In this study we examined dynamic visual acuity as a functional testing of the vestibulo- ocular reflex. Two groups were examined: 22 healthy seniors and 22 healthy young people as controls. We used two types of situations for testing: while walking on a treadmill at a speed of 2, 4 and 5 kmph, and with a subject's head passively moved in yaw and pitch plane. Visual acuity was measured with optotype charts (for the walking test it was a standard Snellen optotype chart at 6 m distance, for the test of head moves it was a Jaeger chart at 30 cm distance). The values obtained in these ways we related to values of a subject's static visual acuity, measured in the same conditions, just before the dynamic situations were examined. We found significant difference of dynamic visual acuity in senior group within each condition tested. We also found a significant decline as for difference of dynamic visual acuity in the senior group compared to young subjects - in the walking test at 4 and 5 kmph and in both head-moving conditions. These results indicate age-related impairment in function of vestibulo-ocular reflex. Based on our results, the test of passive head moves appears to be more suitable for ordinary clinical examination of dynamic visual acuity.

Sjuksköterskor vid Sjukvårdens Larmcentral (SvLC) i Uppsala och Västmanlands län hänvisar regelbundet lågakuta patienter som bedöms inte vara i behov av ambulanssjukvård till alternativa vårdformer. I denna studie kopplades patientdata från SvLC till sjukhusregister för att identifiera patienter som besökte en akutmottagning inom 72 timmar efter en hänvisning vid SvLC. Prevalensen av ett antal utfallsmått undersöktes och logistisk regression användes för att fastställa effekten av ett antal variabler. 20% av hänvisade inringare besökte en akutmottaging inom 72 timmar. Av dessa fick 57% vård på specialistnivå och 37% lades in vid en slutenvårdsenhet. 86% av akutmottagningsbesöken gällde det besvär som patienten kontaktade SvLC för. Äldre patienter hänvisades mindre ofta till alternativa vårdformer, men löpte större risk att kräva vård på specialistnivå och läggas in vid sjukhuset till följd av ett akutmottagningsbesök. Samtal med personer som ringde in flera gånger per månad hänvisades oftare av SvLC än patienter med en kontakt under studiens lopp, medan patienter som ringt in endast ett fåtal gånger besökte akutmottagningen oftare och blev där oftare inlagda. Icke-användning av SvLCs beslutsstöd var vanligare bland hänvisade patienter. Uppdrag som avlsutades utan vidare hänvisning till en annan sjukvårdsinstans resulterade mindre ofta i ett akutmottagningsbesök. Prevalensen av akutmottagningsbesök och inläggningar vid sjukhus efter hänvisning liknar nivån som funnits i andra studier av nordisk prehospital triage. Baserat på resultaten från denna studie föreslås ett antal kvalitetsutvecklingsprojekt samt framtida studier. / Nurses working at the Emergency Medical Dispatch (EMD) centers in the Swedish counties of Uppsala and Västmanland routinely refer patients determined to not require an ambulance to non-emergency care. In this study, hospital records were reviewed to match calls to patients visiting an Emergency Department (ED) within 72 hours of being referred to non- emergency care by an EMD nurse. The prevalence of a number of outcomes was examined, and logistic regression models were used to analyze the effects of several variables of interest. 20% of callers referred to non-emergency medical care visited an ED within 72 hours. Of these, 57% received specialist level care, and 37% were admitted to the hospital. 86% of ED visits were found to be in regards to the condition the patient contacted the EMD for. Elderly patients were less likely to be referred to non-emergency care, but more likely to receive specialist care and be admitted. Very frequent callers were more likely to be referred to non-emergency care, while a moderate rate of contact was associated with increased odds of ED visitation and hospital admission from the ED. Non-utilization of the EMDs’ decision support tool was more common among callers referred to non-emergency care. Calls closed by dispatchers without further referral to other healthcare providers were less likely to result in an ED visit. The prevalence of ED visitations and admissions found in this study are similar to those found in other studies of Scandinavian pre-hospital triage, and a number of possibilities for quality improvement and future studies were identified.

Il est connu que le cannabis, par son action sur le système endocannabinoïde, affecte de multiples paramètres de la vision. Les fonctions de GPR55, un récepteur associé au système endocannabinoïde, ont moins été étudiées que celles des récepteurs cannabinoïdes les plus importants, CB1 et CB2. Nous savons cependant que GPR55 est présent dans la rétine de la souris et qu’il module la croissance et le guidage axonal des cellules ganglionnaires rétiniennes durant le développement. Le but de cette étude est d’étudier les effets de GPR55 sur la vision en utilisant un modèle de souris avec une délétion du gène Gpr55. Des électrorétinographies (ERG) plein champ scotopique et photopique ont été effectuées dans le but d’étudier le rôle du récepteur sur les fonctions rétiniennes. Nous avons trouvé que les souris Gpr55-/- ont, en ERG scotopique, une amplitude réduite de l’onde-b et des potentiels oscillatoires qui ont aussi une latence plus longue. Chez ces animaux, l’onde-a photopique a aussi une amplitude plus basse. Par la suite, pour vérifier les conséquences des déficits de fonction rétinienne sur les fonctions visuelles, le modèle de réflexe optomoteur a été utilisé sur des souris knock-out ou avec des injections systémiques d’un antagoniste et d’un agoniste de GPR55. L’absence de GPR55 retarde le développement de l’acuité visuelle, mais la délétion de Gpr55 ou l’action pharmacologique sur le récepteur ne change pas l’acuité visuelle chez les adultes. La délétion de Gpr55 et l’administration d’un antagoniste du récepteur diminuent la sensibilité au contraste. Ces observations suggèrent que GPR55 peut modifier l'activité des cônes, des cellules bipolaires et des cellules de la rétine interne avec des conséquences comportementales. / The observations on how cannabis affects multiple properties of vision have fostered the interest in the study of the functions of cannabinoid receptors CB1 and CB2 in the visual system. However, other non-classical cannabinoid receptors are thought to be involved in mediating the actions of cannabinoid ligands in the eye. One of these candidate receptors is GPR55, a receptor that modulates the growth and axonal guidance of retinal ganglion cells during development in mice. The purpose of this study was to investigate the effects of the deletion of the Gpr55 gene and the pharmacological modulation of GPR55 on retinal function and visual behavior. Full-field scotopic and photopic electroretinography (ERG) were used to functionally assess the state of the retina. Recordings obtained from Gpr55-/- mice revealed a diminution of the scotopic b-wave and the photopic a-wave responses. These animals also had reduced and delayed oscillatory potentials. The optomotor reflex method was used to evaluate the consequences of Gpr55 deletion on visual acuity and contrast sensitivity. The absence of GPR55 delayed the developmental trajectory of visual acuity in Gpr55 knockout mice without affecting the maximum visual acuity reached in adulthood. Pharmacological manipulation of GPR55 in adult wild-type mice did not alter visual acuity. Both the deletion of Gpr55 and the administration of a receptor antagonist decreased contrast sensitivity while an agonist of GPR55 increased contrast sensitivity. These observations suggest that GPR55 can modify the activity of cones, bipolar cells, and cells in the inner retina with behavioral consequences.

No / PURPOSE: A computer-based interactive binocular treatment system (I-BiT) for amblyopia has been developed, which utilises commercially available 3D 'shutter glasses'. The purpose of this pilot study was to report the effect of treatment on visual acuity (VA) in children with amblyopia. METHODS: Thirty minutes of I-BiT treatment was given once weekly for 6 weeks. Treatment sessions consisted of playing a computer game and watching a DVD through the I-BiT system. VA was assessed at baseline, mid-treatment, at the end of treatment, and at 4 weeks post treatment. Standard summary statistics and an exploratory one-way analysis of variance (ANOVA) were performed. RESULTS: Ten patients were enrolled with strabismic, anisometropic, or mixed amblyopia. The mean age was 5.4 years. Nine patients (90%) completed the full course of I-BiT treatment with a mean improvement of 0.18 (SD=0.143). Six out of nine patients (67%) who completed the treatment showed a clinically significant improvement of 0.125 LogMAR units or more at follow-up. The exploratory one-way ANOVA showed an overall effect over time (F=7.95, P=0.01). No adverse effects were reported. CONCLUSION: This small, uncontrolled study has shown VA gains with 3 hours of I-BiT treatment. Although it is recognised that this pilot study had significant limitations-it was unblinded, uncontrolled, and too small to permit formal statistical analysis-these results suggest that further investigation of I-BiT treatment is worthwhile.

Viruset SARS-CoV-2 binder till det membranbundna enzymet angiotensinkonvertas 2 (ACE2). ACE2 är även en del av Renin-Angiotensin-Aldosteron-systemet (RAAS) och Kallikrein-Kinin-systemet (KKS). Den enzymatiska delen av ACE2 klyvs från cellmembranet vid inbindningen av viruset eller genom enzymet ADAM17 och bildar då cirkulerande ACE2 (sACE2). Syftet med den här litteraturstudien var att undersöka om sACE2 kan kopplas till allvarlighetsgraden av covid-19. Studierna visade blandade resultat. Tre artiklar visade ökande halter sACE2 vid svår covid-19. Två studier visade sjunkande halter sACE2 vid svår covid-19. Två artiklar visade ingen koppling mellan sACE2 och allvarlighetsgraden av covid-19. Då forskningsområdet omkring SARS-CoV-2 är nytt finns det stora variationer i studiernas upplägg, vilket resulterar i att resultaten är osäkra och svåra att jämföra med varandra. Eventuellt kan det finnas en koppling mellan mängden sACE2 och allvarlighetsgraden av covid-19. Mer forskning behövs för att säkerställa om sACE2 i kombination med andra tester kan användas för att upptäcka patienter i risk för allvarlig covid-19. / The virus SARS-CoV-2 binds to the enzyme Angiotensin Converting Enzyme 2 (ACE2) which causes shedding of the extracellular part of the enzyme and produces soluble ACE2 (sACE2). ACE2 is also a part of Renin-Angiotensin-Aldosterone-system (RAAS) and Kallikrein-Kinin-system (KKS). The enzyme ADAM17 also causes ACE2 to shed during inflammation. Since inflammation is an important part of the Covid-19 pathogenesis, the sACE2 levels may affect the pathogenesis of Covid-19. The purpose of this literature study was to investigate a possible connection between sACE levels and Covid-19 severity. Three articles showed high levels of sACE2 in severe Covid-19. Two articles showed low levels of sACE2 in severe Covid-19. Two articles showed no connection between severity of Covid-19 and sACE2 levels.  Due to the novelty of the research area, there are variations in the study set-up. Although inconclusive study results, sACE2 may be used as a secondary biomarker to detect indications of severe Covid-19, but more research is needed.

Damage to the nervous system may cause sensorimotor impairment, often resulting in chronic neuropathic pain. Phantom limb pain affects multiple amputees and the treatment options are limited. A promising treatment option to reduce chronic pain is by training sensory discrimination. At the Center for Bionics and Pain Research, a sensory training device has been developed. Transcranial direct current stimulation (tDCS) is a technique to stimulate different regions of the cerebral cortex. In studies, anodal tDCS of the sensorimotor cortex has shown to improve tactile acuity. Until now, the effect of the sensory discrimination training, performed with the sensory training device, in combination with tDCS has not been tested. The purpose of this master’s thesis was to determine the effect of tDCS applied on the sensorimotor cortex on the outcomes of sensory discrimination training. The purpose was also to compare the effect of two different methods of stimulation, namely conventional and High Definition tDCS. 16 able-bodied participants underwent three single sessions with 40 minutes of sensory discrimination training: one session combined with conventional tDCS, one session combined with High Definition tDCS and one session without tDCS. The tactile acuity was determined by the two-point discrimination test and the Semmes-Weinstein monofilament test, prior to and one hour after each session. This study showed that 40 minutes of sensory discrimination training was sufficient to improve the two-point discrimination in the sensory trained areas, compared to the sensory untrained areas (p=0.02). However, the improvement in two-point discrimination was not statistically significant between the interventions, i.e. the improvement in two-point discrimination for the sessions with brain modulation was not statistically significant compared to the session without brain modulation. The monofilament assessments showed an improvement in monofilament score for the sensory untrained skin patches (p=0.053). This study concluded that single sessions of training was enough to improve two-point discrimination but not monofilament score at the site of stimulation. This study lays a foundation for what parameters to include in future studies.

No / To determine whether Hartmann-Shack wavefront sensing detects differences in optical performance in vivo between poly(methyl methacrylate) (PMMA) and foldable acrylic intraocular lenses (IOLs) and between clear corneal and scleral tunnel incisions and whether optical differences are manifested as differences in visual performance. SETTING: Department of Optometry, University of Bradford, West Yorkshire, United Kingdom. METHODS: This study comprised 74 subjects; 17 were phakic with no ocular pathology, 20 had implantation of a Pharmacia 722C PMMA IOL through a scleral tunnel, 21 had implantation of an Alcon AcrySof IOL through a scleral tunnel, and 16 had implantation of an AcrySof IOL through a corneal incision. Visual acuity and contrast sensitivity testing, ocular optical quality measurement using Hartmann-Shack wavefront sensing, and corneal surface measurement with a videokeratoscope were performed in all cases. RESULTS: There were significant differences between groups in the total root-mean-square (RMS) wavefront aberration over a 6.0 mm pupil (F=3.91; degrees of freedom=3,70; P<.05) mediated at the 4th-order RMS, specifically spherical and tetrafoil aberrations. The PMMA-scleral group had the least aberrations and the AcrySof-corneal group the most. For a 3.5 mm diameter pupil, the total higher-order RMS wavefront aberration was not significantly different between the groups (P>.05). There were no differences between groups in corneal shape, visual acuity, or contrast sensitivity. CONCLUSIONS: Implantation of the spherical PMMA IOL led to a slight reduction in total wavefront aberration compared to phakic eyes. AcrySof IOLs induced more aberrations, especially spherical aberration. Corneal-based incisions for IOL implantation compounded this increase. Studies of the optical performance of IOLs in vivo should use wavefront sensing as the main outcome measure rather than visual measures, which are readily confounded by multiple factors.

京都大学 / 新制・課程博士 / 博士(医学) / 甲第25159号 / 医博第5045号 / 新制||医||1070(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 中山 健夫, 教授 森田 智視, 教授 永井 洋士 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

No / To determine the test-retest reliability of the Randot stereoacuity test when used as part of vision screening in schools. METHODS: Randot stereoacuity (graded-circles) and logMAR visual acuity measures were gathered in an unselected sample of 139 children (aged 4-12, mean 8.1+/-2.1 years) in two schools. Randot testing was repeated on two occasions (average interval between successive tests 8 days, range: 1-21 days). Three Randot scores were obtained in 97.8% of children. RESULTS: Randot stereoacuity improved by an average of one plate (ie, one test level) on repeat testing but was little changed when tested on the third occasion. Within-subject variability was up to three test levels on repeat testing. When stereoacuity was categorised as 'fine', 'intermediate' or 'coarse', the greatest variability was found among younger children who exhibited 'intermediate' or 'coarse'/nil stereopsis on initial testing. Whereas 90.8% of children with 'fine' stereopsis (</=50 arc-seconds) on the first test exhibited 'fine' stereopsis on both subsequent tests, only approximately 16% of children with 'intermediate' (>50 but </=140 arc-seconds) or 'coarse'/nil (>/=200 arc-seconds) stereoacuity on initial testing exhibited stable test results on repeat testing. CONCLUSIONS: Children exhibiting abnormal stereoacuity on initial testing are very likely to exhibit a normal result when retested. The value of a single, abnormal Randot graded-circles stereoacuity measure from school screening is therefore questionable.

No / Postural instability in older people is associated with an increased risk of falling. This experiment investigated the effects of different gaze strategies on postural stability in older people, when using distance single-vision compared with multifocal (progressive addition lens and bifocal) spectacles. METHODS: Eighteen healthy older habitual multifocal spectacle-wearers (mean age 72.1 +/- 4.0 years) participated in a randomised, cross-over study. Postural stability during quiet standing was assessed as the root mean square excursion in the centre of pressure (RMS-COP) in the antero-posterior direction. Ground reaction force data were collected (for 30 seconds), while subjects viewed one of two visual targets (one square metre) of different spatial frequencies and contrasts, while wearing either distance single-vision or multifocal (progressive addition and bifocal) spectacles. The visual targets were positioned either ahead at eye-level or on the ground (viewing distance 2.06 metres) and viewed under the following head-gaze conditions; 'head neutral-gaze forward', 'head flexed-gaze down' and 'head neutral-gaze down'. RESULTS: The type of spectacles worn or the target viewed had no significant effect on postural stability but postural stability deteriorated (antero-posterior RMS-COP excursion increased) in the 'head neutral-gaze down' compared with the 'head flexed-gaze down' and 'head neutral-gaze forward' conditions (5.9, 5.5 and 5.0 mm respectively, p < 0.001). CONCLUSIONS: Multifocal use had no effect on standing postural stability. Irrespective of spectacles worn, when fixating a visual target positioned at ground level, postural stability was better in the 'head flexed-gaze down' condition compared with the 'head neutral-gaze down' condition. A useful strategy to reduce falling in the older person might be to advise multifocal and distance single-vision spectacle-wearers to flex their heads rather than just lower their eyes when looking downwards.