Fixation Position Research Articles

Transient hyphema associated with PRESERFLO® MicroShunt surgery using a double-step knife in patients with glaucoma

To report the frequency of hyphema after PRESERFLO® MicroShunt (PMS) surgery using double-step knife in patients with glaucoma and to investigate its relationship with the tube insertion position. Glaucoma patients who underwent PMS surgery were reviewed. Hyphema was defined as visible hemorrhage in the anterior chamber. The insertion position of PMS was confirmed via gonioscopy. Patient backgrounds in the hyphema and non-hyphema groups were compared, and the course of visual acuity (VA), intraocular pressure (IOP), and time to resolution of hyphema were investigated. 65 of 66 eyes were eligible for consideration. Hyphema had occurred in 23 (35%) eyes. At the end of surgery, anterior chamber bleeding was observed under the microscope in 8 of 23 cases (35%). The tube fixation position was on the scleral spur (25 eyes), on the trabecular meshwork (27 eyes), on the Schwalbe line (10 eyes) and on the corneal side (3 eyes). There was no significant difference of the site of tube insertion between the two groups. All cases of hyphema spontaneously resolved within a few weeks, with stable IOP and recovered VA. It is worth noting that in PMS surgery using the double-step knife, hyphema may occur high frequency even if the tube insertion site is accurately positioned. Patients should be informed of the risk of hyphema before the surgery.

Different Evaluation Strategies of Oncological CT Examinations with Regard to Professional Experience: A Clinical Study Using Eye-tracking.

Contrast-enhanced CT is the standard imaging technique in oncological objectives. Rates of missed pathologies depend on work experience of the respective radiologists. Thus the aim of this study is to analyze the eye movements of professionals while reading CT images in order to evaluate whether the eye-fixation patterns and search strategies of experienced radiologists could explain higher detection rates of pathologies and whether such patterns can be learned.Anonymized images of 10 patients were presented to three medical students and six radiologists with different levels of work experience. During image analysis, ocular fixation positions were recorded using an eye-tracking software tool. The CT scans were analyzed retrospectively, considering the individual course of disease with the issue of successful detection of all pathologies. Visual attention and dwell time of ocular fixation on clinically important abnormalities or areas with pathological findings, general search patterns, and time efficiency were assessed. For statistical analysis, interobserver variability and accuracy of lesion detection were evaluated taking into account individual experience.The results revealed that observer sensitivity depends on work experience due to a more systematic order of inspection and a well-known course of disease, e.g. in case of metastatic spread. The areas of missed pathologies mostly included secondary findings. Inexperienced readers changed the stratification considerably more often and required more time for reporting or detecting pathologies.Our results suggest that experienced radiological physicians reduce their amount of missed findings by looking more systematically at images and by applying a more targeted inspection of clinically important regions. · CT interpretation by radiology residents is faster and less error-prone compared to postgraduate residents. · systematic image analysis is trainable. · engrams tend to be acquired through experience. · Kluge S, Schülke C, Ites HC et al. Different Evaluation Strategies of Oncological CT Examinations with Regard to Professional Experience: A Clinical Study Using Eye-tracking. Fortschr Röntgenstr 2024; DOI 10.1055/a-2452-2180.

Safety and Feasibility of Internal Fixation Using Bioabsorbable Versus Titanium Materials for Short-Level Lamina Reimplantation: A Comparative Clinical Study.

Lamina-implantation is gradually becoming the main surgical method for the treatment of intraspinal tumors. Traditional titanium (Ti) internal fixation not only produces artifacts, which affects the observation of tumors and dural sac closure, but also faces the problem of secondary surgical removal. In this study, absorbable material were used in lamina replantation for the first time and was evaluated for its efficacy and safety. We retrospectively enrolled patients who underwent short-segment lamina replantation for intraspinal tumors in our center from February 2020 to November 2022. After condition matching of the number of fixation segment and fixation position, the baseline information, complications, neurological function, quality of life, spinal mobility and bone healing rate of the absorbable group and the Ti group were compared. Fisher exact, Chi-square, or rank sum test were used for categorical variables, and t-test was used for continuous variables to distinguish differences between groups. Cerebrospinal fluid leak was the most common complication, with no difference between the two groups (12.9% vs. 19.4%, p = 0.366). The bone healing rates of the two groups at 3 months after surgery were 77.4% and 87.1%, respectively, and there was no significant difference (p = 0.508). At 1 year after surgery, the resorbable group showedlower levels of anxiety/depression (1.20 ± 0.41 vs. 1.61 ± 0.61, p = 0.050), however, it did not affect the overall quality of life of the patients at 1 year. Both titanium and absorbable internal fixation have shown good clinical results in the treatment of intraspinal tumors by laminareplantation. Regardless of cost, absorbable screws and plates are also suitable optionsfor patients undergoing lamina replantation, because it has no stress shielding effect and does not require secondary removal. In addition, there are no artifacts in the image, which is more conducive to observing the recurrence of the tumor and the closure of the dural sac.

A clinical study on the effect of axillary approach in the treatment of Ideberg type II scapular glenoid fractures

BackgroundDue to its deep position and complex surrounding anatomy, the scapular glenoid fracture was relatively difficult to deal with especially in cases of severe fracture displacement. Improper treatment may lead to failure of internal fixation and poor fracture reduction, severely affecting the function of the shoulder joint. Inferior scapular glenoid fracture was Ideberg type II fracture, and posterior approach was commonly used to deal with inferior scapular glenoid fracture. However, there are shortcomings of above surgical approach for inferior scapular glenoid fracture, such as insufficient exposure of the operative field, significant trauma, and limited screw fixation direction. This study adopts the axillary approach for surgery, which has certain advantages.MethodsThe clinical data of 13 patients with Ideberg type II scapular glenoid fractures treated from December 2018 to January 2024 were retrospectively analyzed. There were 8 males and 5 females, with an age range of 19 to 58 years and an average age of 38 years. The causes of injury were falls from heights in 7 cases and car accidents in 6 cases. There were 5 cases on the left side and 8 cases on the right side. The time from injury to surgery was 2 to 11 days, with an average of 5.5 days. All cases underwent open reduction and internal fixation through the axillary approach. Postoperative X-ray and CT three-dimensional reconstruction were performed on the next day to evaluate the fracture reduction and the position of internal fixation. During the follow-up period, follow-up examinations were performed every two months in the first half of the year and every three months in the second half. CT scans were performed during the examinations to assess the glenohumeral joint congruence, fracture healing, and position of internal fixation. The shoulder joint function was evaluated at 6 months postoperatively according to the Constant-Murley value score.ResultsThe patients all achieved primary wound healing after surgery, without any complications such as infection or nerve injury. Re-examination on the second day after operation, all fractures obtained excellent reduction, and the internal fixation was in excellent position, and no screw was found to enter the joint cavity. All patients in this group were followed up for 6 to 25 months, with an average follow-up time of 11.7 months. All fractures were bony unioned, and the healing time ranged from 4 to 6 months, with an average healing time of 4.8 months. At 6-month follow-up, according to the Constant-Murley score, 11 cases were excellent and 2 case was good.ConclusionOpen reduction and internal fixation through the axillary approach is an feasible and safe surgical method for the treatment in scapular Ideberg type II glenoid fractures with less stripping of soft tissue, minimal surgical trauma, and the incision is concealed and beautiful. It can provide a strong internal fixation for fractures, so patients can perform functional exercise early after operation, and the clinical results is satisfactory.

Finite element analysis of fixation stability according to reduction position for internal fixation of intertrochanteric fractures

In recent years, finite element analysis (FEA) has been instrumental in comparing the biomechanical stability of various implants for femur fracture treatment and in studying the advantages and disadvantages of different surgical techniques. This analysis has proven helpful for enhancing clinical treatment outcomes. Therefore, this study aimed to numerically analyze fixed stability according to location using FEA. In this study, a virtual finite element model was created based on a clinically anatomically reduced patient. It incorporated positive and negative support derived from intramedullary and extramedullary reduction from the anteroposterior (AP) view and neutral support from the lateral view. The generated model was analyzed to understand the biomechanical behavior occurring in each region under applied physiological loads. The simulation results of this study showed that the average von Mises stress (AVMS) of the nail when performing intramedullary reduction for femoral fixation was 187% of the anatomical reduction and 171% of the extramedullary reduction, and individually up to 2.5 times higher. In other words, intramedullary reduction had a very high possibility of fixation failure compared to other reduction methods. This risk is amplified significantly, especially in situations where bone strength is compromised due to factors such as old age or osteoporosis, which substantially affects the stability of fixation. Extramedullary reduction, when appropriately positioned, demonstrates greater stability than anatomical reduction. It exhibits stable fixation even in scenarios with diminished bone strength. In instances in which the bone density was low in the support position, as observed in the lateral view, the AVMS on the nail appeared to be relatively low, particularly in cases of positive support. Additionally, the femur experienced lower equivalent stress only in the extramedullary reduction-negative position. Moreover, by comparing different reduction methods and bone stiffness values using the same femoral shape, this study offers insights into the selection of appropriate reduction methods. These insights could significantly inform decision making regarding surgical strategies for intertrochanteric fractures.

Posterior Wall Fragments in Acetabular Both-Column Fractures: Morphology, Type, and the Significance of its Projection.

Most both-column acetabular fractures are combined with posterior wall fragments. However, the morphology of this posterior wall is varied, and how to fix this posterior wall remains a controversial topic. To investigate the morphological characteristics of posterior wall fragments of both-column acetabular fractures and select corresponding fixation methods. Data from 352 patients with acetabular fractures admitted to the level one trauma centre in our hospital between January 2006 and December 2022 were collected. The morphology of posterior wall fragments was observed and analyzed in 83 cases of both-column acetabular fractures and classified according to the consistency of posterior wall morphology. A fracture map of the posterior wall was created on a normal template according to the three morphological types of posterior wall fragments. Finally, the high-incidence area of the posterior wall fracture was projected onto the iliac fossa and the medial side of the posterior column to guide the fixation of the posterior wall fragment using the anterior intrapelvic approach. Fractures were divided into four types: I, large posterior wall fragment which was high in the ilium bone (34 cases, 41.0%); II, posterior wall fragment in the acetabular parietal region (18 cases, 21.7%); III, posterior wall marginal fracture (10 cases, 12.0%); and IV, non-combined posterior wall fracture (21 cases, 25.3%). The most common morphologies of the posterior wall fragments of the first two types were mapped and projected onto the anterior iliac inner plate and medial side of the posterior column, where the corresponding area could be used to guide the insertion of the internal fixation. Both-column acetabular fractures combined with posterior wall fractures can be divided into four types according to the morphology of the posterior wall fragment. Understanding the corresponding three-dimensional morphology and projection position of different types of these fragments can help surgeons determine the position and orientation of internal fixation of posterior wall fractures.

Computer-Assisted Preoperative Simulation and Augmented Reality for Plate Fixation Positioning in Genioplasty

Computer-Assisted Preoperative Simulation and Augmented Reality for Plate Fixation Positioning in Genioplasty

Anatomical study of the limited osteotomy suture button fixation Latarjet procedure with coracoacromial ligament preservation

To investigate the morphological characteristics of the glenohumeral joint (including the glenoid and coracoid) in the Chinese population and determine the feasibility of designing coracoid osteotomy based on the preoperative glenoid defect arc length by constructing glenoid defect models and simulating suture button fixation Latarjet procedure. Twelve shoulder joint specimens from 6 adult cadavers donated voluntarily were harvested. First, whether the coracoacromial ligament and conjoint tendon connected was anatomically observed and their intersection point was identified. The vertical distance from the intersection point to the coracoid, the maximum allowable osteotomy length starting from the intersection point, and the maximum osteotomy angle were measured. Next, the anteroinferior glenoid defect models of different degrees were randomly constructed. The arc length and area of the glenoid defect were measured. Based on the arc length of the glenoid defect of the model, the size of coracoid oblique osteotomy was designed and the actual length and angle of the coracoid osteotomy were measured. A limited osteotomy suture button fixation Latarjet procedure with the coracoacromial ligament and pectoralis minor preservation was performed and the position of coracoid block was observed. All shoulder joint specimens exhibited crossing fibers between the coracoacromial ligament and the conjoint tendon. The vertical distance from the tip of the coracoid to the coracoid return point was 24.8-32.2 mm (mean, 28.5 mm). The maximum allowable osteotomy length starting from the intersection point was 26.7-36.9 mm (mean, 32.0 mm). The maximum osteotomy angle was 58.8°-71.9° (mean, 63.5°). Based on the anteroinferior glenoid defect model, the arc length of the glenoid defect was 22.6-29.4 mm (mean, 26.0 mm); the ratio of glenoid defect was 20.8%-26.2% (mean, 23.7%). Based on the coracoid block, the length of the coracoid osteotomy was 23.5-31.4 mm (mean, 26.4 mm); the osteotomy angle was 51.3°-69.2° (mean, 57.1°). There was no significant difference between the arc length of the glenoid defect and the length of the coracoid osteotomy ( P>0.05). After simulating the suture button fixation Latarjet procedure, the highest points of the coracoid block (suture loop fixation position) in all models located below the optimal center point, with the bone block concentrated in the anteroinferior glenoid defect position. The size of the coracoid is generally sufficient to meet the needs of repairing larger glenoid defects. The oblique osteotomy with preserving the coracoacromial ligament may potentially replace the traditional Latarjet osteotomy method.

Comparison of Treatment Outcomes of Different Immobilized Finger Positions After Repair of Flexor Tendon Rupture in Zones I and II: A Nonrandomized Controlled Trial With Historical Control Group.

Introduction The position of finger immobilization after flexor tendon rupture repair is changed to the extended position to prevent flexion contracture of the interphalangeal (IP) joint. However, in Strickland's assessment, We believe that a reduction in TAF (total active flexion) affects the outcome and that extension fixation is not necessarily the primary focus.For example, there are management methods that swap the fixed position between day and night. It is assumed that some effect is sought by placing the fingers in the flexed position. That is, the method of fixation is currently selected at individual facilities through twists and turns; however,the indications and criteria for selecting finger fixation positions are ambiguous, and they are apparently subject to the experience of therapists. This study aimed to characterize follow-up outcomes of flexion and extension fixation after zones I and II flexor tendon rupture repair. Methods This nonrandomized controlled trial with historical controls included 25 patients with flexor tendon ruptures of 30 fingers. The flexion fixation group consisted of 12 patients (n=16 fingers) and the extension fixation group consisted of 13 patients (n=14 fingers). The group with flexion fixation comprised patients who slept with their injured fingers in the flexed position (intervention group). The group with extension was retrospectively selected between April 2017 and March 2019, who slept with their injured finger in the extended position (historical control group). Strickland assessments of the range of motion (ROM) of each joint at the conclusion of hand therapy, the ratio of total active motion of the repaired, to the healthy finger (%TAF), and IP joint extension limitation angles were compared using Mann-Whitney U tests. Ratios of excellent and good ratings based on the Strickland assessment were compared using Fisher exact tests. Result The results of the Strickland assessment showed excellent or goodoutcomes for 22(73%) of 30 fingers, which was in line with our previous findings. Strickland ratings of excellent were achieved in seven (44%) of 16 fingers and four (28%) of 14 fingers in the groups with flexion and extension fixation, respectively. The outcomes for two (22%) of 16 fingers and seven (78%) of 14 fingers in the groups with flexion and extension fixation were, respectively, rated asgood. The proportion of patients rated as excellent was significantly higher in the group with flexionthan extension fixation (p=0.040). The %TAF and the active flexion angle of the distal interphalangeal (DIP) joint were higher in the group with flexionthan extension fixation (p=0008 and p=0.025, respectively). Furthermore, the total angle of the IP joint limit of extension did not significantly differ between the groups. Conclusion Flexion fixation after flexor tendon rupture achieved an excellent Strickland rating and was more effective than extension fixation, especially in terms of the active flexion ROM of the DIP joint. Flexion fixation might be an alternative to extension fixation because the range of flexion should be greater and might provide a range of finger extension motion equivalent to that of extension fixation.

Progress of anterior subcutaneous internal fixation in the treatment of anterior pelvic ring injury

Anterior subcutaneous internal fixation (INFIX) is one of the current representatives of minimally invasive fixation of injuries to the anterior pelvic ring. The nail insertion point of this technique is located at the anterior inferior iliac spinous screw, with an angle of 30° outward and 20° backward. Screw in at an angle, and note that the screw head should be above the deep fascia and maintain a safe distance of 20 to 25 mm from the bone surface. Its improved versions include 3 or 4 nails INFIX with added pubic tubercle screws, unilateral INFIX, short-rod INFIX, and double INFIX. These improvements further enhance stability. The lateral femoral cutaneous nerve (LFCN) is relatively easy to be damaged during anatomy, so special attention should be paid during the operation. Biomechanical stability has advantages over external fixation, and its application is flexible. It is not limited to pubic ramus fracture, symphyseal separation, etc. It also plays an important role in combined anterior and posterior ring fixation. It can be combined with posterior sacroiliac screws, iliac lumbar screws, etc. Fixed etc. Good clinical results have also been reported in children, pregnant women, and people with contraindications for subcutaneous connecting rods. In addition, the current application of robots, reduction frames and other technologies has greatly reduced the difficulty of reduction and improved the quality of closed reduction, making it possible to fix complex pelvic fracture. This technique has high reduction quality and is as effective as traditional steel plates. A common complication is LFCN injury. Careful exposure and adjustment of the position and depth of internal fixation during surgery can effectively avoid this complication.

The influence of bone block graft position on bone dimensional changes in staged onlay horizontal ridge augmentation: A 6-month retrospective cohort study.

To analyze changes in bone dimensions and their modulating factor in bone dimensions 6 months after horizontal ridge augmentation using autogenous bone grafts. Thirty-eight patients with horizontally atrophic alveolar ridges of a single edentulous tooth at the maxillary anterior site were divided into two groups based on the fixation position of the bone block during ridge augmentation surgery (H0, vertical distance from the upper edge of the bone block to the alveolar crest). Patients were classified into a crestal level (CL) group if H0 ≤ 1 mm and a sub-crestal level (SCL) group if H0 > 1 mm. The width and height of the alveolar ridge were recorded using CBCT both before and 6 months after the augmentation procedure. The CL group comprised 20 patients with 23 implants, whereas the SCL group comprised 18 patients with 22 implants. All the augmentation sites exhibited vertical bone resorption. Vertical bone resorption in the SCL group (1.94 ± 2.11 mm) was significantly higher than that of the CL group (0.61 ± 0.64 mm). The SCL group showed significantly lower horizontal bone gain than the CL group (SCL: 1.02 ± 2.30 mm; CL: 3.19 ± 3.17 mm) at the cervical level. Peri-implant marginal bone loss increased significantly in the SCL group (1.00 ± 2.71 mm) compared to the CL group (0.64 ± 0.40 mm). The bone height decreased after horizontal ridge augmentation using autogenous onlay grafting. The fixation position of the bone block was a modulating factor. The SCL group showed more vertical bone loss, less horizontal bone gain 6 months after surgery, and more marginal bone loss after restoration.

Analysis and regulation of driving behavior in the entrance zone of freeway tunnels: Implementation of visual guidance systems in China

In China, visual guidance systems are commonly used in tunnels to optimize the visual reference system. However, studies focusing specifically on visual guidance systems in the tunnel entrance zone are limited. Hence, a driving simulation test is performed in this study to quantitatively evaluate the effectiveness of (i) visual guidance devices at different vertical positions (pavement and roadside) and (ii) a multilayer visual guidance system for regulating driving behavior in the tunnel entrance zone. Furthermore, the characteristics of driving behavior and their effects on traffic safety in the tunnel entrance zone are examined. Data such as the vehicle position, area of interest (AOI), throttle position, steering wheel angle, and lane center offset are obtained using a driving simulation platform and an eye-tracking device. As indicators, the first fixation position (FP), starting deceleration position (DP), average throttle position (TPav), number of deceleration stages (N|DS), gradual change degree of the vehicle trajectory (G|VT), and average steering wheel angle (SWAav) are derived. The regulatory effect of visual guidance devices on driving performance is investigated. First, high-position roadside visual guidance devices effectively reduce decision urgency and significantly enhance deceleration and lane-keeping performance. Specifically, the advanced deceleration performance (AD), smooth deceleration performance (SD), trajectory gradualness (TG), and trajectory stability (TS) in the tunnel entrance zone improve by 63%, 225%, 269%, and 244%, respectively. Additionally, the roadside low-position visual guidance devices primarily target the trajectory gradualness (TG), thus resulting in improvements by 80% and 448% in the TG and TS, respectively. Meanwhile, the pavement visual guidance devices focus solely on enhancing the TS and demonstrates a relatively lower improvement rate of 99%. Finally, the synergistic effect of these visual guidance devices facilitates the multilayer visual guidance system in enhancing the deceleration and lane-keeping performance. This aids drivers in early detection and deceleration at the tunnel entrance zone, reduces the urgency of deceleration decisions, promotes smoother deceleration, and improves the gradualness and stability of trajectories.

Lingering on distraction: Examining distractor rejection in adults with ADHD

ABSTRACT Effective visual search relies on reactively disengaging from distractors when the features of the distractors are unpredictable. Does this ability differ between adults with and without Attention-Deficit/Hyperactivity Disorder (ADHD)?. Participants (36 with ADHD, 46 non-ADHD) completed the additional-singleton task, in which they searched for a unique shape while a uniquely coloured distractor unpredictably appeared on half of the trials. The distractor delayed manual response times in both groups, with no significant group difference. Both groups also demonstrated similar oculomotor capture effects, as indicated by the landing position of initial fixations. However, when initial fixations did land on the distractor, participants with ADHD tended to “linger” on the distractor with additional fixations and longer duration before disengaging from it, compared to those without ADHD. These results suggest that ADHD is associated with deficits in reactively disengaging from distractions rather than deficits in avoiding being captured in the first place.

Effect of Fixed Position on Critical Performance of Aortic Valve in Vitro Testing

Objective — To determine the optimal fixation position by studying the effect of valve and valve fixation position on the key performance during in vitro hydrodynamic testing. Methods — Two self-expanding transcatheter aortic valves were fixed in three different ring positions, tested according to ISO 5840 standard method, and the key performance results were compared and analyzed. Results — When the fixed position of valve and valve ring was aligned with the bottom edge, the mean arterial pressure and regurgitant fraction were the smallest and the effective orifice area was larger. Conclusion — The fixed position of the valve and valve ring has a certain influence on the key performance of the hydrodynamic testing during in vitro testing. The lower fixed position will lead to the smaller effective orifice area. The higher fixed position will lead to the higher regurgitant fraction. Therefore, the optimal fixed position should be determined before the in vitro testing of the aortic valve.

Biomechanical Evaluation of Cannulated Screw Optimization for Stabilization of Pauwels Type Femoral Neck Fractures

Triangular screw configuration (TSC) fixation is widely used in clinics for femoral neck fractures, and the appropriate positions of TSC fixation have not been fully described in the literature. This study investigated the optimal fixation of femoral neck fractures with TSC fixation under nonstandard Pauwels angles to determine the ideal position. To determine the optimal fracture line angle and cannulated screw positions, the Pauwels angle and Rotation and Translate variables were parametrically defined in the fracture line and cannulated screw positions. Considering the equivalent stresses on the fracture surfaces, the effectiveness values of the Rotation and Translate 1, 2 and 3 variables are weak, whereas the effectiveness value of the Pauwels angle is high. Considering the equivalent stress on the screws and that the variable value of Translates 1, 2 and 3 is 7 mm, it can be seen that the reverse triangulation configuration is better, and the Pauwels angle is approximately 54°. Among the parameters examined in the study, Pauwels angle was found to have the highest level of effectiveness on femoral neck fracture surfaces and screws. The findings in this study provide a solid basis for future research; however, further clinical research is warranted.

SpFormer: Spatio-Temporal Modeling for Scanpaths with Transformer

Saccadic scanpath, a data representation of human visual behavior, has received broad interest in multiple domains. Scanpath is a complex eye-tracking data modality that includes the sequences of fixation positions and fixation duration, coupled with image information. However, previous methods usually face the spatial misalignment problem of fixation features and loss of critical temporal data (including temporal correlation and fixation duration). In this study, we propose a Transformer-based scanpath model, SpFormer, to alleviate these problems. First, we propose a fixation-centric paradigm to extract the aligned spatial fixation features and tokenize the scanpaths. Then, according to the visual working memory mechanism, we design a local meta attention to reduce the semantic redundancy of fixations and guide the model to focus on the meta scanpath. Finally, we progressively integrate the duration information and fuse it with the fixation features to solve the problem of ambiguous location with the Transformer block increasing. We conduct extensive experiments on four databases under three tasks. The SpFormer establishes new state-of-the-art results in distinct settings, verifying its flexibility and versatility in practical applications. The code can be obtained from https://github.com/wenqizhong/SpFormer.

Individual differences in human gaze behavior generalize from faces to objects

Individuals differ in where they fixate on a face, with some looking closer to the eyes while others prefer the mouth region. These individual biases are highly robust, generalize from the lab to the outside world, and have been associated with social cognition and associated disorders. However, it is unclear, whether these biases are specific to faces or influenced by domain-general mechanisms of vision. Here, we juxtaposed these hypotheses by testing whether individual face fixation biases generalize to inanimate objects. We analyzed >1.8 million fixations toward faces and objects in complex natural scenes from 405 participants tested in multiple labs. Consistent interindividual differences in fixation positions were highly inter-correlated across faces and objects in all samples. Observers who fixated closer to the eye region also fixated higher on inanimate objects and vice versa. Furthermore, the inter-individual spread of fixation positions scaled with target size in precisely the same, non-linear manner for faces and objects. These findings contradict a purely domain-specific account of individual face gaze. Instead, they suggest significant domain-general contributions to the individual way we look at faces, a finding with potential relevance for basic vision, face perception, social cognition, and associated clinical conditions.

Motor “laziness” constrains fixation selection in real-world tasks

Humans coordinate their eye, head, and body movements to gather information from a dynamic environment while maximizing reward and minimizing biomechanical and energetic costs. However, such natural behavior is not possible in traditional experiments employing head/body restraints and artificial, static stimuli. Therefore, it is unclear to what extent mechanisms of fixation selection discovered in lab studies, such as inhibition-of-return (IOR), influence everyday behavior. To address this gap, participants performed nine real-world tasks, including driving, visually searching for an item, and building a Lego set, while wearing a mobile eye tracker (169 recordings; 26.6 h). Surprisingly, in all tasks, participants most often returned to what they just viewed and saccade latencies were shorter preceding return than forward saccades, i.e., consistent with facilitation, rather than inhibition, of return. We hypothesize that conservation of eye and head motor effort ("laziness") contributes. Correspondingly, we observed center biases in fixation position and duration relative to the head's orientation. A model that generates scanpaths by randomly sampling these distributions reproduced all return phenomena we observed, including distinct 3-fixation sequences for forward versus return saccades. After controlling for orbital eccentricity, one task (building a Lego set) showed evidence for IOR. This, along with small discrepancies between model and data, indicates that the brain balances minimization of motor costs with maximization of rewards (e.g., accomplished by IOR and other mechanisms) and that the optimal balance varies according to task demands. Supporting this account, the orbital range of motion used in each task traded off lawfully with fixation duration.

Eye movements in the development of geometric shape recognition: from sensory-motor processes to theoretical perception

AbstractEfficient recognition of geometric shapes is an important aspect of proficiency in geometry. Building theoretically on the cultural-historical approach enriched by the physiology of activity, we investigate theoretical perception in geometry—the ability to recognize conceptual geometric aspects of visual figures. Aiming to understand the development of theoretical perception, we investigate how sensory-motor processes of eye movements differ between adults and children when perceiving geometric figures. In an empirical study, we explored the variety of perceptual strategies used by first-grade students and compared them with the adults’ perception. The results reveal the contraction of eye movements: with growing expertise, foveal analysis—namely, an inspection of the figures by directing the gaze to their parts—is substituted by extrafoveal analysis—namely, perceiving without looking directly. The variety of the observed children’s perceptual strategies demonstrates that theoretical perception of different figures is heterogeneous. From the suggested theoretical perspective, the direct foveal inspection of particular figures is critical for the development of general anticipatory images of geometric shapes. Our theoretical analysis and empirical findings lead to distinguishing several functions of sensory-motor processes in theoretical perception in geometry. Those functions include positioning the retina in the best way for the comparison of sensory feedback with the geometric shape’s anticipatory image, advancing an anticipatory image based on visual experience, and regulating covert attention. All of these functions need to be taken into account when interpreting the results of eye-tracking studies in mathematics education research. Notably, our research highlights the limitations of the eye-mind hypothesis: direct fixations on a figure are not always needed for its theoretical perception and, the other way around, a fixation position may indicate the comparison of a broad extrafoveal region with an anticipatory image.

The Long-Term Efficacy of Computed Tomography-Navigated Total Hip Arthroplasty: An 18-Year Follow-Up Study.

We retrospectively reviewed 145 consecutive CT-navigated THAs for >15 years. We surveyed the angles placed in both the acetabular and femoral components, survivorship, the occurrence of dislocation, the revision rate, and the fixation grade of the acetabular component. The mean follow-up duration was 18.4 years. Overall, 73.8% of THAs were within the safe zone of Lewinnek. There were four dislocations (2.8%), with three occurring within 1 month after surgery and the other within 7 years after surgery. Revision THA was performed in one case (0.69%); consequently, the survival rate was 99.3%. The fixation grade was evaluated in 144 hips, and those were evaluated as having "no loosening". CT-navigated THA was speculated to contribute to long-term survivorship, with a low rate of loosening, even after 18 years of follow-up. It was speculated that the acetabular component was placed at an acceptable insertion angle and a suitable position for stable initial fixation.