Eye Orientation Research Articles

A long-headed Cambrian soft-bodied vertebrate from the American Great Basin region.

The fossil record suggests that chordates might have been minor components of marine ecosystems during the first major diversification of animal life in the Cambrian. Vertebrates are represented by a handful of rare soft-bodied stem-lineage taxa known from Konservat-Lagerstätten, including Myllokunmingia and Yunnanozoon from the Stage 3 of South China, and Emmonsaspis and Metaspriggina from Stage 4-Drumian deposits of northeast USA and British Columbia. Here, we describe the first soft-bodied vertebrate from the American Great Basin, a region home to a dozen Cambrian Konservat-Lagerstätten. Found in the Drumian Marjum Formation of Utah, Nuucichthys rhynchocephalus gen. et sp. nov. is characterized by a finless torpedo-shaped body that includes a snout-like anterior head bearing anterolateral eyes, approximately 25 thick myomeres, a large branchial chamber with a keel and approximately seven putative dorsal bars and a spiniform caudal process. Using Bayesian inference, our analysis recovers Nuucichthys within the vertebrate stem, closer to the crown than Pikaia, Yunnanozoon and Myllokunmingia, where it forms a polytomy with its Laurentian relatives, Emmonsaspis and Metaspriggina, and a scion consisting of conodonts and crown-group vertebrates. Based on the eye orientation and absence of fins, we tentatively reconstruct Nuucichthys as a pelagic organism with limited swimming abilities (planktonektic).

Upper eyelid morphology and age-related changes in Japanese and Chinese females.

Many consumers use cosmetic eye products to counteract age-related changes in appearance. Measurements of eyelid shape in Asian women have been reported in the frontal view or 45-degree profile only. The aim of this study was to describe morphological characteristics of the upper eyelid in Japanese and Chinese females from the frontal and profile aspects and examine morphological changes with age. Standardized digital photographs of 772 Japanese and 346 Chinese women (15-79 years of age) were acquired in frontal and 90-degree profile aspects. Eleven upper eyelid parameters (e.g., width, length, depth, aperture, and curvature) were measured using image analysis to determine age-related changes and compare by ethnicity. Eyelid width, area between eyebrow and eyelid, and eyelid curvature were comparable for both ethnicities under age 40, but the aging effect was more pronounced in Chinese subjects. Eyelid height, depth, and upper eyelid aperture angle were also comparable for both ethnicities under age 40, but the aging effect was more evident in Japanese subjects. Upper eyelid incline angle, eye orientation, and upper eyelid protrusion angle changed comparably with age for both ethnicities. No prominent age-related changes were evident for eyelid length or area between eyebrow and eye with the eye closed. Upper eyelid morphology changes with age in Japanese and Chinese females, starting around 40 years of age. Ethnic differences are limited in younger age groups but become more prominent with age. The findings suggest that aging affects some upper eyelid features earlier than others.

Realistic 3D human saccades generated by a 6-DOF biomimetic robotic eye under optimal control.

We recently developed a biomimetic robotic eye with six independent tendons, each controlled by their own rotatory motor, and with insertions on the eye ball that faithfully mimic the biomechanics of the human eye. We constructed an accurate physical computational model of this system, and learned to control its nonlinear dynamics by optimising a cost that penalised saccade inaccuracy, movement duration, and total energy expenditure of the motors. To speed up the calculations, the physical simulator was approximated by a recurrent neural network (NARX). We showed that the system can produce realistic eye movements that closely resemble human saccades in all directions: their nonlinear main-sequence dynamics (amplitude-peak eye velocity and duration relationships), cross-coupling of the horizontal and vertical movement components leading to approximately straight saccade trajectories, and the 3D kinematics that restrict 3D eye orientations to a plane (Listing's law). Interestingly, the control algorithm had organised the motors into appropriate agonist-antagonist muscle pairs, and the motor signals for the eye resembled the well-known pulse-step characteristics that have been reported for monkey motoneuronal activity. We here fully analyse the eye-movement properties produced by the computational model across the entire oculomotor range and the underlying control signals. We argue that our system may shed new light on the neural control signals and their couplings within the final neural pathways of the primate oculomotor system, and that an optimal control principle may account for a wide variety of oculomotor behaviours. The generated data are publicly available at https://data.ru.nl/collections/di/dcn/DSC_626870_0003_600.

Effect of binocular visual cue availability on fruit and insect grasping performance in two cheirogaleids: Implications for primate origins hypotheses

Forward-facing eyes with parallel optic axes, which provide a wide field of binocular vision and precise depth perception, are among the diagnostic features of crown primates; however, the adaptive significance of this feature remains contentious. Two of the most prominent primate-origins hypotheses propose that either foraging for fruit or nocturnal predation on insects created selective pressures that led to the evolution of diagnostic primate traits, including a wide binocular field. To determine whether either of these hypotheses provides a viable explanation for the evolution of primates' derived eye orientation, the importance of binocular depth cues for the two tasks invoked by these hypotheses was evaluated experimentally in Microcebus murinus and Cheirogaleus medius, cheirogaleids' considered reasonable living analogs of the earliest euprimates. Performance in grasping insects and fruit was evaluated when the animals made use of their full binocular visual field and when their binocular visual field was restricted using a helmet-mounted blinder. Restriction of the binocular field had no effect on fruit grasping performance; however, restriction of the binocular field resulted in a significant deficit in insect predation performance. Differences in behavioral variables also suggest that insect predation is a more visually demanding task than fruit foraging. These results support the role of insect predation, but not fruit foraging, in contributing to the selective pressures that led to the evolution of parallel optic axes and a wide binocular field in crown primates.

Modeling and Classification of the Behavioral Patterns of Students Participating in Online Examination

Online education has become an essential part of the modern education system, but keeping the integrity of the online examination remains a challenge. A significant increase in cheating in online examinations (from 29.9% before COVID-19 to 54.7% during COVID-19, as per a recent survey) points out the necessity of online exam proctoring systems. Traditionally, educational institutes utilize different questions in onsite exams: multiple-choice questions (MCQs), analytical questions, descriptive questions, etc. For online exams, form-based exams using MCQs are popular though in disciplines like math, engineering, architecture, art, or other courses, paper and pen tests are typical for proper assessment. In form-based exams, students’ attention is toward display devices, and cheating behavior is identified as the deviation of head and eye gaze direction from the display device. In paper- and pen-based exams, students’ main attention is on the answer script not on the device. Identifying cheating behavior in such exams is not a trivial task since complex body movements need to be observed to identify cheating. Previous research works focused on the deviation of the head and eyes from the screen which is more suited for form-based exams. Most of them are very resource-intensive; along with a webcam, they require additional hardware such as sensors, microphones, and security cameras. In this work, we propose an automated proctoring solution for paper- and pen-based online exams considering specific requirements of pen-and-paper exams. Our approach tracks head and eye orientations and lip movements in each frame and defines the movement as the change of orientation. We relate cheating with frequent coordinated movements of the head, eyes, and lips. We calculate a cheating score indicative of the frequency of movements. A case is marked as a cheating case if the cheating score is higher than the proctor-defined threshold (which may vary depending on the specific requirement of the discipline). The proposed system has five major parts: (1) identification and coordinate extraction of selected facial landmarks using MediaPipe; (2) orientation classification of the head, eye, and lips with K-NN classifier, based on the landmarks; (3) identification of abnormal movements; (4) calculation of a cheating score based on abnormal movement patterns; and (5) a visual representation of students’ behavior to support the proctor for early intervention. Our system is robust since it observes the pattern of movement over a sequence of frames and considers the coordinated movement pattern of the head, eye, and lips rather than considering a single deviation as a cheating behavior which will minimize the false positive cases. Visualization of the student behavior is another strength of our system that enables the human proctor to take preventive measures rather than punishing the student for the final cheating score. We collected video data with the help of 16 student volunteers from the authors’ university who participated in the two well-instructed mock exams: one with cheating and another without cheating. We achieved 100% accuracy in detecting noncheating cases and 87.5% accuracy for cheating cases when the threshold was set to 40.

Commissioning and validation of a novel commercial TPS for ocular proton therapy.

Until today, the majority of ocular proton treatments worldwide were planned with the EYEPLAN treatment planning system (TPS). Recently, the commercial, computed tomography (CT)-based TPS for ocular proton therapy RayOcular was released, which follows the general concepts of model-based treatment planning approach in conjunction with a pencil-beam-type dose algorithm (PBA). To validate RayOcular with respect to two main features: accurate geometrical representation of the eye model and accuracy of its dose calculation algorithm in combination with an Ion Beam Applications (IBA) eye treatment delivery system. Different 3D-printed eye-ball-phantoms were fabricated to test the geometrical representation of the corresponding CT-based model, both in orthogonal 2D images for X-ray image overlay and in fundus view overlaid with a funduscopy. For the latter, the phantom was equipped with a lens matching refraction of the human eye. Funduscopy was acquired in a Zeiss Claus 500 camera. Tantalum clips and fiducials attached to the phantoms were localized in the TPS model, and residual deviations to the actual position in X-ray images for various orientations of the phantom were determined, after the nominal eye orientation was corrected in RayOcular to obtain a best overall fit. In the fundus view, deviations between known and displayed distances were measured. Dose calculation accuracy of the PBA on a 0.2mm grid was investigated by comparing between measured lateral and depth-dose profiles in water for various combinations of range, modulation, and field-size. Ultimately, the modeling of dose distributions behind wedges was tested. A 1D gamma-test was applied, and the lateral and distal penumbra were further compared. Average residuals between model clips and visible clips/fiducials in orthogonal X-ray images were within 0.3mm, including different orientations of the phantom. The differences between measured distances on the registered funduscopy image in the RayOcular fundus view and the known ground-truth were within 1mm up to 10.5mm distance from the posterior pole. No clear benefit projection of either polar mode or camera mode could be identified, the latter mimicking camera properties. Measured dose distributions were reproduced with gamma-test pass-rates of >95% with 2%/0.3mm for depth and lateral profiles in the middle of spread-out Bragg-peaks. Distal falloff and lateral penumbra were within 0.2mm for fields without a wedge. For shallow depths, the agreement was worse, reaching pass-rates down to 80% with 5%/0.3mm when comparing lateral profiles in air. This is caused by low-energy protons from a scatter source in the IBA system not modeled by RayOcular. Dose distributions modified by wedges were reproduced, matching the wedge-induced broadening of the lateral penumbra to within 0.4mm for the investigated cases and showing the excess dose within the field due to wedge scatter. RayOcular was validated for its use with an IBA single scattering delivery nozzle. Geometric modeling of the eye and representation of 2D projections fulfill clinical requirements. The PBA dose calculation reproduces measured distributions and allows explicit handling of wedges, overcoming approximations of simpler dose calculation algorithms used in other systems.

Visuo-tactile heading perception.

Self-motion through an environment induces various sensory signals, i.e., visual, vestibular, auditory, or tactile. Numerous studies have investigated the role of visual and vestibular stimulation for the perception of self-motion direction (heading). Here, we investigated the rarely considered interaction of visual and tactile stimuli in heading perception. Participants were presented optic flow simulating forward self-motion across a horizontal ground plane (visual), airflow toward the participants' forehead (tactile), or both. In separate blocks of trials, participants indicated perceived heading from unimodal visual or tactile or bimodal sensory signals. In bimodal trials, presented headings were either spatially congruent or incongruent with a maximum offset between visual and tactile heading of 30°. To investigate the reference frame in which visuo-tactile heading is encoded, we varied head and eye orientation during presentation of the stimuli. Visual and tactile stimuli were designed to achieve comparable precision of heading reports between modalities. Nevertheless, in bimodal trials heading perception was dominated by the visual stimulus. A change of head orientation had no significant effect on perceived heading, whereas, surprisingly, a change in eye orientation affected tactile heading perception. Overall, we conclude that tactile flow is more important to heading perception than previously thought.NEW & NOTEWORTHY We investigated heading perception from visual-only (optic flow), tactile-only (tactile flow), or bimodal self-motion stimuli in different conditions varying in head and eye position. Overall, heading perception was body or world centered and non-Bayes optimal and revealed a centripetal bias. Although being visually dominated, tactile flow revealed a significant influence during bimodal heading perception.

Effect of hook eye alignment on deep hooking rates for stream‐dwelling trout caught with baited circle and J hooks

It has been well documented that circle hooks generally reduce deep hooking of bait-caught fish. However, for decades there has been speculation that the hook eye must be straight relative to the shank for circle hooks to function properly, yet this aspect of hook configuration has rarely been investigated. Using a passive hook set when strikes were detected, we compared deep hooking rates and catch probability for stream-dwelling trout (Yellowstone cutthroat trout [Oncorhynchus clarkii bouvieri Jordan & Gilbert], rainbow trout [O. mykiss Walbaum], and cutthroat trout × rainbow trout hybrids) caught using baited circle and J hooks with the eye either straight with or turned-up from the shank. Landed fish averaged 26 cm in total length and ranged from 11 to 46 cm. Most fish (83%) were hooked either in the upper or lower jaw, but 16% were hooked deeply (i.e., either in the esophagus or the gills). As expected, the deep hooking rate was lower for circle hooks (10%) than for J hooks (24%). Logistic regression model results indicated that hook eye orientation had no effect on deep-hooking, with deep hooking rates of 11.0% and 8.2% for circle hooks with angled-up and straight eyes, respectively, compared to 21.7% and 25.3% for J hooks with angled-up and straight eyes. Model results also revealed that deep hooking probability differed among anglers but did not differ between species and was not related to fish length. Catch probability (i.e., the proportion of fish strikes that resulted in a landed fish) did not differ between hooks or hook eye orientations. Contrary to some perceptions, our results suggest that changing the angle of the hook eye does not affect deep hooking rates when anglers use baited circle hooks to land stream-dwelling trout.

Eye Position Shifts Body Sway Under Foot Dominance Bias in the Absence of Visual Feedback.

PurposeThe purpose of this study was to investigate whether information on extraocular muscle proprioception without visual information affects postural control.MethodsThirty-five healthy young volunteers participated in the study. Postural control outcomes included the center of pressure (CoP) for static standing, the total length of the sway of the CoP (LNG), and the sway area (SA), as well as the mean CoP in the mediolateral and anteroposterior directions. The following five eye-fixing positions were used: eye-up (E-Up), eye-down (E-Down), eye-right (E-Right), eye-left (E-Left), and eye-center (Center eye position). One-way ANOVA and Bonferroni correction was performed for statistical processing. Electrooculograms were recorded to detect eye orientation errors, measured with the eyes closed.ResultsThe results of this study showed no significant difference between the LNG and SA results when comparing respective eye positions (E-up, E-down, E-right, E-left) relative to E-Center (control). However, the average CoP was shifted to the right at E-Up, E-Down, and E-Left.ConclusionThese findings indicate that postural control may be affected by eye-body coordination depending on the position of the eyes, even without visual information.

Prediction of CW chord as a measure for the eye's orientation axis after cataract surgery from preoperative IOLMaster 700 measurement data.

The angles alpha and kappa are widely discussed for centring refractive procedures, but they cannot be determined with ophthalmic instruments. The purpose of this study is to investigate the Chang-Waring chord (position of the Purkinje reflex PI relative to the corneal centre) derived from an optical biometer before and after cataract surgery and to study the changes resulting from cataract surgery. The analysis was based on a large dataset of 1587 complete sets of preoperative and postoperative IOMaster 700 biometry measurements from two clinical centres, each containing: valid data for pupil and corneal centre position, the position of the Purkinje reflex PI originated from a coaxial fixation target, keratometry (K), axial length (AL), anterior chamber depth (ACD), lens thickness (LT), central corneal thickness CCT, and horizontal corneal diameter W2W. The Chang-Waring chord CW was derived from pupil centre and Purkinje reflex PI analysed preoperatively and postoperatively, and a multilinear regression model together with a feedforward neural network algorithm was set up to predict postoperative CW chord from preoperative CW chord, K and biometric distances of the eye. The Y component of CW chord shows a slight shift in the inferior direction in both left and right eyes, before and after cataract surgery. The X component shows some shift in the temporal direction, which is more pronounced preoperatively and slightly reduced postoperatively but with a larger variation. The change in CW chord from preoperative to postoperative shows a slight shift in the superior and nasal directions. Our algorithms for prediction of postoperative CW chord using preoperative CW chord, keratometry and biometry as input data performed with a multilinear regression and a feedforward neural network approach were able to reduce the variance, but could not properly predict the postoperative CW chord X and Y components. The CW chord as the position of the Purkinje reflex PI with respect to the pupil centre can be directly measured with any biometer, topographer or tomographer with a coaxial fixation light. The mean Y component does not differ between right and left eyes or preoperatively and postoperatively, but the mean temporal shift of the X component preoperatively is slightly reduced postoperatively, but with a larger scatter of the values.

Spatial Neglect Midline Diagnostics From Virtual Reality and Eye Tracking in a Free-Viewing Environment.

Purpose: Virtual reality (VR) and eye tracking may provide detailed insights into spatial cognition. We hypothesized that virtual reality and eye tracking may be used to assess sub-types of spatial neglect in stroke patients not readily available from conventional assessments.Method: Eighteen stroke patients with spatial neglect and 16 age and gender matched healthy subjects wearing VR headsets were asked to look around freely in a symmetric 3D museum scene with three pictures. Asymmetry of performance was analyzed to reveal group-level differences and possible neglect sub-types on an individual level.Results: Four out of six VR and eye tracking measures revealed significant differences between patients and controls in this free-viewing task. Gaze-asymmetry between-pictures (including fixation time and count) and head orientation were most sensitive to spatial neglect behavior on a group level analysis. Gaze-asymmetry and head orientation each identified 10 out of 18 (56%), compared to 12 out of 18 (67%) for the best conventional test. Two neglect patients without deviant performance on conventional measures were captured by the VR and eyetracking measures. On the individual level, five stroke patients revealed deviant gaze-asymmetry within-pictures and six patients revealed deviant eye orientation in either direction that were not captured by the group-level analysis.Conclusion: This study is a first step in using VR in combination with eye tracking measures as individual differential neglect subtype diagnostics. This may pave the way for more sensitive and elaborate sub-type diagnostics of spatial neglect that may respond differently to various treatment approaches.

Further delineation and long-term evolution of electroclinical phenotype in Mowat Wilson Syndrome. A longitudinal study in 40 individuals

BackgroundEpilepsy is a main feature of Mowat Wilson Syndrome (MWS), a congenital malformation syndrome caused by ZEB2 variants. The aim of this study was to investigate the long-term evolution of the electroclinical phenotype of MWS in a large population. MethodsForty-individuals with a genetically confirmed diagnosis were enrolled. Three age groups were identified (t1 = 0–4; t2 = 5–12; t3 = >13 years); clinical data and EEG records were collected, analyzed, and compared for age group. Video-EEG recorded seizures were reviewed. ResultsThirty-six of 40 individuals had epilepsy, of whom 35/35 aged >5 years. Almost all (35/36) presented focal seizures at onset (mean age at onset 3.4 ± 2.3 SD) that persisted, reduced in frequency, in 7/22 individuals after the age of 13. Absences occurred in 22/36 (mean age at onset 7.2 ± 0.9 SD); no one had absences before 6 and over 16 years old. Paroxysmal interictal abnormalities in sleep also followed an age-dependent evolution with a significant increase in frequency at school age (p = 0.002) and a reduction during adolescence (p = 0.008). Electrical Status Epilepticus during Sleep occurred in 14/36 (13/14 aged 5–13 years old at onset). Seven focal seizure ictal video-EEGs were collected: all were long-lasting and more visible clinical signs were often preceded by prolonged electrical and/or subtle (erratic head and eye orientation) seizures.Valproic acid was confirmed as the most widely used and effective drug, followed by levetiracetam. ConclusionsEpilepsy is a major sign of MWS with a characteristic, age-dependent, electroclinical pattern. Improvement with adolescence/adulthood is usually observed. Our data strengthen the hypothesis of a GABAergic transmission imbalance underlying ZEB2-related epilepsy.

Modelling 3D saccade generation by feedforward optimal control.

An interesting problem for the human saccadic eye-movement system is how to deal with the degrees-of-freedom problem: the six extra-ocular muscles provide three rotational degrees of freedom, while only two are needed to point gaze at any direction. Measurements show that 3D eye orientations during head-fixed saccades in far-viewing conditions lie in Listing's plane (LP), in which the eye's cyclotorsion is zero (Listing's law, LL). Moreover, while saccades are executed as single-axis rotations around a stable eye-angular velocity axis, they follow straight trajectories in LP. Another distinctive saccade property is their nonlinear main-sequence dynamics: the affine relationship between saccade size and movement duration, and the saturation of peak velocity with amplitude. To explain all these properties, we developed a computational model, based on a simplified and upscaled robotic prototype of an eye with 3 degrees of freedom, driven by three independent motor commands, coupled to three antagonistic elastic muscle pairs. As the robotic prototype was not intended to faithfully mimic the detailed biomechanics of the human eye, we did not impose specific prior mechanical constraints on the ocular plant that could, by themselves, generate Listing's law and the main-sequence. Instead, our goal was to study how these properties can emerge from the application of optimal control principles to simplified eye models. We performed a numerical linearization of the nonlinear system dynamics around the origin using system identification techniques, and developed open-loop controllers for 3D saccade generation. Applying optimal control to the simulated model, could reproduce both Listing's law and and the main-sequence. We verified the contribution of different terms in the cost optimization functional to realistic 3D saccade behavior, and identified four essential terms: total energy expenditure by the motors, movement duration, gaze accuracy, and the total static force exerted by the muscles during fixation. Our findings suggest that Listing's law, as well as the saccade dynamics and their trajectories, may all emerge from the same common mechanism that aims to optimize speed-accuracy trade-off for saccades, while minimizing the total muscle force during eccentric fixation.

眼内房水流动的数值研究

The study of intraocular aqueous humor (AH) flow is helpful to understand the mechanism of some eye diseases such as glaucoma. A numerical study of AH flow inside human eyes with the computational fluid dynamics (CFD) were carried out to address the following flow processes: AH secreted in the posterior chamber by the ciliary body entering the anterior chamber through the iris-lens gap of 5 μm and 30 μm respectively, and discharging through the trabecular meshwork (TM). Detailed flow fields in different eye orientations were analyzed. Results show that, in general the intraocular pressure distributions are similar in all cases; the pressure in the posterior chamber is around 30 Pa higher than that in the anterior chamber with the 5 μm iris-lens gap, and they are almost equal with the 30 μm iris-lens gap. The pressure drop in the TM is noticeable. The pressure difference between the anterior and posterior chambers drives AH from the posterior chamber to the anterior chamber, while the temperature difference between cornea and iris surfaces causes the natural convection, which is the dominant flow in the anterior chamber. The pressure difference due to natural convection is in the magnitude of millipascal, and the higher-pressure region forms where warmer AH gathers. For the vertical orientation, warmer fluid rises along the iris surface and then turns downwards as it encounters the higher resistance in the upper TM regions. The flow then descends along the corneal surface toward the lower TM. For the upward-facing position, AH entering the pupil rises along the center line of the anterior chamber, and moves down along the cornea surface leading to 2 large symmetric recirculation zones. For the downward-facing position, the circulation route is opposite to that of the upward-facing position. With no buoyancy, the averaged velocity will be 1 to 2 orders of magnitude smaller than that with buoyancy.

Low-Noise Magnetic Coil System for Recording 3-Dimensional Eye Movements.

Vestibular and oculomotor research often requires measurement of 3-dimensional (3D) eye orientation and movement with high spatial and temporal precision and accuracy. We describe the design, implementation, validation and use of a new magnetic coil system optimized for recording 3D eye movements using small scleral coils in animals. Like older systems, the system design uses off-the-shelf components to drive three mutually orthogonal alternating magnetic fields at different frequencies. The scleral coil voltage induced by those fields is decomposed into 3 signals, each related to the coil's orientation relative to the axis of one field component. Unlike older systems based on analog demodulation and filtering, this system uses a field-programmable gate array (FPGA) to oversample each induced scleral coil voltage (at 25 Msamples/s), demodulate in the digital domain, and average over 25 ksamples per data point to generate 1 ksamples/s output in real time. Noise floor is <0.036° peak-to-peak and linearity error is < 0.1° during 345° rotations in all three dimensions. This FPGA-based design, which is both reprogrammable and freely available upon request, delivers sufficient performance to record eye movements at high spatial and temporal precision and accuracy using coils small enough for use with small animals.

Numerical modeling of therapeutic lens drug delivery in the anterior human eye for the treatment of primary open-angle glaucoma.

A numerical model of drug delivery from a therapeutic lens in the anterior portion of the human eye has been developed for a more effective treatment plan of primary open-angle glaucoma. The numerical model takes into account the drug diffusion through the therapeutic lens along with heat transfer and aqueous humor flow in different orientations of the human eye (supine (two-dimensional) as well as standing (three-dimensional)). Results illustrate that the drug diffuses through the therapeutic lens to the cornea and is convected into the anterior chamber of the eye due to the temperature gradient across the eye. In addition, eye orientation significantly affects drug delivery with supine orientation providing better and uniform drug exposure in different target regions of the eye as compared to standing in the case of the therapeutic lens. Furthermore, a comparison of the therapeutic efficacy of the therapeutic lens has been done with topical administration and the drug uptake results from both the drug delivery modes have been validated with the experimental data reported in the literature. The developed model may help ophthalmologists to comprehend the transport and retention of different drugs in different domains and orientations of the human eye when administered through a therapeutic lens.

Classification of pachychoroid disease on ultrawide-field indocyanine green angiography using auto-machine learning platform

AimsAutomatic identification of pachychoroid maybe used as an adjunctive method to confirm the condition and be of help in treatment for macular diseases. This study investigated the feasibility of classifying...

Accurate Real‐time 3D Gaze Tracking Using a Lightweight Eyeball Calibration

Abstract3D gaze tracking from a single RGB camera is very challenging due to the lack of information in determining the accurate gaze target from a monocular RGB sequence. The eyes tend to occupy only a small portion of the video, and even small errors in estimated eye orientations can lead to very large errors in the triangulated gaze target. We overcome these difficulties with a novel lightweight eyeball calibration scheme that determines the user‐specific visual axis, eyeball size and position in the head. Unlike the previous calibration techniques, we do not need the ground truth positions of the gaze points. In the online stage, gaze is tracked by a new gaze fitting algorithm, and refined by a 3D gaze regression method to correct for bias errors. Our regression is pre‐trained on several individuals and works well for novel users. After the lightweight one‐time user calibration, our method operates in real time. Experiments show that our technique achieves state‐of‐the‐art accuracy in gaze angle estimation, and we demonstrate applications of 3D gaze target tracking and gaze retargeting to an animated 3D character.

Initiation and response of joint attention bids in autism spectrum disorder children depend on the visibility of the target.

Response to joint attention (RJA) and initiation of joint attention (IJA) are impaired in pre-schoolers with autism spectrum disorder (ASD). Children's response to joint attention may depend on the presence of the target in the child's field of vision or on the type of deictic index (head and eye orientation, pointing and verbalisations) used by the adult to initiate joint attention. This study deals with 50 ASD children aged from 2 years 8 months to 11 years 7 months, with a communicative level comparable to children under 31 months of age, according to the French version of the Early Social Communication Scales (ECSP, by its French acronym). We compared the aforementioned ASD children with 50 typically developing (TD) children, aged 9 to 30 months who had no communication disorders according to the ECSP. During the ECSP test, we analysed joint attention behaviours on three posters present or absent from the children's visual field. We did not observe any difference in the number of IJAs between groups, but ASD children were less responsive than TD children were. Our results showed a developmental progression in the responses of children with ASD if several deictic cues were used by an adult simultaneously (looking and pointing, or looking and verbalising to indicate a target), whether the referent was present or absent from the child's visual field. In addition, we observed developmental progression when the referent was behind the child and the adult only used their gaze to refer to it. Thus, we argue that the type of cues used affects ASD children's response behaviours during joint attention towards a referent that may be present or absent from their visual field.Implications: Regarding the social and the sensory difficulties of children with ASD, many therapeutic approaches focus their intervention methods on non-verbal communication skills and joint attention. This fundamental research makes it possible to identify the most appropriate type of deictic index for children with ASD with developmental delay, depending on the presence or absence of the referent in the child's visual field.

Saccade-induced changes in ocular torsion reveal predictive orientation perception.

Natural orienting of gaze often results in a retinal image that is rotated relative to space due to ocular torsion. However, we perceive neither this rotation nor a moving world despite visual rotational motion on the retina. This perceptual stability is often attributed to the phenomenon known as predictive remapping, but the current remapping literature ignores this torsional component. In addition, studies often simply measure remapping across either space or features (e.g., orientation) but in natural circumstances, both components are bound together for stable perception. One natural circumstance in which the perceptual system must account for the current and future eye orientation to correctly interpret the orientation of external stimuli occurs during movements to or from oblique eye orientations (i.e., eye orientations with both a horizontal and vertical angular component relative to the primary position). Here we took advantage of oblique eye orientation-induced ocular torsion to examine perisaccadic orientation perception. First, we found that orientation perception was largely predicted by the rotated retinal image. Second, we observed a presaccadic remapping of orientation perception consistent with maintaining a stable (but spatially inaccurate) retinocentric perception throughout the saccade. These findings strongly suggest that our seamless perceptual stability relies on retinocentric signals that are predictively remapped in all three ocular dimensions with each saccade.