Dr. Tan et al. make a clear point that for the 2 participants in our study who had complete resolution of their visual hallucinations after cataract surgery, their visual hallucinations might well represent Charles Bonnet syndrome. Although Charles Bonnet syndrome is often not discussed in relation to cataract surgery, there is at least 1 case report of complex visual hallucinations in a patient with cataract that resolved after surgery.A As Charles Bonnet syndrome is thought to occur as a consequence of loss of afferent input to the visual association areas, it can be expected to improve if vision is restored after cataract surgery.
The idea that it is the dynamic changes in visual acuity rather than the actual level of visual acuity that is important in precipitating Charles Bonnet syndrome is an interesting one. Of note, the 2 participants in our study who had complete resolution of their symptoms after cataract surgery did not have severely impaired visual impairment at baseline (logMAR corrected visual acuities of 0.26 and 0.16). As Tan et al. state, classic thinking is that patients with Charles Bonnet syndrome are reassured by being told their visual hallucinations are a common consequence of their eye disease.1 However, visual hallucinations in Charles Bonnet syndrome might not necessarily be trivial to those affected. Up to a third of people with Charles Bonnet syndrome feel that their symptoms have a significant impact on their lives.2 Furthermore, visual hallucinations might also be a symptom of early neurodegenerative disease and this might not be apparent in ophthalmology clinics where cognition is not routinely assessed.3
A recent study that followed 77 people with a diagnosis of Charles Bonnet syndrome4 showed that 26% of them developed some kind of dementia within the average 3-year follow-up. Therefore, people with complex visual hallucinations, particularly if distressed by their symptoms, might benefit from neuropsychiatric input.
1. Menon GJ, Rahman I, Menon SJ, Dujtton GN. Complex visual hallucinations in the visually impaired: the Charles Bonnet syndrome. Surv Ophthalmol
2. Cox TM, ffytche DH. Negative outcome Charles Bonnet syndrome. Br J Ophthalmol. 98, 2014, p. 1236-1239, Available at: http://bjo.bmj.com/content/early/2014/05/12/bjophthalmol-2014-304920.full.pdf
. Accessed September 29, 2015.
3. Jefferis JM, Mosimann UP, Taylor J-P, Clarke MP. “Do your eyes play tricks on you?” Asking older people about visual hallucinations in a general eye clinic. [letter] Int Psychogeriatr. 23, 2011, p. 1014-1015, Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4121673/pdf/emss-59814.pdf
. Accessed September 29, 2015.
4. Lapid MI, Burton MC, Chang MT, Rummans TA, Cha SS, Leavitt JA, Boeve BF. Clinical phenomenology and mortality in Charles Bonnet syndrome. J Geriatr Psychiatry Neurol
Other Cited Material
A. Roever CP, Vyas B, Sheyner I, Stewart J, “Resolution of Visual Hallucinations Cataract Surgery,” poster presented at the annual meeting of the American Geriatrics Society, Washington, DC, May 2011. Abstract in J Am Geriatrics Soc 2011; 59:(suppl 1):S18