The aim of this study is to investigate the changes in the retinal nerve fiber layer thickness of the patients with depression who received electroconvulsive therapy by means of optical coherence tomography.

Major depression (MD) is a mood disorder that is common in the society, has negative effects on emotion, thought and behavior, and leads to significant impairments in functionality. Electroconvulsive therapy (ECT) is a highly effective and reliable biological treatment method used in psychiatric diseases for a long time. The most common use in psychiatry is depression. Studies have shown that ECT causes a broadly distributed increase in brain gray matter volume (especially the temporal lobe) in MD patients. Optical coherence tomography (OCT) is a non-invasive medical imaging method that displays biological tissue layers by taking high resolution tomographic sections. Alterations in the thickness of the retinal nerve fiber layer (RNFL), which is a layer of the ganglion cell complex in the retina of the eye and consists of ganglion cell axons, occur due to axonal damage in the retinal nerve tissue. Since RNFL is in a similar form with the brain gray matter tissue, recently, neurological and psychiatric studies have been conducted to provide data regarding the neurodegeneration occurring in the brain tissue. In the study, it is aimed to assess the possible cortical volume changes of patients by measuring changes in the retinal layers due to ECT in patients with depression. In other words, considering that ECT causes an increase in brain volume, it is to observe whether this increase is reflected in the retinal nerve fiber layer thickness.

Inclusion Criteria:

• Subject diagnosed as unipolar depression
• Subject with depression to be treated with electroconvulsive therapy
• Subject with depression having a Standardized Mini Mental Test score of >23

Exclusion Criteria:

• Any comorbid psychiatric condition (including alcohol / substance use)
• Having any major neurological (i.e.: cerebrovascular disease, multiple sclerosis, etc.) disease
• Having any major medical (i.e.: diabetes mellitus, myocardial infarction, etc.) disease
• History of or having any ocular trauma, disease or surgery, any retinal disease, refraction defect
• To be treated with electroconvulsive therapy in the last 6 months

The study will include 25 volunteered inpatient or outpatient subjects with depression diagnosed with Structured Clinical Interview for DSM 5 Clinical Version (SCID 5/CV) who are followed-up at the Sağlık Bilimleri Üniversitesi Gazi Yaşargil Training and Research Hospital and 25 healthy volunteers matched with these patients in terms of age and gender. In order to measure the severity of the disease, subjects with depression will be administered Hamilton Depression Rating Scale (HAM-D), Young Mania Rating Scale (YMRS) and Clinical Global Impression Scale (CGI) before ECT, after the first ECT session and after the last ECT last session. The Symptom Check List-90-Revised (SCL-90-R) will be administered to healthy volunteers after enrollment.

De-identified individual participant data for all primary and secondary outcome measures will be made available

Data will be available with six months of study completion.

Data access requests will be reviewed by an independent reviewer. Requestors will be required to sign a Data Access Agreement.