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B Lachenmayr

Publications and source records attributed to B Lachenmayr.

At least 19 recordsLinked to original sources
PubMed2006

[Is it possible to compensate for visual field defects?].

Is it possible for a driver to compensate for visual field defects by skill along with eye and head movements? Monocular field defects with a normal second eye are no problem, because a normal binocular visual field is adequate for all areas of traffic. A total bitemporal hemianopia creates a special situation, because the patient loses a three-dimensional space behind a vertical line through the point of fixation. He may have no binocular visual field. In this case the ability to participate in certain traffic situations may be limited with reduced risk profile. A real problem is posed by defects in the binocular visual field, e.g., due to lesions of the suprachiasmal visual pathway or due to ocular diseases causing damage to both eyes (e.g., glaucoma, diabetic retinopathy, etc.). Such defects usually cannot be compensated for, neither by skill nor by eye or head movements. Saccadic eye movement training and other procedures are only of limited help. These procedures may provide some compensation for daily use; a complete restoration of the ability to participate in traffic is not possible. Rare exceptions may be patients with damage to the visual pathway acquired peri- or postnatally or in early childhood when there is still enough plasticity in the visual system to develop mechanisms of compensation by completely changing the system of eye and head movements.

Automobile Driving↗
PubMed2006

[Visual field and road traffic. How does peripheral vision function?].

Peripheral vision is very important for visual perception in all fields of traffic. The central visual field is most important because the major part of information input occurs here. The peripheral parts of the visual field have excellent motion detection and the capability to perceive flicker stimuli. In addition to the central visual field the horizontal parts to the left and right are important, especially for road traffic. Information input occurs in a continuous sequence of saccadic eye movements which transport critical objects into the fovea. After fixation, the observer analyses the object and decides whether or not a reaction is necessary. Triggering of a saccadic eye movement only can occur if the critical object is suprathreshold in size, contrast, colour, motion and temporal modulation. This is the reason why perception of peripheral objects needs more time than the perception of objects in the fovea. Without an intact central and peripheral visual field participation in traffic is not possible.

Automobile Driving↗
PubMed2006

[Traffic ophthalmology. Assessment of ability to drive in road traffic].

Assessment of an individual's ability to drive in road traffic is an important part of the ophthalmologist's work. It fulfils the ophthalmologist's duty to care for the patient and increases general road traffic safety. This assessment requires testing of visual acuity, visual field, mesopic vision and glare, motility, binocular vision and colour vision. Also the optical media and the fundus have to be examined. If an optical aid is necessary, it should be suitable for use in road traffic. In some cases restrictions are necessary, which should be noted in the driver's licence. Testing of visual function has to be performed with standardised procedures according to the recommendations of DOG and BVA. This article will provide readers with an overview of current practices in assessing the ability to drive in road traffic and enable them to render an accurate professional opinion regarding driver's licences.

Accidents, Traffic↗
PubMed2005

[Status of rendering an expert opinion following the changes in the German traffic legislation].

The new traffic legislation in Germany ("FeVAndV") solves at least the most urgent problems for the ophthalmological driver's license assessment which were present in the old, preceding regulations ("FeV"). Many suggestions of the traffic committee of the German Ophthalmological Society ("DOG") were taken into consideration. As expected, the recommendations of the traffic committee concerning an obligatory test of mesopic vision were not adopted into the new legislation. We still have the unacceptable situation that on the one hand the European legislation demands an obligatory test of mesopic vision in suspected candidates and the German legislation even has the necessary key note for a ban on night driving ("05.01"). On the other hand, testing of mesopic vision is not considered on a regular basis in the new German regulations. This is not acceptable from an ophthalmological point of view.

Automobile Driver Examination↗
PubMed2003

[Daytime running light: pros and cons].

Daytime running light (DRL) has been in use for many decades in various countries world-wide. Experience is present from the Scandinavian countries, from Canada and the United States. DRL reduces traffic accidents tremendously and encompasses all participants in road traffic, especially the non-motorized pedestrians and cyclists. Physiological-optical considerations, the technical realisation of DRL and accident statistics will be discussed.

Accidents, Traffic↗
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↗