Optical requirements on magnification systems for intracranial video microsurgery.

INTRODUCTION:The basic idea of video-microsurgery is the improvement of ergonomic conditions in microsurgical procedures by replacing the bulky operating microscope with a compact videosystem. OBJECTIVE:To specify optical requirements on a videosystem for microsurgical intracranial procedures in neurosurgery. METHODS:During 27 microsurgical intracranial procedures (12 cerebellopontine angle and 15 supratentorial) zoom factor, focus distance and illumination parameters of the operating microscope were continuously recorded. Ergonomic aspects were documented as well. RESULTS:The zoom factor ranged from 1.7 to 13.5 in CPA procedures and from 1.4 to 13.4 in supratentorial procedures. The focus distance ranged from 180 mm to 367 mm in CPA procedures and from 188 mm-472 mm in supratentorial procedures. CONCLUSION:From an optical point of view current operating microscopes meet the requirements of intracranial microneurosurgery. However, ergonomically further developments are highly desirable. Video microsurgery is a promising field and could hold a solution to this problem.