title: Long-term visual damage after acute methanol poisonings: Longitudinal cross-sectional study in 50 patients.
abstract: BACKGROUND
  Visual disturbances due to the toxic effect of formic acid in acute methanol poisonings are generally transient. The subjective symptoms of visual toxicity may resolve within few weeks and fundoscopic signs of acute optic neuropathy subside within 1-2 months; therefore, the prevalence of long-term visual sequelae in the population of survivors of poisonings may be underestimated.
  
  
  OBJECTIVE
  To study the prevalence and character of long-term visual sequelae of acute methanol poisonings based on the data from the Czech mass methanol outbreak in 2012.
  
  
  METHODS
  A total of 50 patients with confirmed methanol poisoning were included in this longitudinal cross-sectional study, median age: 48 (range, 23-73) years. The following tests were performed: optical coherence tomography or OCT with evaluation of the retinal nerve fibers layer (RNFL), visual evoked potentials (VEP), magnetic resonance imaging (MRI) of brain, complete ocular examination (visual acuity/field, color vision, contrast sensitivity, and fundus), neurological examinations, and biochemical tests.
  
  
  RESULTS
  Of 50 patients, 7/50 (14%) were discharged with diagnosed visual sequelae and 6/50 (12%) were discharged with both visual and central nervous system sequelae of poisoning. On the follow-up examination, 20/50 (40%) of the patients had long-term visual sequelae, with 8% of blindness. A total of 38% of the patients had abnormal (28% borderline) findings on RNFL, and 40% had abnormal (18% borderline) VEP. Among the patients discharged without detected visual sequelae, 8/37 (22%) had abnormal RNFL and VEP. Patients with visual sequelae had brain lesions more often (70% vs. 27%, p < 0.01). MRI identified optic nerve lesions in 2/20 cases with abnormal VEP only. The groups with and without visual sequelae differed in serum methanol, ethanol, HCO3-, formate, pH, anion gap, and base deficit (all p < 0.01). Visual disturbances on admission and coma were more prevalent in the patients with visual sequelae (p < 0.05). Patients with positive serum ethanol on admission were 93% less likely to have optical axonal damage (OR: 0.07 (95% CI: 0.01-0.8); p < 0.05). No association was found between visual sequelae and type of antidote administered, mode of hemodialysis, or folate substitution. Pre-hospital administration of ethanol seemed beneficial: these patients were 90% less likely to have abnormal RNFL findings (OR: 0.10 (95% CI: 0.02-0.52); p < 0.01).
  
  
  CONCLUSIONS
  The long-term visual sequelae were clearly underestimated on discharge, suggesting a significantly higher amount of patients with long-term sequelae than earlier reported. Thorough examinations before discharge and during follow-up will likely uncover a higher morbidity also after methanol poisonings in general.
authors.affiliation: a Toxicological Information Center, Department of Occupational Medicine , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Sergey
authors.initials: S
authors.lastname: Zakharov
authors.affiliation: a Toxicological Information Center, Department of Occupational Medicine , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Daniela
authors.initials: D
authors.lastname: Pelclova
authors.affiliation: b Department of Ophthalmology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Diblik
authors.affiliation: a Toxicological Information Center, Department of Occupational Medicine , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Urban
authors.affiliation: b Department of Ophthalmology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Kuthan
authors.affiliation: a Toxicological Information Center, Department of Occupational Medicine , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Nurieva
authors.affiliation: a Toxicological Information Center, Department of Occupational Medicine , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Katerina
authors.initials: K
authors.lastname: Kotikova
authors.affiliation: c Department of Biomimetic Electrochemistry , J. Heyrovský Institute of Physical Chemistry of the AS CR , v.v.i, Prague 8 , Czech Republic.|d Institute of Medical Biochemistry and Laboratory Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague , Prague 2, Czech Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Navratil
authors.affiliation: e Institute of Biophysics and Informatics, First Faculty of Medicine of Charles University in Prague, General University Hospital , Prague 2, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Komarc
authors.affiliation: e Institute of Biophysics and Informatics, First Faculty of Medicine of Charles University in Prague, General University Hospital , Prague 2, Czech Republic.
authors.forename: Jaromir
authors.initials: J
authors.lastname: Belacek
authors.affiliation: f Department of Radiology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Seidl
authors.affiliation: f Department of Radiology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Manuela
authors.initials: M
authors.lastname: Vaneckova
authors.affiliation: g Centre for Experimental Medicine, Institute for Clinical and Experimental medicine , Prague 4 , Czech Republic.
authors.forename: Jaroslav A
authors.initials: JA
authors.lastname: Hubacek
authors.affiliation: h Department of Neurology and Center of Clinical Neuroscience , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Bezdicek
authors.affiliation: h Department of Neurology and Center of Clinical Neuroscience , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Klempir
authors.affiliation: i Institute of Clinical and Experimental Dental Medicine, First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Maksim
authors.initials: M
authors.lastname: Yurchenko
authors.affiliation: h Department of Neurology and Center of Clinical Neuroscience , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Evzen
authors.initials: E
authors.lastname: Ruzicka
authors.affiliation: j Department of Addictology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Miovsky
authors.affiliation: j Department of Addictology , First Faculty of Medicine, Charles University in Prague and General University Hospital , Prague 2, Czech Republic.
authors.forename: Barbara
authors.initials: B
authors.lastname: Janikova
authors.affiliation: k The Norwegian CBRNe Centre of Medicine, Department of Acute Medicine , Oslo University Hospital , Oslo , Norway.
authors.forename: Knut Erik
authors.initials: KE
authors.lastname: Hovda
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D001479:Basal Ganglia / Q000187:drug effects / Q000503:physiopathology; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D018153:Czech Republic / Q000453:epidemiology; D003941:Diagnostic Techniques, Ophthalmological; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D000432:Methanol / Q000506:poisoning*; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D009900:Optic Nerve / Q000187:drug effects / Q000503:physiopathology; D011041:Poisoning / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D011237:Predictive Value of Tests; D015995:Prevalence; D065840:Protective Factors; D020127:Recovery of Function; D012160:Retina / Q000187:drug effects / Q000503:physiopathology; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014786:Vision Disorders / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D014785:Vision, Ocular / Q000187:drug effects*; D055815:Young Adult
chemical_list: D000432:Methanol
keywords: acute methanol poisoning; health sequelae of poisoning; hospital treatment; long-term visual damage; treatment outcome