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B Lachenmayr

Publications and source records attributed to B Lachenmayr.

At least 19 recordsLinked 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↗
PubMed1996

[Effect of low alcohol concentrations on visual attention in street traffic].

There is currently public discussion as to whether the legal limit of blood alcohol concentration of drivers might be reduced from 0.8% to 0.5%. To acquire information concerning this problem, we measured temporal parameters of saccades and analysed the overall eye-movement behaviour with various blood ethanol concentrations. Eye movements were registered with an IR eye tracker and analysed while the subjects followed a randomly moving stimulus on a CRT screen and during presentation of a realistic traffic scene of 4 min duration on a TV screen. Alcohol has a significant effect on latency, velocity and accuracy of saccades, even at low concentrations between 0.4% and 0.6%. Because of the altered "gaze activity", the inflow of visual information is reduced in a state of inebriation. Our results are a further argument for reducing the legal limit of blood alcohol concentration to 0.5%.

Adult↗
PubMed1996

[Informative value of psychophysical examinations aside from conventional white-white perimetry].

In addition to routine light-sense perimetry testing, elementary visual function, i.e., light difference sensitivity, numerous methods and procedures were developed to test more complex psychophysical threshold criteria in glaucoma patients in order to detect functional glaucomatous loss earlier. The various methods differ with respect to the area of the visual field tested (central, perimetric, global or Ganzfeld stimulation) and the psychophysical threshold criteria (spatial and/or temporal transfer, color, complex criteria including form perception, etc.). Two domain proved to be of special interest: examination of the temporal transfer properties (flicker stimulation, motion perception, "motion-defined-form") and testing of the short-wave-length cone system (blue/yellow perimetry). The blue cone system is part of the parvocellular pathway, criteria in the field of temporal transfer may be allocated to the magnocellular pathway. There is histopathological evidence that ganglion cell axons of the magnocellular system are prone to glaucomatous damage in an earlier stage of the disease. There may even be some kind of specific damage. The role of various psychophysical procedures are discussed with reference to data in the literature and own experience with special emphasis on the practical applicability for early diagnosis of functional glaucomatous damage.

Color Perception Tests↗
PubMed1995

[Driving with light during the day?].

In various Scandinavian countries the use of headlights during daytime (daytime running light DRL) is obligatory since many years. In Canada all new cars have to be equipped with a daytime running light since 1990. Whether or not in Germany or in the southern neighbouring countries a daytime running light should be used is matter of controversial discussion during the least years. Daytime running light increases the visibility of oncoming cars tremendously. Not only the drivers, but also pedestrians and cyclists profit from this gain of visibility. Especially drivers with poor vision, who will become more and more frequent during the coming years due to the increase of percentage of older drivers, have a specific profit from daytime running light. Potentially negative side-effects of daytime running light are: reduction of visibility of the brake-lights, glare, loss of visibility for pedestrians and cyclists, damage to the retina, increase of fuel consumption. All these arguments are either not crucial or cannot be documented by statistical data. On the other hand the data which are available up to now concerning frequency of accidents in those countries and areas in which daytime running light was used or is used, show a trend, sometimes even a statistical significant reduction of daytime accidents. This reduction is especially pronounced for accidents with pedestrians and cyclists. Overall, there are more and better arguments for using daytime running light, also in Germany. A technical alternative would be an automatic switching of the headlights if horizontal illuminance drops below a specific limit, e.g. 2000-3000 lx. Such an automatic procedure would increase the percentage of cars using headlights in critical situations during daytime.

Accidents, Traffic↗
PubMed1994

[Limitation of lens power in automobile drivers].

High plus lenses may cause defects in the peripheral visual field. Simple full vision lenses or lenticular lenses without a masked transition zone caused an absolute ring scotoma in the mid-periphery. Patients who were glasses of this type cannot see well enough to drive safely. Although modern edge finishes with masking of the transition zone reduce this problem, visual disturbances in the periphery of the lenses cannot be completely eliminated. A recommendation recently issued by the German Ophthalmological Society concerning maximum lens powers for motorists is aimed at preventing visual field defects of this type.

Automobile Driver Examination↗
PubMed1994

[15 years automated perimetry--where does the path lead?].

15 years ago the first fully automated perimeter became available, the Octopus 201, developed by Fankhauser in Bern. Some of the objections which were raised in those days against automated perimeters have turned out true, many, however, not. From todays perspective automated perimetry has brought tremendous advantages for clinical routine diagnosis. The essential power of automated perimetry is its ability to obtain quantitative data which can be processed statistically. The examination of the central visual field may be performed in a much more sophisticated way than by manual kinetic testing. Automated perimetry, however, also has its draw-backs, which are mostly due to mistakes or errors by the examiner, not so much to the method itself. For routine light-sense perimetry the upcoming years will give us faster and optimized testing strategies. Procedures for automated interpretation of visual field data will be developed. The interest in more complex perimetric test criteria goes on one hand into the direction of independence of disturbancies of the optical media (e.g. temporal criteria), on the other hand into the differentiation of various cell populations in the visual system (Blue/Yellow-Perimetry; Motion-Defined-Form etc.). For objective perimetry a powerful system for pattern-ERG and pattern-VECP with a spatial resolution comparable to standard perimetric tests is available. Also in these fields of perimetry the coming years will bring interesting and revolutionary new developments which will open new diagnostic dimensions.

Electroretinography↗
PubMed1994

[Dependence of the sensitivity of the central visual field on hemoglobin-oxygen saturation].

Retinal function is very sensitive to changes in hemoglobin oxygen saturation. Characteristic ophthalmological symptoms of oxygen deficiency are: changes in color perception, visual field defect, eye flickering, reduction of visual acuity, seeing double images, defects in neural image interpretation. To test the dependency of changes in the central visual field sensitivity on different degrees of oxygen saturation, 48 probands (48 monocular tests) 20-50 years of age were examined in the altitude simulation chamber of the Aviation Medicine Institute of German Air Force at zero altitude (= 500 m) and at 10,000 ft (ca. 3,500 m height). Three types of experiments were performed: determination of abnormal quotient using a Heidelberg anomaloscope; determination of changes in color vision by saturated and disaturated panel D-15 test; determination of differences in light sensitivity for white, red, blue and green light by a threshold test using a Humphrey Field Analyzer (640) as perimeter. At zero level (500 m) hemoglobin-oxygen saturation was 97% +/- 1%. At 10,000 ft this value decreased to 83% +/- 3%. Hypoxic hypoxia caused neither significant AQ changes nor did it induce reproducible changes in color vision by the panel D-15 test. However, anoxia resulted in significant (P < 0.01) differences in light sensitivity in phototopic range.

Adult↗
PubMed1994

[What visual information does the automobile driver need for safe driving in street traffic?].

In daytime traffic the driver experiences a tremendous input of visual information: His problem is to extract the relevant stimuli in order to have an adequate reaction. Traffic at dusk or nighttime, however, is characterized by the fact that even a driver with full visual function approaches his physiological limit. By assessing real traffic situations under various circumstances of weather and illumination (daytime, dusk, nighttime, city traffic, country road) limits of adaptation luminance, object size, object contrast and color are demonstrated. In addition, typical distributions of luminance in the visual field of the driver and the distributions of size and location of relevant objects are quantified. For glare situations typical values of glare angle and corneal illuminance of the glare light and the induced reduction of contrast are determined. Our data demonstrate the type of visual information required by the driver in order to drive safely in road traffic. These data allow conclusions to be made with respect to minimum requirements of visual function for car drivers.

Automobile Driver Examination↗
PubMed1990

[Predicting visual acuity in media opacities and uncorrectable refractive errors. Assessing so-called "retinal visual acuity"].

Three different components contribute to the modulation transfer function of the visual system: (1) formation of the optical image (refractive media, pupil); (2) scattering of light in the prereceptoral layers of the retina; (3) neuronal processing in the retina und superior visual centers. In the presence of media opacities or non-correctable refractive errors, the clinical question often arises as to which macular function can be expected under the assumption of normal optical image formation (e.g. prior to cataract extraction, corneal transplantation, or vitrectomy). Simple tests such as light projection, color discrimination, and two-point discrimination cannot provide adequate information about macular function. The same holds true for the global luminance ERG. The X-ray phosphene is obsolete. The Maddox rod (with limitations), transilluminated Amsler grid, and various entoptic phenomena (Purkinje vascular phenomenon, foveal chagrin, Haidinger's brushes, blue field phenomenon) are available as qualitative subjective tests. Maxwellian view systems with pinhole aperture (potential acuity meter PAM) and the interferometers (retinometer, visometer, SITE-IRAS interferometer) provide quantitative subjective methods. The flash VECP is primarily a qualitative objective test that allows semiquantitative acuity prediction under special conditions (unilateral opacities). Psychophysical criteria that are less affected by the quality of the retinal image show promising developments in future subjective tests, e.g. optotypes in positive contrast, optotypes or targets superimposed on a background of optical noise, or hyperacuity. Future objective test developments are pattern VECP or even pattern ERG elicited by interferometric stimulation, speckle VECP and focal ERG.

Cataract↗
PubMed1990

[Measuring temporal transmission properties of the visual system. Diagnostic value in suspected optic nerve neuritis].

The temporal transfer properties of the visual system were examined in 157 patients with suspected acute optic neuritis or papillitis. Foveal modulation sensitivity was measured as a function of temporal frequency (DeLange curve) both for the affected eye and the unaffected fellow eye. Patients with acute optic neuritis typically show a reduction of foveal modulation sensitivity at all temporal frequencies, high temporal frequencies above 10 cps being more markedly affected. The aim of the present study was to determine the sensitivity and specificity of this simple psychophysical procedure for the diagnosis of neuritis or papillitis in a reasonably large population of patients with suspected acute optic neuritis or papillitis. In each case the final diagnosis was confirmed by evaluation of the clinical signs and symptoms, the course of disease and additional diagnostic procedures, e.g. electrophysiology, perimetry, neurological examination including CT, lumbal puncture and examination of cerebrospinal fluid. In 136 cases (86.6%) the result read from the DeLange curve was correctly positive or negative. In 17 cases (10.8%) the DeLange curve indicated a false-positive and in 4 cases (2.6%), a false-negative result.

Flicker Fusion↗
PubMed1989

[Peripheral vision--function and significance].

The human retina may be divided into two parts, representing different functional capabilities: the center, i.e., the fovea, and the much greater periphery. Under photopic conditions the fovea has a very high spatial resolution, a high light-difference sensitivity, and a good perception of slow movements. Opposed to this the periphery shows an especially high temporal resolution and a good perception of fast movements. This enables the visual system to detect dangerous objects appearing in the periphery as soon as possible and to induce a detailed analysis in the fovea after triggering a fixational movement.

Fovea Centralis↗
PubMed1989

Fate of late complications in type I diabetic patients after successful pancreas-kidney transplantation.

The success rate of pancreas transplantation allows us to study in more detail the potential beneficial effects of normoglycemia on secondary complications in diabetes mellitus. We report a prospective follow-up (mean 26 mo) of metabolic control, neuropathy, retinopathy, and peripheral microcirculation in 31 patients with type I (insulin-dependent) diabetes (mean age 33 +/- 1 yr; mean duration of diabetes 21 +/- 1 yr) after combined kidney and segmental pancreas grafting. All patients had normal HbA1 levels. Glucose tolerance (GT), insulin, C-peptide, and glucagon were normal in 22 patients, and impaired oral GT with reduced insulin secretory capacity was seen in 9 patients. During follow-up, there was no deterioration of GT and insulin release. Vascular risk factors, e.g., hypertension, cholesterol, and triglycerides, decreased after grafting. Autonomic neuropathy improved clinically, and R-R variation increased significantly in 3 of 18 patients. Peripheral neuropathy improved clinically in 46% of patients and did not deteriorate in the others. Motor nerve conduction velocity increased greater than 20% in 8, less than 20% in 12, and was unchanged in 8 of 28 recipients. Most of the patients (n = 30) had pretransplant laser treatment of their advanced retinopathy. Posttransplant visual acuity improved at least more than one line in 56%, stabilized in 32%, and deteriorated in 12% of patients. Patients with functioning grafts for greater than 1 yr had no further deterioration of visual acuity. Vitreous hemorrhage frequency and severity dropped markedly from pretransplant (from 69 to 24%) 10 mo after grafting. Retinal morphology remained stable in all eyes except two.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Automated flicker perimetry].

Flicker fusion frequency (FFF), the threshold criterion of flicker perimetry, is a functional parameter of the temporal transfer properties of the visual system. An automated flicker perimeter suitable for clinical routine purposes is presented that allows perimetric examination of the central visual field with high spatial resolution. The intent of the present study was to investigate the outcome of flicker perimetry in comparison to static light-sense perimetry. In the majority of cases of ocular hypertension and suspected glaucoma (n = 31), chronic open-angle glaucoma (n = 36) and acute neuritis/papillitis (n = 10) defects are indicated by flicker perimetry in areas of the visual field with normal light sensitivity according to static light-sense perimetry (Octopus 201, program G 1). In many cases of preproliferative diabetic retinopathy (n = 10), however, flicker perimetry indicates fewer defects than static perimetry (Octopus 201, program 32). The results collected up to now suggest that automated flicker perimetry might represent a specific functional test of the retinal Y-ganglion cells.

Diabetic Retinopathy↗
PubMed1988

[Perimetry yesterday and today].

The historical development of perimetry, from the first technical devices for testing the visual field (arc perimeter) through the manual hemispherical perimeters (Tübingen and Goldmann perimeters) to the latest developments in automated, computer-controlled perimeters, is described with reference to the basic measuring methods and strategies on the one hand and technical realization on the other. The future development of perimetry will be characterized by a refinement of measured value statistics and the testing of perimetric procedures that test more complex physiological functions than sensitivity to differences (e.g., analysis of temporal transmission characteristics in flicker perimetry.

Europe↗
PubMed1987

[Study of early glaucomatous visual field defects with the automatic perimeter Topcon SBP-1000. Comparative study with the Octopus 201 perimeter].

The automatic perimeter TOPCON SBP-1000 uses light emitting diodes (LED's) for stimulus generation and thus completely differs from the projection type perimeter OCTOPUS 201. In order to get some first idea about the capabilities of the TOPCON SBP-1000 22 eyes of 18 patients with early glaucomatous visual field defects were examined both with the glaucoma program/TOPCON SBP-1000 and program 31/OCTOPUS 201. Field defects were divided into three groups according to the total loss (program DELTA/OCTOPUS 201): group I with a total loss of 0 dB, group II with a total loss of 1-200 dB, group III with a total loss greater than 200 dB. Evaluation and comparison of visual field results is done after discussing the most important technical parameters and fundamental aspects of methods and strategies using the total percentage of "normal" test points, "small relative defects", "deep relative defects" and "absolute defects". We could show that specificity and sensitivity for the detection of earliest field defects are quite equal both in the TOPCON SBP-1000 and in the OCTOPUS 201. Concerning the detection of more pronounced visual field defects the TOPCON-perimeter has a somewhat smaller sensitivity as a result of the different definition of the category "normal"; at the same time there is a tendency for showing up more "absolute defects" instead of "deep relative defects". Technical parameters and strategies are discussed critically taking into consideration the practical experience obtained during this first routine testing.

Adult↗