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Biomedical subjects

R Welt

Publications and source records attributed to R Welt.

12 recordsLinked to original sources
PubMed1992

Biophysical characteristics of the Meibomian lipid layer under in vitro conditions.

The biophysical behaviour of the Meibomian gland secretion was tested under in vitro conditions. Thereby, simultaneous recording of surface pressure and surface potential was performed. The Meibomian lipid layer was compared with other surface-active components like polyvinylalcohol and polyvinylpyrrolidone. On the other hand, Eledoisin was tested as an example for a surface-inactive substance. An attempt was made to describe the biophysical interaction between a given artificial tear substitute and the Meibomian lipid layer. With respect to the surface potential Dipalmitoyl-phosphatidyl-choline was established as an analogue for Meibomian gland secretion. Fluorescence measurements in the presence of a cyanine dye (1 N,N'dioctadecyloxacarbocyanine) were used as a method to localize the site of the characteristic potential change. From the fluorescence spectra under compression we conclude that the molecular change takes place at the lipid-subphase interface of the Meibomian lipid layer.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1991

[Preoperative microbiologic diagnosis before elective intraocular interventions and prevention of infection with tobramycin eyedrops. Results of a multicenter study].

Preoperative conjunctival smears of 313 asymptomatic patients before cataract surgery were evaluated in an open multi-center study in 10 German surgical eye care centers from May to August 1987. 230 evaluable isolates of 198 patients (= 61.1%) on agar plates with a 48 h incubation period revealed 190 gram-positive (most frequent isolates: 62.2% coagulase negative Staph., 13.5% coagulase positive Staph.) and 40 gram negative agents (most frequent isolates: 3.0% Proteus sp., 2.2% Pseudomonas sp.). Coinfections with gram-positive organisms were seen in 22%, and with gram-negative organisms in 9% of cases. Newly acquired potentially pathogenic bacteria were demonstrated after one day (5-8 drops 3 mg/ml Tobramycin (Tobramaxin; 1 x ointment in the evening 3 mg/100 mg Tobramycin (Tobramaxin] of topical prophylaxis in 6 of 115 (= 5.2%) previously negative and 22 of 198 (= 11%) previously positive conjunctival cultures. Coagulase negative Tobramycin sensitive Staph. persisted in 41 of 110 patients (= 37.3%) and coagulase positive Tobramycin-sensitive Staph. in 4 of 30 (= 13.3%). Each of the gram-negative bacteria could be eliminated after one day of topical prophylaxis with Tobramycin eye drops and ointment in this study. The statistically determined elimination rate estimated for a one-day topical prophylaxis with Tobramycin in asymptomatic culture-positive persons was 77.5-89.8% (95% confidence interval/Pearson and Clopper). The statistically determined probability for potentially pathogenic bacteria in a previously culture-negative patient after topical preoperative Tobramycin prophylaxis was 3.1-13.2% (95% confidence interval/Pearson and Clopper). Thus, additional supportive antibiotic measures are to be taken pre- and perioperatively by the intraocular surgeon to minimize the risk of postoperative endophthalmitis.

Adolescent↗
PubMed1991

[Pattern-reversal visual evoked potentials and electroretinography in the early diagnosis of chronic simple glaucoma].

For differential, therapeutic, and prognostic reasons the recognition of early lesions in glaucoma chronicum simplex is very important. Besides sophisticated ophthalmological investigations optic nerve and retinal functions can be tested by flash and pattern-reversal evoked visual potentials and electroretinograms. 38 glaucomatous eyes were investigated by VEP and ERG applying single and flicker flashes as well as transient pattern-reversal stimuli of different check sizes. The results related to the degree of visual field disturbances show the damage of retinal and neuronal elements in a descending order affecting first of all the macular cones, then the rod system, and later on the elements of the second retinal neuron. The ganglion cells seems to be affected after all.

Chronic Disease↗
PubMed1990

[Glare test and bright light vision in cataract patients].

Cataract patients and healthy subjects have been examined with the Miller-Nadler Glare-Tester to prove if the results of the glare test show any correlation between the glare disability score and the outdoor visual acuity facing sun. The outdoor vision of cataract patients with a high glare disability score was clearly impaired compared with their indoor vision. Healthy eyes with a normal glare disability score did not show any impairment of visual acuity facing sun. The results of the glare disability examination can therefore be used as a reference for the decision of a cataract operation.

Adult↗
PubMed1986

[Eye and skin manifestations of endogenous oxalosis of the protracted type (follow-up)].

The present paper reports the authors' observations in a rare case of primary hereditary oxalosis (adult type). Four years after renal function loss, calcium oxylate deposits were found in the skin and in both retinae. In spite of hemodialysis and a special diet, the deposits increased considerably during an observation period of 19 months. The skin was indurated and the genucubital articulations were immobilized. In spite of incipient circumscribed edema the retinal changes did not cause any detectable restriction of function, as the fovea was not involved and the retinal border was only slightly affected.

Adult↗
PubMed1985

[Corneal endothelium variants in the area of corneal changes].

Contact specular microscopy of the corneal endothelium and subsequent image analysis permit investigations of corneal endothelium reactions after circumscribed corneal damage. The extent and development of an endothelial process can thus be estimated.

Adult↗
PubMed1978

[Lamellar keratoplasty, ipsilateral rotation-autokeratoplasty and contralateral autokeratoplasty (author's transl)].

During the years 1967--1977, there were performed about 500 mostly perforating keratoplasties. Among these there were special groups: 50 lamellar keratoplasties (43 central, 7 marginal), 5 perforating ipsilateral rotation-autokeratoplasties 2 perforating contralateral autokeratoplasties. The results encourage to use these special keratoplasties more often instead of the usual perforating keratoplasty.

Corneal Diseases↗
PubMed1976

[Electro-ophthalmological observations on the course of unilateral tapetoretinal degenerations (author's transl)].

A 32-year-old female patient suffering from a unilateral tapetoretinal degeneration for at least 7 years was investigated. The affected eye exhibits a typical fundus, concentric reduction of visual field, and a monophasic course of dark adaptation. The electroretinogram of the affected eye is extinguished; the electrooculogram does not show a light peak. The visual evoked cortical potential of both eyes shows a normal amplitude-stimulus intensity function. However, the first negative deflection exhibits a small difference of implicit time between the normal and affected eye. The normal eye does not show any pathological alteration.

Adult↗