History Your Diagnosis Discussion The diagnosis in this issue is Charles Bonnet syndrome (CBS). The term is used to describe individuals who have severe sight problems and begin to see things that they know are either not there or not real.1-4 Sometimes called visual hallucinations, the images can take the form of patterned straight lines or detailed pictures of people or buildings. The imagery can be enjoyable, frightening and/or sometimes upsetting.1-4 CBS affects people who have significant sight loss. It usually affects only people who lost their sight later in life, although it can affect people of any age. It typically manifests its first symptoms after a period in which sight is suddenly worsened. Swiss philosopher Charles Bonnet (1720-1793) first described the condition in 1760 when his grandfather, who was left virtually blind by cataracts, described seeing birds and buildings that were not there.1 Although CBS was made familiar to the medical community more than 200 years ago, clinicians do not often diagnose the condition. One reason: the syndrome remains poorly understood and underpublicized. Also, the people who experience CBS don"t like to talk about it for fear of being thought of as mentally ill.1-3 Etiopathological theories suggest that daily, normal visual demands stop the brain from creating its own pictures (outside of dreaming). When people suffer loss of sight, their brains are no longer deluged by a constant influx of visual stimuli. When the mechanism that suppresses the formation of random imagery degrades, new fantasy pictures or old pictures stored in the brain are somehow released and experienced as though actually seen.1 The experiences frequently happen when the sufferer is sitting alone, somewhere quiet, in a familiar place or when lying in bed. The images may begin as patterns and/or lines and evolve to become complicated brickwork, mosaic or tiles. Other images include more complicated pictures of people or places. Often whole scenes, such as landscapes or groups of people, appear; they may appear life-size or tiny, and the images last from seconds to minutes.1,2 Although the visions themselves may not be anything frightening, it is disquieting to most to see strangers in one"s home or automobile. If sight is not restored, the images often fade within a year to 18 months of their beginning.1 Some success in the way of treatment has been reported with medications such as valproate and olanzapine.5,6 Helen Abdal, O.D., contributed to this case.
A 67-year-old Haitian female was referred to our office by her primary-care physician after she reported that the floating spots she had seen for the last 10 years had turned into "little people."
She was in good health except for hypertension, for which she took medication. She had no significant ocular history, and all other historical elements were noncontributory.
The patient reported that the floating spots she had seen for the past 10 years had transformed into "little people." (Artist"s rendering of little people shown here.)
Best-corrected visual acuity measured 20/800 O.D. and hand motion O.S. There was no afferent pupillary defect. Biomicroscopy revealed grade IV hypermature cataracts in both eyes. Intraocular pressure measured 19mm Hg O.U.
We could not view the posterior pole with binocular indirect ophthalmoscopy or 78D binocular indirect biomicroscopy.
How would you approach this case? Does this patient require additional tests? What is your diagnosis? How would you manage this patient? What is the likely prognosis?
Additional tests included red light laser interferometry to determine the possible outcome and prognosis of surgical extraction of the cataracts and B-scan ultrasonography to ascertain the integrity of the retina, nerve and posterior segment. It was determined that cataract surgery could be safely performed. The patients cataract were removed, and the results were spectacular. Visual acuity was 20/100 O.U. at one day post-op with minimal inflammation and no complications. The "floating people" phenomenon faded almost instantaneously.
1. Royal National Institute of the Blind. Charles Bonnet Syndrome. www.rnib.org.uk/xpedio/groups/public/documents/publicwebsite/public_rnib003641.hcsp. Accessed 17 November 2005.
2. Nesher R, Nesher G, Epstein E, Assia E. Charles Bonnet syndrome in glaucoma patients with low vision. J Glaucoma 2001 Oct;10(5):396-400.
3. Au Eong KG, Fujii GY, Ng EW, et al. Transient formed visual hallucinations following macular translocation for subfoveal choroidal neovascularization secondary to age-related macular degeneration. Am J Ophthalmol 2001 May;131(5):664-6.
4. Santhouse AM, Howard RJ, Ffytche DH. Visual hallucinatory syndromes and the anatomy of the visual brain. Brain 2000 Oct;123 ( Pt 10):2055-64.
5. Hori H, Terao T, Shiraishi Y, Nakamura J. Treatment of Charles Bonnet syndrome with valproate. Int Clin Psychopharmacol 2000 Mar;15(2):117-9.
6. Coletti Moja M, Milano E, Gasverde S, et al. Olanzapine therapy in hallucinatory visions related to Bonnet syndrome. Neurol Sci 2005 Jul;26(3):168-70.
