When designing the frontal hairline for hair transplantation patients, esthetic preference as well as the progression of hair loss should be considered1. With regard to female- and male-pattern hair loss, creating the frontal hairline is relatively easier in female patients than in male patients2. The current trend in female hair transplantation highlights that the majority of hairline reconstructions are performed not for correcting female-pattern hair loss but for cosmetic purposes, so great emphasis is placed on designing the hairline according to esthetic preference3,4.

In the hairline transplantation procedure, a frame for the desired forehead shape is created by designing a frontal hairline. Here, the overall forehead shape and hairline height are important aspects5. The round forehead shape is considered the standard forehead shape for Asians6. However, Lehman7 claimed that beauty should be evaluated using a unified standard, regardless of racial and ethnic characteristics, social background, and personal preferences. Furthermore, esthetic preference can be affected by various factors like gender, age, education, economic conditions, and a place of residence8.

The hairline height was defined as the point between the eyebrows to the lowest hairline, and the mid-lower face, the area between the eyebrows and the lowest jaw line, as illustrated in Fig. 1, 2, respectively. We obtained informed consent for using the photos from the female model. Eight photographs were fabricated for the survey. The triangular, round, rectangular, and M-shaped frontal hairline images were generated9 (Fig. 1). We also aimed to determine the preferred hairline height in the round forehead shape. Four photographs with different forehead heights in the round shape were also fabricated (Fig. 2). As opposed to the standard forehead height shown in all photographs in Fig. 1 (upper : mid-low=1 : 2), in Fig. 2, 1 photograph showed low forehead height (upper : mid-low=0.9 : 2), and 2 high forehead height (upper : mid-low=1.1 : 2, 1.2 : 2, respectively).

The survey was emailed to 609 participants (290 men and 319 women) from November 3rd, 2011 to November 9th, 2011 via the online survey site "www.mysenic.com"; of them, 14 participants had undergone hair transplantation. The respondents were asked to choose the hairline they preferred from among the 4 photographs in Fig. 1, 2 each. The results of the statistical analysis of the preferences are shown in Fig. 1, 2. The M-shaped hairline contour was the most preferred contour, followed by the rectangular contour, round contour, and triangular contour, which was the least preferred. Regarding the hairline height in the round forehead shape, the low mid-face to upper face ratio, 2 : 1, was the most preferred height (Fig. 2B). The next most preferred hairline was that in Fig. 2A, followed by those in Fig. 2C, and Fig. 2D with the highest height, which was the least preferred height.

The relationship between hairline contour and sex, age, marital status, education, geographic location, history of hair loss, satisfaction with own hairline, history of hair loss treatment, desire for hair transplantation showed no statistical significance. However, a significant association was found between history of hair transplantation and hairline contour preference, as those that had undergone hair transplantation preferred the triangular or round contour.

Significant differences were found in forehead height preference between both sexes and between those with or without history of hair transplantation. As opposed to women, men preferred the lower forehead heights, and those who had a history of hair transplantation preferred the highest forehead height. There was no statistically significant difference in the relationship between forehead height and other factors mentioned above.

The group that had undergone hair transplantation preferred the triangular and round hairline contours and the highest forehead height. The 2 reasons behind this finding could be as follows: the participants who underwent hair transplantation preferred relatively narrow foreheads, and the information they received about hair transplantation from the hospitals, as part of their marketing strategies, and other factors during hair transplantation led to changes in the preferences of those participants-the latter case holds more weight age over the former case.

Generally, people obtain information about hairlines from the homepages of the hospitals where hair transplantation is performed. The information provided by the hospitals mainly discusses the round hairline and limited options are provided for hairline contours. Usually, the frontal hairline is designed on the forehead of the patient before transplantation, and the patient is asked to confirm the contour; this procedure is done by drawing the outline of the hairline on the patient's forehead using a pen, and it is difficult for the patient to imagine the final appearance with fully grown hair, so the patients tend to accept the recommendations of the doctors.

We suggest that the doctors have access to patient preference and refrain from performing the transplantation procedure for the standard round contour in all patients. For this purpose, the patient's image can be simulated with various hairline contours to determine the one preferred by the patient.

Furthermore, the survey results cannot be considered entirely reliable because the sincerity of the respondents is questionable, as the survey was conducted online. Moreover, pre-determined forehead shape and hairline height were used in the survey. In addition, the small number of participants that had undergone hair transplantation also reduced the reliability of the findings. For obtaining reliable results, future studies with a large sample size need to be conducted.