thers have shown that the presence of the globe is
necessary to generate the eye blink potential.3 Data
from our subject blinded in the right eye by trauma
confirm this. The only response from the blind side
was a small deflection less than 5% of the amplitude
of response from the normal side and presumed to be
an electromyographic (EMG) response.
Since EOGs derived from standardised eye
movements and from the blink potential appear to be
similar, it is reasonable to assume that both measures
reflect activity from the same generator, namely the
corneoretinal potential.
Individuals with severely impaired vision have
difficulty in fixating targets and thereby produce eye
movements of varying magnitude. As demonstrated
by our blind subject the eye blink potential amplitude
appeared to be less variable than responses to gaze
towards an imagined target. It has also been possible
to measure the blink EOG in several psychotic
patients who had great difficulty in sustaining
attention and attending to the flashing fixation targets.
Although the rate of blinking varied considerably
among subjects,45 even the lowest rates permit the
comeoretinal potential to be sampled frequently and
conveniently. Thus it would be possible to plot an
EOG with many more data points should that be
desirable. Measurement of continuous voluntary eye
movement responses, by contrast, was very fatiguing
for one of the authors (D.D.).
As a practical point attachment of electrodes in a
vertical line was faster for the technician, and more
comfortable for the patient, than the conventional
horizontal placement, which required attachment of
electrodes near the medial canthus.
It has generally been assumed that the eye rotates
upward during eye blinks, thus generating a potential
analogous to a vertical eye movement.6-8 However,
Matsuo and his colleagues were unable to see eye
movement or record an eye blink potential from a
patient with unilateral total facial nerve palsy. The
blink potential from the non-paralysed side was
normal.3 Unfortunately the data in this report do not
aid in resolving this controversy. It is of some interest,
however, that our blind subject generated a larger
response when looking down than when looking up.
When asked to look up as far as possible he generated
a response only 20% larger than those shown in Fig.
4. In comparison with our normal subjects his eye
blink response amplitude was also much smaller. This
suggests, although it does not prove, that eye movement
does occur during the blink response. If, as
Matsuo et al. suggest, the response is produced by a
wiping action of the eyelid over a stationary cornea,
one would assume that the absolute magnitude in this
subject would have been larger and similar to the
amplitude of response from combined upward and
downward movement.
.