Characterization of Normal Mediolateral Angular Direction of Lower Eyelid Eyelashes in Different Age Groups.

Abstract

To characterize the normal eyelash mediolateral angular direction of the lower eyelid in different age groups. Sixty patients were divided into 3 groups: G1 - 6 to 12 years; G2 - 20 to 35; and G3 - 60 to 85. Digital photographs were obtained and eyelids were divided in lateral, central, and medial portions. Eyelash mediolateral angular direction relative to a baseline was measured and data were compared between portions and groups. The mean eyelash mediolateral angular direction in the medial portion were: G1: 133.79° ± 17.56° SD; G2: 137.74° ± 10.5° SD; and G3: 116.05° ± 26.71° SD. The mean difference in angle between G1 and G3 was 17.74° (p = 0.015) and between G2 and G3 was 21.69° (p = 0.000). The mean eyelash mediolateral angular direction in central portion were: G1: 64.36° ± 12.58° SD; G2: 77.07° ± 12.17° SD; and G3: 84.9° ± 18.48° SD. The mean difference between Group 1 and 2 was 12.71° (p = 0.001) and between Group 1 and 3 was 20.54° (p = 0.000). The mean eyelash mediolateral angular direction in the lateral portion were: Group 1: 40.57° ± 6.78° SD; Group 2: 37.21° ± 5.69° SD; and Group 3: 38.48° ± 8.35° SD. This study identified that lashes in the lateral portion of lower eyelid tend to maintain the same angular position throughout life. On the central and medial portions it tends to approach a 90° angle with age. The authors believe that this modification throughout life may be related to factors, such as involutional horizontal eyelid laxity and orbicular muscle modifications.