Hallucinations are characteristic of some forms of mental
illness and can be frightening, causing distress to those who endure them. They
can also occur after taking hallucinogenic drugs, with the possibility of both pleasant
and unpleasant "trips".
Visions are part of the lore of religions like Judaism and
Christianity. These visions may result from mental illness or from drug use, but they also occur when these conditions do not
apply. There may be an expectancy of seeing an angel, or the Virgin Mary, and
an excited mental state may be common in these cases, but no drugs are involved
and nor is mental illness. What then is the basis of these visions?
Let's begin to answer that question by looking at two visions
described in the Holy Bible:
Daniel's vision [1]
Having seen a number of animals (this must have been in a
dream as he was lying face down?), Daniel then recounts:
..there stood before me as the appearance of a
man.. ..he came near where I stood: and when he came, I was afraid, and fell
upon my face.. ..as he was speaking with me, I was in a deep sleep on my face
towards the ground: but he touched me, and set me upright
Cornelius' vision [2]
Cornelius was a devout Christian centurion who:
..saw in a vision evidently about
the ninth hour of the day an angel of God coming in to him..
I assume that the ninth hour was in daylight and that his
vision was not a dream, but we have no information on his state of wakefulness.
Both these visions, and those of others, could be explained
by Charles Bonnet Syndrome. Charles Bonnet was born in Geneva in 1720 and qualified
as a lawyer, although he probably never practised the law [3]. He was always
fascinated by Natural History and wrote papers in the field of Entomology while
still training to be a lawyer, later making many contributions to Botany when
his eyesight began to fail during his twenties. Bonnet could then no
longer work on small-scale observation and it was not only his sight that
failed - he already had hearing loss from the age of seven [3]. As someone who
suffered from sensory deprivation, he became interested in this subject and the
way that it influenced the incidence of visions. He studied the phenomenon in
his elderly grandfather and it is from these descriptions that he is best known
in the medical world.
We can describe Charles Bonnet Syndrome (CBS) as [4]:
..the occurrence of recurrent or
persistent complex visual hallucinations often of a pleasant nature, which may
be considered pseudohallucinations, in individuals with preserved insight and
intellectual function without altered consciousness, cognitive or psychiatric
disturbances, sleep disorders, or focal neurological lesions and often
associated with ophthalmic pathology. CBS occurs predominantly in elderly, visually
impaired people.
Further in their review, Menon and colleagues [4] state:
The typical CBS hallucination has
been variously described as a sudden sharply focussed, immobile image, most
often the face or figure of a person, which occurs when the patient is alert,
with eyes open and vanishes spontaneously after a period of seconds.
However, there are other causes than failing eyesight for
the occurrence of hallucinations [4]:
Charles Bonnet-type hallucinations
have also been documented in the absence of ocular or neurological disease, in
type II diabetes mellitus with normal vision, in leprosy, in association with
HIV infection.. ..and in the elderly, where they can occur in the absence of
apparent cause.. ..it is interesting that fatigue and disturbances of vigilance
have been implicated as relevant to the emergence of hallucinations, as they
are more likely to occur during states of drowsiness.
Knowing this about the incidence of CBS, does it provide an
explanation for the visions of Daniel and Cornelius described above? Could the
phenomenon explain other visions that are so vivid to "observers" that
do not have mental illness or use drugs? The visions are certainly real to
those that have them and this is not surprising if they result from the neural
pathways used to interpret visual images from the eyes via the optic nerves. It
is rather like a mental short-cut that accesses the processing power of the
brain, without the need for a direct stimulus.
[1] http://www.kingjamesbibleonline.org/
section of Daniel Chapter 8
[2] http://www.kingjamesbibleonline.org/
Acts Chapter 10 verse 3
[3] Thomas R. Hedges Jr. (2007) Charles Bonnet, his life,
and his Syndrome. Survey of Ophthalmology
52: 111-114.
[4] G. Jayakrishna Menon, Imran Rahman, Sharmila J. Menon
and Gordon N. Dutton (2003) Complex visual hallucinations in the visually
impaired: the Charles Bonnet Syndrome. Survey
of Ophthalmology 48: 58-72.
