Today I want to address the factors that affect cosmetic density in hair transplants. Firstly there are the anatomic factors. The single most important factor anatomically is the caliber of the hair. An increase in just .1mm of the diameter of the hair follicle can add up to 30% increased cosmetic density. The other anatomic factors that contribute are skin color to hair color contrast (the more contrast, the more you see through the hair), and curly versus straight hair (curly hair looks thicker than straight hair).
Then there is the follicles per cm squared, which is the amount of follicles transplanted in any given area. Normal non balding scalp can have a density of between 60-100 follicles per cm squared. The minimum density that should be transplanted into any bald area should be at least 30 follicles per cm squared. As we transplant more follicles per cm squared we achieve greater cosmetic density. It requires a much higher degree of skill to transplant a high number of follicles per cm squared.
In summary, there are both anatomic and surgical factors that contribute to cosmetic density. It is imperative that prospective patients looking at pre and post hair transplant photos take the anatomic characteristics into account when considering hair transplant results.
All the best,
Marc Dauer, M.D.