Retinal Optical Coherence Tomography in Bipolar Disorder: A Scoping Review

Abstract

Background: Bipolar disorder (BD) is a psychiatric condition with significant health implications due to its comorbidities, premature mortality, and functional impairments. Despite extensive research on treatment and rehabilitation, gaps remain in diagnosis and monitoring. Therefore, there is a need for biomarkers to identify individuals at risk for disease progression or exacerbation. Developmentally part of the central nervous system, the retina represents a possible marker for observing BD-related structural and functional alterations in the brain.

Summary: The retina's structure can be assessed through optical coherence tomography (OCT), a noninvasive and cost-effective method. Retinal alterations, particularly in the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), have been associated with neurodegenerative and psychiatric disorders in cross-sectional OCT studies. This scoping review discusses findings on retinal changes in BD as well as their association with disease characteristics like symptom severity and illness duration and highlights OCT as a potential diagnostic tool in BD treatment.

Key findings: The majority of studies indicate RNFL and GCL thinning in BD patients, which was found to correlate with clinical characteristics in some studies. Although the data are currently limited, there is a possibility that retinal biomarkers could facilitate monitoring of BD, but more research needs to be conducted to observe the relationship between these parameters and BD. Moreover, other factors (e.g., treatment, metabolic and inflammatory conditions) may impact retinal changes, which highlights the need for longitudinal studies to clarify these relationships. Further research should focus on replicating current findings, understanding the role of inflammation, and differentiating between retinal regions affected by BD.

Background: Bipolar disorder (BD) is a psychiatric condition with significant health implications due to its comorbidities, premature mortality, and functional impairments. Despite extensive research on treatment and rehabilitation, gaps remain in diagnosis and monitoring. Therefore, there is a need for biomarkers to identify individuals at risk for disease progression or exacerbation. Developmentally part of the central nervous system, the retina represents a possible marker for observing BD-related structural and functional alterations in the brain.

Summary: The retina's structure can be assessed through optical coherence tomography (OCT), a noninvasive and cost-effective method. Retinal alterations, particularly in the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL), have been associated with neurodegenerative and psychiatric disorders in cross-sectional OCT studies. This scoping review discusses findings on retinal changes in BD as well as their association with disease characteristics like symptom severity and illness duration and highlights OCT as a potential diagnostic tool in BD treatment.

Key findings: The majority of studies indicate RNFL and GCL thinning in BD patients, which was found to correlate with clinical characteristics in some studies. Although the data are currently limited, there is a possibility that retinal biomarkers could facilitate monitoring of BD, but more research needs to be conducted to observe the relationship between these parameters and BD. Moreover, other factors (e.g., treatment, metabolic and inflammatory conditions) may impact retinal changes, which highlights the need for longitudinal studies to clarify these relationships. Further research should focus on replicating current findings, understanding the role of inflammation, and differentiating between retinal regions affected by BD.

Keywords: Bipolar disorder; Ganglion cell layer; Optical coherence tomography; Retina; Retinal nerve fiber layer.

Fig. 1.

PRISMA flowchart of the study selection process. *145 records excluded because they did not investigate OCT or BP; 10 records excluded because they were errata, case reports, reviews, or preprints (5 reviews, 2 case reports, 1 comment, 1 preprint, 1 erratum).