Visual hallucinations might be a common presentation in Psychiatry words. But there is an interesting neuro-ophthalmological condition where a person may be psychologically normal, yet he or she may see shadows, things, or persons vividly, despite being visually impaired.

Case Reference

A seventy-year-old woman with bilateral advanced open-angle glaucoma visited our outpatient department for a regular check-up. She was systemically all right without any neurological or psychological disability. She had poor vision in both the eyes for past five years. A few weeks before her appointment, she started seeing flashes of light. A few days later, she started seeing grey human figures sitting on her sofa in her room. They would stay for hours and then vanish into thin air. She couldn’t tell this to anyone for fear of being stamped as an insane person. She confessed to me so that I could treat her symptoms. After excluding neurological and psychiatric causes, side effects of medications, and a thorough metabolic work-up, she was diagnosed to be suffering from Charles Bonnet Syndrome (CBS).

Charles Bonnet Syndrome also called ‛Phantom Vision’ is a condition where visual hallucinations are seen by patients as a result of damage to the visual pathway. The person has intact cognition and an insight that the hallucinations are unreal. In 1760, Charles Bonnet first described the visual hallucinations associated with the syndrome that was experienced by his ninety-year-old grandfather with poor vision^.

Commenting on the increasing trend of Charles Bonnet Syndrome, it’s a very rare vision disorder but quite serious. Approx two cases, last year were treated in our Disha Eye Hospitals Branch. And every year the number of patients is restricted to 2 to 3. Yes, the number is quite low. The prime reason behind this is the lack of consciousness and reluctance amongst the elderly generation. We are quite confident that if a proper channel of communication can be established with elderly people who are patients of Age-Related Macular Degeneration then there will be an escalation in the total number of cases. 

Moreover, according to a report, the concept of CBS is no longer uncommon. The overall prevalence of CBS is found to be 0.5% (5/1000), 0.8% (1/120) found in those with low visual acuity, 0.6% (2/346) in the elderly, 0.8% (1/120) in both the elderly and the ones with low visual acuity. The percentage of people with Macular Disease who are undergoing visual hallucinations is 39% whereas it is 20% for the people with Glaucoma involved in visual rehabilitation.

There are various theories explaining the occurrence of CBS, but the main hypothesis is ‛Deafferentation Theory’ which suggests that the hallucinations are due to increased activity in the occipital cortex due to reduced sensory input in the eye. Common etiologies include macular degeneration, glaucoma, cataracts, retinitis pigmentosa, high myopia, cerebral infarctions, diabetic retinopathy, and venous occlusion. The prevalence of CBS varies from 6.7% to 8.1%. The hallucinations may be simple photopsias, grid-like patterns, and branching forms to complex images of people, vehicles, and miniature objects. They may last from hours to a few days.

CBS might be under-reported due to a lack of awareness and fear of being labeled as mentally ill. In a study, 47% of the patients reported their hallucinations, and one-third of the medical practitioners were unaware or uncertain about the condition.

Unfortunately, there is no definitive treatment for CBS. Management mainly includes patient counseling and education. Reassuring the patient that the condition is benign and has occurred as a response to visual loss, may reduce the anxiety and suffering. A few techniques to reduce the hallucinations include blinking eyes rapidly, improving the lighting conditions, moving to a different room, turning on the TV or radio, meditation, and other relaxation methods. Improving social interaction, visual rehabilitation, and psychiatric medications like Olanzapine, and Pregabalin have been beneficial in some patients. Recently, transcranial direct current stimulation (TDCS) to the visual cortex has been found to reduce the frequency of hallucinations.

So, awareness about the disease process in CBS is essential for the proper management of such patients. The ophthalmologist has an important role to play as early recognition of the signs and symptoms will reduce the agony of the patient and prevent misdiagnosis and unnecessary psychiatric treatments.

About the author- Dr. Ruby Misra, Consultant, Disha Eye Hospitals