Nonorganic visual loss, or functional blindness, is estimated to account for up to 5% of all presentations of blindness. This form of blindness can be ascribed to either a psychogenic aetiology or to malingering. Psychogenic blindness is often a manifestation of conversion disorder, in which a psychiatric condition impairs the normal physical functioning of the affected individual. This could lead to both motor and sensory defects, given that they are not better explained by an organic cause, which should be ruled out by investigations that prove an intact visual system. The individual would also commonly have an identifiable source of stress or trauma. Conversion disorders are less prevalent in older adults, and they may be missed where there are organic comorbidities.

A 67-year-old male with a recent history of stroke was diagnosed with a major depressive disorder, characterized by low mood, anhedonia, insomnia, fatigue, poor appetite, poor concentration, feelings of guilt, negative feelings about life, and hopelessness. Multiple social problems and family conflicts were identified as possible precipitating factors. Sertraline led to some good initial response, although it was later discontinued. A few months later, he developed severe depression with irritability and suicidal ideation, and he was repeatedly requesting euthanasia. At this point, there was a sudden loss of his vision. Following a thorough ophthalmology evaluation, neurological assessment, and investigations including MRI of the head, cortical blindness was ruled out. As a result, he was diagnosed with visual conversion disorder. After recommencing treatment for his depression with a psychotherapeutic approach as well as vortioxetine antidepressant medication, the visual loss resolved, and the issue has not recurred since then. There was also a significant improvement in his mood. He no longer feels suicidal and appears to be brighter and more socially interactive.

Uncertainty regarding aetiology might initially arise if the patient has a history of trauma or a pathological condition that could cause blindness, such as diabetic retinopathy or stroke, both of which would have been differential diagnoses in the patient in this case had they not been debunked by further investigations, which included neuro-ophthalmic assessments and radiographic studies. The patient's improvement with antidepressants and counselling further supports the diagnosis of visual conversion disorder.

Functional blindness, which is an aspect of conversion disorder, may be a representation of how detrimental undiagnosed and untreated depression could be.