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Martel et al. report the prevalence, features and risk factors of visual hallucinations following eye removal (1). The findings indicate that visual hallucinations may be a significant and prevalent association of eye amputation, occurring in around one-third of cases. Throughout the paper, visual hallucinations are referred to as phantom visions, and categorised under the broad catchment of the phantom eye syndrome that includes pain and tactile sensations as well as visual hallucinations. Although the authors speculate phantom visions could be considered a subtype of Charles Bonnet syndrome (CBS) they are reluctant to refer to them as CBS, perhaps because of the longstanding debate as to whether CBS should be used to refer to a specific type of visual hallucination or a specific underlying cause (2,3). Where CBS is used to refer to a specific hallucination type, it is typically reserved for complex hallucinations and excludes the simple, ‘elementary’ hallucinations described as the most common experiences following enucleation. The consequence is that a range of terms have evolved to describe symptoms that have the same cause, adding confusion to the literature and hindering research and extensive efforts to raise awareness and establish appropriate patient management pathways for people with visual hallucinations (4-6).
It is our opinion that both the simple and complex visual hallucinations described in the study should be referred to as Charles Bonnet syndrome....
It is our opinion that both the simple and complex visual hallucinations described in the study should be referred to as Charles Bonnet syndrome. In fact, irrespective of eye condition or visual pathway disease, surveys that include both simple and complex hallucinations find a similar ratio of simple to complex as that described by the authors following eye removal (see for example 7,8) and it has been argued previously that restriction of the use of CBS to denote complex hallucinations only should be revisited (3). Broadening the term to include simple and complex phenomena reflects current practice (9,10) and has become particularly pressing as the International Classification of Diseases (ICD-11) now includes CBS for the first time, using it to refer to the specific causal mechanism of visual release.
Inconsistent terminology in the visual hallucination literature threatens to widen the gap between patients and appropriate referral to support services. This problem is particularly acute in CBS due to low awareness of the condition among physicians (7, 11). There is need for unity to ensure all patients receive accurate and clear messaging about visual hallucinations and can be signposted to relevant organisations, such as Esme’s Umbrella, for advice and support.
1. Martel A, Baillif S, Thomas P, et al. Phantom vision after eye removal: prevalence, features and related risk factors. British Journal of Ophthalmology, Published Online First: 12 May 2021. doi: 10.1136/bjophthalmol-2021-319091
2. ffytche DH. Visual hallucinatory syndromes: past, present, and future. Dialogues in Clinical Neuroscience. 2007;9(2):173-189.
3. ffytche DH. Visual hallucinations and the Charles Bonnet syndrome. Current Psychiatry Reports. 2005;7(3): 168-79.
4. O'Brien J, Taylor JP, Ballard C, Barker RA, Bradley C, Burns A, Collerton D, Dave S, Dudley R, Francis P, Gibbons A. Visual hallucinations in neurological and ophthalmological disease: pathophysiology and management. Journal of Neurology, Neurosurgery & Psychiatry, 2020; 91(5): 512-519.
5. Carpenter K, Jolly JK, Bridge H. The elephant in the room: understanding the pathogenesis of Charles Bonnet syndrome. Ophthalmic and Physiological Optics, 2019; 39(6): 414-421.
6. Best J, Liu PY, ffytche D, Potts J, Moosajee M. Think sight loss, think Charles Bonnet syndrome. Therapeutic Advances in Ophthalmology, 2019. doi:10.1177/2515841419895909
7. Cox TM, ffytche DH. Negative outcome Charles Bonnet Syndrome, British Journal of Ophthalmology, 2014; 98: 1236-9.
8. Santhouse AM, Howard RJ, ffytche DH. Visual hallucinatory syndromes and the anatomy of the visual brain. Brain. 2000;123: 2055-64
9. Jones L, Moosajee M. Visual hallucinations and sight loss in children and young adults: a retrospective case series of Charles Bonnet syndrome. British Journal of Ophthalmology, Published Online First: 15 September 2020. doi: 10.1136/bjophthalmol-2020-317237
10. Jones L, Ditzel-Finn L, Potts J, Moosajee M. Exacerbation of visual hallucinations in Charles Bonnet syndrome due to the social implications of COVID-19. BMJ Open Ophthalmology, 2021; 6(1), p.e000670.
11. Gordon KD, Felfeli T. Family physician awareness of Charles Bonnet syndrome, Family Practice, 2018; 35(5): 595-8.