"Through the looking glass": Optical physics, issues, and the evolution of neuroendoscopy

Although the concept of endoscopy has existed for centuries, a practical, working neuroendoscopic system did not emerge until last century, as a result of numerous contributions and refinements in optical technology, illumination sources, and instrumentation. Modern neuroendoscopy would not be a flourishing field, as it is today, without the dedication, innovation, and implementation of emerging technology by key contributors including Maximilian Nitze, Walter Dandy, and Harold Hopkins. Despite several inherent and unique limitations, neuroendoscopic surgery is now performed for a variety of intraventricular, skull base, and spinal operations. In this review, the history of neuroendoscopy, key players who envisioned how the inner workings of the human body could be visualized "through the looking glass," and current state and future potential for neuroendoscopic surgery are discussed. Future directions of neuroendoscopic surgery will likely be guided by further miniaturization in camera and optical technology, innovations in surgical instrumentation design, the introduction of robotics, multi-port minimally invasive surgery, and an enhanced ability to perform bimanual microdissection.