Microsurgery. It is an outpatient operation in which microscopic instruments are used to remove the vitreous gel and manipulate other tissues. The surgery is done with the patient sedated, lying under a powerful microscope. As you can appreciate from the schematic, operating in that small space requires steady hands. The patient goes home with a patch and drops to help healing. It is usually not painful.
Umm.... Vitreous is the gel the fills the eye. It is removed with a high speed cutting/sucking instrument inserted about 3.5 mm back from the cornea, along with a irrigator and a light source--3 ports in all.