Reliability of Periocular Anthropometry: A Comparison of Direct, 2-Dimensional, and 3-Dimensional Techniques

Determining Asymmetry Thresholds in Anophthalmia/Microphthalmia Using a Three-dimensional Animated Model

PURPOSE

Congenital microphthalmia and anophthalmia are rare development disorders with underdevelopment of the orbital region, resulting in asymmetry of the face. No clear guidelines exist to determine when these deviations are acceptable.

METHODS

The face of a healthy 6-year-old child was three-dimensionally scanned. On this scan, we modeled various incremental degrees of facial asymmetries using three-dimensional modeling software. We modeled for smaller palpebral fissures, sunken eyes, and downward displacement of the eye. We also tested whether adjusting the vertical palpebral fissure height in relation to the horizontal palpebral fissure width affected perception. A total of 22 videos were created in which the model turned the head horizontally and vertically. We created a questionnaire asking raters how acceptable the face is, on a linear scale from 0 to 10.

RESULTS

Results showed a correlation between the degree of asymmetry and the acceptability score of the raters. Enophthalmos of ≥6 mm, palpebral fissure width ≤79% compared with the other eye, and 2 mm or more downward displacement of the eye resulted in a significant different acceptability score. The desire for correction was strongly increased when these thresholds were exceeded. Adjusting the vertical palpebral fissure height to the horizontal palpebral fissure width resulted in a worse acceptability score.

CONCLUSION

A unilateral sunken eye (enophthalmos) of 6 mm or more, asymmetric horizontal palpebral fissure length of ≤79%, and a lower position of one eye of more than 2 mm resulted in unacceptable judgment. These data can be used to evaluate treatment outcome in children treated for congenital microphthalmia and anophthalmia.

Gender- and Age-Related Characterization of Lower Eyelid Morphology: Three-Dimensional Analysis in a Chinese Population

BACKGROUND

The lower eyelid region is a critical component of the face. It is essential to establish anthropometric reference values for the evaluation of aging, surgical planning and assessment of outcomes in periocular esthetic and rejuvenation procedures. This study aims to provide comprehensive anthropometric data on the Chinese lower eyelid region, into account factors such as sex and age, through three-dimensional imaging analysis.

METHOD

Three-dimensional facial images were obtained from 84 healthy Chinese individuals aged between 20-35 and 50-65 years, as well as eight patients aged between 20 and 35 who presented with eyelid bags. A total of 27 landmarks were identified, leading to the generation of corresponding 21 lines, 5 curves, 4 angles, 2 areas and 5 ratios. The measurements were compared among different age groups, genders and young patients with or without eyelid bags.

RESULTS

Compared to females, males exhibited a more elongated palpebral fissure, lower tear trough and lid-cheek junction, smaller inner and outer canthus angles, as well as a larger area and proportion of the lower palpebral region. As age progressed, the height and width of the palpebral fissure and inner canthus angle decreased gradually, which was accompanied by sagging of the tear trough and lid-cheek junction, an increase in lower eyelid area and swelling of the lower eyelid. Young patients undergoing eyelid bags demonstrated larger and more swelling lower eyelid which held clinical significance for rejuvenation surgery.

CONCLUSION

Males exhibited a higher proportion of the brow-eye unit occupied by the lower eyelid region compared to females. Elderly individuals displayed noticeable drooping of the tear trough and lid-cheek junction, accompanied by swelling in the lower palpebral region. These findings can serve as standard references for esthetic procedures and reconstructive periocular operations.

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 Table of Contents or online Instructions to Authors www.springer.com/00266.

Protocol Establishment and Reliability Verification of Three-Dimensional Digital Stereophotogrammetry in Lower Eyelid Anthropometry

BACKGROUND

Three-dimensional (3D) stereophotogrammetry has been widely used in anthropometry for both medical and esthetic purposes. However, no studies have assessed its reliability on measuring the lower eyelid by 3D imaging. This study aimed to establish a standardized 3D anthropometric protocol for lower eyelid region and validate its reliability.

METHODS

Fifty-eight participants (116 eyes) were recruited with mean age of 39.14 ± 11.25 years. Two sets of VECTRA 3D images were taken for each subject, and each set of images was individually measured twice by two raters. Twenty-seven landmarks were identified in the lower eyelid region, and then 19 linear, 4 curvilinear, 7 angular and 2 areal metrics were assessed for intrarater, interrater and intramethod reliability.

RESULTS

High reliability was found in this 3D imaging-based lower eyelid anthropometry. The mean absolute difference within 2 intrarater measurement were 0.22 and 0.08 units, the technical errors measurement were 0.31 and 0.15 units, the relative errors of measurement were 0.90% and 0.31%, the relative technical errors of measurement were 1.53% and 0.64%, and the intra-group correlation coefficient was 0.99 and 0.99. The results for interrater measurement were 0.53 units, 0.59 units, 2.94%, 3.41% and 0.96, and for intramethod measurement were 0.71 units, 0.77 units, 4.12%, 4.05% and 0.95 units, respectively.

CONCLUSION

3D stereophotogrammetry is reliable for lower eyelid anthropometry. The standardized protocol can be further applied for many purposes such as lower eyelid aging evaluation, surgical related assessment and periocular rejuvenation plan.

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 .

Current status of optical scanning in facial prosthetics: A systematic review and meta-analysis

Purpose To assess the accuracy of scanning technologies for constructing facial prostheses on human faces.Study selection Our systematic search was performed on five databases. Studies reporting on human volunteers (P) whose faces were scanned with a scanning technology were eligible. The anthropometrical interlandmark distances (ILDs) were used as indicators of accuracy; the ILDs are measured on the virtual models (I) and directly on the faces (C). The virtual models deviated from their true values (O). Studies reporting the measurements on patients with or without facial deformities were included, but cadavers or inanimate objects were reasons for exclusion. We performed a mean difference (MD) / standardized MD analysis with a random effect model. The difficulties regarding the scanning procedure mentioned in the articles were also assessed.Results We found 3723 records after duplicate removal. Twenty five articles were eligible for the qualitative review, and ten articles were included in the quantitative synthesis. Eight different ILDs were compared in MD analyses. The differences were between -0.54-0.43 mm. We also performed a regional three-dimensional analysis to compare scanning technologies in each major region. No significant differences were found in any of the regions and axes. The most mentioned difficulties were artifacts due to motion or blinking.Conclusions The results suggest no systematic skew in linear dimensions neither between direct caliper measurements nor between measurements on the scanned models, scanning technologies, or facial regions.

Can smartphones be used for routine dental clinical application? A validation study for using smartphone-generated 3D facial images

OBJECTIVES

To compare the accuracy of smartphone-generated three-dimensional (3D) facial images to that of direct anthropometry (DA) and 3dMD with the aim of assessing the validity and reliability of smartphone-generated 3D facial images for routine clinical applications.

MATERIALS AND METHODS

Twenty-five anthropometric soft-tissue facial landmarks were labelled manually on 22 orthognathic surgery patients (11 males and 11 females; mean age 26.2 ± 5.3 years). For each labelled face, two imaging operations were performed using two different surface imaging systems: 3dMDface and Bellus3D FaceApp. Next, 42 inter-landmark facial measurements amongst the identified facial landmarks were measured directly on each labelled face and also digitally on 3D facial images. The measurements obtained from smartphone-generated 3D facial images (SGI) were statistically compared with those from DA and 3dMD.

RESULTS

SGI had slightly higher measurement values than DA and 3dMD, but there was no statistically significant difference between the mean values of inter-landmark measures across the three methods. Clinically acceptable differences (≤3 mm or ≤5°) were observed for 67 % and 74 % of measurements with good agreement between DA and SGI, and 3dMD and SGI, respectively. An overall small systematic bias of ± 0.2 mm was observed between the three methods. Furthermore, the mean absolute difference between DA and SGI methods was highest for linear (1.41 ± 0.33 mm) as well as angular measurements (3.07 ± 0.73°).

CONCLUSIONS

SGI demonstrated fair trueness compared to DA and 3dMD. The central region and flat areas of the face in SGI are more accurate. Despite this, SGI have limited clinical application, and the panfacial accuracy of the SGI would be more desirable from a clinical application standpoint.

CLINICAL SIGNIFICANCE

The usage of SGI in clinical practice for region-specific macro-proportional facial assessment involving central and flat regions of the face or for patient education purposes, which does not require accuracy within 3 mm and 5° can be considered.

Bézier curves as a total approach to measure the upper lid contour: redefining clinical outcomes in palpebral surgery

AIMS

To define and quantify the upper lid contour by adapting Bézier curves with a newly developed software in normal subjects, assessing their reliability.

METHODS

Fifty eyes of 50 healthy patients with no ocular pathology were included in this study from October 2020 to November 2020. All measurements were performed on Bézier curves adjusted to the upper lid contour. An original software was used to measure the radial and vertical midpupil-to-lid margin distances (MPLD), temporal-to-nasal (T/N) ratios, contour peak location and grade of superposition (GS) and asymmetry (GA) indexes. We calculated differences in the variables measured regarding age, gender or the side of the eye being assessed.

RESULTS

The mean Bézier curve showed an excellent level of inter-rater reliability (intraclass correlation coefficient of 0.99). The median GS index of each eyelid to the mean Bézier curve was 95.4%, 8.5 IQR, and the median GA index was 3%, 3.4 IQR. The mean contour peak location was -0.35 mm, SD 0.45. Overall, the mean central MPLD was 4.1 mm, SD 0.6. No significant differences were found between male and female patients in variables derived from Bézier curves.

CONCLUSION

Bézier curves may become a very useful tool for the assessment of upper lid contour, contour peak and symmetry. GS and GA indexes, along with the T/N area ratio are potential outcomes for this purpose. All current variables can be obtained just from one single Bézier curve measurement. Our results offer an in-depth exhaustive description of these variables and their distribution in the normal population.

Age-related changes of the periocular morphology: a two- and three-dimensional anthropometry study in Caucasians

PURPOSE

To determine age-and sex-related changes in periocular morphology in Caucasians using a standardized protocol.

METHODS

Healthy Caucasian volunteers aged 18-35 and 60-90 years old were recruited from the Department of Ophthalmology, Faculty of Medicine and University Hospital, Cologne, between October 2018 and May 2020. Volunteers with facial asymmetry, facial deformities, history of facial trauma, facial surgery, botox injection, eyelid ptosis, strabismus, or nystagmus, were excluded. Standardized three-dimensional facial photos of 68 young volunteers and 73 old volunteers were taken in this clinical practice. Position changes of endocanthion, pupil center, and exocanthion were analyzed in different age and gender groups, including palpebral fissure width (PFW): distance between endocanthions (En-En), pupil centers (Pu-Pu), exocanthions (Ex-Ex), endocanthion and nasion (En-Na), pupil center and nasion (Pu-Na), exocanthion and nasion (Ex-Na), endocanthion and pupil center (Pu-En), exocanthion and pupil center (Pu-Ex), and palpebral fissure inclination (PFI); angle of endocanthions to nasion (En-Na-En), pupils to nasion (Pu-Na-Pu), exocanthions to nasion (Ex-Na-Ex); endocanthion inclination (EnI), and exocanthion inclination (ExI).

RESULTS

PFW, En-En, Ex-Na, Pu-Ex, PFI, ExI, and Ex-Na-Ex were significantly different between the young and old groups (p ≤ 0.004). There were sex-related differences in PFW, Ex-Ex, En-Na, Pu-Na, Ex-Na, Pu-En, PFI, and EnI between both groups (p ≤ 0.041).

CONCLUSION

The position change of the pupil is minimal relative to age; it is preferred to establish the reference plane to describe periocular changes. The endocanthion tends to move temporally and inferiorly, while the exocanthion tends to shift nasally and inferiorly with age.

The role of the lateral tarsal strip procedure in modern ophthalmic plastic surgery-A review

Introduction

The lateral tarsal strip is one of the basic surgical techniques in ophthalmic plastic surgery. It is used in many indications, predominantly in ectropion repair. Even though there are alternatives, it is probably one of the most popular techniques in ophthalmic plastic surgery. The lateral tarsal strip is also part of bigger surgical procedures (such as midface lifting, entropion surgery, reconstruction surgery, or a part of some surgical approaches to the orbit). The aim of this review is to assess the most common ways of usage of the lateral tarsal strip, to cover its alternatives, and to discuss the future of this technique.

Methods

We have search PubMed and Web of Science and went through articles about lateral tarsal strip. We have also searched for other techniques that used the lateral tarsal strip and included these articles in our review. We have analyzed the major articles and made a review about the topic.

Results

As a natural part of many advanced surgical techniques and as a major surgical technique for lower eyelid ectropion repair, the lateral tarsal strip remains an important part of modern ophthalmic plastic surgery.

Validation of the Portable Next-Generation VECTRA H2 3D Imaging System for Periocular Anthropometry

Purpose

Portable three-dimensional imaging systems are becoming increasingly common for facial measurement analysis. However, the reliability of portable devices may be affected by the necessity to take three pictures at three time points. The purpose of this study was to evaluate the effectiveness of portable devices for assessing the periocular region.

Methods

In 60 Caucasian volunteers (120 eyes), four facial scans (twice for each instrument) using the portable VECTRA H2 and static VECTRA M3 devices were performed; patients' heads were kept straight, looking ahead, with a neutral facial expression. One assessor set 52 periocular landmarks in the periocular area of each image and subsequently assessed intra- and inter-device reliability by comparing two within-device measurements and one between-device measurement, respectively.

Results

The mean absolute difference (MAD) (0.13 and 0.12 units), relative error of measurement (REM) (0.61 and 0.68%), technical error of measurement (TEM)(1.02 and 0.80 units), relative TEM (rTEM) (5.51 and 4.43%), and intraclass correlation coefficient (ICC) (0.89, 0.89) showed good intra-device reliability for M3 and H2; MAD (0.63, 0.62 units), REM (2.83, 2.69%), TEM (1.31, 1.10 units), rTEM (7.62, 5.57%), and ICC (0.79, 0.83) indicated that inter-device reliability deteriorated compared to intra-device reliability and that the inter-device reliability of the first scan (moderate) was lower than that of the average of the two scans (good).

Conclusions

The portable VECTRA H2 device proved reliable in assessing most periocular linear distances, curve distances, and angles; some improvement in inter-device reliability can be achieved by using the average of two scans.

Investigating the Reliability of Novel Nasal Anthropometry Using Advanced Three-Dimensional Digital Stereophotogrammetry

Three-dimensional surface imaging systems (3DSI) provide an effective and applicable approach for the quantification of facial morphology. Several researchers have implemented 3D techniques for nasal anthropometry; however, they only included limited classic nasal facial landmarks and parameters. In our clinical routines, we have identified a considerable number of novel facial landmarks and nasal anthropometric parameters, which could be of great benefit to personalized rhinoplasty. Our aim is to verify their reliability, thus laying the foundation for the comprehensive application of 3DSI in personalized rhinoplasty. We determined 46 facial landmarks and 57 anthropometric parameters. A total of 110 volunteers were recruited, and the intra-assessor, inter-assessor, and intra-method reliability of nasal anthropometry were assessed through 3DSI. Our results displayed the high intra-assessor reliability of MAD (0.012-0.29, 0.003-0.758 mm), REM (0.008-1.958%), TEM (0-0.06), rTEM (0.001-0.155%), and ICC (0.77-0.995); inter-assessor reliability of 0.216-1.476, 0.003-2.013 mm; 0.01-7.552%, 0-0.161, and 0.001-1.481%, 0.732-0.985, respectively; and intra-method reliability of 0.006-0.598°, 0-0.379 mm; 0 0.984%, 0-0.047, and 0-0.078%, 0.996-0.998, respectively. This study provides conclusive evidence for the high reliability of novel facial landmarks and anthropometric parameters for comprehensive nasal measurements using the 3DSI system. Considering this, the proposed landmarks and parameters could be widely used for digital planning and evaluation in personalized rhinoplasty, otorhinolaryngology, and oral and maxillofacial surgery.

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.

Reliability of Stereophotogrammetry for Area Measurement in the Periocular Region

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.

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.

A novel approach quantifying the periorbital morphology: A comparison of direct, 2-dimensional, and 3-dimensional technologies

BACKGROUND

The measurement of anatomical structures is critical in plastic and reconstructive surgery. However, few detailed and standardized measurements have been widely used in the periorbital region. This study aimed to evaluate the feasibility of a novel detailed and standardized protocol with 2D and 3D technologies, and explore the relationship between them and direct measurements.

METHODS

Fifty healthy Caucasians (100 eyes) between 20 and 68 years old were recruited and captured for 3D photographs by VECTRA M3 3D Imaging System. Subsequently, 24 landmarks were located on each 3D photographs following a standardized protocol, and then 19 linear and 3 angular periorbital variables were measured. Furthermore, two-dimensional (2D) and direct measurements were conducted on each subject and compared with 3D measurements and one another.

RESULTS

The grand r means across all measurements were 0.77, 0.78, and 0.88 for direct vs. 2D values, direct vs. 3D values, and 3D vs. 2D values, respectively. The mean absolute differences were 1 mm (ranging from 0.2 mm to 3.7 mm) between direct and 3D measurements, 1 mm (ranging from 0.04 mm to 2.4 mm) between direct and 2D measurements, and 1 mm and 6.6° (ranging from 0.04 mm or 0.5° to 3 mm or 12.8°) between 2D and 3D measurements.

CONCLUSIONS

This study verified the feasibility of this detailed and standardized landmark localization protocol for assessing the periorbital morphology with 2D and 3D technologies. This protocol may work as a bridge communicating with all studies involving any of the three technologies in the future.