It also replaces that which simply leaks out of the various incisions in the eye. The other is the suction tube. Here one can see clearly the tube penetrating the eye visible though the pupil. After addition of fluid to lubricate the eye, a lens is placed directly on the eyeball to allow better visibiity of the interior. During actual operations on the interior the room lights are dimmed to allow a better view of the interior.
All light comes from the light tube.
In this photo the blood is actually being sucked out although it is difficult to see in this still photo.