Homonymous Visual Field Defects Research Articles

THE STUDY OF POSTERIOR CORTICAL ATROPHY USING ONLINE SURVEYS AND SOCIAL MEDIA

Posterior cortical atrophy (PCA) is a rare neurodegenerative syndrome with prominent cortical visual dysfunction and early sparing of memory that is most commonly associated with Alzheimer's disease (AD) pathology.1 Focal cortical syndromes, such as PCA, can inform our understanding of cortical vulnerability to AD pathology. The rarity of the diagnosis, however, creates barriers to further study. Social media sites such as Facebook, with over 1 billion daily users, provide an opportunity to reach people affected by rare disorders, as previously demonstrated.2 We aimed to explore the use of social media platforms to examine patient, caregiver, and physician experiences with PCA. After IRB approval, three electronic surveys were launched and targeted to patients and caregivers on a PCA patient Facebook page and to physicians on a Listserv of the North American Neuro-ophthalmology Society. Surveys were designed to characterize PCA clinical histories, caregiver burden, and physician experience with PCA. RedCap was used for secure, online data collection. Eighty-two surveys were completed by patients (n=45) from several countries and physicians (n=37). Patients reported difficulty with driving (98%), performing simple math (93%), reading (90%), writing and drawing (90%), and depth perception (90%), while decreased color vision (77%) and homonymous hemianopic visual field defects (73%) were the most common findings by Neuro-ophthalmologists. The majority of patients reported using donepezil and memantine and perceived benefits from memantine more than other medications. Caregiver surveys thus far (N=17) indicate most are sole care providers with a high degree of stress, anxiety, and depression, and a Caregiver Strain Index average of 7 indicated a high level of stress. PCA has a major impact on activities associated with independent living and places a significant burden on caregivers. The majority of patients were prescribed medications indicated for AD, and neuro-ophthalmologists reported color vision loss and homonymous visual field defects as very common. Despite inherent validity issues, social media platforms hold promise for reaching those affected by, or caring for, rare disorders such as PCA and can provide new directions for investigations. 1. Crutch SJ et al. Lancet Neurol.2012;11(2):170–8. 2. Davies W. Orphanet J Rare Dis.2016;11(1):151.

Chromatic pupillography in hemianopia patients with homonymous visual field defects.

The pupil light reflex is considered to be a simple subcortical reflex. However, many studies have proven that patients with isolated occipital lesions with homonymous hemianopia show pupillary hemihypokinesia. Our hypothesis is that the afferent pupillary system consists of two pathways: one via intrinsically photosensitive retinal ganglion cells (ipRGCs), the other running through the normal RGCs via the visual cortex. The purpose of this study was to test the hypothesis of these two separate pupillomotor pathways. 12 patients (59.1±18.8years) with homonymous hemianopia due to post-geniculate lesions of the visual pathway and 20 normal controls (58.6±12.9years) were examined using chromatic pupillography: stimulus intensity was 28lx corneal illumination, stimulus duration was 4.0s, and the stimulus wavelengths were 420±20nm (blue) and 605±20nm (red), respectively. The examined parameters were baseline pupil diameter, latency, and relative amplitudes (absolute amplitudes compared to baseline), measured at maximal constriction, at 3s after stimulus onset, at stimulus offset, and at 3s and 7s after stimulus offset. The relative amplitudes for the red stimulus were significantly smaller for hemianopia patients compared to the normal controls [maximal constriction: 35.6±5.9% (hemianopia) to 42.3±5.7% (normal); p=0.004; 3s after stimulus onset: p=0.004; stimulus offset: p=0.001]. No significant differences in any parameter were found between the two groups using the blue stimulus. The results support the hypothesis that the ipRGC pathway is mainly subcortical, whereas a second, non-ipRGC pathway via the occipital cortex exists.

Impaired visual competition in patients with homonymous visual field defects.

Intense visual training can lead to partial recovery of visual field defects caused by lesions of the primary visual cortex. However, the standard visual detection and discrimination tasks, used to assess this recovery process tend to ignore the complexity of the natural visual environment, where multiple stimuli continuously interact. Visual competition is an essential component for natural search tasks and detecting unexpected events.Our study focused on visual decision-making and to what extent the recovered visual field can compete for attention with the ’intact’ visual field. Nine patients with visual field defects who had previously received visual discrimination training, were compared to healthy age-matched controls using a saccade target-selection paradigm, in which participants actively make a saccade towards the brighter of two flashed targets. To further investigate the nature of competition (feed-forward or feedback inhibition), we presented two flashes that reversed their intensity difference during the flash. Both competition between recovered visual field and intact visual field, as well as competition within the intact visual field, were assessed.Healthy controls showed the expected primacy effect; they preferred the initially brighter target. Surprisingly, choice behaviour, even in the patients’ supposedly ‘intact’ visual field, was significantly different from the control group for all but one. In the latter patient, competition was comparable to the controls. All other patients showed a significantly reduced preference to the brighter target, but still showed a small hint of primacy in the reversal conditions.The present results indicate that patients and controls have similar decision-making mechanisms but patients’ choices are affected by a strong tendency to guess, even in the intact visual field. This tendency likely reveals slower integration of information, paired with a lower threshold. Current rehabilitation should therefore also include training focused on improving visual decision-making of the defective and the intact visual field.

Combined Transcranial Direct Current Stimulation and Vision Restoration Training in Subacute Stroke Rehabilitation: A Pilot Study

BackgroundVisual field defects after posterior cerebral artery stroke can be improved by vision restoration training (VRT), but when combined with transcranial direct current stimulation (tDCS), which alters brain excitability, vision recovery can be potentiated in the chronic stage. To date, the combination of VRT and tDCS has not been evaluated in postacute stroke rehabilitation. ObjectivesTo determine whether combined tDCS and VRT can be effectively implemented in the early recovery phase following stroke, and to explore the feasibility, safety and efficacy of an early intervention. DesignOpen-label pilot study including a case series of 7 tDCS/VRT versus a convenience sample of 7 control patients (ClinicalTrials.gov ID: NCT02935413). SettingRehabilitation center. SubjectsPatients with homonymous visual field defects following a posterior cerebral artery stroke. MethodsSeven homonymous hemianopia patients were prospectively treated with 10 sessions of combined tDCS (2.mA, 10 daily sessions of 20 minutes) and VRT at 66 (±50) days on average poststroke. Visual field recovery was compared with the retrospective data of 7 controls, whose defect sizes and age of lesions were matched to those of the experimental subjects and who had received standard rehabilitation with compensatory eye movement and exploration training. ResultsAll 7 patients in the treatment group completed the treatment protocol. The safety and acceptance were excellent, and patients reported occasional skin itching beneath the electrodes as the only minor side effect. Irrespective of their treatment, both groups (treatment and control) showed improved visual fields as documented by an increased mean sensitivity threshold in decibels in standard static perimetry. Recovery was significantly greater (P < .05) in the tDCS/VRT patients (36.73% ± 37.0%) than in the controls (10.74% ± 8.86%). ConclusionIn this open-label pilot study, tDCS/VRT in subacute stroke was demonstrated to be safe, with excellent applicability and acceptance of the treatment. Preliminary effectiveness calculations show that tDCS/VRT may be superior to standard vision training procedures. A confirmatory, larger-sample, controlled, randomized, and double-blind trial is now underway to compare real-tDCS− versus sham-tDCS−supported visual field training in the early vision rehabilitation phase. Level of EvidenceIV

The Effects of Compensatory Scanning Training on Mobility in Patients with Homonymous Visual Field Defects: Further Support, Predictive Variables and Follow-Up.

IntroductionPeople with homonymous visual field defects (HVFD) often report difficulty detecting obstacles in the periphery on their blind side in time when moving around. Recently, a randomized controlled trial showed that the InSight-Hemianopia Compensatory Scanning Training (IH-CST) specifically improved detection of peripheral stimuli and avoiding obstacles when moving around, especially in dual task situations.MethodThe within-group training effects of the previously reported IH-CST are examined in an extended patient group. Performance of patients with HVFD on a pre-assessment, post-assessment and follow-up assessment and performance of a healthy control group are compared. Furthermore, it is examined whether training effects can be predicted by demographic characteristics, variables related to the visual disorder, and neuropsychological test results.ResultsPerformance on both subjective and objective measures of mobility-related scanning was improved after training, while no evidence was found for improvement in visual functions (including visual fields), reading, visual search and dot counting. Self-reported improvement did not correlate with improvement in objective mobility performance. According to the participants, the positive effects were still present six to ten months after training. No demographic characteristics, variables related to the visual disorder, and neuropsychological test results were found to predict the size of training effect, although some inconclusive evidence was found for more improvement in patients with left-sided HVFD than in patients with right-sided HFVD.ConclusionFurther support was found for a positive effect of IH-CST on detection of visual stimuli during mobility-related activities specifically. Based on the reports given by patients, these effects appear to be long-term effects. However, no conclusions can be drawn on the objective long-term training effects.

Difficulties in Daily Life Reported by Patients with Homonymous Visual Field Defects: Erratum.

Difficulties in Daily Life Reported by Patients with Homonymous Visual Field Defects: Erratum.

Visual Rehabilitation in Chronic Cerebral Blindness: A Randomized Controlled Crossover Study.

The treatment of patients suffering from cerebral blindness following stroke is a topic of much recent interest. Several types of treatment are under investigation, such as substitution with prisms and compensation training of saccades. A third approach, aimed at vision restitution is controversial, as a proper controlled study design is missing. In the current study, 27 chronic stroke patients with homonymous visual field defects were trained at home with a visual training device. We used a discrimination task for two types of stimuli: a static point stimulus and a new optic flow-discontinuity stimulus. Using a randomized controlled crossover design, each patient received two successive training rounds, one with high contrast stimuli in their affected hemifield (test) and one round with low-contrast stimuli in their intact hemifield (control). Goldmann and Humphrey perimetry were performed at the start of the study and following each training round. In addition, reading performance was measured. Goldmann perimetry revealed a statistically significant reduction of the visual field defect after the test training, but not after the control training or after no intervention. For both training rounds combined, Humphrey perimetry revealed that the effect of a directed training (sensitivity change in trained hemifield) exceeded that of an undirected training (sensitivity change in untrained hemifield). The interaction between trained and tested hemifield was just above the threshold of significance (p = 0.058). Interestingly, reduction of the field defect assessed by Goldmann perimetry increases with the difference between defect size as measured by Humphrey and Goldmann perimetry prior to training. Moreover, improvement of visual sensitivity measured by Humphrey perimetry increases with the fraction of non-responsive elements (i.e., more relative field loss) in Humphrey perimetry prior to training. Reading speed revealed a significant improvement after training. Our findings demonstrate that our training can result in reduction of the visual field. Improved reading performance after defect training further supports the significance of our training for improvement in daily life activities.

Radiological Findings in Children and Adolescents with Homonymous Visual Field Defects: Types of Lesion and Frequency

Radiological Findings in Children and Adolescents with Homonymous Visual Field Defects: Types of Lesion and Frequency

Optic radiation injury in a patient with intraventricular hemorrhage: a diffusion tensor tractography study.

Optic radiation injury in a patient with intraventricular hemorrhage: a diffusion tensor tractography study.

Driving with Homonymous Visual Field Defects: Driving Performance and Compensatory Gaze Movements

Aim of this pilot study was to assess the driving performance and its relationship to the visual search behavior, i.e., eye and head movements, of patients with homonymous visual field defects (HVFDs) in comparison to healthy-sighted subjects during a simulated driving test. Eight HVFD patients and six healthy-sighted age- and gender-matched control subjects underwent a 40-minute driving test with nine hazardous situations. Eye and head movements were recorded during the drive. Four out of eight patients passed the driving test and showed a driving performance similar to that of the control group. One control group subject failed the test. Patients who passed the test showed an increased number of head and eye movements. Patients who failed the test showed a rightwards-bias in average lane position, probably in an attempt to maximize the safety margin to oncoming traffic. Our study supports the hypothesis that a considerable subgroup of subjects with HVFDs show a safe driving behavior, because they adapt their viewing behavior by increased visual scanning.

Driving with Homonymous Visual Field Defects: Driving Performance and Compensatory Gaze Movements

Aim of this pilot study was to assess the driving performance and its relationship to the visual search behavior, i.e., eye and head movements, of patients with homonymous visual field defects (HVFDs) in comparison to healthy-sighted subjects during a simulated driving test. Eight HVFD patients and six healthy-sighted age- and gender-matched control subjects underwent a 40-minute driving test with nine hazardous situations. Eye and head movements were recorded during the drive. Four out of eight patients passed the driving test and showed a driving performance similar to that of the control group. One control group subject failed the test. Patients who passed the test showed an increased number of head and eye movements. Patients who failed the test showed a rightwards-bias in average lane position, probably in an attempt to maximize the safety margin to oncoming traffic. Our study supports the hypothesis that a considerable subgroup of subjects with HVFDs show a safe driving behavior, because they adapt their viewing behavior by increased visual scanning.

Corresponding Ganglion Cell Atrophy in Patients With Postgeniculate Homonymous Visual Field Loss.

The goal of our study was to look for the presence of homonymous ganglion cell layer-inner plexiform layer complex (GCL-IPL) thinning using spectral-domain optical coherence tomography (SD-OCT) in patients with a history of adult-onset injury to the postgeniculate pathways with rigorous radiological exclusion of geniculate and pregeniculate pathology. We performed a retrospective review of twenty-two patients (ages 24-75 y, 6 men, 16 women) with homonymous visual field (VF) defects secondary to postgeniculate injury examining the GCL-IPL with SD-OCT. An additional fifteen patients (ages 28-85 y, 5 men, 10 women) with no visual pathway pathology served as controls. Using segmentation analysis software applied to the macular scan, a normalized asymmetry score was calculated for each eye comparing GCL-IPL thickness ipsilateral vs contralateral to the patient's brain lesions. We found that 15 of the twenty-two subjects had a relative thinning of the GCL-IPL ipsilateral to the postgeniculate lesion in both eyes (represented by a positive normalized asymmetry score in both eyes), whereas a similar pattern of right/left asymmetry was found in 4 controls (P = 0.0498). The magnitude of asymmetry was much greater in subjects compared with controls (P = 0.0004). There was no association between the degree of GCL-IPL thinning and the mean deviation on automated VF testing. A moderate correlation (R = 0.782, P = 0.004) between the magnitude of thinning and latency from onset of retrogeniculate injury was observed only after excluding patients beyond a cutoff point of 150 months. This data provides compelling new evidence of retrograde transsynaptic degeneration causing retinal ganglion cell loss after postgeniculate visual pathway injury.

Drivers with visual field defects; diagnosis, health and experiences

Not being able to drive your own car can be devastating for mobility, health, finances and self-esteem. Driving is a visually demanding task (Owsley et al., 2008) and insufficient visual field can lead to revoked license. Acquired brain damage can impair the visual field and stroke is a very common diagnosis among drivers with visual field defects. de Haan et al. (2015) identified several undocumented difficulties among patients with homonymous visual field defects. License holders with visual field defects and interested in being assessed in a driving simulator were invited to answer a short web questionnaire. During the period December 2013 to June 2015, close to 400 people responded. The group is however not representative for the population of drivers with visual filed defects. Instead, it comprise the subgroup that is most concerned to get a new driver license issued (or to keep the license if it not yet withdrawn). A vast majority in the studied group was men (83 %). Almost 3 out of 4 were aged 55 years or more. The three most common diagnosis were stroke (39 %), glaucoma (31 %) and diabetes (13 %). General health status, vision and driving ability was self-estimated as very good or relatively good by 90-95 % of the respondents on a 5-grade scale. Weekly distance driven was estimated to 200 km (median). Involvement in accidents with only property damage, near-accidents and personal injury accidents during the period 2008-2013 was experienced by 8 %, 5 % and 1 %, respectively. Drivers with visual field defects regard themselves as healthy and good drivers. The drivers do often not understand the withdrawal of the driving license; many comments that they had driven for many years without any problems and that they can compensate for the defect by head movements.

Difficulties in Daily Life Reported by Patients With Homonymous Visual Field Defects.

Homonymous visual field defects (HVFD) are common after postchiasmatic acquired brain injury and may have a significant impact on independent living and participation in society. Vision-related difficulties experienced in daily life are usually assessed using questionnaires. The current study 1) links the content of 3 of these questionnaires to the International Classification of Functioning, Disability and Health (ICF) and 2) provides analyses of vision-related difficulties reported by patients with HVFD and minimal comorbidities. Fifty-four patients with homonymous hemianopia or quadrantanopia were asked about difficulties experienced in daily life because of their HVFD. This was performed during a structured interview including 3 standardized questionnaires: National Eye Institute Visual Functioning Questionnaire, Independent Mobility Questionnaire, and Cerebral Visual Disorders Questionnaire. The reported difficulties were linked to the ICF according to the ICF linking rules. Main outcome measures were presence or absence of experienced difficulties. The ICF linking procedure resulted in a classification table that can be used in future studies of vision-related difficulties. Besides well-known difficulties related to reading, orientation, and mobility, a high proportion of patients with HVFD reported problems that previously have not been documented in the literature, such as impaired light sensitivity, color vision, and perception of depth. A systematic inventory of difficulties experienced in daily life by patients with HVFD was performed using the ICF. These findings have implications for future study, assessment and rehabilitation of patients with HVFD.

Asymmetry in the Collision Judgments of People With Homonymous Field Defects and Left Hemispatial Neglect.

Although the impact of homonymous visual field defects (HFDs) on mobility has been investigated previously, the emphasis has been on obstacle detection. Relatively little is known about HFD patients' ability to judge collisions once an obstacle is detected. We investigated this using a walking simulator. Patients with HFDs (n = 29) and subjects with normal vision (NV; n = 21) were seated in front of a large screen on which a visual simulation of walking was displayed. They made collision judgments for a human figure that appeared for 1 second at lateral offsets from the virtual walking path. A perceived-collision threshold was calculated for right and left sides. Symmetrical collision thresholds (same on left and right sides) were measured for participants with NV (n = 21), and right (n = 9) and left (n = 7) HFD without hemispatial neglect. Participants with left neglect (n = 10) showed significant asymmetry with thresholds smaller (compared to the NV group and other HFD groups) on the blind (P < 0.001) and larger on the seeing (P = 0.05) sides. Despite the asymmetry, the overall width of the zone of perceived collision risk was not different, suggesting a relatively uniform rightward deviation in judgments of the left neglect group. Left neglect was associated with rightward asymmetry in collision judgments, which may cause collisions on the left side even when an obstacle is detected. These behaviors may represent the spatial misperceptions in body midline described previously in patients with left neglect.

Non-invasive electric current stimulation for restoration of vision after unilateral occipital stroke

Occipital stroke often leads to visual field loss, for which no effective treatment exists. Little is known about the potential of non-invasive electric current stimulation to ameliorate visual functions in patients suffering from unilateral occipital stroke. One reason is the traditional thinking that visual field loss after brain lesions is permanent. Since evidence is available documenting vision restoration by means of vision training or non-invasive electric current stimulation future studies should also consider investigating recovery processes after visual cortical strokes. Here, protocols of repetitive transorbital alternating current stimulation (rtACS) and transcranial direct current stimulation (tDCS) are presented and the European consortium for restoration of vision (REVIS) is introduced. Within the consortium different stimulation approaches will be applied to patients with unilateral occipital strokes resulting in homonymous hemianopic visual field defects. The aim of the study is to evaluate effects of current stimulation of the brain on vision parameters, vision-related quality of life, and physiological parameters that allow concluding about the mechanisms of vision restoration. These include EEG-spectra and coherence measures, and visual evoked potentials. The design of stimulation protocols involves an appropriate sham-stimulation condition and sufficient follow-up periods to test whether the effects are stable.This is the first application of non-invasive current stimulation for vision rehabilitation in stroke-related visual field deficits. Positive results of the trials could have far-reaching implications for clinical practice. The ability of non-invasive electrical current brain stimulation to modulate the activity of neuronal networks may have implications for stroke rehabilitation also in the visual domain.

Driving with homonymous visual field loss: Does visual search performance predict hazard detection?

Introduction Stroke often causes homonymous visual field loss, which can lead to exclusion from driving. Retention of a driving licence is sometimes possible by completing an on-road assessment, but this is not practical for all. It is important to find simple tests that can inform the assessment and rehabilitation of driving-related visual-motor function. Method We developed novel computerised assessments: visual search; simple reaction and decision reaction to appearing pedestrians; and pedestrian detection during simulated driving. We tested 12 patients with stroke (seven left, five right field loss) and 12 controls. Results The homonymous visual field defect group was split into adequately compensated or inadequately compensated groups based on visual search performance. The inadequately compensated group had problems with stimuli in their affected field: they tended to react more slowly than controls and in the driving task they failed to detect a number of pedestrians. In contrast, the adequately compensated group were better at detecting pedestrians, though reaction times were slightly slower than controls. Conclusion We suggest that our search task can predict, to a limited extent, whether a person with stroke compensates for visual field loss, and may potentially identify suitability for specific rehabilitation to promote return to driving.

Homonymous Visual Field Loss and Its Impact on Visual Exploration: A Supermarket Study.

Homonymous visual field defects (HVFDs) may critically interfere with quality of life. The aim of this study was to assess the impact of HVFDs on a supermarket search task and to investigate the influence of visual search on task performance. Ten patients with HVFDs (four with a right-sided [HR] and six with a left-sided defect [HL]), and 10 healthy-sighted, sex-, and age-matched control subjects were asked to collect 20 products placed on two supermarket shelves as quickly as possible. Task performance was rated as "passed" or "failed" with regard to the time per correctly collected item (TC -failed = 4.84 seconds based on the performance of healthy subjects). Eye movements were analyzed regarding the horizontal gaze activity, glance frequency, and glance proportion for different VF areas. Seven of 10 HVFD patients (three HR, four HL) passed the supermarket search task. Patients who passed needed significantly less time per correctly collected item and looked more frequently toward the VFD area than patients who failed. HL patients who passed the test showed a higher percentage of glances beyond the 60° VF (P < 0.05). A considerable number of HVFD patients performed successfully and could compensate for the HVFD by shifting the gaze toward the peripheral VF and the VFD area. These findings provide new insights on gaze adaptations in patients with HVFDs during activities of daily living and will enhance the design and development of realistic examination tools for use in the clinical setting to improve daily functioning. (http://www.clinicaltrials.gov, NCT01372319, NCT01372332).

Genetic causes of acute visual loss

AbstractGenetic causes of acute visual loss are relatively rare, but these still need to be considered in the differential diagnosis, especially in the relevant clinical context. In this presentation, classical genetic disorders affecting the optic nerve will be discussed with a particular focus on Leber hereditary optic neuropathy (LHON). LHON is a primary mitochondrial DNA (mtDNA) disorder and three point mutations within the mitochondrial genome account for the vast majority of cases, namely: m.3460G&gt;A, m.11778G&gt;A and m.14484T&gt;C. It typically affects young adult males who present with bilateral severe visual loss in the second or third decade of life. In addition to the canonical LHON mutations, other pathogenic mtDNA mutations have been reported that can result in both syndromic and non‐syndromic optic neuropathies. Acute visual loss in genetic disorders can also be secondary to pathology involving the retrochiasmal visual pathways, for example, in MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke‐like episodes). The cardinal clinical manifestations in this group of patients are homonymous hemianopic visual field defects or cortical blindness.

Stress-indicators and exploratory gaze for the analysis of hazard perception in patients with visual field loss

The perception of traffic hazards is crucial for timely driving reactions. In this study we examine if the perception of hazardous objects can be determined by means of combined eye-tracking recordings and stress-related indicators in drivers suffering from binocular visual field loss. An increased rate of traffic accidents has been reported for this group of patients, which may lead to driving prohibition. The sole recording of gaze movements may not be sufficient for reliable identification of traffic object perception. Even if a traffic hazard is fixated by the driver, inattention or the presence of higher visual deficits may lead to an inappropriate driving response.We examined how stress-related indicators, i.e., skin conductance and heart rate, can complement and improve the eye-tracking based analysis of object perception. In a driving simulator study, we assessed the driving performance and hazard perception ability of subjects with binocular visual field loss (eight with homonymous visual field defects and seven with advanced glaucoma) and 15 healthy-sighted control subjects. Seven out of 15 subjects with visual field defects failed the driving assessment, eight passed the test. One healthy-sighted subject failed the driving test.Drivers with visual field defects showed a significant increase in skin conductance in 93% of situations with adequate reaction to the approaching hazard (69% for heart rate changes. 92% and 81% for healthy drivers, respectively). Furthermore, we identified five out of 120 total situations where the drivers looked at the traffic hazard but failed to react (look-but-not-react). Four of these situations were associated with a change in skin conductance, which can be interpreted as a perceived hazard, but an inadequate behavioral driving response. In one situation, no change in skin conductance was observed (look-but-not-perceived). In eight situations, although drivers did not fixate the traffic hazard, adequate driving reaction was observed. Four of these situations were also associated with changes in skin conductance (perceived-without-look). However, 43% and 44% of all significant increases in skin conductance and heart rate, respectively, occurred without the presence of a traffic hazard.In summary, our findings suggest that the sole analysis of the driver’s eye movements does not reliably reveal whether a traffic hazard was perceived. Additional recordings of stress-related parameters, such as heart rate, and especially skin conductance, can confirm hazard perception and be used as a complementary method for the evaluation of exploratory eye movements and driving behavior.