More Info: Because age-related macular degeneration (AMD) affects the macula of the eye responsible for central and detailed vision, seeing hallucinations of shapes or objects is not uncommon especially in advanced cases. Hallucinating as a result of sudden vision impairment is known as Charles Bonnet Syndrome.
Complex Visual Hallucinations
Visual hallucinations are prevalent in those with macular degeneration. In some cases, the hallucinations are far more vivid and elaborate than seeing simple geometric shapes. Unfortunately the experts are quite sure what causes them or what predisposes a patient with AMD to them. Several studies have examined the topic with a few finding common factors.
The extent of the loss of vision does not appear to predispose patients with AMD to visual hallucinations. [Abbot, 2007]
Though there is no clear evidence as to why these hallucinations occur, there are some strong theories. An article published in December 1992 issue of The American Journal of Psychiatry pointed to sensory deprivation as the cause of hallucinations in patients with macular degeneration. [“Visual Hallucinations in Patients with Macular Degeneration” The American Journal of Psychiatry]
Doctors Joseph DeRose and Timothy Polk describe the condition as similar to that of the phantom limb pain experienced by amputees. The brain does not recognize the vision loss causing the cortical neurons to continue to fire in the absence of stimulation resulting in hallucinations. [“DeRose” Age Related Macular Degeneration]
Charles Bonnet Syndrome
Hallucinating as a result of sudden vision impairment is known as Charles Bonnet Syndrome. Named for the naturalist who first described the condition in 1759, it affects 50-60% of patients suffering from severe visual loss. [“Vision Loss and Visual Hallucinations: the Charles Bonnet syndrome.” National Center for Biotechnology Information]
The condition can result from age-related macular degeneration, cataracts, glaucoma, trauma, diabetic retinopathy with maculopathy, or retinal detachment. The syndrome is characterized by visual hallucinations that are extremely complex in the absence of sound. They can seem very real causing many suffering from these hallucinations to fear that they are suffering from dementia or insanity. In fact, in a survey published in March 2005 issue of Archives of Ophthalmology, 63% of the visually impaired participants experiencing hallucinations feared being labeled as insane were they to admit to them. [“Complex visual hallucinations in the visually impaired: a structured history-taking approach.” Archives of Ophthalmology]
Abbott, EJ. “Visual Loss and Visual Hallucinations in Patients with Age-related Macular Degeneration (Charles Bonnet Syndrome).” Investigative Opthalmology and Visual Science 48.3 (2007): 1416023. Print.
In this study, Abbot et al. attempted to match the extent of visual acuity loss and central visual field loss to visual hallucinations. He investigated whether the progression in loss mirrors the complexity of the visual hallucinations. In both cases, there seemed to be no connection.
Holroyd, S , MC Nicholson, GA Chase, SC Wisniewski, D Finkelstein, and PV Rabins. “Visual Hallucinations in Patients with Macular Degeneration.” The American Journal of Psychiatry 149.12 (1992): 1701-1706. Print.
DeRose, O.D., M.S., Joseph L., and Timothy Polk, M.D.. “Age Related Macular Degeneration.” Maryland Department of Health and Mental Hygiene. N.p., n.d. Web. 2 Feb. 2011. www.dhmh.maryland.gov/optometry/pdf/AMD_DeRose.pdf.
“Vision Loss and Visual Hallucinations: the Charles Bonnet syndrome.” National Center for Biotechnology Information. N.p., n.d. Web. 2 Feb. 2011. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2683559/.
Menon, GJ.. “Complex visual hallucinations in the visually impaired: a structured history-taking approach.” Archives of Ophthalmology 123.3 (2005): 349-355. Print.
Quote: “Among patients undergoing photocoagulation for macular degeneration, hallucination occur in about 60% usually a few days after the procedure. Hallucinations may also occur simultaneous to the onset of visual loss, so that in some cases it is the complaint of visual hallucinations that leads to the discovery of the visual field defect.”
Source: Walsh and Hoyt’s Clinical Neuro-Ophthalmology
6th ed. Philadelphia: Lippincott Williams & Wilkins, 2005. Print.