Purpose: To characterize the nature and frequency of Charles Bonnet syndrom
e in glaucoma patients with low vision.
Patients and Methods: All patients attending the glaucoma clinic during a p
eriod of 10 months who had visual acuity of 20/80 or less in both eyes were
included in this study. Each patient was questioned about the occurrence o
f visual hallucinations. Those who responded positively had a thorough inte
rview relating to the characteristics of the hallucinations. Medical histor
y and social history were taken, followed by a complete ocular examination.
Results: Eighty-nine patients met the inclusion criteria. Eleven patients (
12.3%), eight men and three women, admitted to having experienced visual ha
llucinations. Except for one case, the patients did not disclose this exper
ience previously. Eight patients had one repeatable hallucination, and thre
e patients experienced more than one sight. The visions were usually sharp,
and the figures were occasionally incomplete. Most hallucinations were chr
omatic. Frequency of hallucinations varied between daily and weekly, and du
ration was mostly a few minutes. In addition to glaucoma, nine of the eleve
n patients had other ocular findings that could have contributed to the red
uction of vision.
Conclusion: Visual hallucinations are not rare in glaucoma patients with lo
w vision. Patients tend to conceal their experience of visual hallucination
s, but a discussion of these phenomena with the patient and assurance of th
eir harmless nature will reduce his or her anxiety and concerns.