Retinal abnormalities and their relationship with social cognition in patients with schizophrenia and their healthy siblings

Objective: This study aimed to investigate retinal abnormalities and their relationship with social cognitive function, and to assess whether retinal changes could be observed in the healthy siblings of patients with schizophrenia in a similar manner, suggesting their potential as an endophenotype. Method: The study included 28 patients with schizophrenia, 28 of their siblings, and 28 healthy control subjects. Social cognition tests were administered, and measurements of the retinal nerve fiber layers (RNFL), ganglion cell layer plus inner plexiform layer (GCL+IPL), and cup volumes were obtained using optical coherence tomography (OCT). Results: Analyses revealed no differences between the groups in RNFL thickness. The cup volume was significantly larger in both eyes of the patient group compared to the control group. The mean thickness of the GCL+IPL in the left eye was significantly lower in the patient group compared to the healthy control group, with a similar difference also observed between the siblings of patients and the control group. A statistically significant difference was found among all groups in the total scores of social cognition tests. A weak correlation was identified between retinal layer thicknesses and social cognition test scores in both the patient and sibling groups. Conclusion: These findings suggest that GCL+IPL thickness can be a useful endophenotype for the early diagnosis of schizophrenia. While retinal changes do not predict cognitive symptoms in patients with schizophrenia, they may play an important role in identifying high-risk groups.