- from wikipediaThis measurement scale was first introduced by Dr. James Hamilton in the 1950s and later revised and updated by Dr. O'Tar Norwood in the 1970s.
Class I represents an adolescent or juvenile hairline and is not actually balding. The adolescent hairline generally rests on the upper brow crease.
Class II indicates a progression to the adult or mature hairline that sits a finger’s breath (1.5cm) above the upper brow crease, with some temporal recession. This also does not represent balding.
Class III is the earliest stage of male hair loss. It is characterized by a deepening temporal recession.
Class III Vertex represents early hair loss in the crown (vertex).
Class IV is characterized by further frontal hair loss and enlargement of vertex, but there is still a solid band of hair across top separating front and vertex.
Class V the bald areas in the front and crown continue to enlarge and the bridge of hair separating the two areas begins to break down.
Class VI occurs when the connecting bridge of hair disappears leaving a single large bald area on the front and top of the scalp. The hair on the sides of the scalp remains relatively high.
Class VII patients have extensive hair loss with only a wreath of hair remaining in the back and sides of the scalp.