Background: Recently, researchers have conducted many studies on the potential contribution of the retina and other eye structures on schizophrenia. This study aimed to evaluate differences in iris characteristics between patients with schizophrenia and healthy individuals so as to find more easily accessible and easily measurable biomarkers with a view to improving clinical assessments and furthering our understanding of the disease.
Methods: Overall, 80 patients with schizophrenia and 52 healthy individuals were included in the case group and the control group, respectively. Iris images were collected from all subjects to compare differences in the structure and color of the iris. The Positive and Negative Symptom Scale (PANSS) and the Modified Overt Aggression Scale (MOAS) were used to evaluate the clinical symptoms and characteristics of 45 first-episode untreated schizophrenics, and analyzed correlations between iris characteristics and schizophrenia symptoms.
Results: There were significant differences in iris crypts (P < 0.05) and pigment spots (P < 0.01) between the case and control group, but no significant difference was found in iris wrinkles (P < 0.05). The logistic regression analysis demonstrated that the total iris crypts [odds ratio (OR) 1.166, 95% confidence interval (CI) 1.022– 1.330] and total iris pigment spots (OR 1.815, 95% CI 1.186– 2.775) increased the risk of suffering from schizophrenia. Furthermore, it was demonstrated that the number of iris crypts was positively associated with the MOAS score (r=0.474, P < 0.01). Moreover, the number of the iris pigment spots (r=0.395, P < 0.01) and wrinkles (r=0.309, P < 0.05) were positively correlated with the subjects’ negative symptom scores, respectively.
Conclusion: Iris crypts and pigment spots were identified as potential biomarkers for detecting schizophrenia. In patients with first-episode untreated schizophrenia, iris characteristics may help psychiatrists to identify the illness and its severity, and to detect characteristic clinical symptoms.
Keywords: schizophrenia, biomarker, iris, crypt, pigment spot