title: Optic Nerve Dysfunction in Obstructive Sleep Apnea: An Electrophysiological Study.
abstract: OBJECTIVE
  The aim of this study was to evaluate the integrity of the visual system in patients affected by obstructive sleep apnea (OSA) by means of electroretinogram (ERG) and visual evoked potential (VEP).
  
  
  METHODS
  We performed electrophysiological study of the visual system in a population of severe OSA (apnea-hypopnea events/time in bed ≥ 30/h) patients without medical comorbidities compared to a group of healthy controls similar for age, sex, and body mass index. Patients and controls did not have visual impairment or systemic disorders with known influence on the visual system. ERG and VEP were elicited by a reversal pattern generated on a television monitor at low (55') and high (15') spatial frequencies stimulation. Daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS) in both patients and controls.
  
  
  RESULTS
  In comparison with healthy controls (n = 27), patients with OSA (n = 27) showed a significant latency delay coupled with a significant amplitude reduction of P100 wave of VEP at all spatial frequencies in both eyes. No significant differences between groups were detected as concerning ERG components. No correlations were found between polygraphic parameters, ESS scores, or VEP and ERG components in OSA patients.
  
  
  CONCLUSIONS
  This study documented that patients with OSA, without medical comorbidities, present VEP alteration as documented by lower amplitude and longer latency of the P100 component than healthy controls. These altered electrophysiological findings may be the expression of optic nerve dysfunction provoked by hypoxia, acidosis, hypercarbia and airway obstruction, frequently observed in patients with OSA. Hence, we hypothesize that OSA per se may impair optic nerve function.
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Liguori
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Maria Giuseppina
authors.initials: MG
authors.lastname: Palmieri
authors.affiliation: Neurology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Pierantozzi
authors.affiliation: Department of Experimental Medicine and Surgery, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Cesareo
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Romigi
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Izzi
authors.affiliation: Neurology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.|Fondazione Santa Lucia IRCCS, Rome, Italy.
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Marciani
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Oliva
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.|Department of Experimental Medicine and Surgery, University of Rome 'Tor Vergata', Rome, Italy.|Fondazione Santa Lucia IRCCS, Rome, Italy.
authors.forename: Nicola Biagio
authors.initials: NB
authors.lastname: Mercuri
authors.affiliation: Sleep Medicine Centre, Neurophysiopathology Unit, Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Placidi
mesh_terms: D000138:Acidosis / Q000150:complications; D000328:Adult; D016022:Case-Control Studies; D004596:Electroretinography; D005074:Evoked Potentials, Visual; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications; D008297:Male; D009900:Optic Nerve / Q000503:physiopathology*; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D012894:Sleep Stages
keywords: ERG; OSA; VEP; optic nerve; visual system