In one hand the surgeon holds the arthroscope with its camera and light source; in the other he holds the instruments required for the arthroscopic surgery.
The surgeon's view is thus contained by the rounded shape of the arthroscope. This is an arthroscopic photograph of normal joint cartilage within the knee.
What is an arthroscope?
As 'arth' means 'joint', the word 'arthrosopic' indicates that it relates to looking into a joint. The image is relayed to a mounted TV monitor, so the surgeon is looking up at the image while operating with his hands and instruments.