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Pupil Dilation (pupil + dilation)

Distribution by Scientific Domains

Medical Sciences	83%

Selected Abstracts

RTVue Fourier-domain OCT: reproducibility of RNFLT and macular thickness measurements

ACTA OPHTHALMOLOGICA, Issue 2009
A GARAS
Purpose To evaluate the reproducibility of peripapillary retinal nerve fiber layer thickness (RNFLT) and macular thickness (MT) measurements with the RTVue-100 Fourier-domain optical coherence tomography, and to determine the influence of pupil dilation, patients' experience in examinations and severity of glaucoma. Methods One eye of 14 normal subjects, 11 patients with moderate, 12 patients with severe glaucoma and 40 screening trial participants were imaged 5 times on the same day. For the hospital-based patients, the measurement series was repeated after pupil dilation and 3 months later. Results For the RNFLT and the MT parameters, intrasession intraclass correlation coefficient (ICC) varied between 93.9 and 99.0%, intrasession coefficient of variation (CV) between 1.95 and 5.69 %, and intratest variability between 3.11 and 9.13 µm. Most thickness values, all intrasession CV and intratest variability values and the signal strength index remained unchanged after pupil dilation. Most intrasession CV values increased significantly with increasing disease severity. Patients' experience in imaging examinations had no influence on intrasession CV. Intratest variability and intrasession CV represented 79.1 to 98.6 % and 77.1 to 95.0 % of test-retest variability and intervisit CV, respectively. Conclusion Reproducibility of RNFLT and MT measurement with the RTVue-100 OCT are satisfactory for clinical purposes both in normals and glaucoma patients. Pupil dilation and patients' experience in imaging examinations do not influence the reproducibility of the measurements clinically significantly. Commercial interest [source]

Impairment due to cannabis and ethanol: clinical signs and additive effects

ADDICTION, Issue 6 2010
Jørgen G. Bramness
ABSTRACT Aims Studies have shown that the impairing effects of ,-9-tetrahydrocannabinol (THC) are dose-related. Cannabis intake increases the risk of traffic accidents. The purpose of this study was to see how different clinical tests and observations were related to blood THC concentrations and to determine whether the combined influence of THC and ethanol was different from either drug alone. Design A retrospective cross-sectional forensic database study. Setting Drivers apprehended by the police suspected of driving under the influence of alcohol other drugs. Participants We investigated 589 cases positive for THC only. In addition, 894 cases with THC and ethanol were included. A comparison was made with 3480 drivers with only ethanol in their blood and 79 drivers who tested negative. Measurements Data were analytical results of blood samples and the 27 clinical tests and observations included in the Norwegian clinical test for impairment (CTI). Findings No relationship was found between blood THC concentration and most of the CTI tests. Blood THC concentration was, however, related to conjunctival injection, pupil dilation and reaction to light and to the overall risk of being judged impaired. When THC and ethanol were detected together the risk of being judged impaired was increased markedly. Conclusions This study demonstrates that cannabis impairs driving ability in a concentration-related manner. The effect is smaller than for ethanol. The effect of ethanol and cannabis taken simultaneously is additive. Conjunctival injection, dilated pupils and slow pupil reaction are among the few signs to reveal THC influence. [source]

RTVue Fourier-domain OCT: reproducibility of RNFLT and macular thickness measurements

From epidemiology to lysyl oxidase like one (LOXL1) polymorphisms discovery: phenotyping and genotyping exfoliation syndrome and exfoliation glaucoma in Iceland

ACTA OPHTHALMOLOGICA, Issue 5 2009
Fridbert Jonasson
Abstract. The first Icelandic articles on exfoliation syndrome (XFS) and exfoliation glaucoma (XFG) appeared some 35 years ago in 1974. Articles since then have included epidemiology, pedigree-based and twin-studies as well as investigations into XFG response to medical therapy and XFS/XFG genetics. All studies found XFS/XFG to be common in Iceland and to be age-related. The Reykjavik Eye Study (RES), a population-based epidemiological study, was first conducted in 1996. The RES found that XFS and XFG prevalence in patients aged 50 years and older was 11% and that XFS/XFG was more common in women than in men. These results were confirmed in 5- and 12-year incidence studies that also suggested that detailed characterization of the phenotype is important, including pupil dilation. In the RES, eyes with XFS were found to be clinically unilateral in about half of cases and to have higher mean intraocular pressure (IOP) than non-XFS eyes. However, XFS was not found to be associated with central corneal thickness, corneal curvature, anterior chamber depth, lens thickness, lens opacification or optic disc morphology. About 15% of persons with XFS had XFG, and XFG eyes had higher risk of developing visual impairment and blindness than eyes with primary open-angle glaucoma. The first genetic studies on Icelanders, conducted about 12 years ago, were linkage studies and were unsuccessful in discovering the genetics behind XFS/XFG. However, in 2007 a genome-wide association study in Iceland using more than 300 000 markers [single nucleotide polymorphisms (SNPs)] on a relatively small number of patients did discover that lysyl oxidase like 1 (LOXL1) on chromosome 15q24 is a major gene for XFS/XFG. These results have now largely been replicated world-wide. [source]

Visualisation of reverse pupillary block using AC-OCT in primary pigment dispersion syndrome

ACTA OPHTHALMOLOGICA, Issue 2007
R LAEMMER
Purpose: To describe morphologic characteristics associated with secondary IOP elevation due to pigment release after pupil dilation in primary melanin dispersion syndrome. Methods: The history of a 49 year old male patient with primary pigment dispersion syndrome and secondary ocular hypertension is described. Besides detailed ophthalmologic examination including slit lamp biomicroscopy, gonioscopy as well as IOP and Laser-Flare measurement (KOWA FC-1000; Kowa, Tokyo, Japan) before and after pupil dilation, anterior segment optical coherence tomography was performed before and after Nd:YAG laser iridotomy and in medical miosis. Results: After pupil dilatation IOP increased up to 46 mmHg at the right eye but no IOP elevation was recognised at the left eye. Measurement by Laser-Flare Cell Meter revealed no cells in undilated state but 13.4 cells/ 0.075 ,l at the right and 4.0 cells/ 0.075 ,l at the left eye after mydriasis. Nd:YAG laser iridotomy was recommended for the right eye to the patient recently. Iris configuration detected by OCT demonstrates a concave shape before iridotomy more pronounced temporal than nasal which resolves after application of pilocarpin as well as after performance of Nd:YAG laser iridotomy. Conclusions: The effect of Nd:YAG laser iridotomy as a prophylactic but potentially causal treatment in pigmentary glaucoma can be easily visualized by OCT as a fast and non-contact procedure. [source]

Resource allocation and fluid intelligence: Insights from pupillometry

PSYCHOPHYSIOLOGY, Issue 1 2010
Elke Van Der Meer
Abstract Thinking is biological work and involves the allocation of cognitive resources. The aim of this study was to investigate the impact of fluid intelligence on the allocation of cognitive resources while one is processing low-level and high-level cognitive tasks. Individuals with high versus average fluid intelligence performed low-level choice reaction time tasks and high-level geometric analogy tasks. We combined behavioral measures to examine speed and accuracy of processing with pupillary measures that indicate resource allocation. Individuals with high fluid intelligence processed the low-level choice reaction time tasks faster than normal controls. The task-evoked pupillary responses did not differ between groups. Furthermore, individuals with high fluid intelligence processed the high-level geometric analogies faster, more accurately, and showed greater pupil dilations than normal controls. This was only true, however, for the most difficult analogy tasks. In addition, individuals with high fluid intelligence showed greater preexperimental pupil baseline diameters than normal controls. These results indicate that individuals with high fluid intelligence have more resources available and thus can solve more demanding tasks. Moreover, high fluid intelligence appears to be accompanied by more task-free exploration. [source]