Optimum shadow-casting illumination for endoscopic task performance.
OBJECTIVE
Task performance improves with the use of a balanced degree of shadow and illumination compared with no or maximum shadow contrast; and overhead shadow-casting illumination is better than side illumination.


METHODS
The standard task entailed touching target points on an undulating surface by using a surgical hook. Each run consisted of 13 target points in a random sequence. Five settings were investigated: no shadow; 22%, 42%, and 65% shadow contrast created by overhead illumination; and 22% shadow contrast produced by side illumination. Each surgeon completed 3 runs with each setting in a random order.


METHODS
Research laboratory at the Surgical Skills Unit, Ninewells Hospital, Dundee, Scotland.


METHODS
Ten surgical trainees.


METHODS
Number of errors and execution time.


RESULTS
Shadow contrast settings had fewer errors than shadowless imaging (P<.001). Work with overhead 22% shadow contrast had a lower error rate than side illumination (P<.001). With overhead illumination, 22% and 42% shadow contrast were accompanied by a lower error rate than maximum shadow contrast of 65% (P<.001 and P =.005, respectively). No significant difference was found in the execution time.


CONCLUSIONS
Optimum endoscopic task performance is obtained with overhead shadow-casting illumination and a balanced degree of illumination and shadow contrast.
Department of Surgery and Molecular Oncology, Ninewells Hospital and Medical School, Dundee, Scotland.
Rajineesh K
RK
Mishra
George B
GB
Hanna
Stuart I
SI
Brown
Alfred
A
Cuschieri
D000704:Analysis of Variance; D004724:Endoscopy; D004867:Equipment Design; D006804:Ergonomics; D013502:General Surgery / Q000193:education*; D006801:Humans; D008029:Lighting; D011597:Psychomotor Performance; D018709:Statistics, Nonparametric; D013647:Task Performance and Analysis