Decreases in retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in schizophrenia, relation to insight: a controlled study

Objective: The present study aimed to examine retinal nerve fiber layer (RNFL) and ganglion cell inner plexiform layer (GCIPL) thicknesses in schizophrenia patients according to the control group and in schizophrenia patients with good and poor insight. Methods: Sixty-three patients with schizophrenia recruited from the outpatient clinic of psychiatry and 39 healthy controls were included in the study. Patients were separated to two groups: good insight (n=31) and poor insight (n=32) schizophrenia. Group with schizophrenia were evaluated by using Positive and Negative Symptoms Scale (PANSS), Scale to Assess Unawareness of Mental Disorder. Changes in RNFL and GCIPL of all participants were analyzed with spectral optical coherence tomography (OCT). Results: Schizophrenia patients with good and poor insight were similar according to mean age of onset for illness, mean duration of illness, mean number of hospitalizations and mean daily used antipsychotic doses equivalent to chlorpromazine. There was no difference between the schizophrenia patients and the control group in terms of age and gender. In patients with schizophrenia all quadrants of RNFL, superior temporal (ST), superior (S), and inferior (I) quadrants of GCIPL were thinner than the controls. Inferior, inferior nasal quadrants of GCIPL and all quadrants of RNFL except nasal quadrant in schizophrenia patients with poor insight was found to be thinner than the schizophrenia patients with good insight and controls. Discussion: OCT can be used to detect neurodegeneration in schizophrenic patients. It can be argued that the GCIP layer may be a more sensitive biomarker than other retinal layers, requiring further investigation in this area.