Dynamic 3D Face Asymmetry App
Facial symmetry means that both sides of the face, right and left, are alike on median sagittal plane. The term “Facial asymmetry” refers to imbalance of an individual’s facial features on either side of their face. Facial asymmetry is quantified by means of 3D-photography based measurements. Methods available for clinicians to identify and assess facial asymmetry of three-dimensional (3D) ones, are stereo photogrammetry, laser scanning and contact digitalization but are expensive and time consuming methods and not easily available.
App take advantage of iPhone’s trueDepth front camera and take surface scans of subjects’ faces continuously. TrueDepth camera provides depth data in real time allowing stereo photogrammetry imaging. A wireframe texture of grid lines appears over users face matching the size, shape, topology of the user's face in real time.
The word “symmetry” derives from Greek and comes from “syn” (together) and “metron” (meter). Symmetry means that both sides of the face, right and left, are alike. The term “asymmetry” refers to dissimilarity between components, altering the balance between structures. When applied to facial morphology, symmetry refers to the correspondence in the size, shape, and arrangement of facial features on opposite sides of the median sagittal plane. Soft tissues, bones, and teeth contribute to symmetry. Asymmetry denotes disturbances between these components . Most people have some slight facial asymmetry, and this is the normal biological situation in humans; i.e., the two sides are not perfect mirror images. When photographs of the face are compared with photographs consisting of two left or two right sides of the face, we observe three different faces. This is called natural subclinical asymmetry and is a normal situation and is less than 1mm difference in each side.
Historically, we have relied on time-consuming and limited direct patient measurement (direct anthropometry) to quantitate facial features.Past methods of measurement of facial asymmetry have included various 2-D photographs. These records have proven useful but they are limited because of their 2-D representation of a 3-D structure.Today, with the advent of three dimensional photogrammetry imaging systems, we can perform an infinite number of quantitative facial measurements on static archived images (indirect anthropometry). Whereas traditional techniques have allowed only for the measurements of distances orangles, we are now able to compare surface features of the face in a three-dimensional manner with high degrees of accuracy and resolution. Innovative three-dimensional imaging technology is rapidly becoming part of the routine evaluation of patients with facial differences, 3D techniques represent a fundamental advancement for improving our knowledge of facial asymmetry, and they may provide more precise and accurate measurements.
Facial asymmetry is quantified by means of 3D-photography based measurements.
Methods available for clinicians to identify and assess facial asymmetry of three-dimensional (3D) ones, stereophotogrammetry, laser scanning and contact digitalization
Three-dimensional photography seems to solve many of these dilemmas, as it is noninvasive and does not expose subjects to radiation. This technology allows accurate representation of facial soft tissue and morphologies, and it can be used to compare and predict medical outcomes. This technology could be allows accurate representation of facial soft tissue and morphologies, and it can be used to compare and predict orthodontic outcomes.A quantitative assessment of asymmetry allows to assess the severity of the problem and place it within or outside the range of normative
Three-dimensional photogrammetry has become a routine part of patient evaluation in orthodontics, oral surgery, and plastic surgery. Although the technology has been rapidly adopted because of its ability to capture surface anatomy with ease and speed and without radiation.
TrueDepth is what Apple calls the technology in the iPhone’s front camera that powers the phone’s Face ID.The TrueDepth camera works by projecting thousands of invisible dots onto your face and analysing them to create a depth map of your face. Infrared image of the user’s face ace is converted in 3D mesh geometry matching the size, shape, topology of the user's face in real time and a wireframe texture of grid lines are painted onto a real face. Face mesh conform to the shape of the user's face, even as the user blinks, talks, and makes various expressions. To make the displayed face model follow the user's expressions, retrieve an updated face meshes
Why app is useful and which are the research potential where it might be proven a power tool Usually, most cases are slight and aren’t noticeable.facial asymmetry is a valuable indicator for asymmetrical 1.temporomandibular joint affection in juvenile idiopathic arthritis patients 2. developmental dysplasia of the hip (DDH) 3. Torticollis
Facial asymmetry as being congenital, developmental, or acquired; the clinical implications, evaluation, and treatment planning and management may vary accordingly. Medical conditions that can be used as an adjuvant tool to measure objectively facial asymmetries in real time and App could be proven in the future as useful tool to evaluate the following medical situation for early diagnosis and follow up more details are presented below
Facial asymmetry is the imbalance of an individual’s facial features on either side of their face and a usually many neurological diseases present with facial asymmetry. The neurological causes of asymmetry of the face can be divided into four groups: The neurological causes of asymmetry of the face can be divided into four groups: anomalies of the cranial nerves, developmental disturbances, myopathies, and other causes, anomalies of the cranial nerves, developmental disturbances, myopathies, and other such as headaches
Stroke early diagnosis
Can be used as tool for quick and to objectively discover the facial symmetry during development of stroke. As a stroke interrupts the blood supply to the brain, it is important to receive help to restore blood flow quickly. Dead brain cells cannot revive, and acting quickly will help prevent brain cell death. According to the Centers for Disease Control and Prevention (CDC)Trusted Source, individuals who arrive at the emergency department within 3 hours after their first symptoms often have fewer long-term effects 3 months poststroke. Stroke can cause facial drooping and muscle weakness that affects the eyes, lips, and mouth on one or both sides of the face.Typically, stroke affects the lower part of one side of the face and not the forehead. However, if the stroke is in the brainstem, it may affect the forehead. Stroke may cause: pulling down of the eyelids, cheeks, or corners of the mouth,difficulty smiling voluntarily involuntary appearance of smiling, drooling slurred speech
A Stroke's facial symptoms include drooping , muscle weakness, and paralysis of facial muscle . A person's eyelids, cheeks, or mouth may droop on one side left or right App can measure the asymmetry of facial features and might be useful in early discovery of impending stroke by early slight detection of left or right asymmetry. The app measure in real time and normally left or right face side should remain green in case the individual is not affect while a stroke is developing a asymmetry red points would appear left or right side and remain so remaining image of face ay.
The eyelids and corners of the mouth may appear pulled down, and a person may be unable to smile or speak clearly. Facial symptoms of stroke often improve over time-physical therapy and rehabilitation help people regain strength in the facial affected muscles-, although the recovery process may take months or even years this can be measured objectively by the app .
Other conditions that might app be used to monitor treatments like
1.Bell’s palsy: This condition causes sudden and usually temporary one-sided facial weakness. It is responsible for 70% of cases of facial paralysis and typically improves over several weeks. Doctors may also call it “acute peripheral facial palsy of unknown cause,” as they are not always sure why it happens. Sometimes, a viral infection triggers the symptoms.
2. Injury: Roughly 10–23% of facial paralysis cases are due to fractures and wounds that damage the facial nerves.
3. Infection: The chickenpox virus, herpes zoster, can live in the nerves for years after the initial infection. It can then reactivate and affect the facial nerves. This is called Ramsay Hunt syndrome. Lyme disease is a bacterial infection that can also cause facial palsy.
4.Other Neurological conditions: Multiple sclerosis and myasthenia gravis may cause facial drooping.
5.. Tumors: Rarely, tumors on the face or in the brain compress or damage facial nerves, leading to paralysis.
Notice Face asymmetry is obvious after stroke .
Box player at young age facial bone malformation later at adult age
Failed botox treatment left see asymmetry produces by overzealous botox injection treatment at forehead
Chronic stress-induced elevation in cortisol may alter its own negative regulation with multiple long-term consequences for physical and psychological health. One of the most reliable physical traits associated with mental, apparent physical health, and competitiveness is the degree of facial fluctuating asymmetry studies, they measured 15 different facial features to determine asymmetry in the face. They found that subjects with more asymmetric faces also had harder childhoods. Trauma, stress, illness, and even exposure to cigarette smoke during childhood development all seemed to contribute to asymmetry.
Hypertilorism, prone sleep position, tooth extractions malformed dentures or any facial asymmetry in rare syndromes where diagnosis is hard to established by naked eye app could be prove helpful in subclinical cases where tiny difference are not seen Could help to diagnose subclinical syndrome where face asymmetry is implicated like
Parry–Romberg syndrome (PRS), Asymmetric crying facies (ACF), Dyke–Davidoff–Masson syndrome Harlequin syndrome ,Klippel–Feil syndrome,CHARGE syndromeHOXA1 syndromes,Isolated Hereditary Congenital Facial Paresis (HCFP) ,Facioscapulohumeral muscular dystrophy ,Titinopathy,Myotonic dystrophy (MD) type 1 Nemaline myopathy, Carey–Fineman–Ziter syndrome (CFZS) and perhaps more than these
Aesthetics medicine dentistry,Plastic, maxillofacial ,dental Surgery orthodontics.
Symmetry of the face is the one of the most important features for the perception of attractiveness. Facial asymmetry is the imbalance of an individual’s facial features on either side of their face. Usually, most cases are slight and aren’t noticeable.
The degree of asymmetry has a negative impact on functional and facial aesthetics. Anthropological research has shown that symmetry and averageness are important keys to the attractiveness of human faces .
The concept of facial symmetry is very significant to attractiveness. The problem of facial asymmetry is complex and has a wide range of possible causes. Analysis of facial features is useful for dentists, surgeons, orthodontists, and aesthetic medicine specialists. The causes of facial asymmetry are significant, especially from the orthodontic and dental points of view. Generally, the biggest concern people have regarding facial asymmetry is aesthetics. Studies have found that the symmetry of one’s face can affect how attractive you appear to others and that humans usually prefer a more symmetrical look. Asymmetries can cause double chins, “weak chin,” or sunken cheeks. These conditions can be a source of anxiety for many patients who see their smile possibilities reflected in the symmetry filter. Many patients with more severe cases of facial asymmetry feel insecure about their smile.
Every plastic surgeon will at some point see a patient who complains that his or her face is asymmetric, and while this may or may not be clinically evident, the severity of the asymmetry may be hard to quantitate. Mild asymmetry by one observer may be classified as moderate or severe asymmetry by another. Three-dimensional photogrammetry is expensive method and definitely not available to common surgeon. A quantitative assessment of asymmetry allows to assess the severity of the problem and place it within or outside the range of normative symmetry in addition could be to follow patient’s progress along with surgical intervention.
In cosmetic surgery, bridging the anticipation gap between the patients and the physicians can be challenging if there lacks objective and transparent information exchange during the decision-making and surgical process. Facial symmetry has been correlated with attractiveness and is one of the fundamental goals of both reconstructive and aesthetic facial plastic surgery.
In cosmetic surgery, bridging the anticipation gap between the patients and the physicians can be challenging if there lacks objective and transparent information exchange during the decision-making and or surgical process. Botox treatment evaluation, treatment evaluation of collagen filling in various procedures etch . To measure objectively Wrinkle Progression how time affect your face in time how The evolution of singles to measure and quantify the degree of age by simple number.
Diagnose and monitor orthodontic malformations -treatment .Young people’s jawlines are still developing, meaning an orthodontist can redirect their growth and stop asymmetry in its tracks.The best way to prevent facial asymmetry from causing problems is first to diagnose and start treatment as early as possible at the earliest possible age with the help of either braces or, in more severe cases, corrective jaw surgery. Facial asymmetry can disrupt the way someone speaks and eat and even cause jaw or head pain.
1.Taylor HO, Morrison CS, Linden O, Phillips B, Chang J, Byrne ME,
Sullivan SR, Forrest CR. Quantitative facial asymmetry: using three-dimensional photogrammetry to measure baseline facial surface symmetry. J Craniofac Surg. 2014;25(1):124-128.
2. Justyna Chojdak-Łukasiewicz ,Bogusław Paradowski Facial Asymmetry: A Narrative Review of the Most Common Neurological Causes .Symmetry 2022, 14(4), 737; https://doi.org/10.3390/sym14040737
3. Tolleson SR, Kau CH, Lee RP, English JD, Harila V, Pirttiniemi P, Valkama M. 3-D analysis of facial asymmetry in children with hip dysplasia. Angle Orthod. 2010 Jul;80(4):519-24. doi: 10.2319/082009-472.1. PMID: 20482357; PMCID: PMC8966455.
4. Baratta VM, Linden OE, Byrne ME, Sullivan SR, Taylor HO. A Quantitative Analysis of Facial Asymmetry in Torticollis Using 3-Dimensional Photogrammetry. Cleft Palate Craniofac J. 2022 Jan;59(1):40-46. doi: 10.1177/1055665621993284. Epub 2021 Feb 17. PMID: 33593100.
5. Akbari MR, Khorrami Nejad M, Askarizadeh F, Pour FF, Ranjbar Pazooki M, Moeinitabar MR. Facial asymmetry in ocular torticollis. J Curr Ophthalmol. 2015 Nov 23;27(1-2):4-11. doi: 10.1016/j.joco.2015.10.005. PMID: 27239567; PMCID: PMC4877722.
6.Kittur D. The fate of facial asymmetry after surgery for "muscular torticollis" in early childhood. J Indian Assoc Pediatr Surg. 2016 Apr-Jun;21(2):57-60. doi: 10.4103/0971-9261.176936. PMID: 27046975; PMCID: PMC4790129.
Regarding its plausibility app offers no diagnosis or treatment. App provide an early indication that further evaluation may be warranted by Speciality Doctor. Algorithm in App detects in surface Irregularity between left and right site of the face. Explicitly is announced that the app is not for diagnosis. Clinical judgment and experience are required to properly use the software. App alone do not replace an M.D. or specialist. All information received from the App output must be reviewed before any attempted treatment. The software is not for primary image interpretation. Any influence to the operators in making decisions remains User own responsibility and experience. App does not dispense medical advice. Patient should seek a doctor’s advice in addition using this app and or before making any medical decisions for themself. Never substitute or replace doctors advice or change treatment modalities based on any measured outcome. App indicated for assisting healthcare professionals for scientific reasons. Clinical judgment and experience are required to properly use app and further research and validation is pending in coming future.
How it works app-Method-Technique
While user facing the iPhone’s front camera (TrueDepth), like phone’s Face ID holding - no special head position or modifications needed -, app starts surface scans of subjects’ faces continuously. A wireframe texture of grid lines appears over users face on screen matching the size, shape and topology of the user's face in real time. Subjects face should preferably be centred on screen, user should keep the facial musculature as relaxed as possible, avoiding also shaking hand movements while holding the phone.
1220 unique predefined anthropometric landmarks of face (numbered with IDs from 0 to 1219) points are automatically and continuously captured over face surface. At user’s face a purple sphere usually below nose is printed and represents the center of x-, y-, z-coordinate system- origin point (0, 0, 0). Yellow cylinders from origin point outline x-, y-, z-axis, and perpendicular planes are depicted with different colours, saggital plane is depicted blue, frontal plane is depicted red and transverse plane is depicted green. Facial mid linear saggital plane (blue plane) divides in two sector the face right (+ x) and left (-x). User should remember that right side of face is depicted in left side of the screen.
Topography of each anthropometric landmarks points over face (ID numbers) by default can be visually identified and also can be studied with more details as an exported scene file (scn) in Xcode, or any other app that reads scn files. Geometry is continuously registered over face’s wireframe from left and right side namely 587 points left, 587 points right and 46 points in midline saggital face plane.Distances of anthropometric landmarks points to sagittal plane (+x) from right and the distance of mirrored anthropometric landmarks points to left side (-x) side are calculated for each pair, which represent the same reflected topographical face region left or right. Theoretically, bilateral landmarks on a perfectly symmetrical face should have equal but opposite values for the x coordinate (e.g., right -5 mm; left +5 mm ). Mean value of left and right distances for respective pairs are calculated and should be 0 in case of perfect symmetry. Deviation of anthropometric landmarks points toward one side right or left are depicted over face’s side with colour respectively, namely differences in pair points from 0 mm to 1 mm are depicted in green colour and considered symmetric, between 1 mm to 2 mm are depicted in yellow colour - borderline asymmetric, and over 2 mm points are depicted in red colour - asymmetric. Lateral deviation of 2 mm or more was employed as a critical value to separate asymmetry from symmetry. Points are turning colour by default at the side of face with the maximum absolute values, (e.g., right x=-10 mm; left x=+4 mm ; absolute values difference is 6 mm > 2mm, maximum absolute value is 10 on the right side, thus red coloured point (>2mm) appears over right side of face).
Dominant face side (Dom) is also computed and presented on screen. In case left side of face is dominant the value L is depicted at Dom, or R value is depicted in case the right side of face is dominant.
Asymmetry index (AI) % is calculated, - mean average of asymmetry of 1220 - which indicates the degree of to which the geometry of the surface of the face deviates from perfect symmetry. If the shape of face is symmetric, then AI index is zero %. The greater the deviations of face shape from perfect symmetry, the higher the value of AI in %.
Average distances from the left side in mm (AvgL), average distances from the right side in mm (AvgR) and Maximum distance difference from symmetric nodes of the two sides are being calculated (MaxDiff).
By default more than 1mm difference in distances from mid saggital blue plane for each bilateral pair of anthropometric point, turns colour of points from green to yellow and over 2mm to red respectively. By pressing plus or minus button, threshold from 1 mm is changed to the desired value of sensitivity respectively (e.g. by pressing the plus button more value is added over 1mm thus less sensitivity is selected).
By selecting off the planes button, 3D planes and axis disappear from screen.
By switching off, numerical values of predefined anthropometric landmarks identification unique number of points over wireframe no longer appear and a coloured circle-dot is depicted instead.
Points are turning colour by default at the side of face with the maximum absolute values, (e.g., right x=-10 mm; left x=+4 mm ; absolute values difference is 6 mm > 2mm, maximum absolute value is 10 on the right side, thus red coloured point (>2mm) appears over right side of face). By turning the button to min, colour of points are turned at the side of face this time with the minimum absolute values.
By pressing the button the current screen is saved in photo album as a captured image.
All parameters are being calculated in real time namely several times in sec. Shaking hand movements while holding the phone or movement of subject can affect face measuring. User can select by seeing on screen the best motionless face position and by pressing the Freeze button the real time calculation stops and freezes at current scene thus avoiding lag errors at measurements. Data from face wire frame are stored internally meanwhile real time screen recordings pause and the same button changes description to unfreeze and appears over the button.
Once the freeze button have been pressed, all graphical and calculated data can be exported by pressing other buttons like, save stl, save scn, and report for the frozen time moment. By pressing the same button again, named unfreeze this time, real time measurements are restored once again.
By pressing button over screen the currently frozen face grid mask is converted in stl file format and exported in preferred location where later can be processed with third party stl editor.
By pressing button over screen the currently frozen face grid mask is converted in scn file format (scenekit serialised format) and exported in preferred location where can be seen and processed by X-code and converted in various formats.
By pressing report button all measurements are exported in txt format. The output contains :
- the geometry of the 1220 total anthropometric points represented by unique predefined number (ID number) of face points vertices over face - the topography that can be visually identified in scn file - and the corresponding vertex x,y,z coordinate values.
- raw distances list (x value) for each predefined number of anthropometric point (ID) from saggital plane (point ID, distance in meters)
• Pairs of points (ID) for left and (ID) right respectively. Pairs represent the same mirrored topological points over face
• (ID middle) for 46 middle points with distance in meters from mid saggital plane.
• Pairs (ID left ID right ) - raw distances list for each respectively and final difference of them.
• Face Symmetric Vertices Distances List (right vertex ID, left vertex ID, corresponding distances in meters, difference) are presented
• the center of mass (median), the scatter matrix, and the eigenvalues.
In quick review
Dom = …(L or R) (Domination Side)
AI = ……………% (Global Asymmetry Index)
AvgL = ………mm (Average distances from the left side in mm)
AvgR = …..…..mm (Average distances from the right side in mm)
MaxDiff = ……mm (Maximum distance difference from symmetric nodes of the two sides)
Colour of points
0 - 1(x Sensitivity) mm —> green (symmetric)
1(x Sensitivity) - 2(x Sensitivity) mm —> yellow (borderline asymmetric)
> 2(x Sensitivity) mm —> red (asymmetric)