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Wolfgang Wesemann

Wolfgang Wesemann

PhD

About

51
Publications
5,599
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982
Citations
Additional affiliations
April 1977 - August 1989
University of Hamburg
Position
  • Research Assistant

Publications

Publications (51)
Article
In den letzten Jahren wurden 3 internationale Vorschriften zur Sehschärfebestimmung novelliert. DIN EN ISO 8596:2018 schreibt den Landolt-Ring als Normsehzeichen vor und spezifiziert die Darbietungsbedingungen. In einem informativen Anhang werden erstmals „klinische Sehzeichen“ gelistet. Dies sind z. B. die ETDRS-Tafel, der Snellen-Haken und Kinder...
Article
Objective: To determine whether the prevalence and magnitude of myopia among children and young adults wearing spectacles has increased in Germany from 2000 to 2015. Material and methods: A total of 1,223,410 refraction values from 278,432 male and 333,273 female subjects between 5 and 30 years of age were analyzed. All subjects had received a n...
Article
Human contrast vision and its quantitative assessment are gaining more attention. Publications on this topic can be confusing due to the overabundance of differing definitions and quantification of contrast vision. As a case in point, in Germany, contrast ratios as required for certain driving licenses and the DIN-defined contrast ratio are recipro...
Article
To study the factors influencing the reliability (accuracy) of autorefractometry before and after laser in situ keratomileusis (LASIK) for myopia and myopic astigmatism. Retrospective case series. A total of 250 consecutive eyes (132 patients, mean age 37 years) were included from the Department of Ophthalmology, J.W. Goethe University, Frankfurt,...
Article
In 2009 the DIN 58220 norms for determination of visual acuity were revised. The new rules came into force on 1(st) November 2009. The new regulations on expert assessment of visual acuity (DIN norm 58220, part 3) are particularly important for ophthalmologists because as a result of the revisions the approach to testing visual acuity in patients w...
Article
Full-text available
Contrast perception is an important visual function. Contrast sensitivity (CS) is affected by to optical reasons (aberrations, scatter, diffraction) or neural dysfunction (e.g., glaucoma, optic nerve diseases). In clinical practice the measurement of CS is relevant for disease monitoring, expert opinions, roadworthiness assessment, and recruitment...
Article
Full-text available
Die Kontrastempfindlichkeit (KE) ist eine wesentliche Sehfunktion. Sie kann aus optischen (Aberrationen, Streuung, Beugung) oder neuralen Gründen (z. B. bei Glaukom oder Neuritis nervi optici) herabgesetzt sein. In der klinischen Praxis spielt die Prüfung der KE bei Verlaufskontrollen, Gutachten, Fahrtauglichkeitsprüfungen und Einstellungsuntersuch...
Article
The purpose of this study was to evaluate three psychophysical tests for the measurement of contrast sensitivity (CS) and disability glare (DG) at different luminance levels. In 60 eyes of 60 individuals (group 1: 20 healthy eyes of young individuals; group 2: 20 healthy eyes of elderly subjects; group 3: 20 eyes with nuclear cataract), CS with bes...
Article
The purpose of the present study was to evaluate a computerized test for measurement of contrast sensitivity thresholds under variable ambient and glare luminance levels. A total of 40 eyes of 40 healthy subjects were examined with the FF-CATS and the Functional Acuity Contrast Test (FACT) at 0.167 cd/m(-2) (mesopic) and 167 cd/m(-2) (photopic). Me...
Article
According to optical diffraction theory, a visual acuity of 20/3.5 is possible in human eyes with pupil diameters larger than 6 mm. This theoretical value cannot be obtained in practice - in fact visual acuity is limited by the scale of the mosaic of the retinal cones. Anatomical data and the model by Helmholtz-Hering suggest that visual acuity of...
Article
Full-text available
According to optical diffraction theory, a visual acuity of 20/3.5 is possible in human eyes with pupil diameters larger than 6 mm. This theoretical value cannot be obtained in practice—in fact visual acuity is limited by the scale of the mosaic of the retinal cones. Anatomical data and the model by Helmholtz-Hering suggest that visual acuity of hu...
Article
If different ways for correcting refractive errors of the human eye have to be compared, accurate and reproducible measurement procedures are necessary. Binocular visual acuity of 130 students without pathologies was measured with the Freiburg Visual Acuity Test, the Bailey-Lovie chart and a Landolt ring chart (4 orientations). The reproducibility...
Article
To determine the accuracy of measurement by the SureSight autorefractor (software version 2.0) and the influence of accommodation. Pediatric Section, Department of Ophthalmology, University of Hamburg, Hamburg, Germany. In a series of comparative measurements, autorefractor readings were compared with cycloplegic retinoscopy in 195 eyes of 108 pati...
Article
Hintergrund: Um verschiedene Methoden zur Korrektion von Refraktionsfehlern des Auges miteinander vergleichen zu können, sind Verfahren zur genauen und reproduzierbaren Sehschärfeprüfung erforderlich. Methoden: Der binokulare Visus von 130 Versuchspersonen ohne pathologische Augenveränderungen wurde mit dem Freiburger Visustest (FVT), einer Landolt...
Article
To determine the accuracy of measurement by the Nikon Retinomax handheld autorefractor and its ability to relax accommodation. Pediatric Section, Department of Ophthalmology, University of Mainz, Germany. To perform a series of comparative measurements, autorefractor readings were obtained on healthy young adults (students) and on children aged 2 t...
Article
Full-text available
Vernier onset/offset thresholds were measured both psychophysically and with the steady-state VEP by introducing a series of horizontal breaks in a vertical square-wave luminance grating. Several diagnostic tests indicated that the first harmonic component of the evoked response generated by periodic modulation of offset gratings taps mechanisms th...
Article
Full-text available
We try to improve the accuracy of eccentric photorefraction by taking more information into account than just the size and tilt of the crescent. Based on Gaussian optics and the assumption of an isotropic scattering retina, a theoretical analysis of the light-intensity distribution in the pupils of astigmatic eyes is presented. The method is applie...
Article
A measurement of ametropia with a table-top mounted autorefractor can be difficult or impossible on children--especially when the children are very young or handicapped. A hand-held autorefractor, however, may be successfully applied in some of these problematic cases. Results of comparative measurements are presented concerning the accuracy and ap...
Article
Hintergrund Die objektive Bestimmung der Refraktionswerte mit einem normalen Autorefraktometer kann bei Kindern problematisch oder unmöglich sein, wenn die Kinder zu klein oder behindert sind oder Abwehrreaktionen zeigen. Mit dem handgehaltenen Autorefraktometer gelingt die Refraktometermessung auch bei vielen dieser Problempatienten. Methoden Es w...
Article
The visual abilities of infants and small children, who are unable to communicate verbally, can be determined with "objective" visual acuity tests as, e.g., preferential looking (PL) or visual evoked potentials (VEP). Both methods provide an estimate of grating visual acuity, but are unable to determine optotype visual acuity. Grating acuity, howev...
Article
The legibility of three selected sets of optotypes: (1) letters; (2) Snellen E; and (3) KOLT test have been compared to the Landolt ring in a study based on the German Standard DIN 58220, Part 2 and the International Standard ISO 8597. The letters were printed in the standard typeface used on German street signs (sans serif Linear-Antiqua, Typeface...
Article
Full-text available
Observer sensitivity to oscillatory step displacements of sine-wave gratings was investigated at various loci in the visual field (0-30 degrees) as a function of contrast. Detection thresholds at 10 Hz and high grating contrasts were approximately 11-15 arcsec in the fovea and 37-47 arcsec at 30 degrees eccentricity. At any given contrast, threshol...
Article
Full-text available
An optical analysis of eccentric photorefraction (photoretinoscopy) of astigmatic eyes is presented. The size and the angular tilt of the dark crescent appearing in the subject's pupil are derived as a function of five variables: the ametropia of the eye (Dsph, Dcyl, axis), the eccentricity of the flash, e, and the distance of the camera from the s...
Article
Die Erkennbarkeit der vier Zeichen eines Kindersehschärfetests (Kolt-Test nach Lithander, 1984) wurde nach dem standardisierten Anschlußverfahren an den Landoltring (DIN 58220 bzw. 1SO/DIS 8596/7) geprüft. Wir fanden, dass bei gleichgroßen Optotypen die Sehzeichen des Kolt-Tests etwas leichter zu erkennen sind als der Landoltring. Der Kolt-Test erg...
Article
Multiple-beam interference fringes have been projected onto the retina to serve as a size reference for fundus photography. The absolute fringe spacing is determined by measurable parameters. The interference fringes are extremely narrow so that fringe maxima and fundus structures can be perceived equally well, and a high precision of measurement i...
Article
Contrast response functions (CRFs) for the VEP were obtained with a Discrete Fourier Transform (DFT) technique employing swept contrast gratings. VEP CRFs in infants were found to have a form similar to those observed in adults, being linear functions of log contrast over a range of near-threshold contrasts. CRFs with low and high contrast lobes we...
Article
Full-text available
Contrast response functions (CRFs) for the VEP were obtained with a Discrete Fourier Transform (DFT) technique employing swept contrast gratings. VEP CRFs in infants were found to have a form similar to those observed in adults, being linear functions of log contrast over a range of nearthreshold contrasts. CRFs with low and high contrast lobes wer...
Article
In order to determine the performance of seven automatic infrared (IR) eye refractors, measurements have been conducted on a model eye as well as on normal subjects and patients under standardized conditions. Concerning the model eye, a range of measurement slightly smaller than specified and linearity errors have been detected on several instrumen...
Article
Incoherent image formation in human eyes that have scattering eye media is investigated as a function of the particle size and the optical density of the scattering medium and for test targets that differ in form and size. For single scattering by large particles (much greater than lambda), a point-spread function and the associated modulation-tran...
Article
The cortical response to stereoscopic stimuli was measured as a function of disparity using visual evoked potentials (VEP). The stereoscopic stimulus consisted of a dynamic random-dot pattern that portrayed a three-dimensional horizontal grating. Disparity of the grating was variable between 0 and 18 arc min, step size being 4.22 arc s. Evoked resp...
Article
In a comparative study, subjective refractions were carried out on 115 normal subjects and 118 patients with four instruments (Humphrey Vision Analyzer, Möller/CooperVision Visutron, Reichert SR-IV, Rodenstock/Coburn Phoromat). The accuracy of the prescriptions obtained, the visual acuity results and the measurement time required were analyzed. The...
Article
In a comparative study, subjective refractions were carried out on 115 normal subjects and 118 patients with four instruments (Humphrey Vision Analyzer, Möller/CooperVision Visutron, Reichert SR-IV, Rodenstock/Coburn Phoromat). The accuracy of the prescriptions obtained, the visual acuity results and the measurement time required were analyzed. The...
Article
A laser interferometer for visual-evoked-potential (VEP) stimulation that allows a rapid pattern reversal in less than 0.5 ms and a continuous variation of the spatial frequency of the pattern is described. The interferometer is applied for the assessment of objective visual acuity. The Fourier transform of the VEP response to the rapid pattern rev...
Chapter
Simultaneous stimulation of transient cortical potentials by checkerboard reversal of both hemifields is comparable to successive stimulation. Even mild hemiopic visual field impairment by lesions of the central visual pathways correspond to significant deformations of potentials for the affected hemifield. Advantages are a real comparability of th...
Article
A Topcon Retinal Camera TRC-FET 3 was tested for several weeks under laboratory and clinical routine conditions. The optical properties turned out as good and meet the requirements for retinal cameras in all details. Remarkable is the high speed of the imaging system, which allows working with low flash energies and with high flash frequency. The r...
Article
The implementation of the European Union's directive on driving licences offers the optometric and optical profession an opportunity to raise with national authorities the issue of vision and driving. It is generally accepted within the profession that vision plays an essential part in driving. It is estimated that 90% of the sensory information us...

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