Mitigating Visual Discomfort on Head Mounted Displays using Estimated Gaze Dependent Depth of Field

<p>Virtual Reality (VR) applications on Head Mounted Displays (HMDs) are now more common and accessible for personal viewing than before with the introduction of consumer-level devices like the Oculus Rift. However, exposure to VR applications on HMDs results in significant discomfort for the majority of people, the severity of which can both increase or decrease after repeated exposures. This is disadvantageous for the development and adoption of VR, as a long adaptation period cannot be relied on for making Virtual Environments palatable. Symptoms of discomfort caused by the viewing of content on VR devices including HMDs are historically described as “Simulator Sickness” and include eye fatigue, headaches, nausea and sweating; symptoms very similar to those experienced by sufferers of motion sickness. We refer to the specific subset of Simulator Sickness Symptoms caused by visual stimuli as symptoms of “Visual Discomfort”. A conflict between accommodation and vergence depth cues on stereoscopic displays is known to be a significant cause of visual discomfort. This report describes a psychophysical evaluation used for judging the effectiveness of dynamic Depth of Field (DoF) blurring on reducing visual discomfort caused by initial exposure to stereoscopic content on HMDs. Our DoF implementation adjusts the focal region of stereoscopic content based on an estimation of users’ view vectors in real time and is realised in a commercial game engine. Participants report a significant reduction of visual discomfort using a simulator sickness questionnaire when DoF blurring is enabled. On average, a 34% reduction in our sickness measure is observed, indicating that dynamic DoF blurring is an effective rendering technique for reducing visual discomfort.</p>

Mitigating Visual Discomfort on Head Mounted Displays using Estimated Gaze Dependent Depth of Field

<p>Virtual Reality (VR) applications on Head Mounted Displays (HMDs) are now more common and accessible for personal viewing than before with the introduction of consumer-level devices like the Oculus Rift. However, exposure to VR applications on HMDs results in significant discomfort for the majority of people, the severity of which can both increase or decrease after repeated exposures. This is disadvantageous for the development and adoption of VR, as a long adaptation period cannot be relied on for making Virtual Environments palatable. Symptoms of discomfort caused by the viewing of content on VR devices including HMDs are historically described as “Simulator Sickness” and include eye fatigue, headaches, nausea and sweating; symptoms very similar to those experienced by sufferers of motion sickness. We refer to the specific subset of Simulator Sickness Symptoms caused by visual stimuli as symptoms of “Visual Discomfort”. A conflict between accommodation and vergence depth cues on stereoscopic displays is known to be a significant cause of visual discomfort. This report describes a psychophysical evaluation used for judging the effectiveness of dynamic Depth of Field (DoF) blurring on reducing visual discomfort caused by initial exposure to stereoscopic content on HMDs. Our DoF implementation adjusts the focal region of stereoscopic content based on an estimation of users’ view vectors in real time and is realised in a commercial game engine. Participants report a significant reduction of visual discomfort using a simulator sickness questionnaire when DoF blurring is enabled. On average, a 34% reduction in our sickness measure is observed, indicating that dynamic DoF blurring is an effective rendering technique for reducing visual discomfort.</p>

High prevalence of long-term olfactory, gustatory, and chemesthesis dysfunction in post-COVID-19 patients: a matched case-control study with one-year follow-up using a comprehensive psychophysical evaluation

Background: Using an age and gender matched-pair case-control study, we aimed to estimate the long-term prevalence of psychophysical olfactory, gustatory , and chemesthesis impairment at least one year after SARS-CoV-2 infection considering the background of chemosensory dysfunction in non-COVID-19 population. Methodology: This case-controlled study included 100 patients who were home-isolated for mildly symptomatic COVID-19 between March and April 2020. One control regularly tested for SARS-CoV-2 infection and always tested negative was matched to each case according to gender and age. Chemosensory function was investigated by a comprehensive psychophysical evaluation including ortho- and retronasal olfaction and an extensive assessment of gustatory function. Differences in chemosensory parameters were evaluated through either Fisher’s exact test or Kruskal-Wallis test. Results: The psychophysical assessment of chemosensory function took place after a median of 401 days from the first SARS-CoV-2 positive swab. The evaluation of orthonasal smell identified 46% and 10% of cases and controls, respectively, having olfactory dysfunction, with 7% of COVID-19 cases being functionally anosmic. Testing of gustatory function revealed a 27% of cases versus 10% of controls showing a gustatory impairment. Nasal trigeminal sensitivity was significantly lower in cases compared to controls. Persistent chemosensory impairment was associated with emotional distress and depression. Conclusion: More than one year after the onset of COVID-19, cases exhibited an excess of olfactory, gustatory , and chemesthesis disturbances compared to matched-pair controls with these symptoms being associated to emotional distress and depression.

Ageing and Olfactory Dysfunction in Trisomy 21: A Systematic Review

Purpose: The olfactory system is particularly vulnerable in an ageing brain, both anatomically and functionally, and these brain changes are more pronounced among individuals with trisomy 21. Furthermore, the age of the system starts to deteriorate, and the mechanism involved is unclear in an individual with trisomy 21. Therefore, the present review aims to summarise the available information related to this topic and to suggest questions still unanswered which can be a subject of further research. Methods: A systematic literature search of trisomy 21 and olfactory dysfunction was conducted using PubMed/MEDLINE and Scopus electronic database following PRISMA guidelines. References and citations were checked in the Google Scholar database. Reports were extracted for information on demographics and psychophysical evaluation. Then, the reports were systematically reviewed based on the effects of ageing on the three olfactory domains: threshold, discrimination, and identification. Results: Participants with trisomy 21 show an early onset of olfactory impairment, and the age effect of the olfactory deficit is fully expressed at age > 30 years old. The three olfactory domains, threshold, discrimination, and identification, are suggested to be impaired in trisomy 21 participants with age > 30 years old. Conclusions: Olfactory dysfunction in an individual with trisomy 21 commences at a relatively young age and affects the three olfactory domains. A challenge for the future is to quantitatively establish the olfactory function of an individual with trisomy 21 at all ages with more detailed measurements to further understand the pathophysiology of this brain deterioration.

Six-month psychophysical evaluation of olfactory dysfunction in patients with COVID-19

This study prospectively assessed the six-month prevalence of self-reported and psychophysically measured olfactory dysfunction in subjects with mild-to-moderate COVID-19. Self-reported smell or taste impairment was prospectively evaluated by SNOT-22 at diagnosis, 4-week, 8-week, and 6-month. At 6 months from the diagnosis, psychophysical evaluation of olfactory function was also performed using the 34-item culturally adapted University of Pennsylvania Smell Identification Test (CA-UPSIT). 145 completed both the 6-month subjective and psychophysical olfactory evaluation. According to CA-UPSIT, 87 subjects (60.0%) exhibited some smell dysfunction, with 10 patients being anosmic (6.9%) and 7 being severely microsmic (4.8%). At the time CA-UPSIT was administered, a weak correlation was observed between the self-reported alteration of sense of smell or taste and olfactory test scores (Spearman’s r=-0.26). Among 112 patients who self-reported normal sense of smell at last follow-up, CA-UPSIT revealed normal smell in 46 (41.1%), mild microsmia in 46 (41.1%), moderate microsmia in 11 (9.8%), severe microsmia in 3 (2.3%), and anosmia in 6 (5.4%) patients; however, of those patients self-reporting normal smell but who were found to have hypofunction on testing, 62 out of 66 had self-reported reduction in sense of smell or taste at an earlier time point. Despite most patients report a subjectively normal sense of smell, we observed a high percentage of persistent smell dysfunction at 6 months from the diagnosis of SARS-CoV-2 infection, with 11.7% of patients being anosmic or severely microsmic. These data highlight a significant long-term rate of smell alteration in patients with previous SARS-COV-2 infection.

Psychophysical Evaluation of the Olfactory Function: European Multicenter Study on 774 COVID-19 Patients

Background: The objective evaluation of the olfactory function of coronavirus disease 2019 patients is difficult because of logistical and operator-safety problems. For this reason, in the literature, the data obtained from psychophysical tests are few and based on small case series. Methods: A multicenter, cohort study conducted in seven European hospitals between March 22 and August 20, 2020. The Sniffin-Sticks test and the Connecticut Chemosensory Clinical Research Center orthonasal olfaction test were used to objectively evaluate the olfactory function. Results: This study included 774 patients, of these 481 (62.1%) presented olfactory dysfunction (OD): 280 were hyposmic and 201 were anosmic. There was a significant difference between self-reported anosmia/hyposmia and psychophysical test results (p = 0.006). Patients with gastroesophageal disorders reported a significantly higher probability of presenting hyposmia (OR 1.86; p = 0.015) and anosmia (OR 2.425; p < 0.001). Fever, chest pain, and phlegm significantly increased the likelihood of having hyposmia but not anosmia or an olfactory disturbance. In contrast, patients with dyspnea, dysphonia, and severe-to-critical COVID-19 were significantly more likely to have no anosmia, while these symptoms had no effect on the risk of developing hyposmia or an OD. Conclusions: Psychophysical assessment represents a significantly more accurate assessment tool for olfactory function than patient self-reported clinical outcomes. Olfactory disturbances appear to be largely independent from the epidemiological and clinical characteristics of the patients. The non-association with rhinitis symptoms and the high prevalence as a presenting symptom make olfactory disturbances an important symptom in the differential diagnosis between COVID-19 and common flu.

High prevalence of long-term psychophysical olfactory dysfunction in patients with COVID-19

This study prospectively assessed the long-term prevalence of self-reported and psychophysically measured olfactory dysfunction in subjects with mild-to-moderate COVID-19. Self-reported smell or taste impairment was prospectively evaluated by SNOT-22 at diagnosis, 4-week, 8-week, and 6-month. At 6 months from the diagnosis, psychophysical evaluation of olfactory function was also performed using the 34-item culturally adapted University of Pennsylvania Smell Identification Test (CA-UPSIT). 145 completed both the 6-month subjective and psychophysical olfactory evaluation. According to CA-UPSIT, 87 subjects (60.0%) exhibited some smell dysfunction, with 54 (37.2) being mildly microsmic, 16 (11.0%) moderately microsmic, 7 (4.8%) severely microsmic, and 10 patients (6.9%) being anosmic. At the time CA-UPSIT was administered, a weak correlation was observed between the self-reported alteration of sense of smell or taste and olfactory test scores (Spearman r=-0.26). Among 112 patients who self-reported normal sense of smell at last follow-up, CA-UPSIT revealed normal smell in 46 (41.1%), mild microsmia in 46 (41.1%), moderate microsmia in 11 (9.8%), severe microsmia in 3 (2.3%), and anosmia in 6 (5.4%) patients; however, of those patients self-reporting normal smell but who were found to have hypofunction on testing, 62 out of 66 had self-reported reduction in sense of smell or taste at an earlier time point. Despite most patients report a subjectively normal sense of smell, we observed a high percentage of persistent smell dysfunction at 6 months from the diagnosis of SARS-CoV-2 infection, with 11.7% of patients being anosmic or severely microsmic. These data highlight a significant long-term rate of smell alteration in patients with previous SARS-CoV-2 infection.

Remote psychophysical evaluation of olfactory and gustatory functions in early-stage coronavirus disease 2019 patients: the Bologna experience of 300 cases

BackgroundAn objective evaluation of coronavirus disease 2019 in the first days of infection is almost impossible, as affected individuals are generally in home quarantine, and there is limited accessibility for the operator who should perform the test. To overcome this limitation, a recently validated psychophysical self-administered test was used, which can be performed remotely in the assessment of early-stage coronavirus disease 2019 patients.MethodsOlfactory and gustatory functions were objectively assessed in 300 patients in the first 7 days from coronavirus disease 2019 symptom onset.ResultsSeventy per cent of the patients presented olfactory and/or gustatory disorders. The dysfunctions detected were mainly complete anosmia (47 per cent) or ageusia (38 per cent). A significant correlation was found between taste dysfunction and female gender (odds ratio = 1.936, p = 0.014) and fever (odds ratio = 2.132, p = 0.003).ConclusionThe psychophysical evaluation protocol proposed is an effective tool for the fast and objective evaluation of patients in the early stages of coronavirus disease 2019. Chemosensitive disorders have been confirmed to be frequent and early symptoms of the coronavirus infection, and, in a significant number of cases, they are the first or only manifestation of coronavirus disease 2019.