Effect of binasal occlusion (BNO) on the visual-evoked potential (VEP) in mild traumatic brain injury (mTBI).
OBJECTIVE
The purpose of the experiment was to assess the effect of binasal occlusion (BNO) on the visually-evoked potential (VEP) in visually-normal (VN) individuals and in those with mild traumatic brain injury (mTBI) for whom BNO frequently reduces their primary symptoms related to abnormally-increased visual motion sensitivity (VMS).


METHODS
Subjects were comprised of asymptomatic VN adults (n = 10) and individuals with mTBI (n = 10) having the symptom of VMS. Conventional full-field VEP testing was employed under two conditions: without BNO and with opaque BNO which blocked regions on either side of the VEP test stimulus. Subjective impressions were also assessed.


RESULTS
In VN, the mean VEP amplitude decreased significantly with BNO in all subjects. In contrast, in mTBI, the mean VEP amplitude increased significantly with BNO in all subjects. Latency was normal and unaffected in all cases. Repeat VEP testing in three subjects from each group revealed similar test-re-test findings. Visuomotor activities improved, with reduced symptoms, with BNO in the mTBI group.


CONCLUSIONS
It is speculated that individuals with mTBI habitually attempt to suppress visual information in the near retinal periphery to reduce their abnormal VMS, with addition of the BNO negating the suppressive influence and thus producing a widespread disinhibition effect and resultant increase in VEP amplitude.
Department of Biological and Vision Sciences, SUNY State College of Optometry, New York City, NY, USA. kciuffreda@sunyopt.edu
Kenneth J
KJ
Ciuffreda
Naveen K
NK
Yadav
Diana P
DP
Ludlam
D000328:Adult; D001930:Brain Injuries / Q000503:physiopathology / Q000534:rehabilitation / Q000628:therapy*; D005074:Evoked Potentials, Visual; D005139:Eyeglasses; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology / Q000534:rehabilitation / Q000628:therapy*; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D013037:Spatial Behavior; D014786:Vision Disorders / Q000503:physiopathology / Q000534:rehabilitation / Q000628:therapy*; D058609:Visual Field Tests; D014795:Visual Pathways / Q000293:injuries / Q000503:physiopathology*