A Systematic Review and Meta-Analysis on Contrast Sensitivity in Schizophrenia.

Background and hypothesis: Understanding perceptual alterations in mental disorders can help uncover neural and computational anomalies. In schizophrenia, perceptual alterations have been reported for many visual features, including a deficit in contrast sensitivity, a key measure of visual function. The evidence supporting this deficit, however, has not been comprehensively synthesized.

Study design: We conducted a systematic review and meta-analysis of studies measuring contrast sensitivity in individuals with schizophrenia and healthy controls. Our search identified 46 studies, of which 43 focused on chronic patients.

Study results: We found that patients with chronic schizophrenia have reduced contrast sensitivity (g = 0.74; 95% CI, 0.55 to 0.93; P = 8.2 × 10-10). However, we found evidence that the deficit could be driven by medication. Additionally, none of the studies estimated attentional lapses, leaving it uncertain whether a potentially higher frequency of lapses in patients contributes to the observed deficit. Furthermore, only two studies comprehensively assessed visual acuity, complicating the understanding of the role of spatial frequency in the observed deficit.

Conclusions: While we identified a robust deficit in contrast sensitivity among chronic schizophrenia patients, the influence of attentional lapses and medication on this impairment remains unclear. We make several suggestions for future research to clarify the underlying mechanisms contributing to this deficit.