Retinal single-layer analysis with optical coherence tomography (OCT) in schizophrenia spectrum disorder.

BACKGROUND: Volume reductions in brain structures of patients with schizophrenia spectrum disorder (SSD) have repeatedly been found in voxel-based morphometry MRI studies. Hence, an underlying neurodegenerative etiological component of SSD is currently being discussed. In recent years, the imaging method of optical coherence tomography (OCT) has shown its potential in evaluating structural changes in the retina in patients with confirmed neurodegenerative disorders, providing a window into the brain. METHODS: Twenty-six patients with schizophrenia or schizoaffective disorder and 23 age- and sex-matched healthy controls were examined with the Heidelberg Spectralis OCT system to derive a single-layer analysis of both retinas. The segmentation of retinal layers was manually corrected to minimize artifacts and software imprecisions. RESULTS: Compared to the control group, SSD patients showed reduced thickness and volume measurements for nearly all retinal layers, and these differences reached significance for macular volume, macular thickness, retinal nerve fiber layer (RNFL) and inner nucleiform layer (INL). Furthermore, a significant correlation between the duration of illness and the total volume of the RNFL was found. CONCLUSION: Our OCT measurements demonstrate reduced single retinal layer thickness in patients with SSD. In the context of the MRI volume changes, our results provide further evidence that structural changes seen in the brain of patients are also observable in the retina, potentially allowing further insights into the different components of the nervous system that are altered in this highly etiologically complex disorder.

Retinal changes in patients with major depressive disorder - A controlled optical coherence tomography study.

BACKGROUND: Recent studies on the pathophysiology of major depression (MD) indicate that degenerative and inflammatory processes may play a role. This finding is supported by magnetic resonance imaging (MRI)-based meta-analysis that show volume reductions in circumscribed areas of the brain in patients with MD. Using optical coherence tomography (OCT), retinal changes have been demonstrated in neurodegenerative disorders. In light of this inflammatory/degenerative hypothesis, we tested whether patients with MD exhibit retinal alterations that might correlate with the severity and duration of the disease. METHODS: Patients with MD and age- and gender-matched healthy controls were recruited for the measurement of the total volume and thickness of their retina as well as the thicknesses and volumes of five different retinal layers using single-layer-analysis provided by the spectral-domain-OCT. RESULTS: OCT data from 28 patients with MD and 20 healthy controls were available for evaluation. The exploratory intra-individual group comparison of the two eyes showed a small but significant difference in the retinal total volume (right = 8.69mm3; left = 8.72mm3; p = 0.03) only in patients with MD. There were no other significant differences between the patients with MD and the healthy controls with respect to the OCT measurements. LIMITATIONS: The small group size as well as the absence of correction for multiple testing due to the exploratory design should be considered as limitations of our study. CONCLUSION: While retinal total volume differs between the eyes of patients with MD, the comparison of retinal parameters between these patients and age- and gender-matched healthy volunteers did not show any differences.

From Imaging the Brain to Imaging the Retina: Optical Coherence Tomography (OCT) in Schizophrenia.

Optical Coherence Tomography (OCT) is a noninvasive imaging method, which provides an in vivo image of the retina. It allows for quantitative measurements of retinal and macular thickness, including single-layer analysis. Because the retinal nerve fibre layer comprises the first axons of the visual pathway and is unmyelinated, it can be considered a unique anatomical model, which may provide insight into the pathophysiological processes of diseases with a neurodegenerative character. In fact, past OCT studies have emphasized the role of the visual pathway as an ideal structure for exploring neurodegeneration and have demonstrated the potential of the method as an instrument for longitudinally monitoring structural changes in neurological disorders such as multiple sclerosis. Progress in signal processing and advancements to the OCT technique enables the illustration of structural changes in the retinal layers in a quick, reproducible, and objective manner with a spatial resolution comparable to those of histological slices.Findings from computer-based magnetic resonance imaging analyses and neuropathological studies support the hypothesis of a degenerative component of certain psychiatric disorders such as schizophrenia. Studies in schizophrenia incorporating OCT are currently rare and have yielded further heterogeneous results. This article elucidates the method of OCT and the retina's role as a "window to the brain". Furthermore, in delineating the degenerative components of schizophrenia, we discuss the possible applications of OCT in the schizophrenia population.