Upper eyelid morphology and age‐related changes in Japanese and Chinese females

Abstract

Background

Many consumers use cosmetic eye products to counteract age‐related changes in appearance. Measurements of eyelid shape in Asian women have been reported in the frontal view or 45‐degree profile only. The aim of this study was to describe morphological characteristics of the upper eyelid in Japanese and Chinese females from the frontal and profile aspects and examine morphological changes with age.

Materials and methods

Standardized digital photographs of 772 Japanese and 346 Chinese women (15‐79 years of age) were acquired in frontal and 90‐degree profile aspects. Eleven upper eyelid parameters (e.g., width, length, depth, aperture, and curvature) were measured using image analysis to determine age‐related changes and compare by ethnicity.

Results

Eyelid width, area between eyebrow and eyelid, and eyelid curvature were comparable for both ethnicities under age 40, but the aging effect was more pronounced in Chinese subjects. Eyelid height, depth, and upper eyelid aperture angle were also comparable for both ethnicities under age 40, but the aging effect was more evident in Japanese subjects. Upper eyelid incline angle, eye orientation, and upper eyelid protrusion angle changed comparably with age for both ethnicities. No prominent age‐related changes were evident for eyelid length or area between eyebrow and eye with the eye closed.

Conclusion

Upper eyelid morphology changes with age in Japanese and Chinese females, starting around 40 years of age. Ethnic differences are limited in younger age groups but become more prominent with age. The findings suggest that aging affects some upper eyelid features earlier than others.

1. INTRODUCTION

Eyelid shape is commonly perceived to change with age (e.g., sagging and furrowing around the eyes), and many women use cosmetic eye products to counteract age‐related changes in appearance. With the onset of the COVID‐19 pandemic and the need to wear masks, many consumers have focused attention on their eyes, and sales of eye makeup products continue to be strong, representing up to 1.8 billion euros for China and Japan in 2022 (unpublished internal data).

Japanese and Chinese women are reported to be concerned about eyelid shape and associated age‐related changes. For Japanese women, concern over eyelid sagging tends to start in their late 40s and becomes the main concern about their eyes from the age of 55 (unpublished internal consumer research). To help address this, cosmetic companies offer eye products for anti‐aging effects to lift and tighten the eye contours (unpublished internal data), and eye makeup products in general have been shown to help create a youthful impression by increasing feature contrast and perceived size of the eyes. ¹ , ² , ³

Previous research has described age‐related changes in eye morphology, such as some eyelid dimensions, in women of different ethnicity, including Japanese and Chinese women. However, measurements of eyelid shape in Asian women have been reported only in the frontal view or 45‐degree profile view ⁴ , ⁵ , ⁶ , ⁷ , ⁸ , ⁹ and not in the full 90‐degree profile view. Moreover, in the frontal view, the age‐related changes were reported only between older and younger women, ⁶ , ⁹ with no numerical data provided for narrower age groups.

Against this background, this study measured 11 upper eyelid parameters, including length, height, and curvature, in the frontal and full 90‐degree profile views in order to determine the 3D morphology of the upper eyelid in Japanese and Chinese females. Historically, because many Japanese originated from China, we then compared the findings of the Japanese and Chinese females to determine whether or not eyelid morphology and age‐related changes were similar between them.

2. MATERIALS AND METHODS

2.1. Subjects

This studied analyzed data obtained in a series of typology studies conducted by L'Oréal Research and Innovation in China in 2006 and 2011 and in Japan in 2009. The subjects were 772 Japanese women (mean age, 44.13 years, SD 16.67; range, 15–74 years) living in the Greater Tokyo Area, with parents of Japanese origin, and 346 Chinese women (mean age, 41.23 years (SD 14.36); range, 18–79 years) living in Shanghai, with parents of Chinese origin. The number of subjects in each age group (from their 10s to 70s) is shown in Table 1. All were healthy, had no medical conditions affecting the face, were free from any past surgical facial procedures, and provided informed consent to participate after receiving an explanation of the purpose of the study.

TABLE 1.

Age distribution of the subjects in this study.

Japanese women (n = 772)
Age (years)	15‐19	20‐29	30‐39	40‐49	50‐59	60‐69	70‐74
	65	130	129	130	130	146	42

Chinese women (n = 346)
Age (years)	18‐19	20‐29	30‐39	40‐49	50‐59	60‐69	70‐79
	10	78	85	84	53	17	19

2.2. Image acquisition

Full face photos were taken in a dedicated dark room with the Bench HeadScan shooting table (Orion Concept 0074TM, Tours, France), using a NIKON D300 digital camera with NIKON objective lens (28‐105 mm lens, aperture f/22, speed 1/60 s, ISO 200, resolution 300 dpi). The volunteers wore a gray cape to eliminate reflection from their clothes and a white cap and were seated in a chair with their head position fixed in order to standardize the distance and angle to the camera. They were asked to adopt a neutral expression. Although lighting conditions and distance between the face and the camera differed between the Japan and China studies, length and area were calculated for each subject using iris size as the reference. ¹⁰

2.3. Measurement of upper eyelid parameters

A total of 11 parameters were measured (Table 2). Ten were measured on individual subjects’ photographs using Adobe Photoshop CS6 (Figure 1). Assuming an average iris size of 12 mm (11.7‐12.4 mm), values in pixels were converted into metric units. ⁷ , ¹⁰

TABLE 2.

Upper eyelid parameter measurements analyzed in this study.

Parameter no.	Photographic view	Parameter measured	Definition
1	Front	Eyelid width (mm)	Distance between the two horizontal axes defined by the endocanthion and exocanthion
2	Front	Eyelid height (mm)	Distance between the upper eyelid margin to the lower part of the eyebrow
3	90° profile	Eyelid length (mm)	Distance from the upper eyelid margin to the eye crease (mm); when no eye crease was observed, distance between the eyelid margin to the eyebrow
4	90° profile	Eyelid depth (mm)	Distance between the eyelid margin to the vertical line defined by the exocanthion
5	Front	Area between eyebrow and eye—eye open (cm2)	Area between the eyelid arc and the eyebrow, eyes open
6	Front	Area between eyebrow and eye—eye closed (cm2)	Area between the eyelid arc and the eyebrow, eyes closed
7	Front	Eye orientation (degrees)	Inclination of the horizontal axis of the eye between the endocanthion and exocanthion
8	90° profile	Upper eyelid aperture angle (degrees)	Angle between the horizontal axis and the upper eyelid, with the exocanthion as the apex
9	90° profile	Upper eyelid incline angle (degrees)	Angle between the horizontal axis and the eyelid, with the eyelid margin as the apex
10	90° profile	Upper eyelid protrusion angle (degrees)	Angle between the vertical axis and the line defined by the lower eyelid margin and upper eyelid margin
11	Front, 90° profile	Curvature (r)	Curvature of the eyelid from the top view

FIGURE 1.

Ten of the eleven upper eyelid parameters measured in Japanese and Chinese females according to the numbered parameters described in Table 1.

In addition, the remaining parameter, the curvature (r) of the upper eyelid, was calculated as follows.

$$r=\frac{{\left(\mathrm{eye}\mathrm{width}/2\right)}^2+{\left(\mathrm{eyelid}\mathrm{depth}\right)}^2}{2\mathrm{eyelid}\mathrm{depth}}$$

The area between the eyebrow and eyelid in the eye closed condition (parameter 6) was measured in a smaller number of Chinese participants due to a study limitation (n = 228 instead of n = 346 for all other parameters, Table 1).

2.4. Statistical treatment

The effect of age on upper eyelid parameters according to ethnicity was analyzed using ANOVA with Tukey's multiple comparison test, with statistical significance set at p < 0.05. SPSS ver 23 (IBM, Armonk, New York, USA) was used for the analyses.

Comparisons of upper eyelid morphology by ethnicity in each age group were examined by Student's t‐test, using R‐based internal software. Statistical significance was set at p < 0.05.

3. RESULTS

The mean values of all upper eyelid parameters for each age group and ethnicity are shown in the Appendix. Representative frontal and 90‐degree profile views of the upper eyelid in younger and older Japanese women are shown in Figure 2.

FIGURE 2.

Representative frontal and 90‐degree profile views of younger (< 30 years) and older (> 70 years) Japanese women.

3.1. Length and area (parameters 1–6)

Eyelid width (parameter 1) was comparable between the Japanese and Chinese subjects until their 50s and there was no significant age effect until this age. Eyelid width was significantly reduced in both cohorts from their 60s onward (Figure 3A). This decrease in width was greater for Chinese subjects.

FIGURE 3.

Age‐related changes in upper eyelid morphology in Japanese and Chinese females for width (A), height (B), length (C), and depth (D) parameters (1 to 4). Asterisks indicate significant differences between the two ethnicities (p < 0.05). Bars indicate 95% confidence intervals.

Eyelid height (2) was comparable between Japanese or Chinese subjects until their 40s. Eyelid height increased significantly in Japanese subjects after their 40s, but no age effect was observed for Chinese subjects (Figure 3B).

Eyelid length to eye crease (3) was greater in Chinese subjects. For Japanese subjects, eyelid length did not show any significant change in length with age until their 60s and was significantly shorter in their 70s. No age effect was observed in Chinese subjects (Figure 3C).

Eyelid depth (4) was smaller in Japanese subjects than in Chinese subjects after their 30s. Eyelid depth reduced in Japanese subjects from their 40s to 70s, but no age effect was observed in Chinese subjects (Figure 3D).

Area between the eyebrow and eyelid in the eye open condition (5) increased steadily in Japanese women from their 20s to 70s, with a significant increase observed in their 60s. Chinese women showed comparable changes until their 50s but showed a greater increase in area in their 60s and 70s compared with Japanese women (Figure 4A).

FIGURE 4.

Age‐related changes in upper eyelid morphology in Japanese and Chinese females for area‐related parameters (5 and 6). Asterisks indicate significant differences between the two ethnicities (p < 0.05). Bars indicate 95% confidence intervals.

Area between the eyebrow and eyelid in the eyes closed condition (6) was comparable between Japanese and Chinese subjects until their 40s. The area did not change significantly in Japanese subjects after their 20s, and no change was observed in Chinese subjects until their 50s (Figure 4B).

3.2. Angle (parameters 7–10)

Eye orientation angle (7) and age‐related changes showed no significant differences between the Japanese and Chinese subjects. Eye orientation angle continued to decrease after their 30s for both ethnicities, with a significant change evident for Japanese subjects in their 50s and for Chinese subjects in their 60s (Figure 5A).

FIGURE 5.

Age‐related changes in upper eyelid morphology in Japanese and Chinese females for angle‐related parameters (7 to 10). Asterisks indicate significant differences between the two ethnicities (p < 0.05). Bars indicate 95% confidence intervals.

Upper eyelid aperture angle (8) was larger in Japanese subjects than in Chinese subjects from their 20s to 70s and increased steadily from their 10s to 70s, with significant increases observed from their 30s onward. For Chinese subjects, although the same tendency was observed, significant increases were first observed in their 70s compared with in their 30s (Figure 5B).

Upper eyelid incline angle (9) was larger in Chinese subjects at all ages compared with Japanese subjects and gradually decreased from their 20s to 70s, with a significant difference seen between their 20s and 70s for both ethnicities (Figure 5C).

Upper eyelid protrusion angle (10) increased for both Chinese and Japanese subjects starting in their 40s. There was a significant increase observed in Chinese subjects between their 30s and 40s and in Japanese subjects between their 40s and 70s. At all ages, Chinese subjects had a larger angle than Japanese subjects and these differences increased with age (Figure 5D).

3.3. Curvature (r)

For Japanese subjects, curvature was significantly smaller in their 10s compared with in middle‐age onward, in their 40s to 70s. However, no significant difference in curvature was evident between their 20s and 70s. For Chinese subjects, curvature was significantly smaller in their 10s compared with their 20s, 30s, and 40s and was significantly decreased between their 60s and 70s (Figure 6).

FIGURE 6.

Age‐related changes in upper eyelid morphology in Japanese and Chinese females for curvature parameter (11). Asterisks indicate significant differences between the two ethnicities (p < 0.05). Bars indicate 95% confidence intervals.

4. DISCUSSION

In this study, we measured 11 upper eyelid parameters across a broad and continuous age range, from both frontal and 90‐degree profile views, and analyzed the aging process and when aging became evident. This study was conducted to provide additional understanding of upper eyelid morphology, in terms of three‐dimensional descriptions and the aging process, in Japanese and Chinese women. Overall, we found that the upper eyelid morphology of both cohorts changed with age and started to become noticeable at 40 years of age, but with some ethnic differences. Age‐related changes in upper eyelid shape were evident in both cohorts in both the frontal and 90‐degree profile views. Morphology was comparable between the young Japanese and Chinese subjects, but the appearance of the aging effect was slightly earlier for some parameters according to ethnicity.

Eyelid width decreased after 50 years of age for both ethnicities but especially for Chinese women. This probably relates to sagging above the outer corner of the eyes. Eyelid length was measured as the horizontal distance between the external and outer corner of the eyes in this study, which provides a value close to measurements of eye length in previous studies. ⁵ , ⁷ The orientation of the eyes, marked by a tilt of 9 degrees on average for 10‐ and 20‐year‐old Japanese and Chinese women, becomes more horizontal with age. These changes with age were previously reported for both eye length and orientation, although Chinese women had a larger tilt angle of eye length than Japanese women. ⁷ This could be linked to the age distribution of the subjects in the two studies: our youngest age group for Chinese women, where a large tilt angle is expected, is under‐represented.

Measurements of eyelid height, length, and depth changed with age in our Japanese subjects starting in their 30s to 40s, whereas no such changes were observed in our Chinese subjects. This finding for our Chinese subjects is not in agreement with those of Chong et al. who reported increasing eyelid height in a Chinese Han population, ⁴ as we found in our Japanese subjects.

Observed in full profile, the eyelid started to protrude above the eye after the 40s and covered the external corner of the eye in both Japanese and Chinese subjects, but was more prominent in the Chinese cohort. Conversely, eyelid depth decresed more with age in Japanese women than in Chinese women. For both ethnicities, the upper eyelid incline angle decreased with age, probably due to hollowing of the eyes. Therefore, we expect that with age, the eyelid morphology of Japanese and Chinese women will be different. Japanese women are more prone to stretched, thin eyelids and to hollowing of the eyes, which is related to a decrease in muscle tissue in the upper eyelid region, ⁹ orbital fat resorption, ¹¹ and change in the globe position with age. ¹² On the other hand, the eyelids of Chinese women will present with more drooping, which is related to an increase in skin thickness and a decrease in elasticity with age. ¹³

4.1. Limitations

Our subjects ranged in age from their 10s to their 70s, but due to recruitment difficulties, the youngest groups (age 15–19 years in Japan and 18–19 years in China) and the oldest groups (over 70 in Japan and over 60 in China) were underrepresented. For our Chinese subjects especially, measurement data for those aged 18–19 years and over 60 years should be considered with care as there were fewer than 20 participants in these age groups. In addition, this study analyzed data collected in Tokyo and Shanghai, which may not be representative of the general female population in each country.

Eyelid shape might be affected by the menstrual cycle. However, as our study analyzed measurements from at least 78 subjects in each age group between 20 and 49 years for both ethnicities, we consider that any hormonal effects were averaged out among the women. In addition, a decrease in upper eyelid thickness from morning to afternoon with a decrease in puffiness has also been reported, ¹⁴ but as our subjects in different age groups were randomly scheduled to be photographed throughout the day from morning to evening, we consider that the effect of morning puffiness was cancelled out. While eyelid puffiness may also be affected by the menstrual cycle, the effect was likely cancelled out by the number of subjects in our study.

The measurement method that we used may have resulted in some inaccuracy. The face is three dimensional, so measuring upper eyelid morphology on two‐dimensional images will lead to some approximation, and taking manual measurements has the potential for experimenter bias effects. As the upper eyelid is composed of soft tissue, its shape changes with eye movement. The subjects in our study were asked to fix their gaze at a given spot in front of them, but flash from the camera and muscle tension due to holding this position may have affected the natural shape of the eye. Despite those approximations, we clearly observed age and ethnicity effects.

This study focused on identifying changes in upper eyelid morphology with age using numerical data. Given that the type of eyelid crease also affects the appearance of the eye and application of eye makeup, we are considering complementing our numerical data with an expert assessment of eyelid crease type ⁶ in future research.

Lastly, as life habits change, the signs of aging described in this study could also change. For example, consumers are increasingly aware of the damaging effect of UV light on the skin and the need for sun protection. As photoaging is a large part of the aging process, ¹⁴ , ¹⁵ it is possible that young to middle‐aged people will present with delayed signs of UV‐related aging.

5. CONCLUSION

Upper eyelid morphology changes with age in Japanese and Chinese women, starting around 40 years of age. Ethnic differences are limited in younger age groups but become more prominent with age. Our findings suggest that aging affects some upper eyelid features earlier than others. We believe that our findings can help the development of eye makeup and skin care adapted to each consumer's need.

CONFLICT OF INTEREST STATEMENT

Authors are employees of L'Oreal Research & Innovation.

ETHICS STATEMENT

Ethics committee approval was not required for research. All subjects were fully informed about the objectives of the study and provided written informed consent. The study was conducted following the principles of the Declaration of Helsinki and in accordance with the company's privacy policy pertaining to research volunteers.

1. APPENDICES

A1, A2

TABLE A1.

Upper eyelid parameter measurements in Japanese women.

			Age group (years)
Parameter no.	Photographic view	Parameter measured	15‐19 (n = 65)	20‐29 (n = 130)	30‐39 (n = 129)	40‐49 (n = 130)	50‐59 (n = 130)	60‐69 (n = 146)	70‐74 (n = 42)
1	Front	Eyelid width (mm)	26.2 ± 1.3	26.6 ± 1.4	26.7 ± 1.4	26.8 ± 1.4	26.6 ± 1.6	26.2 ± 1.6	26.0 ± 1.4
2	Front	Eyelid height (mm)	12. ± 2.3	12.9 ± 2.6	13.9 ± 3.3	14.0 ± 3.3	14.5 ± 3.0	15.5 ± 4.0	16.8 ± 3.7
3	90° profile	Eyelid length (mm)	6.7 ± 1.9	6.9 ± 2.6	7.0 ± 2.2	7.0 ± 2.5	7.3 ± 2.6	7.6 ± 2.9	8.4 ± 2.5
4	90° profile	Eyelid depth (mm)	12.1 ± 1.4	11.6 ± 1.6	11.5 ± 1.4	11.1 ± 1.6	10.5 ± 1.6	10.2 ± 1.7	9.4 ± 1.6
5	Front	Area between eyebrow and eye—eyes open (cm2)	3.7 ± 0.6	4.1 ± 0.7	4.3 ± 0.9	4.3 ± 0.9	4.4 ± 0.8	4.5 ± 1.02	4.7 ± 1.0
6	Front	Area between eyebrow and eye—eye closed (cm2)	5.9 ± 0.7	6.6 ± 0.8	6.7 ± 1.0	6.8 ± 1.0	6.7 ± 1.1	6.6 ± 1.2	6.7 ± 1.1
7	Front	Eye orientation (degrees)	9.1 ± 2.1	9.3 ± 2.6	8.6 ± 2.6	8.4 ± 2.9	7.4 ± 2.5	7.9 ± 2.8	7.8 ± 2.1
8	90° profile	Upper eyelid aperture angle (degrees)	32.3 ± 6.1	34.4 ± 4.4	35.7 ± 5.2	38.0 ± 4.7	40.6 ± 5.7	40.7 ± 6.0	43.1 ± 7.0
9	90° profile	Upper eyelid incline angle (degrees)	75.6 ± 13.9	68.9 ± 16.7	63.4 ± 14.2	59.7 ± 14.3	53.8 ± 16.5	49.7 ± 13.8	44.7 ± 11.5
10	90° profile	Upper eyelid protrusion angle (degrees)	11.0 ± 4.8	10.3 ± 4.4	11.9 ± 5.6	11.5 ± 5.8	12.7 ± 6.0	14.4 ± 6.6	14.5 ± 7.2
11	Front, 90° profile	Curvature	13.3 ± 0.7	13.6 ± 0.8	13.6 ± 0.8	13.8 ± 0.9	13.9 ± 0.9	13.7 ± 1.1	13.9 ± 0.9

Data are presented as the mean ± standard deviation.

TABLE A2.

Upper eyelid parameter measurements in Chinese women.

			Age group (years)
Parameter no.	Photographic view	Parameter measured	18‐19 (n = 10)	20‐29 (n = 78)	30‐39 (n = 85)	40‐49 (n = 84)	50‐59 (n = 53)	60‐69 (n = 17)	70‐79 (n = 19)
1	Front	Eyelid width (mm)	26.4 ± 2.3	27.4 ± 2.2	27.5 ± 2.0	27.4 ± 1.9	26.8 ± 1.9	23.7 ± 1.5	22.7 ± 2.0
2	Front	Eyelid height (mm)	11.8 ± 2.6	12.7 ± 3.17	12.8 ± 2.8	13.1 ± 2.7	11.8 ± 2.3	12.0 ± 2.5	13.3 ± 3.3
3	90° profile	Eyelid length (mm)	8.4 ± 1.8	7.5 ± 2.0	7.9 ± 2.1	7.7 ± 2.1	7.9 ± 1.7	7.6 ± 1.8	8.4 ± 2.0
4	90° profile	Eyelid depth (mm)	12.3 ± 2.0	12.2 ± 2.2	12.6 ± 2.0	12.6 ± 2.0	11.9 ± 2.1	11.8 ± 3.3	11.6 ± 2.9
5	Front	Area between eyebrow and eye—eyes open (cm2)	3.6 ± 1.1	4.1 ± 1.1	4.1 ± 1.0	4.3 ± 1.0	3.8 ± 0.8	3.1 ± 0.8	3.4 ± 0.7
6	Front	Area between eyebrow and eye—eye closed (cm2)	7.3 ± 0.6	7.3 ± 1.3	7.6 ± 1.1	7.7 ± 1.1	6.9 ± 1.1	NA	NA
7	Front	Eye orientation (degrees)	9.3 ± 2.3	9.4 ± 2.4	8.9 ± 2.7	9.2 ± 2.5	8.1 ± 2.6	6.9 ± 3.0	7.4 ± 3.6
8	90° profile	Upper eyelid aperture angle (degrees)	30.4 ± 4.2	30.8 ± 5.5	31.8 ± 5.8	31.7 ± 5.7	34.2 ± 5.0	34.1 ± 6.7	36.1 ± 7.5
9	90° profile	Upper eyelid incline angle (degrees)	90.1 ± 15.6	78.3 ± 12.4	75.7 ± 14.6	70.1 ± 11.6	64.6 ± 10.2	64.1 ± 10.3	58.8 ± 9.9
10	90° profile	Upper eyelid protrusion angle (degrees)	15.5 ± 6.0	16.3 ± 6.8	16.9 ± 6.1	18.6 ± 6.3	22.3 ± 5.7	27.3 ± 6.0	25.7 ± 5.0
11	Front 90° profile	Curvature	13.5 ± 1.2	14.1 ± 1.3	14.0 ± 1.2	14.0 ± 1.1	13.8 ± 1.6	12.4 ± 0.9	11.7 ± 1.1

Data are presented as the mean ± standard deviation. NA, not applicable.

Udodaira K, Yokoyama E, Zhu T, Wang Y, Zhao L. Upper eyelid morphology and age‐related changes in Japanese and Chinese females. Skin Res Technol. 2024;30:e13604. 10.1111/srt.13604

DATA AVAILABILITY STATEMENT

Research data are not shared.