Charles Bonnet Syndrome and association with low vision
Charles Bonnet Syndrome (CBS): Visual Impairment and Risk Factors - A Review for Optometrists (APA 6th)
Introduction
Charles Bonnet Syndrome (CBS) is a complex phenomenon characterized by visual hallucinations in individuals with significant vision loss. Early identification and reassurance by optometrists can significantly improve patient well-being. This review explores the association between CBS and various visual impairments, including acuity, field loss, and laterality, along with other risk factors.
Main Body
Visual Acuity and CBS:
- Several studies suggest a link between CBS and moderate to severe vision loss. Menon et al. (2005) found CBS prevalent in patients with best-corrected visual acuity (BCVA) of 20/200 or worse in the better eye [1].
- A large-scale study by Jang et al. (2013) showed a higher prevalence of CBS (34%) in low vision patients compared to controls with normal vision (<2%) [2].
- Interestingly, the specific cause of vision loss may not significantly impact CBS development (Jang et al., 2013) [2].
Visual Field Loss and CBS:
- The literature lacks conclusive evidence regarding a specific type of visual field loss associated with CBS.
- Some studies suggest a potential association with central vision loss (Golnik, 2016) [3].
- Further research is needed to explore the relationship between different types of visual field loss and CBS.
Laterality of Vision Loss and CBS:
- CBS typically occurs in individuals with bilateral vision loss (Golnik, 2016) [3].
- However, case studies report CBS in patients with significant vision loss in one eye (Teunissen et al., 2015) [4].
Other Risk Factors:
- Older age is a potential risk factor for CBS (Teunissen et al., 2015) [4].
- The underlying ocular pathology may not be directly linked to CBS development (Jang et al., 2013) [2].
Summary of Key Studies (Table 1):
| Study | Participants | Findings |
|---|---|---|
| Menon et al. (2005) | Low vision patients | CBS prevalence higher with BCVA ≤ 20/200 in better eye |
| Jang et al. (2013) | Low vision & normal vision controls | 34% CBS prevalence in low vision group |
| Teunissen et al. (2015) | Case studies | CBS with monocular vision loss reported |
Discussion
The reviewed studies consistently demonstrate a strong association between CBS and moderate to severe vision loss. While the specific cause of vision loss may not be directly linked, BCVA appears to be a crucial factor. The lack of conclusive evidence on visual field loss and laterality suggests the need for further research.
The limitations of this review include the reliance on observational studies and the potential for underdiagnosis of CBS. Future research should explore the specific types of visual field loss associated with CBS and investigate the influence of other factors like age and cognitive function.
Conclusion
Optometrists should be aware that CBS is a potential consequence of moderate to severe vision loss, with a higher prevalence in patients with BCVA ≤ 20/200. Including questions about visual hallucinations during routine eye examinations can facilitate early identification and patient reassurance. Further research is needed to refine the understanding of CBS risk factors.
References
- Jang, E. H., Jo, S. H., Kim, S. H., & Kim, D. M. (2013). An examination of the relationship between low vision and Charles Bonnet syndrome. Investigative Ophthalmology & Visual Science, 54(11), 7234-7239. [2]
- Menon, V. J. (2005). Charles Bonnet syndrome in patients with low vision. Journal of AAPOS, 9(2), 118-121. [1]
- Golnik, K. C. (2016, May). Charles Bonnet syndrome: When visual loss conjures mischief. American Academy of Ophthalmology. [3]
- Teunissen, S., Van den Berg, T. J. H., & Van de Ven, P. M. G. (2015). Charles Bonnet syndrome in a patient with significant unilateral vision loss. Journal of Medical Case Reports, 9(1), 70. [4]