title: Decreases in ganglion cell layer and inner plexiform layer volumes correlate better with disease severity in schizophrenia patients than retinal nerve fiber layer thickness: Findings from spectral optic coherence tomography.
abstract: BACKGROUND
  Optic coherence tomography (OCT) is a new, contactless and fast neuroimaging method. Previous studies have observed thinning of the retinal nerve fibre layer (RNFL) in many neurodegenerative diseases, and researchers have suggested that correlations exist between the thinning of the RNFL and the neurodegeneration detected with other imaging methods or the severity of illness. More recently, OCT has been used in patients with schizophrenia. RNFL thinning has also been detected in these patients. With more sophisticated devices, segmentation of the retina and measurements of the ganglion cell layer (GCL) and internal plexiform layer (IPL) can be performed.
  
  
  METHODS
  We measured the RNFL thickness and the GCL and IPL volumes in 40 treatment refractory patients with schizophrenia, 41 treatment responsive refractory patients and 41 controls using spectral-OCT, and we evaluated the correlations between the disease severity and OCT measurements.
  
  
  RESULTS
  The global RNFL thickness and GCL and IPL volumes were decreased in the patients with schizophrenia compared with the controls. In addition, the GCL and IPL volumes were lower in the treatment refractory patients with schizophrenia compared to the treatment responsive patients. Using parameters such as the Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impression (CGI) scores, the disease duration and number of hospitalizations, correlations between the GCL and IPL volumes and disease severity were stronger than the correlations between the RNFL and the disease parameters.
  
  
  CONCLUSIONS
  Our findings suggest that OCT can be used to detect neurodegeneration in schizophrenia and that the GCL and IPL volumes can also be used to monitor the progression of neurodegeneration.
authors.affiliation: Adiyaman University, Psychiatry Department, Adiyaman, Turkey. Electronic address: mustacelik@yahoo.com.
authors.forename: M
authors.initials: M
authors.lastname: Celik
authors.affiliation: Adiyaman University, Psychiatry Department, Adiyaman, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Kalenderoglu
authors.affiliation: Adiyaman University, Ophthalmology Department, Adiyaman, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Sevgi Karadag
authors.affiliation: Adiyaman University, Psychiatry Department, Adiyaman, Turkey.
authors.forename: O
authors.initials: O
authors.lastname: Bekir Egilmez
authors.affiliation: Adiyaman Research and Education Hospital, Adiyaman, Turkey.
authors.forename: B
authors.initials: B
authors.lastname: Han-Almis
authors.affiliation: Adiyaman University, Ophthalmology Department, Adiyaman, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Şimşek
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009929:Organ Size; D011569:Psychiatric Status Rating Scales; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012559:Schizophrenia / Q000175:diagnosis / Q000473:pathology; D013223:Statistics as Topic; D041623:Tomography, Optical Coherence / Q000379:methods*
keywords: Ganglion cell layer; Inner plexiform layer; Optic coherence tomography; Schizophrenia