A modified 3D stereophotogrammetry-based distraction test for assessing lower eyelid tension.

AIM: To investigate the reliability of a modified three-dimensional distraction test (3D-DT) and three-dimensional pinch test (3D-PT) for assessing lower eyelid tension (LET). METHODS: A cross-sectional study was conducted among 97 volunteers including 97 eyelids with no history of trauma, tumor, or reconstructive surgeries. Six three-dimensional photographs were acquired for each participant, including two photographs obtained in a neutral position (NP), two using a modified 3D-DT with a 15.9-grammes stainless steel eyelid hook performed, and two using 3D-PT. RESULTS: The mean absolute differences between NP, 3D-DT, and 3D-PT measurements varied between 0.07 and 7.42, 0.10 and 13.10, and 0.07 and 15.97, respectively; technical error of measurement varied between 0.05 and 7.81, 0.09 and 10.19, and 0.07 and 12.47, respectively; and relative error measurements varied between 0.10% and 11.50%, 0.16% and 30.51%, and 0.11% and 38.75%, respectively. For intra-rater reliability, the intraclass correlation coefficients (ICCs) were more than 0.80 in seven out of eight measurements obtained in the NP and 3D-DT, whereas those obtained in the 3D-PT were as low as less than 0.30 by rater 1; the ICCs of all the measurements obtained in all the positions (NP, 3D-DT, and 3D-PT) were more than 0.80 by rater 2. For inter-rater reliability six out of eight NP and 3D-DT measurements had an ICC greater than 0.80, whereas those of 3D-PT measurements were less than 0.30. For intra-method reliability, the ICCs of all the NP measurements were more than 0.87, whereas those of the six 3D-DT measurements and four 3D-PT measurements were more than 0.80. CONCLUSION: Our study results prove that the modified 3D-DT, which involves the use of an eyelid hook, can be a highly reliable method for evaluating LET. Furthermore, this novel and simple method may be utilized as the basis for further investigation and routine pre- and postoperative clinical evaluation.

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.

A novel standardized distraction test to evaluate lower eyelid tension using three-dimensional stereophotogrammetry.

BACKGROUND: Standardized pre-operative assessment of the lower eyelid tension is essential to determine the optimal surgical technique. However, quantitative analysis using the conventional distraction test is inaccurate and user-dependent. Our purpose was to introduce a novel, standardized three-dimensional distraction test for measuring lower eyelid tension and to determine its standard values in a Caucasian population. METHODS: In 94 participants (50 men and 44 women; age 21-85 years), a 15.9-g weighted eyelid hook was used to pull down the lower eyelid. Two three-dimensional images were acquired with a VECTRA M3 stereophotogrammetry device-one in the neutral position without a hook and the other in the distracted position with the eyelid hook. The images of all participants in both positions were measured twice by a single observer. RESULTS: There was no clinical (>1 mm) or statistically significant difference between the two repeated measurements of all the inter-landmark linear distances in both positions (P≥0.05, respectively). The mean distracted displacement between the neutral and distracted position for margin reflex distance was 5.50±1.53 mm, without any age-specific difference (P=0.08); however, a significant gender-specific difference was observed as men had significantly greater displacement than women (P<0.001). CONCLUSIONS: Our proposed standardized three-dimensional distraction test for assessing lower eyelid tension using an eyelid hook and a simple landmark-based system seems to provide high reliability. This novel and simple method might be helpful for the preoperative planning of eyelid surgeries.

Standardized Three-Dimensional Lateral Distraction Test: Its Reliability to Assess Medial Canthal Tendon Laxity.

BACKGROUND: Assessment of MCT laxity is critical to the surgery options. Our study aimed to analyze the reliability of measuring medial canthal tendon (MCT) laxity by using a novel standardized three-dimensional lateral distraction test (3D-LDT). METHODS: Forty-eight Caucasian volunteers (25 males and 23 females, 96 eyes) between 22 and 84 years of age (55.6 ± 18.6 years old) were included in our study. From a neutral position, the lower eyelid was gently pulled laterally along a horizontal line to define the most distracted position of the lower punctum. Both in the neutral and distracted position, standardized 3D images were acquired for each subject by two observers, and each image were measured twice by two raters. Four landmarks and six corresponding linear measurements were evaluated for intra-rater, inter-rater, and inter-method reliability. RESULTS: Intra-rater, inter-rater and inter-method reliability analyses of 3D-LDT revealed an intraclass correlation of more than 95%, a mean absolute difference of less than 1 mm, and a technical error of measurement of less than 1 mm. Measurements of relative error (2.59-12.04%) and relative technical error (1.83-16.05%) for the inter-landmarks distance from pupil center to the lower punctum were higher than those from limbus nasal center to the lower punctum (6.13-30.39 and 4.34-26.85%, respectively). CONCLUSIONS: This study provided high reliability of the three-dimensional lateral distraction test (3D-LDT) for assessing medial canthal tendon (MCT) laxity, which were never evaluated by digital imaging system. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .