useful conclusions for the planning of future surgeries in children and adults suffering from corneal denervation.
