Optical Coherence Tomography of the Retina in Schizophrenia: Relationships with Visual and Perceptual Function
Miller, Margaret A.
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Background: Visual perceptual impairments are well established in schizophrenia, ranging from deficits in basic visual discrimination to abnormalities in higher-level visual integration. Recent research has identified thinning of retinal layers in individuals with schizophrenia, which may contribute to visual dysfunction. This study utilized optical coherence tomography to examine retinal integrity in individuals with schizophrenia, and investigated the contributions of retinal structure to low- and higher-level visual functions in schizophrenia. Methods: Participants were 12 individuals with schizophrenia-spectrum disorders and 12 age-matched healthy controls. Optical coherence tomography was utilized to obtain measurements for the retinal nerve fiber layer (RNFL), ganglion cell layer and inner plexiform layer (GCL+IPL), and macular volume. Visual functioning was assessed with low-contrast Sloan letter charts and the King-Devick test, a rapid number naming task that requires saccadic eye movements. In addition, visual learning was examined in individuals with schizophrenia using the Brief Visuospatial Memory Test Revised. Results: Individuals with schizophrenia exhibited reduced macular volume (Mschizophrenia = 9.72 mm3, SDschizophrenia = 0.38 mm3; M controls = 10.09 mm3, SDcontrols = 0.35 mm3, p = .023; d = 1.01). Although the differences were not statistically significant, individuals with schizophrenia also had poorer low-contrast visual acuity at both the 2.5% (Mschizophrenia = 37.67, SDschizophrenia = 7.51; Mcontrols = 41.92, SDcontrols = 3.15,p = .078; d = 0.80) and 1.25% levels (Mschizophrenia = 23.25, SD schizophrenia = 7.60; Mcontrols = 26.33, SDcontrols = 5.31, p = .514; d= 0.47), and slower rapid visual scanning (M schizophrenia = 55.60 s, SDschizophrenia = 17.34 s; Mcontrols = 48.50 5, SD controls = 7.62 s,p = .418; d = -0.55) compared to controls. Within the schizophrenia group, thinner RNFL and GCL+IPL were both associated with better low-contrast visual acuity and visual learning (all ps < .05). Conclusions: Results revealed a reduction in macular volume in schizophrenia, which is in line with previous research and expected findings. However, there were no differences in RNFL and GCL+IPL, which is inconsistent with the majority of previous research. This study also provides preliminary evidence of possible impairments in low-contrast visual acuity and rapid visual scanning in schizophrenia. Overall, these findings provide further support for retinal changes and visual deficits as possible biomarkers for schizophrenia. In addition, results support associations between retinal structure and visual perceptual processing. Further investigation into retinal changes and visual perceptual processing in schizophrenia and better characterization of the relationship between retinal structure and cognition may inform treatments.