The retina is sometimes considered a window to the brain due to similarities in development and pathology. Looking into the retina’s ability to mirror the effects of treatment, researchers from Turkey found OCT imaging of RNFL thickness may be helpful in evaluating drug therapies for schizophrenia and bipolar disorder.

The study included 35 patients with schizophrenia, 46 patients with euthymic bipolar disorder and 31 controls. The patients in the schizophrenia group took either risperidone or clozapine. In the bipolar disorder group, a team measured the serum levels of valproate and lithium. Additionally, they calculated the chlorpromazine equivalent doses of antipsychotics and mood stabilizers.

In the bipolar patients, the serum valproate level was a positive predictor for the thickness of the right macular inferior outer and left macular nasal outer regions and the right inferotemporal, left inferotemporal and left temporal RNFL sub-regions.

Of importance, the chlorpromazine equivalent dose of antipsychotics was a negative predictor of thickness in certain optic nerve regions in both schizophrenia and bipolar disorder. In schizophrenia patients, the chlorpromazine equivalent risperidone doses were determined to be a negative predictor of the left nasal and left inferonasal region thickness. No significant difference was determined between the bipolar disorder and schizophrenia groups in macular thickness.

“The outcome of this study implies that valproate has neuroprotective effects on the optic nerve and macula, and this finding is consistent with the literature implying neurotrophic effects of valproate,” the study authors concluded in their paper.