New Insights Into Schizophrenia: A Look at the Eye and Related Structures

Abstract

Background: Schizophrenia is a multifactorial neurodevelopmental disorder associated with cognitive dysfunction and changes in primary sensory processing. This article aims to explore the current insights into the relationship between schizophrenia and different visual disturbances.Methods: To provide a literature review of visual impairments in schizophrenia, we performed a PubMed/MEDLINE and Scopus search to identify all articles in English on the topic up to the end of 2018.Results: Multiple retinal functional and structural abnormalities are found in patients with schizophrenia. Wider retinal venules suggest chronically insufficient brain supply of oxygen and this could contribute to the occurrence of psychotic symptoms. Optical coherence tomography studies showed that retinal nerve fiber layer, macular thickness, and macular volume were significantly lowered in the chronic phase of schizophrenia. Results from electroretinogram recordings have demonstrated different declinations such as abnormalities of a -wave activity in the photoreceptors or b -wave activity in the bipolar and Muller cells. Abnormalities in eye movements, such as a notable decrease in saccades and smooth pursuit eye movements, are one of the most reliable and reproducible impairments associated with schizophrenia. Disrupted visual processing of the magnocellular pathway may result in a decrease of contrast sensitivity, sensory processing, orientation discrimination, visual integration, trajectory and spatial localization, backward masking and motion tracking. Visual perceptual abnormalities occur in more than 60% of schizophrenic patients and these are visual hallucinations, perceptual distortion of colors, shapes and light intensity, decrease in contour integration and surround suppression. Other, frequently present eye disorders include impaired visual acuity, strabismus and nystagmus.Conclusion: Visual impairments are one of the most important features of schizophrenia, which could help in defining the disease state and assigning appropriate treatment.

Recent updates of eye movement abnormalities in patients with schizophrenia: A scoping review

“…Importantly, perception deficits seem to persist exclusively (selectively) in SZ. Therefore, in recent years, some independent research groups have started to actively record eye movements to differentiate patients with SZ from HC 23, 42, 54, 117, 219, 238, 263–265 . Such an approach marks a new beginning of promising continuous years of research on visual disturbances in SZ patients, with eye‐tracking technology revolutionizing mental health screening, even with the use of one's smartphone 266–268 .…”

Association Between Childhood Visual Acuity and Late Adolescent Psychotic Experiences: A Prospective Birth Cohort Study

“…The finding that eye movement abnormalities and squint were not associated with psychotic experiences seems surprising, given that these are some of the most widely replicated neurological abnormalities in schizophrenia. 59 This might be because these measures are associated with psychotic illnesses but not other types of psychotic experience, or because they occur closer to the time when psychotic experiences are established, or result from these.…”

The Use of Electroretinography and Optical Coherence Tomography in Patients with Schizophrenia

“…The use of ERG and OCT, along with the established clinical diagnosis of schizophrenia can help define clear subgroups within schizophrenia as a group of diseases according to ERG and OCT findings. These subgroups would have different prognostic and therapeutic specificities ( 35 , 36 ). We can also expect a clear and defined biologic marker that would increase the accuracy of the disease diagnosis and enable early initiation of treatment.…”