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Biomedical subjects

E Marré

Publications and source records attributed to E Marré.

At least 19 recordsLinked to original sources
PubMed1993

[Pattern-induced flicker colors. An ophthalmologic examination method].

The pattern-induced flicker colours (PIFC), which belong to the subjective colours, are presented here as a method of investigating diseases of the eye and the visual track. Starting with Benham's top, new methods are elaborated for producing PIFC by means of rotating black and white discs and a computer-controlled black and white monitor. The investigations were performed in 40 normal and 111 pathological cases. A differentiation is made concerning the neuronal X-Y system. Different deficiencies result from different diseases. The PIFC are particularly suitable for the differential diagnosis of the neuritis nervi optici.

Adult↗
PubMed1992

Cortical potentials to pattern reversal and luminance onset under ramp stimulation conditions in glaucoma.

Stimulus quantities with a ramp-like temporal course evoke cortical potentials that are delayed and attenuated in comparison with responses evoked by a step-like course. This delay probably depends on temporal transfer characteristics of the activated precortical visual system. In a pilot study, luminance onset and pattern-reversal stimulation using this technique (light-emitting diode stimulator; transition time, 50 ms) were applied to 18 glaucomatous eyes with early visual field damage. The visual evoked cortical potential latency shifts between ramp and step mode were compared with visual field indices (mean defect, corrected loss variance). The pattern-reversal stimulation in ramp mode yielded a significant difference between the glaucoma group and normal subjects (p less than 0.004). The difference between groups with pattern-reversal stimulation in step mode was not significant (p = 0.15). From the determined visual field indices, only the mean defect showed a significant correlation to the measured visual evoked cortical potential latency shift, with both luminance-onset and pattern-reversal stimulation. In glaucoma with early malfunction, the precortical transmission and processing of lower and middle temporal frequencies, which are predominant in ramp-like temporal stimulus courses, are obviously more affected than the transmission of higher frequencies. The ramp stimulation technique for visual evoked cortical potentials might be of interest as a tool to detect early and specific functional defects in glaucoma.

Chronic Disease↗
PubMed1992

The pattern ERG in glaucoma: effect of pattern reversal time.

Pattern reversals with a ramp-like temporal course evoke transient pattern electroretinograms (PERG) that are delayed and attenuated in comparison with responses evoked by a step-like course (abrupt pattern reversals). This delay depends on the reversal time and probably represents a measure for temporal characteristics of the activated retinal structures. A pattern reversal stimulator with adjustable reversal periods (matrix of 8 x 14 rectangular red light emitting diodes, element size 2 degrees x 1 degree, stimulus area 16 degrees x 14 degrees) was used to record transient PERGs from 20 glaucomatous eyes with early or moderate visual field damages (measured with computer perimetry). The q-wave (P1) amplitude difference between the glaucoma group and normal subjects with step-like reversal stimulation was not significant (P = 0.23). On the other hand, a highly significant separation (P < 0.0001) between both groups was possible using the P1 latency at ramp-like stimulation or the response latency shift between step and ramp-like stimulation (Pattern reversal time, 30 ms).

Chronic Disease↗
PubMed1991

[The Nagel anomaloscope in the diagnosis of eye diseases].

The Nagel anomaloscope can be incorporated in the diagnosis of eye diseases. Three parameters are relevant: 1. The measure of the absolute matching range (scale units) 2. The preferred direction of the widened matching range (to red or to green) 3. The luminance matches with the yellow (decreasing matches indicating a pathologic scotopisation). - Six pathologic anomaloscope findings can be differentiated: 1. Pseudoprotanomaly (retinal diseases; type III acquired blue-yellow defects) 2. Symmetrically widened absolute matching range (reduced hue discrimination without reference to its etiopathology) 3. Absolute matching range asymmetrically widened to red with scotopisation (retinal diseases; type III acquired blue-yellow defects or type I acquired red-green defects) or without scotopisation (retinal diseases or optic nerve diseases; type III acquired blue-yellow defects) 4. Absolute matching range asymmetrically widened to green (mostly optic nerve diseases; type II acquired red-green defects) 5. Acceptance of both end matches ("0" up to "73") with scotopisation (retinal diseases) or without scotopisation (optic nerve diseases) 6. Achromatic matches (selective cone diseases, such as Stargardt's dystrophy or progressive cone dystrophy). Indications for anomaloscope examinations and clinical application of the method are discussed in ten cases. The utility of the Rayleigh-equation consists in diagnosing pathologic scotopisation (differential diagnosis between retinal diseases and optic nerve diseases) and in making a quantitative evaluation of the acquired color vision defect (follow-up examination).

Color Perception Tests↗
PubMed1990

[Measuring contrast sensitivity using visual acuity tests in retinal and optic nerve diseases].

The luminance contrast needed to discern various test types was measured with monochromatic and achromatic light to detect discrete functional deficiencies of the retina and optic nerve in cases of normal visual acuity. Landolt rings corresponding to visual acuity levels from 0.04 to 1.0 were used as test types. A significant increase in the necessary minimum contrast was detectable with blue test light on large Landolt rings in patients with diabetic retinopathy, ocular hypertension and glaucoma and with green or yellow test light on medium-sized and small Landolt rings in patients with central serous chorioidopathy and optic atrophy. The additional contrast needed to reach the maximum visual acuity amounts to 14-100% compared with normal visual acuity, depending on the color of the test light and the diagnosis. The amount of contrast needed is greatest in retinal diseases, and it is therefore possible to a certain extent to distinguish these from diseases of the optic nerve.

Humans↗
PubMed1990

[Friedrich August von Ammon (1799-1861) and Dresden ophthalmology in the 1st half of the 19th century].

Friedrich August von Ammon of Dresden took a considerable part in shaping ophthalmology into a scientifically and clinically independent part of medicine, thus inserting himself into the great development of the specialty during the first half of the 19th century. In particular, he investigated the ontogeny of the human eye as well as its pathological anatomy. He edited journals, published monographs, created a school of his own and gained in this way far-reaching influence. As a practitioner, a teacher and a physician-in-ordinary to the King of Saxony, he maintained the tradition of an earlier ophthalmologist of Dresden: Georg Bartisch.

Germany↗
PubMed1990

[Early diagnosis of congenital disorders of color vision with the Velhagen "Pflügerhaken Color Charts for evaluating color perception" in 3,375 preschool children].

In three series of examinations, 3375 male preschool-age children and 93 adult normal trichromates were tested using the Velhagen Pflügerhaken charts. The authors recommend modifying the evaluation of the results slightly by introducing a "doubteful" category for children who make one mistake or who show hesitation and lack of assurance in interpreting the charts. Using this modified form of assessment, diagnoses of "probably achromatopic" and "doubtful" were made in 7.16% and 2.13% respectively of 1689 preschool-age boys. The failure rate during the test and the duration of the examination were age-dependent, and declined with increasing age from 4.15% to 0.45% and from 1.18 min to 0.59 min, respectively. Most mistakes were made with charts nos. 9, 3, and 5. The results of tests with Pflügerhaken charts are fully comparable with those of other internationally used tests for adults. They can be recommended for screening preschool-age children.

Adult↗
PubMed1988

[Color vision in cataract, aphakia and pseudophakia].

Color vision examinations were performed using a clinical test battery and two spectral laboratory methods. With aphakia and iris-clip lenses (ICL) there were slight acquired blue-yellow defects six months to three years after surgery, especially when the more sensitive laboratory methods were used. They were possibly caused by photochemical damage to the retina or by a barrier deprivation syndrome. Color vision with posterior chamber lenses (PCL) was superior to that with ICL, and in aphakic subjects it was quite normal. In the clinical tests no differences could be found between PCLs of clear PMMA material and those with UV absorbing properties. Slight acquired blue-yellow defects in the immediate postoperative phase after implantation of PCLs can be attributed to postoperative irritation and are reversible. Lasting and severe blue-yellow defects indicate inflammation or macular edema.

Adult↗
PubMed1983

Quantitative evaluation of pallor-disc ratio and colour of the optic disc by a photographic method.

A photographic technique is described, which is based on simultaneous photography of the papilla with green and red filters by means of a stereoscopic fundus camera. Using black and white film, the negatives are photometrically measured and the pallor-disc ratio and colour of the papilla are calculated from the densitometric tracings. The latter parameter is quantitatively expressed by a numerical index. The method is demonstrated in a practical example.

Adult↗
PubMed1982

[Not Available].

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Germany↗
PubMed1980

[The functional examination of the visual system by means of delayed triggered VECP (author's transl)].

The VECP represents a brain reaction evoked by fairly abrupt visually perceived changes of one or several environmental features. If the stimulus consists of a finite temporal luminance rise, then the VECP is triggered later as compared to an abruptly appearing stimulus. This delay is an expression of the dynamic input properties of a VECP trigger mechanism. This system evaluates sudden changes of luminance slope and the temporal luminance integral in the first 50 ms after commencement of the stimulus. It may be assumed that deficiencies of the processing of visual information are manifested especially and first of all in a change of the dynamic trigger conditions of VECP. This is shown for colour stimulation (under isolation of the green and red colour mechanism) in different deficiencies of the visual system.

Cerebral Cortex↗
PubMed1979

[Colour vision in squint amblyopia (author's transl)].

Colour vision in squint amblyopia depends on the fixation modus. In eyes with foveolar or unsteady foveolar from fixation the 3 primary colour vision mechanisms (CVMs) gave normal foveolar CVM patterns. The absolute spectral retinal sensitivity was somewhat, but not significantly lowered. The spectral sensitivity for hue discrimination was either normal, or slightly reduced in the short wavelength side, or slightly reduced over the whole visible spectrum. The spectral sensitivity for saturation discrimination showed normal curves. -- In amblyopic eyes with parafoveal to perifoveal fixation mode the absolute spectral retinal sensitivity is lowered for about 0.45--0.60 log units in comparison to an approximately corresponding excentric retinal area in a normal eye. In eyes with parafoveolar to perifoveal fixation mode measurements of CVMs and of hue discrimination gave better results than could be expected with regard to the position of the fixating area as determined by visuscope. The values correspond to those obtained in retinal areas at least as close to the foveola as the amblyopic fixation point, but usually of an even more central position. The sensitivity for saturation discrimination showed no significant disturbance.

Adolescent↗