I would like to help by offering an answer to your direct question, as well as touch on other issues relating to the male eyebrow transplantation procedure.
To answer your question directly, many factors affect follicular graft survival during any hair transplantation procedure.
Firstly, because hair follicular units (or grafts) extracted from the donor area, will usually be found in randomly assorted 1 - 4 hair follicle grafts, the doctor performing the follicular unit extraction (FUE) of the grafts would have to be skilled in the procedure so as to harvest the grafts with the least possible tissue damage - including partial or complete graft transections, fracturing of the neck or bulb etc. Have a look at some of our latest instagram posts/stories to see good FUE harvesting results.
Secondly, because eyebrow hair transplantation utilises single hair follicle grafts (a graft with only 1 hair growing out of it), in other words, grafts with 2-4 hair follicles will need to be sliced down to single follicular units (FUs). The skill level and experience of the technician in this 'Graft Quality Control' process is also vital to graft survival. At our centre, we use microscopes specific for this purpose called 'Mantis Elite' microscopes. To improve survival rates of all our hair transplantation procedures at Terra, we use a storage solution for grafts called hypothermosol to improve the survivability of the follicular grafts.
Thirdly, making of the sites necessary for implantation should be done by a doctor who understands eyebrow transplantation - the technicality of this bit involves understanding hair growth direction - including exit angle and facing (which can be complicated in the eyebrow region), graft sizing and using a customised blade size for single follicular units, the effect of tumescent fluid on hair growth direction and blood supply and the position of the sites should not be made in a manner that would cause trauma to surrounding, existing eyebrow hairs.
For further improvement in graft survival, skilled technicians will be required for gentle handling of these microscopic grafts during the 'implantation' phase of the procedure, where the grafts are placed in sites pre-made by the doctor.
The entire procedure will need to be done by a team that has experience in hair restoration as the grafts should not stay outside of your body for too long (out of body time) as that will affect transplanted graft survival as well.
In addition to answering your questions, I would like you to consider some salient points before choosing the centre that does your eyebrow transplantation:
1. hair from the donor zone may be very different in texture as compared to the eyebrows, for a natural result (the most important end point of all hair restoration/transplantation procedures), the doctor should be assessing your donor hair and comparing it with eyebrow hair. If the variance in texture is too large, the result could appear exceedingly unnatural.
2. implanted hairs take on the characteristics of the donor hairs i.e. the grow at the rate of donor hair, lose pigmentation at the rate of donor hair etc. It would be likely that a considerable amount of effort be put in to style your brows every few days to keep them neat after the transplantation.
3. before consultation with your preferred centre, do some research a to what shape of eyebrows you desire, and also discuss this with your previous brow artist, or semi-permanent makeup artist. During the day of consultation with your doctor, also discuss these design concerns and be sure that the design is something that you are fairly firm on - implanted hairs are permanent and the only way you could get rid of an unsatisfactory result is probably to electrolyse the implanted grafts.
Thank you for taking the time to read my lengthy reply, I hope it helps.
Dr Joshua Chong