18 months post op and hair feels thin, does it look like I have 45 grafts per cm2? (photos)

Hello, Dr. George Abrahamian MD here, from La FUE Hair Clinic, Pasadena, CA.
There are many factors that can influence the final results of a hair transplant. A few of the most important factors include your hair texture, the density of your follicular units (does one graft have one, two, or three or more hairs), and the density with which the transplant is performed. Natural density of hair per centimeter square is 100-200, which translates to approximately 70-100 grafts/follicular units per cm square. If your hair is naturally thin, and a density of restoration is below 70 grafts per cm square, then there will likely be a mismatch in the density of the transplanted area, when compared to non transplanted areas with no hair loss.
Secondarily, the way the clinic performs the density distribution is also very important. Most clinics will use highest density in zone 1 (the two centimeters behind the hairline), and will taper the density down moving into the subsequent zones of the scalp (this is due to the limitations of the donor, since whatever is being harvested for transplant, will no longer grow in the donor). Natural density is approximately 70 grafts per cm square, so if the transplant is performed at 45 grafts per cm square, and the hair texture is also fine and thin, the final outcome can appear thin, see through, and/or mismatched. In these scenarios, a second transplant is often required to improve the overall look.
I hope this helps, best of luck on your hair restoration journey!