The way that most hair transplant surgery is performed currently is to remove a section of scalp with hair that is “protected” from pattern baldness, such as from the back and sides of the head. This flap is then dissected into very small pieces containing one to three hair follicles each. Small slits are cut in the front and top of the head with a scalpel or similar instrument. The harvested pieces of scalp that have from the donor site are then inserted into the newly formed slits. The procedure is repeated until a new hairline is created and the balding scalp is covered with transplanted scalp pieces.
Laser hair transplant uses a cutting laser to make the small slits of the scalp rather than with a scalpel. In general, lasers are only used for this part of the hair transplant process—a different device is used to dissect donor hair from the back of the scalp. Lasers are actually used for a small part of a laser hair transplant, in reality.
Regardless of the extent to which lasers are used, laser hair transplant is different from other, more traditional hair transplant procedures. When laser light energy is used to cut the small slits in front of the scalp, the heat of the cutting laser cauterizes the small blood vessels as it cuts. This minimizes bleeding and bruising in the recipient site. More importantly, it minimizes scar formation at the border between the graft and the recipient area.
Some surgeons argue that this cauterization actually makes it harder for the graft to survive. One of the major determinants of whether transplanted hair follicles will survive is how the graft is supplied with blood. If the skin at the recipient site is immediately and profoundly coagulated and cauterized, the blood cannot reach the graft until new capillaries are formed. New capillaries can take days to form and it is unclear whether this downtime puts the graft in jeopardy.
Initial reports of laser hair transplant are generally favorable. The process is being refined to cause less damage to the recipient site by optimizing the laser in terms of light source type, wavelength of light, pulse duration, and others.
The feared complication both laser hair transplant and more traditional approaches is rejection of the graft by the immune system. This rejection can be thought of in the same way that organ that is transplanted into the body may be rejected by the immune system. In this case, though, the grafts come from another body area on the same person, minimizing the chance of rejection.
Unfortunately there is a theoretical risk that if the laser energy changes proteins in the graft such as collagen than it may appear to immune system as different and induce a reaction.
Some sources have argued that laser hair transplant is somehow less painful than procedures that use a scalpel. This is not accurate. The skin is being broken in both approaches, which is the painful part. The area should be numbed with a local anesthetic prior to and during the procedure, regardless of whether the process incorporates lasers or not. The amount of pain experienced (which should be minimal) is comparable between traditional and laser hair transplant.