Displacement technique and meibomian gland expression

Despite the absence of rosettes and malformed meibomian orifices, meibomian gland dysfunction cannot be easily detected with biomicroscopy unless the gland is expressed. The clarity of the expression at the orifice is sometimes difficult to ascertain. A dark field effect can be produced in conjunction with biomicroscopy to determine the amount of material present in the tear film. A more accurate determination of clarity can be made by expressing the distal contents of the meibomian gland into the tear film with the displacement phenomenon or technique. Dynamic assessment of the expressed contents allows easier differentiation of normal vs. abnormal expression.