Reliability of Stereophotogrammetry for Area Measurement in the Periocular Region

Abstract

Three-dimensional (3D) stereophotography area measurements are essential for describing morphology in the periocular region. However, its reliability has not yet been sufficiently validated. The objective of this study was to evaluate the reliability of 3D stereophotogrammetric area measurements in the periocular region. Forty healthy volunteers had five flat paper objects placed at each of the seven periocular positions including the endocanthion and the upper medial, upper middle, upper lateral, lower medial, lower middle, and the lower lateral eyelid. Two series of photographic images were captured twice by the same investigator. Each image of the first series was measured twice by the same rater, while images of both series were measured once by a second rater. Differences between these measurements were calculated, and the intrarater, interrater, and intramethod reliability was evaluated for intraclass correlation coefficients (ICCs), mean absolute differences (MADs), technical errors of measurements (TEMs), relative errors of measurements (REMs), and relative TEM (rTEM). Our results showed that 21.2% of all ICCs were considered as excellent, 45.5% were good, 27.3% were moderate, and 6.1% were poor. The interrater ICC for the endocanthion location was 0.4% on a low level. MAD values for all objects were less than 0.3 mm², all TEM were less than 1 mm², the REM and rTEM were less than 2% for all objects, showing high reliability. 3D stereophotogrammetry is a highly reliable system for periocular area measurements and may be used in the clinical routine for planning oculoplastic surgeries and for evaluating changes in periocular morphology.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.

Keywords: Area measurements; Periocular region; Reliability; Three-dimensional stereophotography.

Fig. 1

Images of objects 1-4 in the middle of the lower eyelid. Object 1, with an estimated area of approximately 16 mm² (above, left). Object 2, with an estimated area of approximately 64 mm² (above, right). Object 3, with an estimated area of approximately 144 mm² (below, left). Object 4, with an estimated area of approximately 256 mm² (below, right).

Fig. 2

Image of object 5 in seven periocular positions—the endocanthion, and the upper medial, the upper middle, the upper lateral, the lower medial, the lower middle, and the lower lateral.

Fig. 3

VECTRA M3 system used for Stereophotogrammetry analyses.

Fig. 4

The bar graphs show the intrarater, interrater, and intramethod reliability for the intraclass correlation coefficient (ICC), the mean absolute difference (MAD), the technical error of measurement (TEM), the relative error measurement (REM), and the relative TEM (rTEM) for objects 1-4.

Fig. 5

The bar graphs show the intrarater, interrater, and intramethod reliability for the intraclass correlation coefficient (ICC), the mean absolute difference (MAD), the technical error of measurement (TEM), the relative error measurement (REM), and the relative TEM (rTEM) for object 5 in seven different positions.

Fig. 6

Image of object 1 that shows relatively fuzzy boundaries.