title: Multifocal ERG wavelet packet decomposition applied to glaucoma diagnosis.
abstract: BACKGROUND
  Glaucoma is the second-leading cause of blindness worldwide and early diagnosis is essential to its treatment. Current clinical methods based on multifocal electroretinography (mfERG) essentially involve measurement of amplitudes and latencies and assume standard signal morphology. This paper presents a new method based on wavelet packet analysis of global-flash multifocal electroretinogram signals.
  
  
  METHODS
  This study comprised twenty-five patients diagnosed with OAG and twenty-five control subjects. Their mfERG recordings data were used to develop the algorithm method based on wavelet packet analysis. By reconstructing the third wavelet packet contained in the fourth decomposition level (ADAA4) of the mfERG recording, it is possible to obtain a signal from which to extract a marker in the 60-80 ms time interval.
  
  
  RESULTS
  The marker found comprises oscillatory potentials with a negative-slope basal line in the case of glaucomatous recordings and a positive-slope basal line in the case of normal signals. Application of the optimal threshold calculated in the validation cases showed that the technique proposed achieved a sensitivity of 0.81 and validation specificity of 0.73.
  
  
  CONCLUSIONS
  This new method based on mfERG analysis may be reliable enough to detect functional deficits that are not apparent using current automated perimetry tests. As new stimulation and analysis protocols develop, mfERG has the potential to become a useful tool in early detection of glaucoma-related functional deficits.
authors.affiliation: Department of Electronics, University of Alcalá, 28701 Alcalá de Henares, Spain. jmanuel@depeca.uah.es
authors.forename: Juan M
authors.initials: JM
authors.lastname: Miguel-Jiménez
authors.forename: Sergio
authors.initials: S
authors.lastname: Ortega
authors.forename: Luciano
authors.initials: L
authors.lastname: Boquete
authors.forename: José M
authors.initials: JM
authors.lastname: Rodríguez-Ascariz
authors.forename: Román
authors.initials: R
authors.lastname: Blanco
mesh_terms: D004596:Electroretinography / Q000379:methods*; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted