Investigation of the relationship between positive and negativesymptoms in schizophrenia patients and posterior eye segmentoptic nerve and retinal vascular changes

Optical coherence tomography (OCT) has been applied to examine neurodegeneration in schizophrenia for clinical research in recent years, and significant changes in retinal and choroidal structures were detected. Choroidal vascular index (CVI) has recently attracted attention as a specific parameter defined as an inflammation marker in systemic diseases. According to clinical research, CVI values vary in individuals with systemic, autoimmune, developmental, or degenerative diseases compared to healthy individuals. However, there is no study in the literature investigating CVI values in schizophrenia. Furthermore, the relationship between positive and negative symptom severity in schizophrenia and the changes detected in OCT has not yet been clarified. This study aimed to examine the relationship between the severity of positive and negative symptoms and changes in retinal structures and choroidal vascular index in schizophrenia. Our study is a cross-sectional clinical study and consisted of a patient group diagnosed with schizophrenia and a healthy control group in the psychiatry outpatient clinic of Adıyaman University Training and Research Hospital. Sociodemographic Data Form and Positive and Negative Syndrome Scale (PANSS) obtained from psychiatric interviews were used for data collection. A spectral OCT device examined the posterior segment structures of the eyes. The healthy control group consisted of individuals without any diagnosis, examination findings, and drug usage. SPSS 24.0 package program was used to evaluate the data, and the statistical significance level (p-value) was determined as 0.05 or below. Seventy-six patients (26 females, 50 males) and 88 healthy controls (36 females, 52 males) were included in the study based on inclusion and exclusion criteria. There was no statistically significant difference between the control and patient groups in terms of age and gender(p>0.05). The education and employment status of the patient group was lower than the control group (p<0.001), and there was no statistically significant difference between the patient group and the control group in terms of marital status (p=0.493). The choroidal layer thicknesses of the temporal-1500 µm diameters of the healthy control group were significantly thicker than those of the schizophrenia patient group (p=0.002 and p=0.019, respectively). The retinal artery and vein diameters of the schizophrenia patient group were more prominent than the healthy controls (p=0.028 and p=0.003, respectively). CVI values of patients with schizophrenia were found to be statistically significantly higher than the healthy control group (p=0.001). A statistically significant positive correlation was found between PANSS-negative and total scores and choroidal vascular index in patients with schizophrenia (p=0.003 and p=0.042, respectively). A positive and significant correlation was found between the number of hospitalizations, retinal artery and vein diameters (p=0.029 and p=0.03, respectively), and choroidal vascular index (p=0.004) in schizophrenia patients. According to our study, retinal, choroidal area thickness is thicker in patients with schizophrenia than in healthy controls. Retinal artery and vein diameters of patients with schizophrenia are more significant than those of healthy controls. Choroidal vascular index values are higher in patients with schizophrenia than in healthy controls. In addition, more psychotic episodes and hospitalizations in patients with schizophrenia are associated with higher choroidal vascular index values. High negative symptom severity in schizophrenic patients is associated with higher choroidal vascular index values.