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

AIM: To investigate the reliability of a modified threedimensional 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 volunteer s including 97 eyelids with no history of trauma, tumor, or reconstructive surgeries. Six three-dimensional photographs were acquired for each par ticipant, 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.