Charles Bonnet syndrome in glaucoma patients with low vision

To characterize the nature and frequency of Charles Bonnet syndrome in glaucoma patients with low vision.

All patients attending the glaucoma clinic during a period 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 of visual hallucinations. Those who responded positively had a thorough interview relating to the characteristics of the hallucinations. Medical history and social history were taken, followed by a complete ocular examination.

Eighty-nine patients met the inclusion criteria. Eleven patients (12.3%), eight men and three women, admitted to having experienced visual hallucinations. Except for one case, the patients did not disclose this experience previously. Eight patients had one repeatable hallucination, and three patients experienced more than one sight. The visions were usually sharp, and the figures were occasionally incomplete. Most hallucinations were chromatic. Frequency of hallucinations varied between daily and weekly, and duration was mostly a few minutes. In addition to glaucoma, nine of the eleven patients had other ocular findings that could have contributed to the reduction of vision.

Visual hallucinations are not rare in glaucoma patients with low vision. Patients tend to conceal their experience of visual hallucinations, but a discussion of these phenomena with the patient and assurance of their harmless nature will reduce his or her anxiety and concerns.