Digital Photogrammetry for Assessing Medial Canthal Tendon Laxity: Novel Standardized Three-Dimensional Versus Traditional Two-Dimensional Lateral Distraction Test.

PURPOSE:Few studies quantitatively investigated the degree of medial canthal tendon (MCT) laxity using three-dimensional (3D) stereophotography as two-dimensional (2D) imaging systems are still widely used in periocular anthropometry. Hence, in this study, we aimed to compare 2D and 3D technique in assessing MCT laxity and to investigate the correlation between them. METHODS:A cross-sectional study was conducted in randomly recruited healthy volunteers with no history of eyelid disease and surgery. Predictor variables were the linear measurements derived from 2D and 3D images, respectively, and the outcome variable was MCT laxity. Covariates including age and sex were also included in our correlation observations. One-side measurements for each image were randomly selected for our study. Bivariate correlation was applied to evaluate the correlation between 2D and 3D measurements. Linear regression was used to investigate the correlation between the predictor and outcome variables. RESULTS:Ninety-five Caucasian volunteers (50 men and 45 women, 95 eyes) between 22 and 84 years of age (58.5 ± 16.0 years) were included in our study. The 2 sets of measurements for MCT laxity were 3.13 ± 0.75 and 2.62 ± 1.50 mm on 2D images (P = .18) and 2.49 ± 1.58 and 2.58 ± 1.72 mm on 3D images (P = .23). A significant correlation was observed between 3D measurements and MCT laxity (P < .01), while no significant correlation was found between 2D measurements and MCT laxity (P = .64). CONCLUSIONS:Our results revealed that measurements on 3D images could be predictors of MCT laxity and might be applied as a base and a reference for speculating the 3D MCT laxity in further research and clinical evaluation.