Light intensity distribution in images from rigid endoscopes used in minimal access sinus surgery.

Objectives/hypothesis: To investigate the pattern of intensity levels in images generated by the two most commonly used rigid endoscopes angulations in sinus surgery: 0° and 30°.

Methods: An enclosed light box containing an optical square grid, under endoscope illumination set just below saturation level, was used for measuring light distribution levels across test images. Endoscopes with 0° and 30° angulations were tested at 10 mm from the grid, typical for sinus surgery.