Elevated dark adaptation thresholds in traumatic brain injury.
OBJECTIVE
To expand upon earlier findings of elevated dark adaptation (scotopic) thresholds in photosensitive individuals with traumatic brain injury (TBI).


METHODS
To assess scotopic thresholds in individuals with TBI (n = 17) manifesting varying degrees of photosensitivity (mild, moderate or marked), but without retinal dysfunction, to those of non-photosensitive, visually-normal individuals (n = 21) using a hand-held dark adaptometer.


RESULTS
The group mean scotopic threshold for the TBI group was significantly higher than that of the visually-normal group. Over 50% (nine out of 17) of the TBI group exhibited elevated thresholds. There was no correlation between the threshold value and degree of photosensitivity.


CONCLUSIONS
The elevated scotopic thresholds suggest an abnormality in cortical gain control. An anomalous adaptive response may develop due to cortical damage, thereby attenuating subjective light sensation.
Du
T
T
Department of Vision Sciences, State University of New York/State College of Optometry, New York 10036, USA.
Ciuffreda
K J
KJ
Kapoor
N
N
D000328:Adult; D000368:Aged; D001930:Brain Injuries / Q000503:physiopathology*; D003623:Dark Adaptation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation / Q000379:methods*; D012684:Sensory Thresholds / Q000502:physiology*