The Acute Optic Neuritis Network (ACON): Study protocol of a non-interventional prospective multicenter study on diagnosis and treatment of acute optic neuritis
Authors: Asseyer Susanna , Asgari Nasrin , Bennett Jeffrey , Bialer Omer , Blanco Yolanda , Bosello Francesca , Camos-Carreras Anna , Carnero Contentti Edgar , Carta Sara , Chen John , Chien Claudia , Chomba Mashina , Dale Russell C. , Dalmau Josep , Feldmann Kristina , Flanagan Eoin P. , Froment Tilikete Caroline , Garcia-Alfonso Carolina , Havla Joachim , Hellmann Mark , Kim Ho Jin , Klyscz Philipp , Konietschke Frank , La Morgia Chiara , Lana-Peixoto Marco , Leite Maria Isabel , Levin Netta , Levy Michael , Llufriu Sara , Lopez Pablo , Lotan Itay , Lugaresi Alessandra , Marignier Romain , Mariotto Sara , Mollan Susan P. , Ocampo Cassandra , Cosima Oertel Frederike , Olszewska Maja , Palace Jacqueline , Pandit Lekha , Peralta Uribe José Luis , Pittock Sean , Ramanathan Sudarshini , Rattanathamsakul Natthapon , Saiz Albert , Samadzadeh Sara , Sanchez-Dalmau Bernardo , Saylor Deanna , Scheel Michael , Schmitz-Hübsch Tanja , Shifa Jemal , Siritho Sasitorn , Sperber Pia S. , Subramanian Prem S. , Tiosano Alon , Vaknin-Dembinsky Adi , Mejia Vergara Alvaro Jose , Wilf-Yarkoni Adi , Zarco Luis Alfonso , Zimmermann Hanna G. , Paul Friedemann , Stiebel-Kalish Hadas 
Published: February 2023

Optic neuritis (ON) often occurs at the presentation of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). The recommended treatment of high-dose corticosteroids for ON is based on a North American study population, which did not address treatment timing or antibody serostatus. The Acute Optic Neuritis Network (ACON) presents a global, prospective, observational study protocol primarily designed to investigate the effect of time to high-dose corticosteroid treatment on 6-month visual outcomes in ON. Patients presenting within 30 days of the inaugural ON will be enrolled. For the primary analysis, patients will subsequently be assigned into the MS-ON group, the aquapotin-4-IgG positive ON (AQP4-IgG+ON) group or the MOG-IgG positive ON (MOG-IgG+ON) group and then further sub-stratified according to the number of days from the onset of visual loss to high-dose corticosteroids (days-to-Rx). The primary outcome measure will be high-contrast best-corrected visual acuity (HC-BCVA) at 6 months. In addition, multimodal data will be collected in subjects with any ON (CIS-ON, MS-ON, AQP4-IgG+ON or MOG-IgG+ON, and seronegative non-MS-ON), excluding infectious and granulomatous ON. Secondary outcomes include low-contrast best-corrected visual acuity (LC-BCVA), optical coherence tomography (OCT), magnetic resonance imaging (MRI) measurements, serum and cerebrospinal fluid (CSF) biomarkers (AQP4-IgG and MOG-IgG levels, neurofilament, and glial fibrillary protein), and patient reported outcome measures (headache, visual function in daily routine, depression, and quality of life questionnaires) at presentation at 6-month and 12-month follow-up visits. Data will be collected from 28 academic hospitals from Africa, Asia, the Middle East, Europe, North America, South America, and Australia. Planned recruitment consists of 100 MS-ON, 50 AQP4-IgG+ON, and 50 MOG-IgG+ON. This prospective, multimodal data collection will assess the potential value of early high-dose corticosteroid treatment, investigate the interrelations between functional impairments and structural changes, and evaluate the diagnostic yield of laboratory biomarkers. This analysis has the ability to substantially improve treatment strategies and the accuracy of diagnostic stratification in acute demyelinating ON.Trial registrationClinicalTrials.gov, identifier: NCT05605951.