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Results for “Vision Screening”

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At least 1,171 records · Page 65Linked to original sources
PubMed1998

[Reduced visual capacity increases the risk of accidents in street traffic].

BACKGROUND: This study was carried out to investigate the relationship between the frequency of traffic accidents and impaired vision. MATERIALS AND METHODS: Seven hundred and fifty-four drivers involved in accidents were recruited, in addition to 250 accident-free drivers similar in age and driving experience as an control group. The age distribution of the persons involved in traffic accidents (mean 56.3 years) was similar to that of the control group (mean 57.7 years), the difference was not statistically significant. Both groups underwent a complete ophthalmological examination. RESULTS: All three types of accidents (night-time accidents, violations of right of way, accidents during an overtaking manoeuvre) had a statistically significantly higher incidence of reduced photopic visual acuity, mesopic vision and an increased sensitivity to glare. Some other visual functions were also abnormal, with differences according to the type of accident. In particular, there were noticeable differences between the control group and those who were involved in night-time accidents regarding mesopic vision and sensitivity to glare. Concerning mesopic vision, 15% of the 261 persons involved in night-time accidents did not reach the contrast limit of 1:5; with glare, 20.7% failed. In comparison 4% of the control group reached this critical limit without glare and 7.6% with glare. These differences are highly statistically significant. In contrast to these findings, many of the drivers involved in accidents assessed their own visual capability as "excellent". CONCLUSIONS: The results of this study show that reduced mesopic vision and increased sensitivity to glare are accompanied by an increased risk of night-time accidents (for example, collisions with a non-illuminated obstacle). This emphasizes the importance of regular ophthalmological check-ups including visual functions such as mesopic vision and sensitivity to glare, which currently are not required by the traffic laws in Germany.

Accidents, Traffic↗
PubMed1998

[Effect of exposure time using single landolt-rings on visual acuity in normal individuals and patients with nystagmus].

BACKGROUND: The recommendations of the German Society of Ophthalmology (DOG) concerning the examination of candidates or holders of a driving licence allow a maximum time interval of 1 s for identifying a single Landolt-C for normal individuals as well as for patients with nystagmus. The aim of this study was to determine whether visual acuity decreases with shortening of the exposure time. PATIENTS AND METHODS: We measured the visual acuity of 18 patients with manifest nystagmus and 26 normal individuals with single Landolt-C at exposure times of 10 s, 1 s, 0.25 s and 0.1 s. RESULTS: Visual acuity dropped significantly at exposure times of 1 s in the group of patients with nystagmus (P = 0.01). In normal individuals, visual acuity decreased significantly only at exposure times below 1 s. CONCLUSION: Determining visual acuity according to the recommendations of the DOG shows a significant drop of visual acuity in nystagmus patients, but not in normal individuals. Applying the maximum time limit of 1 s exposure time to these patients will ensure that they will be able to identify traffic signs quickly and orient themselves safely.

Adult↗
PubMed2001

[Differentiation between dyslexia and ocular causes of reading disorders].

BACKGROUND: Dyslexia is defined as a reading and/or writing disability persisting after exclusion of organic causes. Studies show that ocular disorders, especially small refraction errors, hypoaccommodation and symptomatic heterophoria, are often not detected or treated in cases of reading and/or writing problems which were otherwise diagnosed as dyslexia. METHODS: We evaluated the data of patients referred to our department from December 1997 to March 2000 with the diagnosis of dyslexia. RESULTS: We found ocular disturbances in 28 (84.8%) out of 33 children, 26 (78.8%) showed improved reading after therapy. They had mostly accommodative problems: uncorrected hyperopia, hypoaccommodation and/or exophoria compensated by accommodative convergence (pathophoria). CONCLUSIONS: Our results underline the importance of the correction of even small refraction and/or motility errors in the presence of reading and writing difficulties.

Accommodation, Ocular↗
PubMed2002

Colour in the eyes of insects.

Many insect species have darkly coloured eyes, but distinct colours or patterns are frequently featured. A number of exemplary cases of flies and butterflies are discussed to illustrate our present knowledge of the physical basis of eye colours, their functional background, and the implications for insect colour vision. The screening pigments in the pigment cells commonly determine the eye colour. The red screening pigments of fly eyes and the dorsal eye regions of dragonflies allow stray light to photochemically restore photoconverted visual pigments. A similar role is played by yellow pigment granules inside the photoreceptor cells which function as a light-controlling pupil. Most insect eyes contain black screening pigments which prevent stray light to produce background noise in the photoreceptors. The eyes of tabanid flies are marked by strong metallic colours, due to multilayers in the corneal facet lenses. The corneal multilayers in the gold-green eyes of the deer fly Chrysops relictus reduce the lens transmission in the orange-green, thus narrowing the sensitivity spectrum of photoreceptors having a green absorbing rhodopsin. The tapetum in the eyes of butterflies probably enhances the spectral sensitivity of proximal long-wavelength photoreceptors. Pigment granules lining the rhabdom fine-tune the sensitivity spectra.

Animals↗
PubMed2006

Long-term effects of tibolone on ocular functions in postmenopausal women.

Hormone replacement therapy has been widely used for the prevention of postmenopausal osteoporosis and treatment of climacteric symptoms for many years, but its effect on ocular functions remains unclear. The aim of the study was to evaluate the long-term effects of tibolone on ocular functions in postmenopausal women. A total of 77 healthy women with at least 1 year of spontaneous menopause were enrolled in the study. Forty women were treated with tibolone for 6 months and 37 women were left untreated. All these patients underwent ophthalmic examination including visual acuity, intraocular pressure (IOP), tear functions, blue-on-yellow and white-on-white Humphrey visual field (HVF), visual evoked potentials (VEP) and electroretinography (ERG). There were significant differences in mean deviation of blue-on-yellow HVF, and oscillatory potentials (O1, O2, and O4) in the ERGs of the chronic tibolone users and the control (P < 0.0001, P = 0.001, P < 0.0001 and 0.05, respectively). However, no significant differences were observed in visual acuity, IOP, tear functions, white-on-white HVF and VEP. We concluded that, although tibolone had no effects on visual acuity, IOP, tear functions and VEP, it might cause some early adverse effects on the electrophysiologic and structural characteristics of the retina, which are detected by these sensitive assays. Randomized placebo-controlled studies with larger groups are needed in future research.

Electroretinography↗
PubMedDate not supplied

Cost-benefit analysis in screening. Unexplained visual loss.

Cost-effectiveness analysis (CEA) and cost-benefit analysis (CBA) are accounting techniques that have been applied to medical decision-making. These techniques are applied here to two alternative diagnostic strategies in the work-up of patients with "unexplained visual loss." The first uses the results of visual field examination to decide if patients should have a CT scan ("visual field strategy"), the second bypasses visual fields and orders a CT scan on all patients ("CT strategy"). The analysis reveals that the visual field strategy is cost-effective only if perimetrists are able to identify hemianopic field defects in more than 80% of cases. It is doubtful that perimetrists are presently as accurate as that. These conclusions must be considered tentative since the epidemiologic data that support them are often weak. Another drawback in applying such an analysis to medical problem-solving is that costs may not accurately reflect patient valuations and choices. Nevertheless, in forcing a more comprehensive consideration of the effects of medical decisions, CEA/CBA is likely to promote increased cost-consciousness and epidemiologic research.

Cost-Benefit Analysis↗
PubMedDate not supplied

Strabismus.

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Child, Preschool↗
PubMed2007

Operator-induced errors in Hartmann-Shack wavefront sensing: model eye study.

PURPOSE: To evaluate the effects of instrument realignment and angular misalignment during the clinical determination of wavefront aberrations by simulation in model eyes. SETTING: Aston Academy of Life Sciences, Aston University, Birmingham, United Kingdom. METHODS: Six model eyes were examined with wavefront-aberration-supported cornea ablation (WASCA) (Carl Zeiss Meditec) in 4 sessions of 10 measurements each: sessions 1 and 2, consecutive repeated measures without realignment; session 3, realignment of the instrument between readings; session 4, measurements without realignment but with the model eye shifted 6 degrees angularly. Intersession repeatability and the effects of realignment and misalignment were obtained by comparing the measurements in the various sessions for coma, spherical aberration, and higher-order aberrations (HOAs). RESULTS: The mean differences between the 2 sessions without realignment of the instrument were 0.020 microm +/- 0.076 (SD) for Z(3)(-1)(P = .551), 0.009 +/- 0.139 microm for Z(3)(1)(P = .877), 0.004 +/- 0.037 microm for Z(4)(0) (P = .820), and 0.005 +/- 0.01 microm for HO root mean square (RMS) (P = .301). Differences between the nonrealigned and realigned instruments were -0.017 +/- 0.026 microm for Z(3)(-1)(P = .159), 0.009 +/- 0.028 microm for Z(3)(1) (P = .475), 0.007 +/- 0.014 microm for Z(4)(0)(P = .296), and 0.002 +/- 0.007 microm for HO RMS (P = 0.529; differences between centered and misaligned instruments were -0.355 +/- 0.149 microm for Z(3)(-1) (P = .002), 0.007 +/- 0.034 microm for Z(3)(1)(P = .620), -0.005 +/- 0.081 microm for Z(4)(0)(P = .885), and 0.012 +/- 0.020 microm for HO RMS (P = .195). Realignment increased the standard deviation by a factor of 3 compared with the first session without realignment. CONCLUSIONS: Repeatability of the WASCA was excellent in all situations tested. Realignment substantially increased the variance of the measurements. Angular misalignment can result in significant errors, particularly in the determination of coma. These findings are important when assessing highly aberrated eyes during follow-up or before surgery.

Calibration↗
PubMed2006

Population-based study of presbyopia in rural Tanzania.

OBJECTIVE: To determine the prevalence of presbyopia in a rural African population. DESIGN: Cross-sectional prevalence study. PARTICIPANTS: One thousand seven hundred nine persons age 40 years and older who resided in 3 villages and randomly selected neighborhoods of Kongwa town, Tanzania. METHODS: Eligible persons were refracted and given best distance correction. Near vision was tested and corrected to the nearest 0.5 diopter. Presbyopia was defined as at least 1 line of improvement on a near visual acuity chart with an addition of a plus lens. RESULTS: A total of 61.7% of eligible participants were presbyopic. A higher prevalence of presbyopia was associated with increased age, female gender, higher educational level, and residence in town (odds ratio = 3.09; 95% confidence interval: 2.46-3.90). The odds of developing presbyopia increased 16% per year of age from age 40 to 50, but the increase was nonsignificant at 1% per year after age 50. More severe presbyopia was associated with female gender and less with education. CONCLUSIONS: This study provides the first population-based data on prevalence of presbyopia in a large, random sample of older Africans and suggests a high rate of presbyopia. Presbyopia plateaus after age 50, and it is more common in females. In addition, the 3-fold increased odds in town versus village dwellers was unexpected and suggests that research of other factors, including environmental factors, is warranted.

Adult↗
PubMed2005

The set-up.

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Aging↗
PubMed2005

Can elderly people take their medicine?

This study used performance tests to assess the cognitive, visual and physical abilities related to taking medicines in the elderly population. The study population consisted of the Swedish Panel Study of Living Conditions of the Oldest Old (SWEOLD II), a nationally representative interview survey. SWEOLD II is a random sample of all community-based and institutionalized persons aged 77+ in Sweden. Five tests related to medication management were administered in the direct interviews (n=492): hand function (opening bottle), vision (reading label), and medication competence (comprehension and calculation). Results showed that 9.4% could not read instructions on a medicine container and 14.6% had difficulty opening a plastic flip-top medicine bottle. The three cognitive tests related to taking medicine resulted in 30.7, 47.4 and 20.1% errors. Combining all the tests revealed that 66.3% of the sample had at least one limitation of capacity related to taking medicine. There were no significant gender differences. Among those people who did not pass all the tests, 31.8% lived alone with no home-help. Taking medicines is a complex task and a large proportion of the Swedish elderly population has cognitive, visual or physical limitations that may hinder their ability to take medicines accurately. Awareness of these limitations is essential to concordance.

Activities of Daily Living↗
PubMed2007

Coverage, utilization and barriers to cataract surgical services in rural South India: results from a population-based study.

OBJECTIVES: To determine the cataract surgical coverage, utilization and barriers to cataract surgery in a rural taluk of south India. STUDY DESIGN: A cross-sectional, community-based survey. METHODS: A house-to-house survey was carried out in 15 villages that were selected by cluster sampling during January to October, 2002. A total of 1505 people aged 50 years and above were tested for visual acuity (VA) and their eyes examined. Cataract surgical coverage was calculated for people and eyes, and for VA levels of <3/60 and <6/60. Information about details of cataract surgery and barriers to cataract surgery were collected using a pre-designed proforma. RESULTS: Cataract surgical coverage was 63% (people) and 51% (eyes) for VA<3/60 compared with 49% (people) and 36% (eyes) for VA<6/60. Of 109 operated eyes, 51.2% of operations were carried out in private hospitals and 33.3% in voluntary/charitable hospitals. Inability to afford the operation (22.9%) and fear of the operation (19.2%) were the main barriers to cataract surgery. CONCLUSIONS: The reasons for underutilization of government hospitals are to be investigated. Awareness of low-cost cataract intraocular lens (IOL) non-governmental organization (NGO) surgery and free-of-cost NGO services available in the region needs to be raised. Barriers to cataract surgical services should be addressed by community-based health-education programmes to improve the uptake of existing services.

Aged↗
PubMed2000

Prediction of letter contrast sensitivity using videokeratographic indices.

PURPOSE: To analyze the relationship between corneal topography and letter contrast sensitivity. METHOD: Experiments were conducted on 59 eyes of 51 patients who had best spectacle-corrected visual acuity of 20/20 or better and no ocular pathology except for the corneal shape. Thirty-nine eyes had an abnormal topographic pattern resulting from keratoconus, and the other 20 eyes showed a normal topographic pattern. Videokeratography was performed with the TMS-2 videokeratoscope, and the surface regularity index, surface asymmetry index, and coefficient of variation of power were obtained for each subject. Letter contrast sensitivity was measured with the CSV-1000LV with spectacle correction. The correlation between the number of correct letters and topographic indices was calculated. RESULTS: The abnormal topography group had a significantly greater loss of letter contrast sensitivity (median = 20 letters) than the normal control (median = 23 letters; P =.0001). There were statistically significant correlations between number of correct letters and the coefficient of variation of power (r = -.77; P =. 001), number of correct letters and surface regularity index (r = -. 76, P =.001), and the number of correct letters and surface asymmetry index (r = -.64; P =.001). The linear regression equation between number of correct letters and the coefficient of variation of power was the number of correct letters = -0.05 x the coefficient of variation of power + 23.2. CONCLUSIONS: Our results suggest that subtle visual deteriorations, which are barely detected by contrast sensitivity testing, can be predicted objectively by the corneal topographic indices.

Adult↗