Eye Tracker Accuracy: Quantitative Evaluation of the Invisible Eye Center Location

Purpose. We present a new method to evaluate the accuracy of an eye tracker based eye localization system. Measuring the accuracy of an eye tracker's primary intention, the estimated point of gaze, is usually done with volunteers and a set of fixation points used as ground truth. However, verifying the accuracy of the location estimate of a volunteer's eye center in 3D space is not easily possible. This is because the eye center is an intangible point hidden by the iris. Methods. We evaluate the eye location accuracy by using an eye phantom instead of eyes of volunteers. For this, we developed a testing stage with a realistic artificial eye and a corresponding kinematic model, which we trained with {\mu}CT data. This enables us to precisely evaluate the eye location estimate of an eye tracker. Results. We show that the proposed testing stage with the corresponding kinematic model is suitable for such a validation. Further, we evaluate a particular eye tracker based navigation system and show that this system is able to successfully determine the eye center with sub-millimeter accuracy. Conclusions. We show the suitability of the evaluated eye tracker for eye interventions, using the proposed testing stage and the corresponding kinematic model. The results further enable specific enhancement of the navigation system to potentially get even better results

Eye tracking based navigation for proton beam therapy

Cancers of the eye, so-called ocular tumors, are a severe disease that may lead to blindness or even death if left untreated. A possibility to remove the tumor from the body of the patient is a so-called enucleation surgery, the removal of the eye. However, it is a drastic action and oncologists usually try to avoid it. Another treatment option is the therapy with protons. The actual proton therapy to treat ocular tumors is very successful and non-invasive. However, the navigation method that is applied for this kind of therapy requires a pre-treatment surgery, where radio-opaque clips are sutured onto the affected eyeball. These clips are used during the actual treatment to align the diseased eye with two orthogonal X-ray units. Hence, the overall treatment is invasive. The work at hand presents an alternative, completely non-invasive navigation method based on eye tracking technology. We present a new treatment scheme with a first eye tracking prototype integrated into the treatment facility at Paul Scherrer Institute (PSI). This system together with a patient specific eye model enables the medical physicist to align the patient’s eye such that the tumor gets accurately treated by the proton beam. Further, we present a second, improved eye tracking system. This time, we propose a stereo eye tracker, which only uses one physical camera to save physical space. We combine a stereo eye tracking algorithm with a clever arrangement of two planar mirrors and a single camera to get high accuracy, precision, and a compact design altogether. Finally, we present a method to quantitatively evaluate the proposed navigation system. Verifying the accuracy of the location estimate of a volunteer’s eye center is not easily possible. This is because the eye center is an intangible point, that does not correspond to an anatomical structure. Our evaluation method is based on an eye phantom on microstages and a corresponding kinematic model. Our research and development may lead to an ocular tumor treatment which will be safer, more cost-effective, and more accessible to patients suffering from this serious disease

Aerospace Medicine and Biology: A continuing bibliography (supplement 221)

This bibliography lists 127 reports, articles, and other documents introduced into the NASA scientific and technical information system in July 1981

Communication Support for People with ALS

Almost all people with amyotrophic lateral sclerosis (ALS) experience a motor speech disorder, such as dysarthria, as the disease progresses. At some point, 80 to 95% of people with ALS are unable to meet their daily communication needs using natural speech. Unfortunately, once intelligibility begins to decrease, speech performance often deteriorates so rapidly that there is little time to implement an appropriate augmentative and alternative communication (AAC) intervention; therefore, appropriate timing of referral for AAC assessment and intervention continues to be a most important clinical decision-making issue. AAC acceptance and use have increased considerably during the past decade. Many people use AAC until within a few weeks of their deaths

The Effects of Transcranial Direct Current Stimulation (tDCS) on Facial Expression Approach/Avoidance in College Students and Faculty with Broad Autism Phenotype

Transcranial Direct Current Stimulation (tDCS) has been proposed as an alternative noninvasive therapy for individuals with autism. This study trained brain activity in college students and / or faculty with Broad Autism Phenotype (BAP) while eye tracking data was collected. The purpose of this study was to determine if tDCS training to the frontal lobes could increase approach toward social interactions in adults classified as BAP as demonstrated by eye-tracking measures in response to faces and gaze fixation. The study included 21 total participants recruited from the Science, Technology, Engineering, and Math (STEM) courses / professions at a Regional East Texas University. Participants were classified as BAP+ based on their scores on the Broad Autism Phenotype Questionnaire (BAPQ). Findings revealed statistically significant differences in the participant revisit gaze and a trend in reduction of fixations and in fixation duration increase after tDCS stimulation. Additionally, this study found a moderate correlation between BAPQ scores and revisit revistors and suggested the closer the family member of the BAP+ participant, the higher the BAP score. The results of the current study support the integration of eye tracking to provide early identification and intervention and propagate the importance of clinicians’ and researchers’ focus on the factors that modulate eye tracking measures to reduce symptomology of ASD and BAP as well as other conditions with overlapping brain regions

Quality of life and treatment-related burden during ocular proton therapy: a prospective trial of 131 patients with uveal melanoma

Background: Proton beam therapy is a well-established treatment option for patients with uveal melanoma (UM). The treatment procedure, in general, includes placing radiopaque clips to ensure exact eye-positioning during radiotherapy, followed by the delivery of proton irradiation. The short-term burden associated with proton therapy in patients with UM has rarely been addressed. In this prospective study, we investigated the physiological and psychological aspects of proton therapy that might affect the well-being of patients during the different stages of treatment. Methods: During the treatment procedure, we conducted longitudinal assessments of the Quality of life (QOL), organ-specific symptoms, and psychological aspects in patients with UM with three questionnaires (EORTC QLQ-C30, EORTC QLQ-OPT30, and GAD-7). Patients completed questionnaires before clip surgery (T0), before proton therapy (T1), after completing treatment (T2), and three months after treatment completion (T3). We also collected data on tumor characteristics and socio-demographics to identify potential risk factors associated with high treatment burdens. Results: We prospectively included 131 consecutive patients. Questionnaire data showed a significant, temporary decline in global QOL and an increase in eye-related symptoms, as a result of the clip surgery (T0-T1). After treatment completion (T2), global QOL improved gradually, and none of the eye-related symptoms significantly deteriorated over the course of proton therapy. The global QOL returned to baseline levels three months after treatment (T3). We identified baseline anxiety as an independent risk factor for experiencing an acute treatment-related burden. Furthermore, we found interactions between GAD7 and patient sex showing that anxiety had a more pronounced effect on QOL outcome in female patients. Conclusion: The short-term treatment-related burden of ocular proton therapy appeared to be largely associated with the preceding clip surgery, rather than the irradiation procedure. We found that anxiety was strongly associated with experiencing QOL issues during the treatment procedure. Our findings could contribute to the development of future strategies for improving the treatment process and psycho-oncologic patient care

Southwest Research Institute assistance to NASA in biomedical areas of the technology

Significant applications of aerospace technology were achieved. These applications include: a miniaturized, noninvasive system to telemeter electrocardiographic signals of heart transplant patients during their recuperative period as graded situations are introduced; and economical vital signs monitor for use in nursing homes and rehabilitation hospitals to indicate the onset of respiratory arrest; an implantable telemetry system to indicate the onset of the rejection phenomenon in animals undergoing cardiac transplants; an exceptionally accurate current proportional temperature controller for pollution studies; an automatic, atraumatic blood pressure measurement device; materials for protecting burned areas in contact with joint bender splints; a detector to signal the passage of animals by a given point during ecology studies; and special cushioning for use with below-knee amputees to protect the integrity of the skin at the stump/prosthesis interface

Aerospace medicine and biology. A continuing bibliography (supplement 231)

This bibliography lists 284 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1982

USSR Space Life Sciences Digest, issue 32

This is the thirty-second issue of NASA's USSR Space Life Sciences Digest. It contains abstracts of 34 journal or conference papers published in Russian and of 4 Soviet monographs. Selected abstracts are illustrated with figures and tables from the original. The abstracts in this issue have been identified as relevant to 18 areas of space biology and medicine. These areas include: adaptation, aviation medicine, biological rhythms, biospherics, cardiovascular and respiratory systems, developmental biology, exobiology, habitability and environmental effects, human performance, hematology, mathematical models, metabolism, microbiology, musculoskeletal system, neurophysiology, operational medicine, and reproductive system