We thank all the children and caregivers who participated in our eye-tracking studies at the Callier Center for Communication Disorders at the University of Texas at Dallas, and at the UNC Carolina Institute for Developmental Disabilities.
N. Sasson was supported by Grant Number UL1RR024982, titled, "North and Central Texas Clinical and Translational Science Initiative" (Milton Packer, M.D., PI) from the National Center for Research Resources (NCRR), a component of the National Institutes of Health (NIH) and NIH Roadmap for Medical Research, and its contents are solely the responsibility of the authors and do not necessarily represent the official view of the NCRR or NIH.&nbsp; Information on NCRR is available at <a href="http://www.ncrr.nih.gov/">http://www.ncrr.nih.gov/</a>.&nbsp; Information on Re-engineering the Clinical Research Enterprise can be obtained from <a href="http://nihroadmap.nih.gov/clinicalresearch/overview-translational.asp">http://nihroadmap.nih.gov/clinicalresearch/overview-translational.asp</a>.
J. Elison was supported by an NRSA award (5-T32-HD007376) from NICHD to the Carolina Consortium on Human Development at the Center for Developmental Science, UNC.

1. Eye-Tracking Equipment
Although a variety of eye-tracking systems are commercially available, those that are most conducive to testing young children with ASD share the following features:
<ol>
 <li>First and foremost, the eye-tracker needs to account for head motion, which if uncorrected, can compromise the integrity of acquired gaze data. While many older systems ensured accurate tracking through head stabilization via the use of a chin-rest or head mounted systems (see Figure 1), these options are not ideal eye-tracking solutions for young children who may resist efforts to restrict head movement, or have equipment placed upon them. Fortunately, most modern commercial infrared video eye-tracking systems use a reference system based on corneal reflections that are resilient to minor head movements. Eye-tracking systems that either offer integrated or remote head tracking solutions are preferred and are now widely available.</li>
 <li>Unobtrusive eye-tracking systems that do not interfere with the testing session are recommended for testing children with ASD. These can be models that are integrated within a display monitor (e.g., Tobii Technology models TX300, T60XL, or T120; SensoMotoric Instruments model RED500), or table-top versions (e.g., Tobii Technology TX300, X120; Applied Science Laboratories model D6 Optics; SR Research model EyeLink 1000) placed inconspicuously within range of the participant. As table-top versions are not locked into a specific screen size, they offer increased methodological flexibility but are less automated and may require more manual adjustment.</li>
 <li>Researchers should also select an eye-tracking system with a sampling rate appropriate for addressing their research questions. Most corneal reflection eye-tracking systems have a minimum sampling rate of 50 Hz (i.e., 50 data points per second), which is adequate for examining young children's perceptual patterns during their visual scanning of static images13 and dynamic videos10. However, researchers interested in subtle oculomotor behavior14 (e.g., smooth pursuit, gain, and/or express saccades) will want to invest in a system with a higher sampling rate (i.e., &ge; 250 Hz). Be aware that in some systems that allow for several sampling rate options, higher sampling rates often are enabled at the expense of freedom of head movement, making it more difficult to keep a kinetic child within eye-tracking range. Higher frame rates require faster sampling and processing of video data, which is typically accomplished by cropping the image obtained from the camera. This results in a reduction of the used field of view, which thereby reduces the range of permissible head movement. Researchers who use systems that offer different sampling rate options should select one that is high enough to address their research question but low enough to allow for expected levels of head movement.</li>
</ol>
2. Testing Environment and Stimuli
<ol>
 <li>Sparse room d&eacute;cor is recommended for the immediate eye-tracking environment in order to minimize the chances that the child's attention is drawn outside the display. Similarly, a dimly lit room helps reduce the salience of competing non-display stimuli.</li>
 <li>However, because some young children with ASD may experience visual and/or auditory hypersensitivities, researchers should avoid testing in a completely darkened room that heightens the brightness of the display or including overly loud or jarring sound effects in their presentations, as these may be aversive for some children with ASD and result in reduced testing compliance. Darkened environments may also increase pupil dilation which can make the pupil more difficult to track, though this may vary depending on the eye-tracking equipment used. For most cases, standard office lighting is recommended.</li>
 <li>To further reduce the chances of the child being distracted away from the display, the experimenter should not be visible to the participating child. This may be achieved by placing a partition between the eye-tracking station and the experimenter-manned host computer or by simply positioning the experimenter out of view from the participant. A second camera can help the experimenter retain a view of the participant in this situation. Indeed, some commercial eye-trackers integrate a camera within the display so that video of the participant is relayed in real time to the host computer for experimenter monitoring.</li>
</ol>
3. Procedures
<ol>
 <li>Young children, particularly those with an ASD, may be apprehensive about experiencing a novel testing environment. While prior familiarity with the testing space and/or experimenter may help to mollify these feelings, this is not always possible. At a minimum, apprehensive children should be accompanied by a parent or familiar adult throughout the testing session. In some cases, researchers should be prepared to be patient while the child becomes accommodated to the new environment.</li>
 <li>Before the testing session begins, the experimenter may choose to have a children's video or cartoon playing on the display monitor. This often helps make the child feel more at ease while also ensuring attention is directed towards the testing display. The experimenter may then take advantage of the child's captured attention to position the child within eye-tracking range and transition directly into the calibration sequence.</li>
 <li>Seating for the child must allow for vertical adjustment in order to ensure that all children, regardless of height and posture, can be positioned within eye-tracking range. While the distance of the chair from the display will depend upon the size of the screen and the desired visual angle, the height of the chair needs to be adjusted based upon the child's stature so that line of sight is standardized across all participants. Because not all children sit in the chair in exactly the same way, it is also often necessary to slightly adjust the participant-to-display distance in order to ensure that each child is positioned at the optimal distance from the screen for acquiring high quality data. This distance will be specified by the eye-tracking manufacturer, and is most easily achieved by using a mobile chair.</li>
 <li>Experimenters may first attempt to have the child, if small enough, sit alone in a buckled car seat on an adjustable lift or in a portable high chair that attaches to adjustable-height office chair. We have also had success using a Rifton chair, particularly with children who have used it previously in classroom or home settings, as it is easy to position and helps restrict mobility that may result in data loss.</li>
 <li>Children who only remain compliant while sitting upon the lap of the caregiver, or who require the body support the caregiver can provide, can also be accommodated by having caregiver sit in an office chair that may be raised or lowered to position the child within the standardized distance parameters. See Figure 2 for an example of this set-up. Statistics regarding lap versus chair sitting should always be retailed for analyzing possible confounds. In order to ensure that only the child's eyes are acquired by the eye tracker, researchers may have caregivers wear infrared-blocking or opaque sunglasses, or simply instruct them to close their eyes during testing. Caregivers should also be instructed to be still and refrain from verbally or non-verbally communicating with the child during the testing procedure.</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/3675/3675fig1.jpg" /> 
Figure 1. A head-mounted eye-tracking system.
<img alt="Figure 2" src="/files/ftp_upload/3675/3675fig2.jpg" /> 
Figure 2. A child may sit on the lap of the caregiver if the child requires physical assistance in sitting, or if it is necessary for maintaining compliance.
<ol start="6">
 <li>For eye-tracking systems that provide the experimenter with a window displaying the participant's eyes within the range of permitted head movement, the child's eyes should be positioned in the middle of the window in order to increase the chances that the eye tracker will retain an image of the eye even if the child slouches, straightens or sways during testing.</li>
 <li>Once properly positioned, the experimenter should begin the calibration procedure. As young children with ASD may be unable or unwilling to follow verbal instructions to look to specific locations on the screen (as is typical for many calibration sequences), the use of dynamic stimuli, accompanied by sound, may more effectively capture attention and thus result in more accurate gaze data. Typically, a 5-point sequence is brief enough to retain the child's attention while also providing an accurate calibration. Eye-tracking studies with infants often employ just a 2-point calibration while a 9-point calibration is typical for investigations with adolescents and adults.</li>
 <li>Experimenters may maximize the child's visual attention to the display during testing by designing a concise and compelling task that has minimal task demands (e.g., a passive viewing task). Further, including an inter-stimulus animation with an accompanying sound effect (perhaps similar to those used during the calibration sequence) can help redirect attention to the display for children whose attention has lapsed. Additionally, positioning this inter-stimulus animation in a predefined location can ensure that all visual scanning patterns begin in the same spot for all participants.</li>
 <li>If the research task is lengthy, the experimenter may use this inter-stimulus animation as an "anchor" to determine if calibration drift is occurring. Typically, if drift exceeds 3 degrees of visual angle, re-calibration should be administered. Additionally, if multiple tasks or trials are included, re-calibration is recommended between each one to eliminate drift over the course of testing.</li>
</ol>
4. Analysis
<ol>
 <li>Most eye-tracking systems yield raw data files that include, at a minimum, a timestamp, X and Y coordinates of the point of regard (sometimes for both eyes), the distance from the display or stimulus, along with an index that characterizes an event or change in stimulus presentation. Some software programs also yield information about pupil diameter and fixation metrics.</li>
 <li>How one chooses to condense the vast amount of raw data is determined by the research question. Most often the goal is to characterize metrics of fixation density and/or oculomotor dynamics. However, once these constructs are characterized, superordinate constructs such as attention and memory can be examined under specific design conditions.</li>
 <li>Fixation Density: While many different algorithms exist that characterize fixation density15, all analyze two primary components: temporal and spatial information. For example, a fixation can be defined as the point of regard remaining within a diameter of 1&deg; of visual angle for at least 100 milliseconds, though these parameters are often anchored by the research question. Common dependent variables include number of fixations, average duration of fixation, and total fixation time, and the spatial arrangement and/or sequence of individual fixations (i.e., scan paths)16.</li>
 <li>Fixation analyses are often conducted within predefined "Areas of Interest" (AOI). Researchers may be interested in whether children with and without ASD differ in their fixation time to specific AOIs (such as the eyes on a face), their latency to first fixate AOIs, or in the patterns of their gaze shifts between AOIs. Additionally, the metrics listed in 4.3 can also be applied to AOI analyses.</li>
 <li>Children with ASD, particularly those with impairments in sustaining attention, often exhibit more missing gaze data than controls. This may occur due less visual attention to onscreen stimuli or by excessive blinking (sometimes produced by an overly bright display or a too dark testing environment). To control for missing data differences between groups, researchers may want to conduct analysis as a proportion of gaze time onscreen instead of in absolute values that can be confounded by missing data. Further, in order to protect against unreliable data caused by insufficient sampling, researchers should require that all participants who are included in the final sample pass a "minimum time" cut off. The specificity of this cut off will vary by study, but in general participants with more missing than recorded data should be considered suspect.</li>
 <li>In contrast to fixation analysis, velocity-based algorithms incorporate the change in Euclidean distance between subsequent recordings and focus primarily on saccades. A saccade is indicated when the velocity (distance/time) exceeds a certain threshold. If concurrent recordings do not exceed this velocity threshold for a specified period of time, a fixation is indicated.</li>
 <li>Oculomotor Dynamics: Characterizing oculomotor dynamics requires a high sampling eye-tracking system that is sufficiently sensitive to subtle changes in eye position and eye movement. Although many dependent variables can be investigated within the scope of oculomotor dynamics including saccades, ocular drift, and pursuit, all indices rest upon the velocity of eye movement. Characterizing this velocity is based on two properties (i.e., distance and time) and thus allows for the examination of other properties of oculomotor dynamics, including the distribution or pattern of saccade velocities, the distribution or pattern of saccade amplitude, the distribution or pattern of saccade duration, as well as the latency of saccade and accuracy of saccade termination (i.e., gain). Common paradigms include visually guided saccade tasks, antisaccade tasks, memory guided saccade tasks, and predictive saccade tasks.7, 17 The extant literature contains a large body of research on saccade dynamics that could benefit interested researchers18-20.</li>
</ol>
5. Representative Results

<img alt="Figure 3" src="/files/ftp_upload/3675/3675fig3.jpg" /> 
Figure 3. Figure 3 represents a fixation map generated in research by our group. Shown here are the individual fixations, depicted by purple circles, by a single child with ASD while viewing a static image. Fixations from this and similar tasks are analyzed across participants to determine if children with and without ASD differ in their visual attention to various AOIs.
<img alt="Figure 4" src="/files/ftp_upload/3675/3675fig4.jpg" /> 
Figure 4. Figure 4 represents an example of a final product that includes many of the steps described above, including: 1) applying a fixation filter to raw gaze data, 2) assigning fixations to specific AOIs, and 3) condensing and comparing patterns of fixations across a group of typically developing (TD) children and a group of children with ASD. More specifically, this figure demonstrates that within a visual exploration paradigm, children with ASD explore (i.e., fixate) fewer social images TD children when "High Autism Interest" (HAI) objects are concurrently displayed. When "Low Autism Interest" (LAI) objects are presented with social stimuli, however, exploration of social images does not differ significantly between groups, suggesting that social attention in ASD is modulated based upon the relative salience of competing stimuli.21

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The authors have nothing to disclose and no conflicts of interest.

The emergence of eye-tracking as an objective and accessible tool for examining perceptual characteristics of psychiatric disorders has facilitated research into the abnormal visual attention and oculomotor patterns that contribute to clinical characteristics of ASD. A particularly promising application of this work has been to study young children with ASD in order to capture early-emerging developmental mechanisms of the disorder. While investigations with this age group are critical for illuminating the early course and characteristics of ASD, doing so with traditional behavioral paradigms has often been challenging given the social and communicative impairments that exist in this population. Eye-tracking can alleviate some of these task demands by providing a direct and quantifiable measure of visual preferences and gaze behavior. Ultimately, this approach may help reveal important information during a critical period in the development of ASD, a process that in turn could inform early identification and intervention efforts.
Despite these benefits, eye-tracking young children with ASD is complicated by a number of methodological challenges. The current protocol details guidelines for implementing eye-tracking with this population. While the suggestions outlined here are limited to common and commercially available corneal-reflection eye-tracking systems, particularly those that do not restrict participant movement and can correct for head motion, they are designed to provide general instruction for interested researchers. Optimal design is often study specific, but general recommendations include selecting equipment and creating a testing environment that are conducive for studying this population, implementing procedures that minimize obstacles and potential distractions, and pursuing appropriate analytic strategies.
The adoption of such practices may expedite eye-tracking research aimed at examining early symptom manifestations of ASD, but they may also pertain to research groups interested in eye-tracking young children more broadly, including infants22, as well as children with developmental disabilities other than autism. Further, researchers may want to build upon these recommendations by incorporating eye-tracking with other physiological measures, such as EEG, galvanic skin conductance and heart-rate monitoring, to provide a more comprehensive profile of psychobiological response. The increasing availability of mobile eye-tracking systems also enhances the possibility to extend the study of gaze behavior in ASD into more ecologically-valid contexts, including live social interaction. These innovative designs are expected to rise in popularity in the coming years.

<table border="1">
<tbody>
 <tr>
 <td>Material Name</td>
 <td>Type</td>
 <td>Company</td>
 <td>Catalogue Number</td>
 <td>Comment</td>
 </tr>
 <tr>
 <td>Eye-tracker</td>
 <td>A stand-alone corneal reflection based system. Eye-tracker is integrated into 24" TFT widescreen monitor. Records at 60Hz.</td>
 <td>Tobii </td>
 <td>Tobii 60XL</td>
 <td>Shown in Figure 2. This is one of several systems that allows for head motion (in this case, within a cubic space of 40x20x27cm from a distance of 60cm, while retaining an average accuracy of ~0.5&deg; of visual angle).</td>
 </tr>
 <tr>
 <td>Eye-tracker Control Software</td>
 <td>&nbsp;</td>
 <td>Tobii </td>
 <td>Tobii Studio v. 2.1.14</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Fixation Analysis Program</td>
 <td>&nbsp;</td>
 <td>Tobii </td>
 <td>Tobii Studio v. 2.1.14</td>
 <td>Fixation analysis in Figure 3 generated using this program. Output in Figure 4 generated in external software. </td>
 </tr>
 </tbody>
</table>

eye tracking young children with autism

The rise of accessible commercial eye-tracking systems has fueled a rapid increase in their use in psychological and psychiatric research. By providing a direct, detailed and objective measure of gaze behavior, eye-tracking has become a valuable tool for examining abnormal perceptual strategies in clinical populations and has been used to identify disorder-specific characteristics1, promote early identification2, and inform treatment3. In particular, investigators of autism spectrum disorders (ASD) have benefited from integrating eye-tracking into their research paradigms4-7. Eye-tracking has largely been used in these studies to reveal mechanisms underlying impaired task performance8 and abnormal brain functioning9, particularly during the processing of social information1,10-11. While older children and adults with ASD comprise the preponderance of research in this area, eye-tracking may be especially useful for studying young children with the disorder as it offers a non-invasive tool for assessing and quantifying early-emerging developmental abnormalities2,12-13. Implementing eye-tracking with young children with ASD, however, is associated with a number of unique challenges, including issues with compliant behavior resulting from specific task demands and disorder-related psychosocial considerations. In this protocol, we detail methodological considerations for optimizing research design, data acquisition and psychometric analysis while eye-tracking young children with ASD. The provided recommendations are also designed to be more broadly applicable for eye-tracking children with other developmental disabilities. By offering guidelines for best practices in these areas based upon lessons derived from our own work, we hope to help other investigators make sound research design and analysis choices while avoiding common pitfalls that can compromise data acquisition while eye-tracking young children with ASD or other developmental difficulties.

Watch this Scientific Journal Video about Eye Tracking Young Children with Autism at JoVE.com

Eye Tracking Young Children with Autism

Eye tracking has long been used to study gaze patterns in typically-developing individuals, but recent technological advancements have made its use with clinical populations, including autism, more feasible. While eye-tracking young children with autism can offer insight into early symptom manifestations, it involves methodological challenges. Suggestions for best practices are provided.

The rise of accessible commercial eye-tracking systems has fueled a rapid increase in their use in psychological and psychiatric research. By providing a ...

Nanyang Technological University

Research

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Medicine

45.3K Views.  University of Texas at Dallas. Eye tracking has long been used to study gaze patterns in typically-developing individuals, but recent technological advancements have made its use with clinical populations, including autism, more feasible. While eye-tracking young children with autism can offer insight into early symptom manifestations, it involves methodological challenges. Suggestions for best practices are provided.

Video: Eye Tracking Young Children with Autism

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

Portable Intermodal Preferential Looking (IPL): Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

One of the defining characteristics of autism spectrum disorder (ASD) is difficulty with language and communication.1 Children with ASD's onset of speaking is usually delayed, and many children with ASD consistently produce language less frequently and of lower lexical and grammatical complexity than their typically developing (TD) peers.6,8,12,23 However, children with ASD also exhibit a significant social deficit, and researchers and clinicians continue to debate the extent to which the deficits in social interaction account for or contribute to the deficits in language production.5,14,19,25
Standardized assessments of language in children with ASD usually do include a comprehension component; however, many such comprehension tasks assess just one aspect of language (e.g., vocabulary),5 or include a significant motor component (e.g., pointing, act-out), and/or require children to deliberately choose between a number of alternatives. These last two behaviors are known to also be challenging to children with ASD.7,12,13,16
We present a method which can assess the language comprehension of young typically developing children (9-36 months) and children with autism.2,4,9,11,22 This method, Portable Intermodal Preferential Looking (P-IPL), projects side-by-side video images from a laptop onto a portable screen. The video images are paired first with a 'baseline' (nondirecting) audio, and then presented again paired with a 'test' linguistic audio that matches only one of the video images. Children's eye movements while watching the video are filmed and later coded. Children who understand the linguistic audio will look more quickly to, and longer at, the video that matches the linguistic audio.2,4,11,18,22,26
This paradigm includes a number of components that have recently been miniaturized (projector, camcorder, digitizer) to enable portability and easy setup in children's homes. This is a crucial point for assessing young children with ASD, who are frequently uncomfortable in new (e.g., laboratory) settings. Videos can be created to assess a wide range of specific components of linguistic knowledge, such as Subject-Verb-Object word order, wh-questions, and tense/aspect suffixes on verbs; videos can also assess principles of word learning such as a noun bias, a shape bias, and syntactic bootstrapping.10,14,17,21,24 Videos include characters and speech that are visually and acoustically salient and well tolerated by children with ASD.

Portable Intermodal Preferential Looking IPL: Investigating Language Comprehension in Typically Developing Toddlers and Young Children with Autism

A reliable home-based way to assess the language comprehension of very young typically developing children, as well as those with autism, is described. The method analyzes children's eye gaze while viewing side-by-side images but hearing an audio that matches only one image. Stimuli are designed with young participants in mind.

One  of the defining characteristics of autism spectrum disorder (ASD) is difficulty  with language and communication.1  Children with ASD's onset of ...

Nerve-sparing Mid-urethral Obstruction (NeMO) in Female Small Rodents

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal model to investigate bladder remodeling in pBOO are female rodents undergoing partial obstruction at the proximal urethra. Variability in the degree of obstruction and animal mortality are major concerns with proximal obstruction. Furthermore, dissecting around the proximal urethra and bladder neck jeopardizes bladder innervation.
We developed a nerve-sparing mid-urethral obstruction (NeMO) model for pBOO avoiding the disadvantages of the traditional model. We approached the urethra just inferior to the pubic symphysis, which obviated the need for laparotomy as well as for dissection in this area; also, the striated urethral sphincter remained untouched. We performed NeMO in female Sprague-Dawley rats (12 obstructions, 6 sham animals) as well as in female C57/bl6 mice (20 obstructions, 18 sham animals). After two weeks, we evaluated bladder function, bladder mass, and body mass.
We had no mortalities among obstructed- or sham-operated female rats; as described for the traditional proximal pBOO-method, we tied the suture around the proximal urethra and a temporarily placed 0.9 mm metal rod. NeMO induced an 85% increase in bladder mass after two weeks, average residual urine volume was 0.4 mL in partially obstructed rats while only 0.03 mL in sham animals. In mice, we tested 3 sizes of cannulas that we placed along the urethra when tying the suture. We found that using a 27-gauge cannula resulted in over 50% animal mortality; placing the 25-gauge cannula did not yield the desired response in increasing bladder mass; utilizing a 26-gauge cannula yielded favorable results with minimal animal mortality (1/8) yet a significant 2-fold increase in bladder mass.

Nerve-sparing Mid-urethral Obstruction NeMO in Female Small Rodents

Traditional modeling of partial bladder outlet obstruction in rodents is fraught with animal mortality. A denervation injury from dissection around the proximal urethra and bladder neck is also of major concern. We developed and evaluated a safe and reliable mid-urethral obstruction model, avoiding the shortcomings of the traditional model.

Partial bladder outlet obstruction (pBOO) has a high prevalence, causes significant patient burden, and immense health care costs. The most common animal ...

Puncture-Induced Iris Neovascularization as a Mouse Model of Rubeosis Iridis

We describe a model of puncture-induced iris neovascularization as a general model for noninvasive evaluation of angiogenesis. The model is also relevant for targeting neovascular glaucoma, a sight-threatening complication of diabetic retinopathy. This method is based on the induction of iris vascular response by a series of self-sealing uveal punctures on BALB/c mice and takes advantage of the postpartum maturation of mouse ocular vasculature. Mouse pups undergo uveal punctures from postnatal day 12.5, when the pups naturally open their eyes, until postnatal day 24.5. Due to the transparency of the cornea, iris vasculature can be analyzed easily through time by noninvasive in vivo methods. Furthermore, the semitransparent iris of BALB/c mice can be flatmounted for detailed immunohistologic analysis with minimal non-specific background staining. In this model, angiogenesis is mainly driven by the inflammatory and plasminogen activating systems. The puncture-induced model is the first to induce iris neovascularization in small rodents, and has the advantage of allowing direct noninvasive in vivo analysis of the angiogenic process. Moreover, the model can be combined with angiogenic modulating substances, which highlights its potential in the study of angiogenesis with an in vivo perspective.

Iris neovascularization, a common complication of ischemic retinal disease, may lead to sight-threatening neovascular glaucoma. Here, we describe a murine protocol for inducing experimental iris neovascularization that may be used for noninvasive evaluation of angiogenesis-modulating substances.

We describe a model of puncture-induced iris neovascularization as a general model for noninvasive evaluation of angiogenesis. The model is also relevant ...

Endoscopic Septoplasty with Limited Two-line Resection: Minimally Invasive Surgery for Septal Deviation

Endoscopic septoplasty is a surgical procedure in otolaryngology that is commonly performed to treat nasal airway obstruction caused by nasal septal deviation. It has a long history with multiple variations. In this article, a modified endoscopic septoplasty procedure using the limited two-line resection (2LoRs) technique at the posterior and inferior junction of the cartilaginous and bony septum is presented based on embryologic and anatomic knowledge of the nasal septum and the biomechanics of cartilaginous behavior. With this procedure, the quadrangular cartilage can be preserved as much as possible, which is helpful in retaining the supporting framework and rigidness of the septum. 2LoRs has been proven effective and sound for the correction of nasal septal deviation with rare complications. This modified procedure can be applied to correct the deviated nasal septum in the absence of any external nasal deformity to improve nasal patency or to improve access to the middle meatus or to the axillary region of the middle turbinate. It may also be used to expand the indications of septoplasty to children and adolescents because of its minimally invasive approach.

Endoscopic septoplasty is a time-honored surgical procedure with multiple variations. This paper focuses on a step-by-step surgical approach to perform a modified septoplasty procedure known as limited two-line resection. This surgical technique can be applied to correct a deviated nasal septum in the absence of an external nasal deformity.

Endoscopic septoplasty is a surgical procedure in otolaryngology that is commonly performed to treat nasal airway obstruction caused by nasal septal ...

Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy

While the number of new treatment options tested in patients with Duchenne muscular dystrophy (DMD) is increasing, there is still no defining of the most reliable assessments regarding therapeutic efficacy. We present clinical and radiological outcome measures used in ambulatory patients participating in our trial &#34;Treatment with L-citrulline and metformin in Duchenne muscular dystrophy&#34;. The motor function measure is a validated test in patients with neuromuscular disorders that consists of 32 items and assesses all three dimensions of motor performance including standing and transfer (D1 subscore), axial and proximal motor function (D2 subscore), and distal motor function (D3 subscore). The test shows high intra- and inter-rater variability but only when strictly following guidelines of the materials, examination steps, and calculation of scores. The 6-minute walk test, timed 10-meter walk/run test, and supine-up time are commonly used timed functional tests that also sufficiently monitor changes in muscle function; however, they strongly depend on patient collaboration. Quantitative MRI is an objective and sensitive biomarker to detect subclinical changes, though the examination costs may be a reason for its limited use. In this study, a high correlation between all clinical assessments and quantitative MRI scans was found. The combinational use of these methods provides a better understanding about disease progression; however, longitudinal studies are needed to validate their reliability.

The aim of this study is to present the most reliable clinical outcome measures and their correlations with quantitative muscle MRI in ambulant patients with Duchenne muscular dystrophy.

While the number of new treatment options tested in patients with Duchenne muscular dystrophy (DMD) is increasing, there is still no defining of the most ...

Using an Automated Hirschberg Test App to Evaluate Ocular Alignment

A smartphone app has been developed to perform the automated photographic Hirschberg test for objective measurement of ocular misalignment. By computing the difference in corneal reflection generated by the phone camera flash relative to the iris center based on high resolution images, the app can measure misalignment with a much higher precision than the naked eye performing the Hirschberg test. It has been validated in a previous clinical evaluation study by comparing to the clinical gold standard-prism and alternate cover test. The goal of this article is to describe the testing techniques regarding how to use the app to measure ocular alignment for different fixation distances, without or with cover to break fusion, as well as angle kappa, so that users can use the app to perform equivalent tests typically done in clinic using prisms.

We present a protocol of using a smartphone app to perform Hirschberg test for measuring manifest and intermittent ocular misalignment (strabismus) under near and far fixation conditions.

A smartphone app has been developed to perform the automated photographic Hirschberg test for objective measurement of ocular misalignment. By computing ...

Electroretinogram Recording for Infants and Children under Anesthesia to Achieve Optimal Dark Adaptation and International Standards

Electroretinogram (ERG) is the only clinical objective test available to assess retinal function. Full-field ERG (ffERG) measures the panretinal rod and cone photoreceptor function as well as inner retinal function and is an important measure in the diagnosis and management of inherited retinal diseases as well as inflammatory, toxic, and nutritional retinopathies. Adhering to international standards and maintaining retinal dark adaptation are critical to acquire valid and reliable dark-adapted (scotopic) and light-adapted (photopic) ffERG responses. Performing ffERG in infants and children is challenging and often requires general anesthesia in the operating room. However, maintaining retinal dark adaptation in the operating room is becoming increasingly difficult given the numerous light sources from anesthesiology monitoring systems and other equipment. A practical and widely applicable method for ffERG testing is described in the operating room that optimizes retinal dark adaptation. The method reduces operating room time by dark-adapting the patient before general anesthesiology is instituted. The operating room is modified for dark adaptation and any remaining light source in the darkened operating room is minimized with the use of a modified portable foldable darkroom that encloses the patient&#8217;s head and the ERG examiner during ffERG scotopic recordings. The simple method adheres to ffERG international standards and provides valid reliable scotopic and photopic ffERG recordings that are critical to assess objective retinal function in this young age group where subjective assessment of visual function such as visual acuity and visual fields are not possible. Furthermore, the ffERG is the gold standard clinical test in detecting early onset inherited retinal diseases including Leber congenital amaurosis where approved gene therapy has become available. In sedated conditions, very low amplitude ffERG signals can be detected due to minimal orbicularis muscle activity interference, which is particularly relevant in patients after gene therapy to detect improved amplitude responses.

Adhering to international standards and maintaining retinal dark adaptation are critical to acquire valid full-field electroretinogram responses in the diagnosis and management of inherited retinal diseases. A practical protocol using a portable darkroom is provided to obtain full-field&#160;electroretinogram for infants and children under sedation or general anesthesia in the operating room setting.

Electroretinogram (ERG) is the only clinical objective test available to assess retinal function. Full-field ERG (ffERG) measures the panretinal rod and ...

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the recognized standard-of-care for blood flow quantification based on phase contrast MRI. While such measurement of blood flow has been possible in adults for decades, methods to extend this capability to fetal blood flow have only recently been developed.
Fetal blood flow quantification in major vessels is important for monitoring fetal pathologies such as congenital heart disease (CHD) and fetal growth restriction (FGR). CHD causes alterations in the cardiac structure and vasculature that change the course of blood in the fetus. In FGR, the path of blood flow is altered through the dilation of shunts such that the oxygenated blood supply to the brain is increased. Blood flow quantification enables assessment of the severity of the fetal pathology, which in turn allows for suitable&#160;in utero&#160;patient management and planning for postnatal care.
The primary challenges of applying phase contrast MRI to the human fetus include small blood vessel size, high fetal heart rate, potential MRI data corruption due to maternal respiration, unpredictable fetal movements, and lack of conventional cardiac gating methods to synchronize data acquisition. Here, we describe recent technical developments from our lab that have enabled the quantification of fetal blood flow using phase contrast MRI, including advances in accelerated imaging, motion compensation, and cardiac gating.

Here we present a protocol for measuring fetal blood flow rapidly with MRI and retrospectively performing motion correction and cardiac gating.

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the ...

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold (TDT) Test

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a reliable measure of sweet, salty, and umami taste detection thresholds from childhood to adulthood. Advantages of the method include procedures that are identical for children and adults, thus allowing the determination of age-related and individual differences in taste perception, if any, and tasks that can be completed in a relatively short time frame, do not rely on continuous attention or require memorization, control for subjective response biases, and minimize the impact of language development. After a 1 hour fast, participants are presented with pairs of solutions; in each pair, one solution is water, and the other solution contains varying concentrations of the tastant.
Using a whole-mouth tasting method, participants taste each solution (without swallowing and with rinsing between tastings) and then point to the solution with a taste or that tastes different from water. The concentration of the stimulus in the subsequent pair increases after a single incorrect response and decreases after two consecutive correct responses. A reversal occurs when the concentration sequence changes direction. The task is deemed completed after the occurrence of four reversals, provided there are a maximum of two dilution steps between two successive reversals, and the series of reversals do not form an ascending pattern. These additional criteria ensure greater reliability in outcomes. The TDT is then calculated as the geometric mean of the concentrations of the four reversals. This method has real-world relevance as it provides information on a dimension of taste perception that is independent of hedonics, and that can change with aging and certain disease states, making it a valuable psychophysical test.

Psychophysical Tracking Method to Assess Taste Detection Thresholds in Children, Adolescents, and Adults: The Taste Detection Threshold TDT Test

Psychophysical tools measure the functionality of the taste system for both research and health assessment purposes. This paper describes a method to measure taste detection thresholds that can determine the lowest concentration of sucrose, sodium chloride, or monosodium glutamate that can be tasted by individuals as young as 6 years.

This paper describes a two-alternative, forced-choice, staircase, tracking procedure, called the Taste Detection Threshold (TDT) test, that provides a ...