CBS Defined

A vision-impaired
person of sound mind experiences
phantom images (visions) in
their visual field.

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Glaucoma is the second leading cause of blindness in the world. Those living with glaucoma- especially in the advanced stages of the condition- are susceptible to CBS. 

The issue of visual acuity

CBS is often linked to low visual acuity. Low visual acuity refers to an inability to read many (lower) rungs of the standard eye chart. In such cases, one is said to have poor central vision and this makes one more prone to CBS. This covers conditions such as macular degeneration and cataracts.

However, linking CBS to low visual acuity can present a misleading picture. Glaucoma is a case in point. Unlike macular degeneration, glaucoma affects one’s side or peripheral vision. Consequently, many who live with glaucoma can record good visual acuity and yet still experience CBS. Repeated case studies have found that CBS can occur where visual acuity is (largely) preserved. This suggests that CBS can potentially occur anywhere along the visual acuity scale from 'normal' to very poor. 



Madill, SA & ffytche, DH (2005). Charles Bonnet syndrome in patients with glaucoma and good acuity. British Journal of Ophthalmology; 89: 785-786.


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