Optical coherence tomography in patients with major depressive disorder

Optical coherence tomography (OCT) has emerged as a significant non-invasive imaging technique in psychiatric research, allowing for detailed structural assessment of the retinal layers. While OCT has been promising for monitoring neurodegeneration in Alzheimer's and Parkinson's diseases, results in major depressive disorder (MDD) remain inconsistent. Building on findings of attenuated electroretinogram (ERG) responses in MDD, indicating functional retinal alterations, this study investigated whether structural retinal changes, such as thinning of retinal layers, also occur in patients with MDD and whether these changes are associated with the severity of depressive symptoms.

OCT examinations were conducted on 31 MDD patients and 60 healthy controls (HC). The thickness and volumes of macular retinal layers were analyzed and correlated with depressive symptoms.

The thickness of the outer nuclear layer (ONL) was significantly reduced in MDD patients (p = 0.003) and negatively correlated with depressive symptoms (BDI-II scores; p = 0.001). The thickness and volume of the ganglion cell and inner plexiform layer were further inversely associated with depressive symptoms in MDD patients (BDI-II and MADRS scores; p < 0.02).

ONL thinning in MDD suggests possible neurodegenerative processes that may disturb signal transmission downstream, as indicated by altered ERG responses in MDD. Further research is essential to determine the reversibility of these structural changes following remission. Structural retinal analysis with OCT offers the potential to complement functional ERG examinations and represents a promising approach for developing diagnostic and therapeutic monitoring tools for MDD.