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Biomedical subjects

W Jaeger

Publications and source records attributed to W Jaeger.

At least 55 records · Page 3Linked to original sources
PubMed1986

[Scanning electron microscopy image of the cells of the conjunctival epithelium in specimens from impression cytology].

Impression cytology specimens of the conjunctiva can be examined by scanning electron microscopy. If a cellulose-acetate filter is pressed onto the conjunctiva, the microvilli-bearing epithelium becomes so firmly attached to the fine meshwork of the filter that the most superficial conjunctival cell layers adhere to the filter. When the filter is removed intercellular connections are destroyed without any damage to the cell membranes being detectable in the SEM image. Since the surface of the corneal epithelium is spread out on the filter and is firmly attached to it the lateral bond between the cells is preserved. Shrinkage is minimal. The posterior surface of the epithelial cells, facing the observer, consists of smooth, porous cell membranes. The nuclei of many cells are clearly distinguishable. Since it can be directly compared with light-microscopic specimens, the SEM image can help provide answers to morphological and pathological questions, and may represent a useful diagnostic aid.

Adult↗
PubMed1986

[Johannes Kepler's contributions to ophthalmologic optics].

Until the beginning of the 17th century it was held that an image is formed in the eye on the anterior surface of the crystalline lens. Ophthalmological optics as a scientific discipline only began with a discovery made by Johannes Kepler. Without performing new experiments, and solely by application of the laws of light refraction, he analyzed the path of light through the eye and demonstrated that an image is formed on the retina and that it is inverted. Acceptance of this discovery was impeded by contemporary prejudices which could imagine nothing but an upright image in the eye, even though this attitude could not explain certain phenomena. Kepler's discovery of the path of light in the eye made it possible to explain the following physical phenomena: central visual acuity, visual field, dark adaptation, and errors of refraction. Physiological diplopia and the mechanism of accommodation were discovered later. The law stating that the intensity of light decreases with the square of distance was also formulated by Johannes Kepler; this law, too, could only be demonstrated after the path of light through the eye had been discovered. In recent years the Keplerian telescope has assumed a practical significance in ophthalmological optics. As a reading aid for individuals with impaired vision it offers a significantly higher magnification than any other optical visual aid.

Germany↗
PubMed1986

[Can the use of infrared photography give evidence of the prognosis of hereditary macular degeneration?].

The question as to whether infrared photography can help determine the prognosis of hereditary macular degeneration cannot be answered simply in the affirmative or negative. Changes in the retinal surface layers are not detected by infrared photography. Therefore, no statement can be made regarding the prognosis of these types of macular degeneration. As far as macular degenerations of the deeper layers of the fundus are concerned, it cannot be stated as a general rule that severe changes in the infrared photograph imply a worse prognosis. Rather, one has to differentiate on the basis of the form and limitations of the defects. Infrared photography furnishes prognostic information by facilitating differential diagnosis between the prognostically favorable central areolar choroidal atrophy and the unfavorable progressive diffuse atrophy of the choroid. Further pointers to the prognosis can be obtained by differentiation between Stargardt's macular degeneration and diseases with favorable prognoses, which appear similar at the fundus, namely central areolar choroidal atrophy and dominant macular degeneration, which has a relatively benign course. In Stargardt's macular degeneration infrared photography seems to provide the following prognostic information: whether the degeneration is limited to the macula; whether flavimaculatus spots appear, or whether diffuse chorioatrophic degeneration will occur.

Atrophy↗
PubMed1986

[Intraocular pulse fluctuations in pressure in neovascularization glaucoma in comparison to other forms of glaucoma (results of direct manometric measurements)].

With tonometric and tonographic measurements it is possible to detect and record oscillations which are synchronous with the intraocular pulse. These oscillations decrease with increasing IOP. In contrast, with direct manometric measurement, the amplitude of the intraocular pulse increases with increasing intraocular pressure. Therefore, in order to determine the intraocular pulse amplitude in patients, direct manometric measurements were performed on blind or almost blind eyes. Intraocular pressure was experimentally elevated by injecting fluid through a cannula into the anterior chamber, using a special Guyon syringe. The course of the drop in pressure and the amplitudes of the intraocular pulse were recorded with the Neuhaus apparatus and a light-spot pen. The most striking result was that in neovascular glaucomas there are excessive pulse amplitudes. The question whether the poor prognosis of neovascular glaucoma is associated with these intraocular pulsations is discussed.

Anterior Chamber↗
PubMed1985

[Most recent developments in the field of optical and electronic visual aids for severely visually handicapped and blind patients].

Magnifying spectacles represent one of the indispensable optical aids (Keplerian systems having surpassed Galilean systems during the last years), closed-circuit television, Optacon, and navigating aids based on ultrasound as environmental sensors. -None of the other navigating aids have proved useful. Initial successes have, however, been achieved with a miniature hand-held camera for closed-circuit television and a portable electronic reading system (View-Scan). Genuine progress has been made with the braille information storage systems, which utilize computer technology to store texts which have been read and written, and subsequently to print them or reproduce them on a screen or in synthetic language. Braillex in the Federal Republic of Germany and Versabraille in the U.S.A. are examples of such systems. In special cases a newly developed stereo photocopy system (Minolta) will be useful for newly blinded adults. However, texts in the form of tactile copies have to be highly magnified in order to be palpable and readable.

Blindness↗
PubMed1985

Tapetochoroidal degeneration combined with cataract and lentodonesis.

Presumably the combination of regional choroidal atrophy, cataract and lentodonesis is a new genetic entity. The hereditary transmission seems to be autosomal-recessive. As the first visual impairment, hemeralopia is noted during the second decade of life. In these early stages patches of choroidal atrophy are limited to the intermediate and perimacular zone. ERGs are not known from these early stages. Later on, no scotopic and only subnormal photopic reactions are registered. The patients can do their work relatively well until the end of the sixth decade, when a cataract develops and the choroidal atrophy gradually extends to the posterior pole. Together with the cataract, a lentodonesis is developing. The lentodonesis is caused by degeneration and elongation of the zonular fibres. Therefore, in order to escape the danger of a lens-subluxation or a lens-luxation into the anterior chamber, an intracapsular extraction should be done at an early stage of lentodonesis. In spite of this, the visual prognosis is poor, since the areas of choroidal atrophy are gradually enlarging. In these late stages the macula seems to be involved in all cases.

Atrophy↗