Symposium on unidentified flying objects: hearings before the Committee on Science and Astronautics, U.S. House of Representatives, Ninetieth Congress, second session, July 29, 1968.

187
warrant
particular
scrutiny
[3].
When
diabetes,
for
example,
is
known
to
be
present,
the
physician
will
look
for
specific
related
abnormal
findings
when
he
checks the
eye
and
does the
neurologic
and
mental
status
examinations.
Since
observations
usually
begin
with the
eye
and/or
some
other sensory
organ, the next
step
(once
adequate
general
medical
screening
has
been
done)
might
natu-
rally
be
a
neuro-ophthalmologic
examination.
This
would
concern
itself
with
the
major
structures
of the
visual
apparatus
and
any
of
their
abnormalities
which
might
influence
accurate
reception
of
the
visual
images
[4].
The
cornea,
the
most
external
structure,
accounts
forvisual
distortion
through
scarring
and
clouding.
These
changes
are
caused
by
such
insults
as
trauma
to
the
eye,
exposure
to
toxic
fumes,
infections,
and
deficiency
or
degenerative
diseases.
Inspection
with
an
ophthal-
moscope
and/or
slit
lamp
will
positively establish
cor-
neal
integrity.
The
lens
of
the
eye
is
the
main
structure
for
directing
light
rays
from
external
phenomena
to the
retina.
It
has
a
wide range
of
possible
variation,
on
both
a
genetic
basis
and,
like
the
cornea,
as
,
a
result
of
aging,
trauma,
deficiency diseases
and
infections.
The
configuration
of
the
lens,
as
it is
suspended
in
front
of
the
eye
by
delicate
muscles,
accounts
for
the
sharpness
(and
shape)
of
the
image
known
as
refractive
ability.
The
aqueous
humor
which
bathes the
lens
is
of
particular
concern because
of
the
pressure
it
exerts
on
the
rest
of
the
eye.
Increased
pressure
changes
in
this
medium,
measurable
with
a
goniometer,
are
re-
sponsible for
glaucoma
which
can
result
in
serious
impairment
of
visual
acuity.
After
a
period
of time,
the
increased pressure
will
also
lead
to
a
characteristic
constriction
of the
visual
fields,
which
can be
estab-
lished
by
examination
(perimetry).
The
vitreous
humor
fills
the
eyeball
and
is
the
other
fluid
through which the
light
rays of
a
visual
image
must
pass
before
they
reach
the
retina.
This
medium
is
subject
to
clouding
and
other
signs
of
early
inflamma-
tion.
"Floaters,"
which
are
abnormal
proteinaceous
particles
in
the
vitreous
humor,
are
sometimes
mistaken
by
people
as
moving
objects
that
are
in
their
outside
environment. Again,
ophthalmoscopic
and
slit
lamp
examination
will
serve
to determine the
status
of the
vitreous
humor.
The
retina
is
the
structure
on
which the
visual
image
is
actually
received;
loosely,
it
can be
likened
to
camera
film.
Located
in
the
posterior
eyeball,
it
is
the
beginning
of the
neural perception linkage
which
eventually reaches
the
brain
and
consciousness.
The
retina
is
subject
to
many
and
varied abnormalities
which can
severely disturb
both
visual
sharpness
(acuity)
and
range
(fields),
as
well
as
color perception.
Retinal
pigment
accumulation, inflammatory,
and
other exudates,
vascular
problems
and
other types of
pathology
can
come
between
an
otherwise observable
event
and
the
retina,
such
that
part
or
all
of the
event
is
obliterated
or
distorted
in
various
ways.
Ophthal-
moscopic
inspection
will
yield
a
great
deal
of
informa-
tion
about
the
anatomic
integrity
of
the
retina,
but
a
complete
assessment
must
also
include
detailed
map-
ping
of
both
visual
fields
by
perimetry,
with
attention
to
the
size
and
shape
of
the
blind
spot.
The
observer's
ability
to
perceive
color
at
the
retinal level
may
be
challenged
with
Ischihara
charts,
which
are
most
pop-
ularly
used
for detecting
color blindness.
These
charts
also
will
pick
up
abnormalities
in
color
perception
which
are
due
to
drugs, other
toxic
conditions,
and
higher,
cortical
integrative
problems.
The
head
of
the
optic
nerve
(disc)
can
also
be
easily
inspected
with
the
ophthalmoscope, as
it
sits
bare
at
the
back
of
the
eye.
The
optic
nerve
is
subject
to
similar
pathologic
processes
as
those
mentioned
above:
i.e.,
developmental,
inflammatory,
metabolic,
and
toxic.
The
color,
texture
and
anatomic
configuration
of the nerve
head
indicate
not
only
the
integrity
of
the
optic
nerve at
this
vital
point
but
also
offer
highly
suggestive
inferential
information
about
the
state
of
the
rest
of
it,
which
is
not
directly
visible.
In
addition,
when
there
is
increased
intracranial
pressure
due
to
any
type
of
brain
abnormality,
it
can
be
reflected
in
the
appearance
of
the
optic
disc.
The
optic
nerves
from
both
eyes
join
in
the
area of
the
pituitary
gland
and
then
redivide
in
such
a
way
that
fibers
from
both
eyes
are
represented in
the
optictracts
that
form.
Each
tract
then
travels
along
either
side
of the
brain
(medial
aspect of
parietal
and
tem-
poral lobes) via
optic
radiations
to the
occipital
cortex.
These
pathways,
although
not
directly
visible,
are
accessible
through the
use of
several
maneuvers.
Com-
posite findings
on
neurologic
examination,
includingvisual
field
results,
are
traditionally
used,
but
optico-
kinetic
studies
should
also
be
done
because
of
the
abundance
of
information
they can
give
about the
integrity
of
the
optic
radiations.
This
involves
the use
of
a
moving,
checkered
tape which the
patient
watches
and
to
which
his
eyes should
involuntarily
respond withrapid,
rhythmic
movements
(nystagmus)
[5].
If,
on
the
basis
of
these
studies,
some
kind
of
local
pathology
or
other
interfering
process
is
suspected,
the
physician
can then
make
use of
special
x-ray procedures
(pneu-
moencephalography,
arteriography)
for
looking at
the
areas in question.
Once
the examining
physician
has
satisfied
himself
as to the
status
of
an
observer's visual
apparatus (to
the
point
where
the
cerebral cortex
takes
over),
he
will
want
next to proceed with
a
detailed
neurologic
exami-
nation.
His
index of
suspicion
about the
presence of
absence of
pertinent central
nervous system
disease
had
already
been
altered
by
his findings
on
general
physical evaluation,
as
well
as from
the
eye exami-
nation.
There
is
a
clinical
format
for
doing
a
complete neu-
rologic
examination;
it is
well-known to
neurologists
and