Visual alterations, peripheral light loss (PLL) and blackout (BO), are components
of acceleration (+Gz) induced loss of consciousness (LOC) and
recovery of consciousness (ROC). The kinetics of loss of vision (LOV) and
recovery of vision (ROV) were determined utilizing ocular pressure induced
retinal ischemia and compared to the kinetics of LOC and ROC resulting from
+Gz-induced cephalic nervous system (CPNS) ischemia. The time from
self-induced retinal ischemia in completely healthy subjects (N
= 104) to the onset of PLL and complete BO was measured. The time
from release of ocular pressure, with return of normal retinal circulation, to
the time for complete recovery of visual fields was also measured. The kinetics
of pressure induced LOV and ROV was compared with previously developed kinetics
of +Gz-induced LOC and ROC focusing on the rapid onset, vertical arm,
of the +Gz-induced LOC and ROC curves. The time from onset of
increased ocular pressure, immediately inducing retinal ischemia, to PLL was
5.04 s with the time to BO being 8.73 s. Complete recovery of the visual field
from BO following release of ocular pressure, immediately abolishing retinal
ischemia, was 2.74 s. These results confirm experimental findings that visual
loss is frequently not experienced prior to LOC during exposure to rapid onset,
high levels of +Gz-stress above tolerance. Offset of pressure induced
retinal ischemia to ROV was 2.74 s, while the time from offset of
+Gz-induced CPNS ischemia to ROC was 5.29 s. Recovery of retinal
function would be predicted to be complete before consciousness is regained
following +Gz-induced LOC. Ischemia onset time normalization in
neurologic tissues permits comparison between different stress-induced times to
altered function. The +Gz-time tolerance curves for LOV and LOC
provide comparison and integration of neurologic state transition kinetics in
the retina and CPNS.