Analysis of facial vascular pattern characteristics in the Korean population

Abstract

Background

Facial erythema is a common problem among patients visiting dermatologists. However, data on the clinical characteristics of facial erythema in healthy people are lacking. We aimed to compare and analyze the severity and pattern of facial vascularity in healthy subjects based on their age and gender.

Materials and Methods

This study included 198 Korean volunteers (126 females and 72 males) with Fitzpatrick skin types II, III, or IV. Fourteen different anatomical areas on the face were divided into facial erythema units. Each unit was scored from one (least erythematous) to five (most erythematous) according to the observed level of erythema on the red images implemented as hemoglobin content. We also evaluated the presence of facial telangiectatic macules.

Results

On average, the perinasal, nasal, and cheek units were the most hypervascular regions. In contrast, the degree of facial erythema was lowest in the labial (perioral), neck, and temporal regions. The average value of erythema was higher in males than in females. Additionally, the severity of erythema tended to increase with age. In both males and females, the number of telangiectatic macules increased with age.

Conclusions

We analyzed the clinical characteristics of erythema in healthy subjects with Fitzpatrick skin types II, III, or IV in the Korean population. This study is expected to be used to identify the neurovascular pathogenesis of the most common regions of facial dermatosis in the future.

1. INTRODUCTION

Facial erythema is a common problem among patients visiting dermatologists. Inflammatory skin diseases like rosacea, contact dermatitis, and seborrheic dermatitis are the main causes of the redness of the face. However, the degree of erythema may increase as one of the symptoms of aging skin. ¹ Cutaneous manifestations of rosacea, a typical skin disease that causes redness of the face, include flushing, persistent erythema on the central face, papules and pustules, phymata, and telangiectasia. ² Not only inflammation, but also hyperreactive neurovasculature, is thought to play a role in the central facial erythema of the pathogenesis of rosacea. ³ The expression and density of cation channels in sensory neurons and keratinocytes in patients with rosacea were higher than in healthy subjects. ⁴ The pathophysiology of facial erythema in patients with rosacea has been studied in many fields, but studies on facial erythema and telangiectasia in healthy people are lacking. The redness of the face is influenced by the distribution of blood vessels and nerves in the face. ⁵ Facial erythema can occur regardless of race, but the degree of erythema may look different depending on skin color. Postinflammatory hyperpigmentation may mask facial erythema. ⁶ Research on facial erythema has mainly focused on patients with skin diseases. Rosacea mainly shows persistent erythema in the centrofacial region, and various medical treatments and light‐based treatments are available to treat it. ⁷ Furthermore, studies were conducted to evaluate the severity of erythema in patients with rosacea. ⁸ However, few studies have examined the distribution of blood vessels in the normal face to investigate the etiology of rosacea.

There are several techniques for measuring skin erythema. Visual assessment is the gold standard for the evaluation of skin erythema. In this method, an experienced investigator measures the intensity of skin erythema by dividing the scale from 3 to 10 points without a tool. ⁵ Even though this method is fast and convenient, it is subjective, and accurate color communication is difficult because the result value may be different for each investigator. The erythema index has been studied in various ways, including the semiquantitative grading scale, the clinician's erythema assessment, and computer‐based algorithms. Although the clinician's erythema assessment is widely used clinically because of its high inter‐rater agreement, errors may still occur because of the judgment of the investigator. Currently, studies that evaluate erythema more objectively using a computer‐based algorithm or artificial intelligence‐based scoring system have been published; however, those are not easily applicable in actual clinical practice. ⁸ , ⁹ Colorimeter and spectrophotometer can then be used to assess facial flushing. It is convenient to use a color scale, and quantification of color change is possible. However, this method also has a limitation in that it is still not objective. ⁵

Skin aging shows various clinical manifestations such as wrinkles, pigmented spots, and telangiectasia. ¹⁰ It involves a decrease in the extracellular matrix and skin support system including cell replacement, immune responsiveness, injury response, barrier function, thermoregulation, and sebum production. ¹¹ In particular, the telangiectasia that was seen in photoaged skin results in less transient or nontransient erythema. ¹²

Several studies on the characteristics of disease‐related erythema have been conducted, but there is a limited standardized data analyzed in healthy people of a wide range of ages. As a result, determining the extent to which measurements in patients with disease deviate from normal values is difficult. Therefore, the objective of this study was to compare and analyze the degree and pattern of facial erythema in healthy subjects based on their age and gender.

2. SUBJECTS

A total of 198 Korean volunteers (126 females and 72 males) with Fitzpatrick skin types II, III, or IV who visited in June and July 2020 were enrolled in this study. This study included subjects aged 20−69 years who were grouped into five age groups (20−29, 30−39, 40−49, 50−59, 60−69 years). Pregnant or lactating females and those who had a history of being diagnosed with dermatological disorders, including facial dermatosis, were excluded from the study.

3. METHODS

3.1. Ethical approval

The ethical and scientific validity of this study were reviewed by DERMAPRO Ltd. The Institutional Review Board approved this study (IRB Certification Number: 1‐220777‐A‐N‐02‐DICN20138). All the protocols were performed in accordance with the principles of the Declaration of Helsinki.

3.2. Facial image acquisition

Photographs of the subjects were taken under standard lighting conditions using the VECTRA XT system (Canfield, USA). Facial three‐dimensional (3D) images were obtained in three modes (standard color, brown, and red), and we analyzed facial vascular patterns using red images. The six cameras in the hardware capture stereo images in 3.5 milliseconds to create a high‐resolution 3D computer model of the subject. The RBX® technology of the VECTRA system implements a skin image with melanin and hemoglobin components, and the image realized through this is composed of red, green, and blue channels. Vascular changes were visualized using RBX® red images. The subjects gently washed their faces with an identical foam cleanser and rested for 10 min under constant temperature and humidity conditions (22 ± 2°C, 50 ± 5% relative humidity) prior to photographing.

3.3. Image analysis

Fourteen different facial erythema units were assigned: frontal, eyebrow, orbital, temporal, zygomatic, nasal, perinasal, labial (perioral), mental, cheek, buccal, mandibular, neck, and auricular units (Figure 1). Each unit was assigned a score from one (least erythematous) to five (most erythematous), according to the observed level of erythema on the red images (Figure 2). The average value of the erythema on the subject was calculated after it was scored independently by two physicians.

FIGURE 1.

Facial erythema units across the face and neck regions.

FIGURE 2.

Severity of erythema index. 1 = least erythematous, 5 = most erythematous.

The presence of telangiectatic macules was analyzed. Telangiectatic macules were defined as lesions that existed in the form of macules on facial images. Red macules related to moderate‐to‐severe acne were excluded.

3.4. Statistical analysis

An independent sample t‐test was used to compare whether there was a difference in the degree of erythema in each unit according to gender within the same age group. Next, the Jonckheere–Terpstra test was performed to evaluate the tendency for the severity of erythema according to age. The one‐way analysis of variance was used to compare erythema severity between different Fitzpatrick skin types. The significance level was set at p < 0.05. All statistical analyses were performed using IBM SPSS Statistics for Windows, version 25.0 (IBM Corp., Armonk, NY, USA).

4. RESULTS

4.1. The severity of facial erythema

The facial erythema unit of each subject was assigned a severity score ranging from one to five. On average, the top three most erythematous units among all age groups were the perinasal, nasal, and cheek units, with average scores of 3.78 ± 0.83, 3.16 ± 0.84, and 2.91 ± 0.75, respectively. The lowest three units were labial (perioral), neck, and temporal, with average scores of 1.36 ± 0.59, 1.38 ± 0.29, and 1.45 ± 0.42, respectively (Table 1). When the severity of erythema was analyzed by age group, perinasal erythema showed the highest severity in all age groups. This pattern was also found when analyzing each male and female group, including all age groups, with average scores of 4.09 ± 0.77 and 3.60 ± 0.82 for males and females, respectively.

TABLE 1.

Severity of erythema scores according to the age groups and erythema units.

Mean (± SD)	Males	Females	20s	30s	40s	50s	60s	Total
Frontal a	2.73 ± 0.78	2.21 ± 0.65	2.09 ± 0.61	2.37 ± 0.68	2.24 ± 0.74	2.68 ± 0.74	2.68 ± 0.79	2.40 ± 0.74
Eyebrow a	1.67 ± 0.60	1.49 ± 0.56	1.43 ± 0.59	1.51 ± 0.60	1.48 ± 0.52	1.77 ± 0.58	1.60 ± 0.57	1.56 ± 0.58
Orbital	2.09 ± 0.74	1.91 ± 0.50	1.61 ± 0.49	2.06 ± 0.63	1.85 ± 0.50	2.20 ± 0.64	2.21 ± 0.52	1.98 ± 0.60
Temporal a	1.63 ± 0.42	1.35 ± 0.39	1.30 ± 0.35	1.39 ± 0.44	1.45 ± 0.38	1.55 ± 0.47	1.57 ± 0.41	1.45 ± 0.42
Zygomatic a	1.38 ± 0.46	1.43 ± 0.38	1.40 ± 0.36	1.50 ± 0.51	1.51 ± 0.44	1.56 ± 0.44	1.65 ± 0.36	1.52 ± 0.43
Nasal	3.68 ± 0.77	2.86 ± 0.73	2.80 ± 0.78	2.98 ± 0.77	3.01 ± 0.89	3.45 ± 0.75	3.62 ± 0.78	3.16 ± 0.84
Perinasal	4.09 ± 0.77	3.60 ± 0.82	3.30 ± 0.80	3.52 ± 0.73	3.67 ± 0.77	4.22 ± 0.71	4.26 ± 0.72	3.78 ± 0.83
Labial (perioral)	1.44 ± 0.70	1.31 ± 0.51	1.07 ± 0.29	1.21 ± 0.49	1.46 ± 0.66	1.52 ± 0.71	1.56 ± 0.59	1.36 ± 0.59
Mental	1.56 ± 0.60	1.72 ± 0.63	1.56 ± 0.59	1.45 ± 0.53	1.55 ± 0.57	1.83 ± 0.68	1.99 ± 0.62	1.66 ± 0.62
Cheek a	3.27 ± 0.66	2.71 ± 0.72	2.57 ± 0.65	2.83 ± 0.76	2.87 ± 0.70	3.13 ± 0.71	3.21 ± 0.80	2.91 ± 0.75
Buccal a	3.08 ± 0.67	2.78 ± 0.73	2.49 ± 0.66	2.78 ± 0.84	3.00 ± 0.68	3.07 ± 0.67	3.13 ± 0.57	2.89 ± 0.72
Mandibular	1.72 ± 0.47	1.62 ± 0.42	1.44 ± 0.36	1.57 ± 0.45	1.72 ± 0.40	1.77 ± 0.46	1.81 ± 0.43	1.66 ± 0.44
Neck a	1.49 ± 0.30	1.32 ± 0.27	1.23 ± 0.34	1.28 ± 0.30	1.41 ± 0.27	1.43 ± 0.21	1.57 ± 0.19	1.38 ± 0.29
Auricular a	2.69 ± 0.90	1.90 ± 0.60	2.20 ± 0.78	2.32 ± 1.07	2.00 ± 0.72	2.23 ± 0.72	2.19 ± 0.73	2.19 ± 0.82

^a An independent sample t‐test revealed significant difference between males and females, p < 0.05.

SD, standard deviation.

Out of 198 subjects, 19 (9.6%) were Fitzpatrick skin type II, 158 (79.8%) were type III, and 21 (10.6%) were type IV. There was no statistically significant difference in mean severity scores between each Fitzpatrick skin type group.

4.2. Analysis of the severity of erythema based on age and gender

A statistical analysis was performed for each age group to determine whether there was a difference in the average value of erythema for each unit by gender. Significant differences were found in the frontal, temporal, mental, and neck regions between males and females in the 20s group. The average values ​​of the frontal, temporal, and neck regions were significantly higher in males, and the mental region was significantly higher in females. In the 30s group, significant differences were found in the zygomatic, nasal, perinasal, cheek, buccal, neck, and auricular regions, and all males had higher erythema than females. In the 40s group, males had significantly higher severity of erythema than females in the frontal, zygomatic, nasal, perinasal, and auricular regions. The 50s group showed significant differences in the frontal, temporal, nasal, perinasal, cheek, neck, and auricular regions between males and females. In the 60s age group, there were significant differences in the frontal, eyebrow, orbital, nasal, cheek, and neck regions according to gender. All of the significant differences observed in the 50−60s group were due to the higher average value of erythema in males than in females. Figure 3 shows the average degree of erythema in males and females at all ages.

FIGURE 3.

The average severity of erythema in males and females.

In this study, we analyzed whether there was a difference in the degree of erythema with age. As a result, in males, the severity of erythema significantly increased with age in all regions except for the zygomatic and auricular regions. Females showed the same tendency, except for the eyebrow and auricular regions (Figure 4).

FIGURE 4.

Facial vascular pattern representing each age and gender.

4.3. Prevalence of telangiectatic macules

The presence of telangiectatic macules on the face of each subject was evaluated. Fifty‐five subjects with red macules as a result of acne were excluded, most of whom were in their 20s and 30s and had centrally distributed lesions (Figure 5A). In both males and females, the proportion and average number of telangiectatic macules increased with age. The number of subjects with telangiectatic macules was higher in females in their 20s but lower in males in other age groups. In particular, telangiectatic macules were observed in all males except one subject in their 50s and 60s (Table 2 and Figure 5B).

FIGURE 5.

An image of erythematous macules related to acne in the 20s (A) and an image of telangiectatic macules in the 60s (B).

TABLE 2.

The number of subjects with telangiectatic macules and the average of the number of macules.

	Male N (%)	Average no. of macules	Female N (%)	Average no. of macules	Total N (%)	Average no. of macules
20s	1 (6.3%)	7.0	2 (8.0%)	4.0	3 (7.3%)	5.0
30s	8 (50.0%)	9.9	10 (40.0%)	5.9	18 (43.9%)	7.7
40s	10 (62.5%)	13.8	14 (56.0%)	7.9	24 (58.5%)	10.3
50s	15 (93.8%)	16.3	17 (68.0%)	10.4	32 (78.0%)	13.2
60s	8 (100.0%)	31.3	23 (88.5%)	10.7	31 (91.2%)	16.5

5. DISCUSSION

In this study, we analyzed 3D facial erythema images to evaluate the degree of erythema according to the age and gender of subjects with Fitzpatrick skin types II, III, or IV. In a previous study evaluating the erythema index according to the anatomical location of healthy subjects, the face was divided into two parts: the forehead and cheek. ¹³ The erythema index was higher in the forehead than in the cheek. When compared with other parts of the human body, such as the abdomen or hand, the forehead and cheek correspond to regions showing a higher vascular index. However, we analyzed one face by dividing it into 14 more subdivided units, which enabled a more detailed analysis than in previous studies. In this study, the most erythematous regions were the perinasal, nasal, and cheek regions. This is consistent with the region's rich blood supply, as revealed in previous studies. In the skin, cutaneous arteries form a vascular pattern characterized by fine dermal anastomoses that are altered by age and disease. The abundant vascular medial portions of the face are the lateral nasal, maxillary, and median nasal processes. ¹⁴

We also observed that, when there was a significant difference in erythema according to gender, the erythema score was higher in males than females in most cases. This might be due to physiological differences between the facial skin of males and females. The facial skin of males is known to have more facial hair and sebaceous content as well as higher facial vascularity than that of females. The larger the hair follicle, the more capillaries there are that supply the vascular network. ⁸ Therefore, the distribution of hair follicles and the pattern of facial vascularity are consistent. As a result of comparing perfusion in the facial skin of males and females using Doppler flowmetry, blood perfusion in the face was higher in males. This was due to the difference in the number of microvessels. ¹⁵ Accordingly, the results of this study, showing that males have more severe erythema than females are consistent with previous studies.

In most facial regions, the degree of erythema increases significantly with age. Li et al. ¹⁶ reported that vascular length increased by 35−156% in the eldest group. In a study by Kelly et al. ¹⁷ , dermal papillary loops were significantly reduced in old skin compared to young skin. There was a tendency for the redness to increase in the forehead and forearm with increasing age; however, there was no significant trend.

Facial telangiectasia macules occur in both rosacea and photoaging skin. Telangiectasia in patients with rosacea has been observed both clinically and histologically. The lumen of the vessels is enlarged in the superficial and middle layers of the dermis. Aging telangiectasia is a typical clinical feature of atrophic photoaging. Clinically, naturally aged skin is smooth, pale, and finely wrinkled. In contrast, photoaged skin is coarsely wrinkled and associated with dyspigmentation and telangiectasia. ¹⁸ Although the mechanism of vessel dilatation has not been fully explained, the dilated, and enlarged vessels seen in telangiectatic photoaging (TP) are a result of highly cleaved collagen fibrils generated by photodamage. ¹²

According to a study by Helfrich et al. ¹² , erythematotelangiectatic subtypes of rosacea and TP are distinct dermatological disorders. Less transient erythema and lateral distribution within the face are the characteristic features of the TP. In our study, when analyzing the presence or absence of telangiectatic macule, cases with a central distribution, such as acne, were excluded. The results showed that the number of subjects with telangiectatic macules significantly increased with age. In a study by Kennedy et al. ¹⁹ , skin aging was related to the development of telangiectasia. Furthermore, lifetime sun exposure also showed a significant correlation with the occurrence of telangiectasia, and the association was stronger among males. In our study, all males except one subject in their 50s and 60s had telangiectatic macules, which can be considered to have the same tendency.

This study had limitations owing to the study design. Bias may occur when a relatively small group is analyzed. Differences may arise because they were evaluated by two independent physicians. In addition, there may be seasonal variations in erythema, and our study was conducted on patients who visited our clinic in June and July, when the weather was relatively hot and humid. For further research, images taken over a long period of time (more than 1 year) are needed. Additionally, there may be limitations in that factors, such as lifestyles, involved in skin aging in healthy subjects have not been identified.

6. CONCLUSIONS

We analyzed the clinical characteristics of erythema in healthy subjects with Fitzpatrick skin types II, III, or IV in the Korean population. Overall, the severity of erythema increased with age, and the rate of telangiectatic macules also increased. Further studies are required to elucidate the association between erythema and aging. It is expected that the reported data will be used as normative data, including anatomical location, age, and gender, which researchers can use to identify the neurovascular pathogenesis of the commonly involved region in facial dermatosis in the future.

AUTHOR CONTRIBUTIONS

T.K., Y.L., Y.H., J.B., M.K., H.A., and M.S. performed the research. T.K., Y.L., and M.S. designed the research study. Y.L., J.B., and M.K. collected the data. T.K., Y.H., H.A., and M.S. analyzed the data and wrote the article.

FUNDING INFORMATION

This research did not receive any specific grants from the public, commercial, or non‐profit sectors.

CONFLICT OF INTEREST STATEMENT

The authors have no conflict of interest to declare.

Kim T‐E, Lee Y, Han Y‐M, et al. Analysis of facial vascular pattern characteristics in the Korean population. Skin Res Technol. 2023;29:e13344. 10.1111/srt.13344

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available on requests from the corresponding author.