title: Electroretinography and optical coherence tomography reveal abnormal post-photoreceptoral activity and altered retinal lamination in patients with enhanced S-cone syndrome.
abstract: OBJECTIVE
  To compare functional abnormalities of enhanced S-cone syndrome (ESCS), as examined using standard and extended electroretinography (ERG), with structural findings and retinal architecture obtained by spectral domain optical coherence tomography (SD-OCT).
  
  
  METHODS
  Four patients with ESCS underwent standard full-field and multifocal ERGs, with extended S-cone and ON/OFF ERG protocols also performed. SD-OCT was also carried out, and longitudinal reflectivity profiles (LRPs) were calculated for the perifoveolar retina.
  
  
  RESULTS
  All four patients exhibited pathognomonic full-field ERG findings for ESCS, with delayed responses of similar waveforms to the same intensity flash under both scotopic and photopic conditions. The amplitudes of the full-field ERGs showed considerable variation between patients, which were not related to the extent of the visual field defects. Multifocal ERGs reflected preserved central function in eyes with good visual acuity (Snellen visual acuity >0.7). The ERGs to S-cone-specific stimulation confirmed the expected predominant activity of the S-cone system in all four patients. The ON/OFF ERG recordings revealed abnormal presence of both ON-response and OFF-response activities in three patients; the remaining patient showed only OFF-response activity. SD-OCT showed a significantly thickened outer nuclear layer in all four patients, as obtained by LRP analysis. Furthermore, in the patient with selective preservation of the OFF-response activity, LRP showed reduced numbers of hyper-reflectivity sub-peaks in the inner plexiform layer.
  
  
  CONCLUSIONS
  Patients with ESCS show characteristic full-field ERG waveform abnormality, predominance of S-cone ERG activity, and thickening of the outer nuclear layer on SD-OCT. Moreover, they can also show abnormal post-photoreceptor connectivity through S-cone-related OFF-bipolar cell activity.
authors: Eye Hospital, University Medical Centre, Grablovičeva 46, 1000, Ljubljana, Slovenia, sustar.majchi@gmail.com.
authors: M
authors: M
authors: Sustar
authors: D
authors: D
authors: Perovšek
authors: I
authors: I
authors: Cima
authors: B
authors: B
authors: Stirn-Kranjc
authors: M
authors: M
authors: Hawlina
authors: J
authors: J
authors: Brecelj
mesh_terms: D000328:Adult; D004252:DNA Mutational Analysis; D004596:Electroretinography / Q000379:methods*; D015785:Eye Diseases, Hereditary / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D057093:Orphan Nuclear Receptors / Q000235:genetics; D012160:Retina / Q000503:physiopathology*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D041623:Tomography, Optical Coherence / Q000379:methods*; D014786:Vision Disorders / Q000175:diagnosis* / Q000235:genetics / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult
chemical_list: C403073:NR2E3 protein, human; D057093:Orphan Nuclear Receptors