[Traffic Aspects in Glaucoma Patients]. / Verkehrsophthalmologische Aspekte für Glaukompatienten.

Glaucomatous damage may lead to morphological and functional deficits. If these deficits affect both eyes, binocular visual field defects may result. If these field defects are in the areas which are most important for the car driver (centre and horizontal meridian) then the driver may no longer be able to participate actively in road traffic. Mesopic vision and sensitivity to glare may also be affected by glaucomatous damage. The most important point is that the patient is alert to problems in this area and he must be directed to possible ways of compensation, especially for mesopic vision and sensitivity to glare. Binocular visual field defects in the relevant areas, however, cannot be compensated for.

[Pitfalls in the determination of distance glasses]. / Fallstricke bei der Bestimmung von Fernbrillen.

The correct determination of distance glasses depends on a correct objective refraction and a subject determination of power and axis of a possible astigmatism in both a coarse and fine manner. In suitable cases a binocular fine refraction under polarized conditions with a red-green test should be performed. Special considerations have to be taken into account in cases of high unilateral congenital or acquired astigmatism as well as in case of congenital or acquired anisometropia or aniseiconia.

[Traffic ophthalmology. Assessment of ability to drive in road traffic]. / Verkehrsophthalmologie. Fahreignungsbegutachtung im Strassenverkehr.

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.

[Visual field and road traffic. How does peripheral vision function?]. / Gesichtsfeld und Verkehr. Wie funktioniert das periphere Sehen?

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.

[Is it possible to compensate for visual field defects?]. / Sind Gesichtsfeldausfälle kompensierbar?

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.

[Status of rendering an expert opinion following the changes in the German traffic legislation]. / Zur Lage der Begutachtung nach der Anderungsverordnung zur FeV.

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.

[Daytime running light: pros and cons]. / TagfahrlichtPro und contra.

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.

[Reduced visual capacity increases the risk of accidents in street traffic]. / Reduziertes Sehvermögen führt zu erhöhtem Unfallrisiko im Strassenverkehr.

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.

[Effect of low alcohol concentrations on visual attention in street traffic]. / Wirkung niedriger Alkoholkonzentrationen auf das Blickverhalten im Strassenverkehr.

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%.

[Informative value of psychophysical examinations aside from conventional white-white perimetry]. / Informationswert psychophysikalischer Untersuchungsmethoden ausser der konventionellen Weiss-Weiss-Perimetrie.

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.

Simulations for FASTPAC and the standard 4-2 dB full-threshold strategy of the Humphrey Field Analyzer.

PURPOSE: This study evaluates the accuracy, reproducibility, and efficiency of FASTPAC, a new fast strategy for automated perimetry using 3-dB steps with single threshold crossing, compared to the standard 4-2 dB full threshold strategy by means of computer simulations. METHOD: An "artificial patient" module was developed to create responses to stimuli by a Monte-Carlo technique from a given probability distribution. The authors performed 10,200 simulations with threshold values ranging from 0 to 50 dB. RESULTS: Results demonstrate an 18% decrease in the number of presentations per threshold determination, which is equal to a similar reduction in testing time. For both strategies, there is a considerable influence of the starting deviation (difference between starting value and actual threshold) on threshold error (difference between estimated threshold and actual threshold): negative starting deviations lead to negative threshold errors and vice versa. This relationship is more pronounced for FASTPAC (slope 0.18 dB/dB, P < 0.0001) than for the full-threshold strategy (slope 0.13 dB/dB, P < 0.0001). In addition, fluctuations of the determined thresholds, described as the distance between the 16th and 84th percentiles of the threshold errors, increase with increasing absolute starting deviations. This is particularly true of FASTPAC: CONCLUSIONS: The influence of the starting value on the threshold determination may lead to a considerable underestimation of visual field defects, accompanied by a higher fluctuation. This is an intrinsic property of both staircase procedures. FASTPAC, however, is more affected than the standard 4-2 dB full-threshold strategy. FASTPAC, therefore, provides time reduction at the expense of accuracy and reliability.

Glaucomatous visual fields. FASTPAC versus full threshold strategy of the Humphrey Field Analyzer.

PURPOSE: This study examined how FASTPAC, a fast strategy for the Humphrey Field Analyzer (HFA), compares to the standard 4/2-dB full threshold strategy in patients with glaucoma. METHOD: The author tested one eye each of 50 patients with glaucoma (23 with only relative defects, 27 with at least one absolute defect; age range, 25 to 79 years; median age, 61.5 years) with both strategies using program 30-2 of the HFA (stimulus size III). Global visual field indices as calculated by Statpac, unweighted mean sensitivity, and examination time were compared. In addition, a point by point analysis of the sensitivity values was performed. RESULTS: Between the two strategies, no significant differences were found for indices directly related to the sensitivity values (mean sensitivity [MS], mean deviation [MD]) or for the actual thresholds. For the entire population, FASTPAC showed higher mean short-term fluctuation (SF; P = 0.018), lower mean pattern standard deviation (PSD; P = 0.006), and mean corrected PSD (CPSD; P < 0.001) values and a time reduction of more than 30% (P < 0.001) compared to the standard strategy. These differences between the strategies were found to be independent of the amount of field loss, except for PSD (P = 0.001). No age influence was present. Statistically significant linear regression (r > 0.70, P < 0.001) was found between the FASTPAC values of MS, MD, PSD, CPSD, and the corresponding values determined with the standard strategy. No correlation exists for SF (r < 0.46, P > 0.030). CONCLUSIONS: FASTPAC provides a considerable time reduction at the cost of higher threshold fluctuation. This may lead to problems in detecting relative defects or changes in differential light threshold in follow-up examinations.

Points of a normal visual field are not statistically independent.

The aim of the present study was to determine whether the sensitivity values at individual test locations in a normal visual field are statistically independent. A total of 144 eyes of 144 normal subjects were tested with the Humphrey Field Analyzer, program 30-2. For each point in the visual field the pairwise correlation of sensitivity values to all other points was calculated together with the angular distance between points. The overall 2775 correlation coefficients were plotted as a function of angular distance. With increasing distance the correlation coefficients decrease continually from 0.63 (distance 6 degrees) to approx. 0.5 (distance 30 degrees and above). The strong relationship between adjacent points that is present at up to 30 degrees is destroyed by intraindividual randomisation of the visual field data. Interindividual randomisation abolishes any correlation. Adjacent locations in a normal visual field are strongly statistically related to each other. Two patterns may be separated; part of the correlation is an intrinsic neighbourhood effect present up to 30 degrees and part is due to the observation that the sensitivity values of a specific visual field are obtained from the same subject and are thus not independent. Therefore, for the calculation of normal values, procedures have to be developed that take the relationship between neighbouring points into consideration.

Deficits in perimetric performance in patients with symptomatic human immunodeficiency virus infection or acquired immunodeficiency syndrome.

PURPOSE: We measured the perimetric performance in patients with either acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus (HIV) disease but without AIDS. METHODS: Light-difference sensitivity in the central field was measured in 74 eyes of 37 patients. The Humphrey Field Analyzer 640, program 30-2 was used. Additionally, 143 eyes of 143 normal control subjects were studied. RESULTS: Mean deviation was significantly reduced in patients with HIV disease compared with control subjects (mean +/- S.E.M., -4.30 +/- 0.52 vs -0.77 +/- 0.15, respectively; P < .0001). Analysis of subgroups demonstrated that patients with lymphadenopathy syndrome or AIDS-related complex (N = 40 eyes; -3.52 +/- 0.41; P < .0001) as well as patients with AIDS (N = 34 eyes; -5.23 +/- 0.97; P < .0001) had a reduced mean deviation. Those comparisons remained significant (P < .0001) when data were analyzed independently for the right eyes and for the left eyes. Corrected pattern standard deviation (3.15 +/- 0.30 vs 1.39 +/- 0.09; P < .0001) was higher in patients with HIV disease compared with control subjects. Again, analysis of subgroups disclosed a significant increase in patients with lymphadenopathy syndrome or AIDS-related complex (2.55 +/- 0.36; P < .0001) as well as in patients with AIDS (3.85 +/- 0.51; P < .0001). Both comparisons remained significant when data were analyzed independently for the right and left eyes. CONCLUSIONS: This study demonstrates visual dysfunction despite normal visual acuity in patients with HIV disease. Our results are consistent with the hypothesis of damage at the neuroretinal level.

[Driving with light during the day?]. / Fahren mit Licht bei Tage?

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.

[15 years automated perimetry--where does the path lead?]. / 15 Jahre automatisierte Perimetrie--Wohin führt der Weg?

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.