To characterize the horizontal angular direction of lower eyelashes in different age groups of Korean patients.

Digital photographs of 122 patients were obtained and the patients were divided into three groups involving children 6–19 years of age, adults 20–64 years of age, and older adults 65–85 years of age. Lower eyelashes were divided into medial, central, and lateral portions. Each portion was subdivided into three parts and the average value of the three parts was obtained for each portion. Horizontal angular directions tangential to the baseline between the medial and lateral canthus were measured and the data were compared between different portions and groups.

The mean horizontal angular directions of the lower eyelash in the medial portions were 142.4 ± 10.8° in children, 137.1 ± 13.8° in adults, and 120.4 ± 13.0° in older adults. There was a negative correlation with age (r = −0.56, p < 0.01). In central portions, the values were 62.8 ± 18.5°, 71.8 ± 14.5°, and 86.0 ± 10.5°, respectively; and in lateral portions they were 23.3 ± 13.7°, 25.3 ± 9.3°, and 29.5 ± 8.1°. There were positive correlations with aging in the central and lateral portions (r = 0.42, p < 0.01; r = 0.16, p = 0.04, respectively).

The mean horizontal angular direction of eye lashes decreases with age in the medial portion of the lower eyelid but increases in the central and lateral portions in Korean patients. This may be related to factors such as stretching of the eyelid and involutional horizontal eyelid laxity and orbicularis muscle changes.