Reliability of periocular anthropometry using three-dimensional digital stereophotogrammetry

Periocular Asymmetry Index in Caucasian Populations Using Three-dimensional Photogrammetry Assessment

OBJECTIVE

To quantitatively assess the periocular asymmetry and investigate its sex and age-related differences in a Caucasian population using three-dimensional (3D) stereophotogrammetry.

METHOD

Standardized 3D photos of the periocular region of 301 Caucasians were taken using the VECTRA M3 3D Imaging System. Standardized landmarks were positioned, and data measurements in the periocular region were obtained from these images using VAM software and assessed using intraclass correlation coefficients (ICC) for reliability. Absolute differences and asymmetry index between the right and the left periocular region were calculated with a focus on gender and age-related differences.

RESULT

Fissure height asymmetry was positively correlated with age (p < 0.01). Furthermore, reflex distance asymmetry was positively correlated with age in the elderly group (p < 0.05). Absolute differences of upper eyelid crease were 0.65 ± 0.79 mm for females and 0.90 ± 0.94 mm for males (p < 0.05). In the elderly group, the absolute differences of reflex distance were 0.664 ± 0.471 mm for males and 0.470 ± 0.408 mm for females (p < 0.05), while the absolute differences of fissure height were 0.619 ± 0.469 mm and 0.436 ± 0.372 mm, respectively (p < 0.05). All measurements had an inter-rater ICC and intra-rater ICC between 0.761 and 0.957.

CONCLUSION

Periocular asymmetry is more prominent in older and male people. 3D photogrammetry is a reliable tool to detect periocular asymmetry and might provide an accurate and effective reference for periocular cosmetic, plastic, and reconstructive surgery in the clinical routine.

LEVEL OF EVIDENCE I

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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

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Quantifying Dermatochalasis Using 3-Dimensional Photogrammetry

BACKGROUND

Creating an appropriate treatment plan for patients with dermatochalasis requires careful investigation of the periocular region. Utilizing photographic documentation can assist physicians in conducting preoperative analysis and managing expectations regarding surgical outcomes.

OBJECTIVES

This study aimed to quantify the periocular characteristics of dermatochalasis patients using standardized 3D imaging and to compare age and sex-related changes in periocular features.

METHODS

In this cross-sectional study, we recruited 145 Caucasian patients with periocular dermatochalasis, comprising 48 men and 97 women, aged between 35 and 91 years. Standardized three-dimensional facial photographs were taken using the 3D Imaging system VECTRA M3. Linear dimensions, curve length, angle, indices, and sizes were measured and analyzed, including palpebral fissure height (PFH), palpebral fissure width (PFW), upper lid fold-palpebral margin distance (FPD), upper palpebral margin length (UPML), lower palpebral margin length (LPML), canthal tilt (CT), palpebral fissure index (PFI), upper eyelid area, and ocular surface area.

RESULTS

In the female group, the left-side PFH was slightly larger than the right-side PFH (P = 0.023), but the difference was less than 1mm. The corresponding PFI also showed a difference in the female group (P = 0.009). Statistically significant differences were shown in genders for specific parameters, except PFI (P = 0.251) and CT (P = 0.098). Among males, PFW (R = -0.523, p < 0.001) and LPML (R = -0.514, P = 0.264) decreased moderately with age. The correlation between UPML and age was weak (R = -0.367, P = 0.010). Similarly, among females, moderate correlations were found between age and PFW (R = -0.566, P < 0.001) and LPML (R = -0.537, P < 0.001). Additionally, PFH (R = -0.315, P = 0.002), UPML (R = -0.381, P < 0.001), and ocular surface area (R = -0.457, P < 0.001) showed weak correlations with age.

CONCLUSIONS

The study found that dermatochalasis usually affects both eyes simultaneously, and age is a significant factor in the morphological changes of certain periocular features regardless of sex. The PFI is not influenced by age or sex. These findings may provide useful information for surgical planning and understanding age-related changes in the periocular area.

LEVEL OF EVIDENCE V

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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 .

Response to Letters Regarding "A Quantitative Three-Dimensional Tear Trough Deformity Assessment and Its Application in Orbital Septum Fat Transposition"

Level of Evidence V 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 .

Quantitative Assessment of Periocular Autologous Fat Transfer Survival Using 3D Stereophotogrammetric Imaging

PURPOSE

To assess periocular autologous fat transfer (AFT) survival by assessment of volume change with sequential 3D VECTRA imaging.

OBJECTIVE

Little is known about the patterns of graft survival of AFT in the periorbital region, especially in cases involving prior radiotherapy or trauma. The aim of this pilot study was to characterize fat survival following AFT in patients with a broad range of clinical indications, with and without a history of prior radiotherapy, for both periocular and orbital AFT, and in a subgroup of patients with an anophthalmic socket.

METHOD

A single-institution, prospective cohort study involving 18 applications of AFT for volume augmentation in the periocular and orbital area. All patients had sequential 3D VECTRA photographs following a validated standardized protocol. Patient demographics, including gender, age, ethnicity, underlying diagnosis, and volume of fat injected, were also collected.

RESULTS

In total 13 patients were enrolled, 9 female (69.2%) and 4 male (31.0%). Mean age at the time of surgery was 47.8 years. Patients had volume deficiency secondary to a variety of causes; the most common cause was postenucleation socket syndrome following trauma in 6 patients (46.2%). The mean fat survival volume at the 1-month postoperative point was 70% and 55% by 6 months. AFT conducted with a multiport cannula for fat harvesting use had an initial higher rate of fat reabsorption with ANOVA p = 0.002, however, this was not observed at the later follow-up periods. There was no statistically significant difference in fat survival between abdominal or thigh donor fat sites. There was no statistically significant difference in residual injected volume at the early follow-up period between patients who had prior radiotherapy and those who did not p = 0.8496.

CONCLUSION

AFT is an effective treatment for periorbital volume compromise with an acceptable survival rate in all categories of patients. Complex etiologies such as radiotherapy-related orbital and midface dysgenesis should not be a contraindication for AFT, with no difference in outcomes.

Development and Validation of a Comprehensive Perioral Evaluation Method Using Three-Dimensional Stereophotogrammetry

BACKGROUND

The non-invasive three-dimensional (3D) stereophotogrammetry is widely used in anthropometry for medical purpose. Yet, few studies have assessed its reliability on measuring the perioral region.

OBJECTIVES

This study aimed to provide a standardized 3D anthropometric protocol for the perioral region.

METHODS

38 female and 12 male Asians were recruited (mean age 31.6 ± 9.6 years). Two sets of 3D images using the VECTRA 3D imaging system were acquired for each subject, and two measurement sessions for each image were performed independently by two raters. 25 landmarks were identified, and 28 linear, 2 curvilinear, 9 angular and 4 areal measurements were evaluated for intrarater, interrater, and intramethod reliability.

RESULTS

Our results showed high reliability of 3D imaging-based perioral anthropometry by mean absolute difference (0.57 and 0.57 unit), technical error measurement (0.51 and 0.55 unit), relative error of measurement (2.18% and 2.44%), relative technical error of measurement (2.02% and 2.34%), and intraclass correlation coefficient (0.98 and 0.98) for intrarater 1 and intrarater 2 reliability; respectively 0.78 unit, 0.74 unit, 3.26%, 3.06% and 0.97 for interrater reliability; and respectively 1.01 unit, 0.97 unit, 4.74%, 4.57% and 0.95 for intramethod reliability.

CONCLUSIONS

This standardized protocol utilizing 3D surface imaging technologies are feasible and highly reliable in perioral assessment. It could be further applied for diagnostic purpose, surgical planning and therapeutic effect evaluation in clinical practice in relation to perioral morphologies.

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 Quantitative Three-Dimensional Tear Trough Deformity Assessment and Its Application in Orbital Septum Fat Transposition

BACKGROUND

Existing evaluation tools of tear trough deformity are based on subjective impression of clinicians. More accurate quantitative assessment methods are needed. This study aimed to propose a quantitative three-dimensional assessment method for the tear trough deformity in comparison with the Barton's grading system and apply it to the efficacy evaluation of orbital septum fat transposition.

METHODS

117 healthy Chinese adults (234 eyes) were enrolled and divided into four groups according to the Barton's grading system. Three-dimensional facial images were captured using Vectra H1 handheld camera. 6 anthropometric landmarks were identified on each eye and 8 linear measurements were generated accordingly. Intra-observer reliability was determined and measurements were compared between groups. Pre- and post-operative three-dimensional measurements were compared in 19 patients who received lower blepharoplasty with orbital septum fat transposition.

RESULTS

The severity of tear trough was positively correlated with age (P < 0.001) but not BMI (P = 0.145) or gender (P = 0.280). Intra-rater reliability of the 8 linear measurements was excellent except for the vertical distance between the palpebrale inferioris margin and the tear trough below the pupillary center. Intergroup comparison showed that the horizontal distance between the lateral end of tear trough (P < 0.001) and medial canthus and the sagittal vector from tear trough point toward eyelid bag point (P = 0.009) increased with grade, while the vertical distance from mid-pupil to palpebrale inferioris margin decreased gradually (P = 0.001). Orbital septum fat transposition significantly improved the tear trough deformity as assessed by these three-dimensional measurements.

CONCLUSIONS

We demonstrated a novel quantitative evaluation method of the tear trough deformity using three-dimensional stereophotogrammetry and proved it to be valid and reliable. It showed good value of clinical application and might help with periorbital rejuvenation planning and outcome assessment.

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 .

Evaluation of the Portable Next-Generation VECTRA H2 3D Imaging System for Measuring Upper Eyelid Area and Volume

BACKGROUND

Although a portable 3-dimensional (3D) imaging system has been used for periocular measurement analysis, this system has yet to be tested and validated for periocular area and volume measurements.

OBJECTIVES

The aim of this study was to define the upper eyelid and upper eyelid fold region through a modified landmark strategy and validate a portable 3D imaging system for area and volume measurements in this periocular region.

METHODS

Eighty-one healthy adult Caucasians underwent 3D facial imaging with the VECTRA M3 (static) and VECTRA H2 (portable) 3D imaging systems (Canfield Scientific, Inc., Parsippany, NJ). Subsequently, the upper eyelid and upper eyelid fold regions were selected according to a modified landmark localization strategy. Direct measurements of area and volume were performed to assess intrarater, interrater, intramethod, and intermethod reliability, and to compare the agreement between the 2 devices.

RESULTS

The VECTRA M3 and H2 showed high reliability on upper eyelid area measurements. Excellent intra-, inter-, and intramethod reliability agreements were observed in intraclass correlation coefficient; very good agreement in intrarater reliability was observed in the relative error of measurement (REM) and relative technical error of measurement (rTEM); and good inter- and intramethod reliability were observed in the REM and rTEM. For area measurement of the upper eyelid fold, the intrarater, interrater, and intramethod reliability of the M3 was lower than that of the H2. Both systems had poor intrarater, interrater, and intramethod reliability for volume measurements in the upper eyelid and upper eyelid fold region.

CONCLUSIONS

This new portable 3D imaging system achieved excellent or very good reliability values for standardized direct measurements of the upper eyelid and upper eyelid fold region, although volume measurements seem less reliable.

Optimization of a Novel Automated, Low Cost, Three-Dimensional Photogrammetry System (PHACE)

Introduction

Clinical tools are neither standardized nor ubiquitous to monitor volumetric or morphological changes in the periorbital region and ocular adnexa due to pathology such as oculofacial trauma, thyroid eye disease, and the natural aging process. We have developed a low-cost, three dimensionally printed PHotogrammetry for Automated CarE (PHACE) system to evaluate three-dimensional (3D) measurements of periocular and adnexal tissue.

Methods

The PHACE system uses two Google Pixel 3 smartphones attached to automatic rotating platforms to image a subject's face through a cutout board patterned with registration marks. Photographs of faces were taken from many perspectives by the cameras placed on the rotating platform. Faces were imaged with and without 3D printed hemispheric phantom lesions (black domes) affixed on the forehead above the brow. Images were rendered into 3D models in Metashape (Agisoft, St. Petersburg, Russia) and then processed and analyzed in CloudCompare (CC) and Autodesk's Meshmixer. The 3D printed hemispheres affixed to the face were then quantified within Meshmixer and compared to their known volumes. Finally, we compared digital exophthalmometry measurements with results from a standard Hertel exophthalmometer in a subject with and without an orbital prosthesis.

Results

Quantification of 3D printed phantom volumes using optimized stereophotogrammetry demonstrated a 2.5% error for a 244μL phantom, and 7.6% error for a 27.5μL phantom. Digital exophthalmometry measurements differed by 0.72mm from a standard exophthalmometer.

Conclusion

We demonstrated an optimized workflow using our custom apparatus to analyze and quantify oculofacial volumetric and dimensions changes with a resolution of 244μL. This apparatus is a low-cost tool that can be used in clinical settings to objectively monitor volumetric and morphological changes in periorbital anatomy.

Comparison of a custom Photogrammetry for Anatomical CarE (PHACE) system with other Low- Cost Facial Scanning Devices

Purpose

To compare a custom Photogrammetry for Anatomical CarE (PHACE) system with other cost-effective 3-dimensional (3D) facial scanning systems to objectively characterize morphology and volume of periorbital and adnexal anatomy.

Methods

The imaging systems evaluated include the low-cost custom PHACE system and commercial software product for the iPhone called Scandy Pro (iScandy) application (Scandy, USA), and the mid-priced Einscan Pro 2X (Shining3D Technologies, China) device and Array of Reconstructed Cameras 7 (ARC7) facial scanner (Bellus3D, USA). Imaging was performed on a manikin facemask and humans with various Fitzpatrick scores. Scanner attributes were assessed using mesh density, reproducibility, surface deviation, and emulation of 3D printed phantom lesions affixed above the superciliary arch (brow line).

Results

The Einscan served as a reference for lower cost imaging systems because it qualitatively and quantitatively renders facial morphology with the highest mesh density, reproducibility (0.13 ± 0.10 mm), and volume recapitulation (approximately 2% of 33.5 μL). Compared to the Einscan, the PHACE system (0.35 ± 0.03 mm, 0.33 ± 0.16 mm) demonstrated non-inferior mean accuracy and reproducibility root mean square (RMS) compared to the iScandy (0.42 ± 0.13 mm, 0.58 ± 0.09 mm), and significantly more expensive ARC7 (0.42 ± 0.03 mm, 0.26 ± 0.09 mm). Similarly, the PHACE system showed non-inferior volumetric modeling when rendering a 124 μL phantom lesion compared to the iScandy and more costly ARC7 (mean percent difference from the Einscan: 4.68 ± 3.73%, 9.09 ± 0.94%, and 21.99 ± 17.91% respectively).

Conclusions

The affordable PHACE system accurately measures periorbital soft tissue as well as other established mid-cost facial scanning systems. Additionally, the portability, affordability, and adaptability of PHACE can facilitate widespread adoption of 3D facial anthropometric technology as an objective measurement tool in ophthalmology.

Reproducibility of Three-Dimensional Volumetric Measurement of Periocular Tumor Models

INTRODUCTION

In this study, we measured the volume of customized tumor models in the periocular area using three-dimensional (3D) stereophotogrammetry and evaluated the reproducibility of these measurements.

METHODS

Five tumor models of different colors and sizes were placed in different periocular positions, and 3D facial images were obtained from 68 healthy adult volunteers. Subsequently, the volumes of the tumor models were measured, and the intra- and interrater reproducibility was assessed.

RESULTS

The gray 6 mm model revealed the highest reliable measurements in both Caucasians (intra- and interrater intraclass correlation coefficients of 0.981 and 0.899, mean absolute difference of 1.446 and 3.327 mm³, relative error measurement of 3.497% and 8.120%, technical error of measurement of 1.450 and 3.105 mm³, and relative technical error of measurement of 3.506% and 7.580%) and Asians (0.968 and 0.844, 1.974 and 4.067 mm³, 4.772% and 9.526%, 2.100 and 4.302 mm³, and 5.076% and 10.076%, respectively). The highest reliability of measurements in the lateral upper eyelid (0.88 and 0.95, 4.042 and 3.626 mm³, 9.730% and 9.020%, 5.714 and 3.358 mm³, and 9.730% and 8.350%, respectively) and medial upper eyelid (0.81 and 0.89, 4.313 and 4.226 mm³, 9.730% and 9.020%, 6.098 and 4.069 mm³, and 9.730% and 8.350%, respectively) with eyes closed was evident in Caucasians, while the same trend (0.841 and 0.815, 2.828 and 3.757 mm³, 9.860% and 9.840%, 4.052 and 4.308 mm³, and 9.860% and 9.740%, respectively) was observed in Asians in the medial canthus with eyes closed.

CONCLUSIONS

This study confirms, for the first time, the high reliability of periocular tumor volume measurements using 3D stereophotogrammetry, suggesting its feasibility for eyelid tumor measurement. Further trials are required to investigate its clinical use for documentation and follow-up of different eyelid tumors.

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.

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.

Validating three-dimensional imaging for volumetric assessment of periorbital soft tissue

Purpose: To evaluate the accuracy and interobserver variability of three-dimensional (3D) stereophotogrammetric imaging for volumetric assessment in the periorbital region and to propose a protocol for measurement. Methods: A cross-sectional study was performed. Fifty-eight normal adult subjects had photographs taken using the VECTRA M3 imaging system on two separate occasions at a single center teaching hospital. The primary study outcome measurement was mean volume change in the periorbital region, using different methods of image analysis with the following variables: registration method, eyes open or closed, eyelids measured separately or together, extension of area measured to include mid-face. Accuracy was defined as the agreement between paired images with no measured change in volume (0 mL). The agreement between two independent observers was assessed using Bland-Altman plots. Results: There was a statistically significant difference (P < .0001) between the different methods of measurement, with registration of images having the most effect (partial eta squared 0.229). A mean change in volume of 0.11 ± 0.13 mL was reported for the most accurate method. Agreement between observers was confirmed (highest Intraclass Correlation Coefficient 0.63). Conclusions: Assessment of volumetric change in the periorbital region using 3D image reconstruction is accurate with good interobserver repeatability and is suitable for clinical use. A protocol for data acquisition using the VECTRA M3 is proposed. 3D image reconstruction holds promise to enable diagnosis, treatment monitoring, and surgical outcome evaluation in ocular adnexal disease.

Three-dimensional periorbital asymmetry assessment of congenital microphthalmia children with a structured light 3D scanning system

Congenital microphthalmia is a rare phenotype characterized by eye growth retardation. Due to the lack of eyeball stimulation, children suffering from congenital microphthalmia always have bony orbital maldevelopment, which leads to facial asymmetry. In the present study, a structured light 3D scanning system was used as a novel method to measure the three-dimensional periorbital asymmetry in children with congenital microphthalmia. Children with unilateral congenital microphthalmia of 0-6 years old were enrolled in the present study. All participants underwent an ultrasound scan to measure the axial length, and accepted the structured light 3D scanning system for their periorbital appearance. The degree of periorbital asymmetry was evaluated using 17 facial landmarks within a three-dimensional cartesian coordinate system (the X-axis represented the horizontal direction, the Y-axis represented the vertical direction, and the Z-axis represented the sagittal direction). Paired student t-test and ANOVA were used in the present study. A three-dimensional periorbital topography was also established to further illustrate the periorbital asymmetry. A total of 67 children were recruited, which included 31 boys and 34 girls. The axial length on the affected side (12.28 ± 3.35 mm) was generally smaller than that on the unaffected side (20.54 ± 1.65 mm, P < 0.001). When grouped by age, the periorbital asymmetry mainly manifested in the Y-axis and Z-axis directions. The unaffected side had a higher orbitale superior (5.09 ± 0.35 vs. 3.02 ± 0.30, P < 0.001) and a lower orbitale inferior (-19.52 ± 0.51 vs. -16.90 ± 0.53, P < 0.001) in 0-1 year old group. Same performances were also found in the 1-3 and 3-6 age groups. When grouped according to the proportion of axial length on the bilateral sides, seven of the 12 Y-values and all 12 Z-values had statistical differences. The structured Light 3D scanning system may serve as a beneficial complementary tool for computed tomography, in order to better understand the periorbital deformities caused by congenital microphthalmia.

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

BACKGROUND

Three-dimensional (3D) imaging has become increasingly popular in aesthetic surgery. However, few studies have emphasized its application in the periocular region.

OBJECTIVE

To provide evidence supporting the reliability of generalizing periocular measurements obtained using caliper-derived direct anthropometry and 2-dimensional (2D) photogrammetry to 3D stereophotogrammetry.

MATERIALS AND METHODS

Periocular surfaces were captured using a stereophotogrammetry system for 46 normal Caucasian individuals. Twenty-two periocular variables were directly, 2-dimensionally, and 3-dimensionally measured. Reliability of these measurements was evaluated and compared with each other.

RESULTS

The results revealed that, for direct (intra-rater reliability only), 2D, and 3D anthropometry, overall intra-rater and inter-rater intraclass correlation coefficient estimates were 0.88, 0.99 and 0.97, and 0.98 and 0.92, respectively; mean absolute differences were 0.84 mm, 0.26 and 0.36 units, and 0.35 and 0.67 units, respectively; technical error of measurement (TEM) estimates were 0.85 mm, 0.25 and 0.36 units, and 0.32 and 0.65 units, respectively; relative error measurement estimates were 6.46%, 1.69% and 2.74%, and 1.67% and 5.11%, respectively; and relative TEM estimates were 6.25%, 1.62% and 2.78%, and 2.12% and 5.12%, respectively.

CONCLUSION

Stereophotogrammetry and the authors' landmark location protocol yield very good reliability for a series of 2D and 3D measurements.

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.