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result(s) for
"Investigative techniques of ocular function and vision"
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Retinal vessel segmentation by improved matched filtering: evaluation on a new high-resolution fundus image database
by
Cernosek, Pavel
,
Svoboda, Ondrej
,
Hornegger, Joachim
in
Applied sciences
,
automatic assessment
,
Biological and medical sciences
2013
Automatic assessment of retinal vessels plays an important role in the diagnosis of various eye, as well as systemic diseases. A public screening is highly desirable for prompt and effective treatment, since such diseases need to be diagnosed at an early stage. Automated and accurate segmentation of the retinal blood vessel tree is one of the challenging tasks in the computer-aided analysis of fundus images today. We improve the concept of matched filtering, and propose a novel and accurate method for segmenting retinal vessels. Our goal is to be able to segment blood vessels with varying vessel diameters in high-resolution colour fundus images. All recent authors compare their vessel segmentation results to each other using only low-resolution retinal image databases. Consequently, we provide a new publicly available high-resolution fundus image database of healthy and pathological retinas. Our performance evaluation shows that the proposed blood vessel segmentation approach is at least comparable with recent state-of-the-art methods. It outperforms most of them with an accuracy of 95% evaluated on the new database.
Journal Article
“Taste Strips” – A rapid, lateralized, gustatory bedside identification test based on impregnated filter papers
2009
Objective
To elaborate normative values for a clinical psychophysical taste test (“Taste Strips”).
Background
The “Taste Strips” are a psychophysical chemical taste test. So far, no definitive normative data had been published and only a fairly small sample size has been investigated. In light of this shortcoming for this easy, reliable and quick taste testing device, we attempted to provide normative values suitable for the clinical use.
Setting
Normative value acquisition study, multicenter study.
Methods
The investigation involved 537 participants reporting a normal sense of smell and taste (318 female, 219 male, mean age 44 years, age range 18–87 years). The taste test was based on spoonshaped filter paper strips (“Taste Strips”) impregnated with the four (sweet, sour, salty, and bitter) taste qualities in four different concentrations. The strips were placed on the left or right side of the anterior third of the extended tongue, resulting in a total of 32 trials. With their tongue still extended, patients had to identify the taste from a list of four descriptors, i. e., sweet, sour, salty, and bitter (multiple forcedchoice). To obtain an impression of overall gustatory function, the number of correctly identified tastes was summed up for a “taste score”.
Results
Taste function decreased significantly with age. Women exhibited significantly higher taste scores than men which was true for all age groups. The taste score at the 10
th
percentile was selected as a cut-off value to distinguish normogeusia from hypogeusia. Results from a small series of patients with ageusia confirmed the clinical usefulness of the proposed normative values.
Conclusion
The present data provide normative values for the “Taste Strips” based on over 500 subjects tested.
Journal Article
The reliability and validity of the Korean version of the Epworth sleepiness scale
by
Lee, Joo Hwa
,
Johns, Murray W.
,
Lee, Seung Hoon
in
Activities of daily living
,
Adult
,
Biological and medical sciences
2011
Objective
The Epworth sleepiness scale (ESS) is widely used to measure the subject's average sleep propensity across those different situations in daily life, particularly in patients with sleep-disordered breathing. The purposes of this study were to test the hypothesis that the Korean version of the ESS (KESS) is valid and evaluate its usefulness.
Materials and methods
We developed the KESS, which involved translating into Korean and then translating back into English to check its accuracy. A total of 273 participants (181 obstructive sleep apnea (OSA)—37 mild, 61 moderate, 83 severe, 32 simple snoring and 60 normal) were included in this study. All subjects completed the overnight polysomnograph and 53 of the total subjects were randomly selected for a retest with the questionnaire approximately 2∼4 weeks later. The associations between KESS and the degree of OSA were examined through ANCOVA, adjusted for age, sex and BMI
.
Results
The total score and each item's score of KESS in patients with OSA were significantly higher than subjects with normal controls (
p
< 0.01). As the severity of OSA increased, the KESS showed significantly increasing patterns (
p
for trend <0.01). The KESS in patient groups showed good internal consistency (Cronbach's
α
= 0.90) and test–retest reliability (
r
= 0.78 to 0.93).
Conclusion
The KESS is a reliable and valid tool for screening patients with daytime sleepiness in Korea.
Journal Article
The Epworth Sleepiness Scale: translation and validation study of the Iranian version
by
Aminian, Omid
,
Rahimi Golkhandan, Ania
,
Sedaghat, Mojtaba
in
Adult
,
Biological and medical sciences
,
Clinical research
2013
Purpose
The main purpose of this study was to assess the reliability and validity of the Iranian version of the Epworth Sleepiness Scale (ESS-IR).
Methods
This was a cross-sectional study of 507 suspicious patients either to obstructive sleep apnea (
n
= 466) or narcolepsy (
n
= 41) in order to carry out a psychometric evaluation of the ESS-IR by performing reliability, validity, and responsiveness analyses. Reliability of the ESS-IR was assessed by internal consistency and test–retest reliability. Validity of the instrument was assessed using several statistical approaches including construct validity (exploratory factor analysis), discriminant validity, and criterion validity. Responsiveness of the ESS-IR was assessed by comparing the ESS-IR total score before and after 6–9 months of continues positive airway pressure (CPAP) treatment in 16 patients with obstructive sleep apnea (OSA).
Results
The ESS-IR had an acceptable internal consistency and test–retest reliability. Factor analysis in both groups showed a two-factor solution for the ESS-IR, but the first factor showed statistically significant loads in all items. In addition, the ESS-IR discriminated well between patients with and without OSA. There is a fair correlation between the ESS-IR total score and multiple sleep latency test results that is not significant at all. Finally, the ESS-IR was found to be responsive to change where the total score was significantly decreased after CPAP treatment (
P
< 0.001).
Conclusion
The findings suggest that the ESS-IR is a reliable and valid measure for evaluating daytime sleepiness and now can be used in research and clinical settings in Iran.
Journal Article
Limits of the Epworth Sleepiness Scale in older adults
2013
Purpose
Excessive daytime sleepiness (EDS) in older adults is associated with obstructive sleep apnea, falls, reduced quality of life, and mortality. The Epworth Sleepiness Scale (ESS) is widely used to assess sleepiness. However, EDS assessment with the ESS may not be accurate in older adults. We aimed to (1) describe the responsiveness of nondemented older subjects to the ESS and (2) compare the self-report ESS scores to those of close relatives (CR) proxy and identify factors influencing any discrepancies between them.
Methods
This is a cross-sectional observational study including 104 independently living nondemented older subjects with daytime sleepiness complaints and 104 nondemented CRs. Cognitive tests (Mini-Mental State Examination) and the ESS were completed separately by subjects and CRs to assess the subject’s daytime sleepiness.
Results
Almost 60 % of subjects and CRs were not able to answer at least one question on the ESS. Despite the fact that all subjects complained of EDS, only 24 % of them had an abnormal ESS score (>10). Subjects rated their sleepiness lower (7.10 ± 4.31) than their CR proxy did (9.70 ± 5.14) (
p
< 0.0001). In multivariate analysis, an increase in age and a decrease in cognitive status of the subjects appeared related to the difference in ESS between subject and CR.
Conclusions
The majority of older adults were not able to answer all of the ESS items. The ESS may underestimate sleepiness severity in older subjects. Despite EDS complaints in all subjects, only one quarter of them had a pathological ESS score.
Journal Article
Sleepiness and sleep-disordered breathing in truck drivers
by
Pais-Clemente, Manuel
,
Catarino, Rosa
,
Lunet, Nuno
in
Accidents
,
Accidents, Occupational - statistics & numerical data
,
Accidents, Traffic - statistics & numerical data
2014
Background
Portugal has one of the highest road traffic fatality rates in Europe. A clear association between sleep-disordered breathing (SDB) and traffic accidents has been previously demonstrated. This study aimed to determine prevalence of excessive daytime sleepiness (EDS) and other sleep disorder symptoms among truck drivers and to identify which individual traits and work habits are associated to increased sleepiness and accident risk.
Methods
We evaluated a sample of 714 truck drivers using a questionnaire (244 face-to-face interviews, 470 self-administered) that included sociodemographic data, personal habits, previous accidents, Epworth Sleepiness Scale (ESS), and the Berlin questionnaire (BQ).
Results
Twenty percent of drivers had EDS and 29 % were at high risk for having obstructive sleep apnea syndrome (OSAS). Two hundred sixty-one drivers (36.6 %) reported near-miss accidents (42.5 % sleep related) and 264 (37.0 %), a driving accident (16.3 % sleep related). ESS score ≥11 was a risk factor for both near-miss accidents (odds ratio (OR) = 3.84,
p
< 0.01) and accidents (OR = 2.25,
p
< 0.01). Antidepressant use was related to accidents (OR = 3.30,
p
= 0.03). We found an association between high Mallampati score (III–IV) and near misses (OR = 1.89,
p
= 0.04).
Conclusion
In this sample of Portuguese truck drivers, we observed a high prevalence of EDS and other sleep disorder symptoms. Accident risk was related to sleepiness and antidepressant use. Identifying drivers at risk for OSAS should be a major priority of medical assessment centers, as a public safety policy.
Journal Article
A new non-contact optical device for ocular biometry
by
Mallen, E A H
,
Santodomingo-Rubido, J
,
Gilmartin, B
in
Adult
,
Anterior Chamber - anatomy & histology
,
anterior chamber depth
2002
Background: A new commercially available device (IOLMaster, Zeiss Instruments) provides high resolution non-contact measurements of axial length (using partial coherent interferometry), anterior chamber depth, and corneal radius (using image analysis). The study evaluates the validity and repeatability of these measurements and compares the findings with those obtained from instrumentation currently used in clinical practice. Method: Measurements were taken on 52 subjects (104 eyes) aged 18–40 years with a range of mean spherical refractive error from +7.0 D to −9.50 D. IOLMaster measurements of anterior chamber depth and axial length were compared with A-scan applanation ultrasonography (Storz Omega) and those for corneal radius with a Javal-Schiötz keratometer (Topcon) and an EyeSys corneal videokeratoscope. Results: Axial length: the difference between IOLMaster and ultrasound measures was insignificant (0.02 (SD 0.32) mm, p = 0.47) with no bias across the range sampled (22.40–27.99 mm). Anterior chamber depth: significantly shorter depths than ultrasound were found with the IOLMaster (−0.06 (0.25) mm, p <0.02) with no bias across the range sampled (2.85–4.40 mm). Corneal radius: IOLMaster measurements matched more closely those of the keratometer than those of the videokeratoscope (mean difference −0.03 v −0.06 mm respectively), but were more variable (95% confidence 0.13 v 0.07 mm). The repeatability of all the above IOLMaster biometric measures was found to be of a high order with no significant bias across the measurement ranges sampled. Conclusions: The validity and repeatability of measurements provided by the IOLMaster will augment future studies in ocular biometry.
Journal Article
Varying Effects of Corneal Thickness on Intraocular Pressure Measurements with Different Tonometers
Aims
To compare the intraocular pressure (IOP) measurements using the Goldmann applanation tonometer (GAT), noncontact tonometer (NCT), and ocular blood flow tonometer (OBFT), and to evaluate the effects of varying central corneal thickness (CCT) on the readings.
Methods
Ultrasound pachymetry and tonometry were performed on 170 eyes. Using the corrected GAT values that took CCT into account as the standard, we calculated the NCT and OBFT measurement errors related to the CCT variable by a linear regression model. Group comparisons were performed with the
χ
2
test and one-way ANOVA test. The correlation between the various tonometer measurements was analysed by Pearson's correlation method.
Results
Both the NCT (
r
=0.872,
P
<0.001) and OBFT measurements (
r
=0.861,
P
<0.001) were highly correlated with the GAT measurements. IOP measurements using the three tonometers were all correlated with CCT (all
P
<0.001), with the NCT measurements showing the greatest regression coefficient (
β
=0.063,
r
=0.650) and the GAT measurements the least (
β
=0.037,
r
=0.496). A linear regression model indicated that a 10
μ
m change in CCT resulted in a NCT measurement deviation of 0.47–0.98 mmHg and an OBFT measurement deviation of 0.29–0.81 mmHg.
Conclusion
Pressure readings with the GAT, NCT, and OBFT are all affected by CCT, with the NCT being the one most affected and the GAT the least. Our findings suggest CCT an essential variable to consider in interpreting IOP readings, especially for the NCT measurements.
Journal Article
Relationship of Gender, Body Mass Index, and Axial Length with Central Retinal Thickness Using Optical Coherence Tomography
2005
Background
Optical coherence tomography (OCT) acquires cross-sectional retinal images with high resolution using low-coherence interferometry. Few studies have studied the effect of demographic data and ocular parameters that may affect central retinal thickness. In this study, these factors were used as parameters to analyse if any significant relationship exists with central retinal thickness.
Methods
Volunteers with a best-corrected visual acuity of 6/12 or better and no evidence of ocular abnormalities or interventions were recruited from October 2001 to March 2003. Body mass index (BMI), autorefraction, and keratometry recordings were measured, followed by applanation tonometry and A-scan ultrasonography. The central retinal thickness of the right eye was analysed using a scan length of 3 cm. Another 25 eyes were selected for interobserver reproducibility.
Results
In all, 117 normal subjects (60 male and 57 female subjects) were recruited. The mean thickness of the central retina with a diameter of 1 mm was 203±23
μ
m for male and 189±20
μ
m for female subjects. Age, intraocular pressure, and keratometric readings were not significantly correlated with central retinal thickness. Using multiple regression, gender, BMI, axial length, and signal-to-noise ratio (
P
<0.05) were significantly associated with the central retinal thickness. The intraclass correlation coefficient was 0.98 for interobserver reproducibility.
Conclusion
OCT has a high interobserver reproducibility. The male gender, larger BMI, and longer axial length are associated with a significantly thicker central retina and these parameters should be considered for assessing retinal thickening and baseline comparisons in future studies.
Journal Article