A system for treating meibomian gland dysfunction. The base has a housing having first and second compartments separated by a partition with an aperture. Furthermore a process is described which is applied for the manufacture of a cup of this type. Furthermore the arthroscope has a ball shaped slider close to its distal end. The differential valve piston comprises working surfaces of at least two different diameters such that changes in chamber pressures effect different axial forces upon the piston.