Biomedical subjects
D Linnert
Publications and source records attributed to D Linnert.
[The tensile strength of human zonule and its alteration with age (author's transl)].
A series of 91 cryoextractions was performed on autopsy material. The scleral section was placed near to the chamber angle and was nearly circumferential (about 330 degrees). Cornea and adjacent sclera could be flapped over this way, and did not interfere with a straightforward lens extraction. The pupil was medically dilated. A cryoprobe was fixed to a specially constructed scale, and frozen to the anterior pole of the lens. Its weight was counterbalanced by a plastic water container at the other end of the scale. The extraction was performed by filling additional water into the counterbalancing container. The statistical evaluation of the results showed a very significant dependence of the average tensile strength on age. However, a considerable standard deviation was found throughout all ages. The nutritional state of the autopsy bodies and the time interval between death and start of the measurement had no significant influence. The differences between right and left eyes were also not significant, as could be expected. The methodological error remained small. Age proved to be an unreliable indicator for the tensile strength of the zonule. All results apply to clear lenses. We known from clinical experience that the tenacity of the zonule may also be different in the various types of cataract.
[Changes in the indications and techniques in the surgery of retrobulbar orbital tumours (author's transl)].
In the past 3 decades, surgery of retrobulbar tumours was mainly done by neurosurgeions (transfrontal orbital approach) or ENT surgeons (transethmoidal approach), especially in Europe. More recently, especially in USA this has changed and the majority of these cases, in an increasing number of hospitals, are now treated by a modified Krönlein operation, usually performed by ophthalmic surgeons. In this paper we tried to elucidate the background of this development. Ultrasound exophthalmometry (Fig. 3), ultrasound A- and B-scans of the orbital tissues (Fig. 4 and 5) and computerized axial X-ray-tomography of the orbits (Fig. 6) improved the preoperative diagnoses markedly. In the most cases it is now possible to decide preoperatively on the existence, size and location (and sometimes even on the nature) of a spaceoccupying lesion in the orbit. The technic and the instruments for Krönlein's operation have been improved (Krönlein-Berke, Fig. 8-11). The oscillating saw (Stryker) facilitates the resection of the bone, and microsurgical technics are now preferred for removal of the tumour from the orbit. The modified Krönlein operation is also recommended for orbital decompression in severe endocrine exophthalmos, provided the lateral orbital wall is removed to the described extent.
[On the proof of late sequelae of bulbal and orbital contusion (author's transl)].
Contusion cataracts may develop long time after injury, without visible lens changes in the interval. The lens opacities appear like those known in senile cataracts if the eye was injured after the 45th year of age. Demonstration of other traumatic changes becomes then very important for the evaluation of the role of the accident as a cataract cause. As late sequelae of eye (and orbit) contusion, enophthalmos and supersensitivity of the pupil to adrenergic drugs can be found. Ultrasound exophthalmometry proved to be more accurate for checking the former than Hertel's optical exophthalmometry alone. The pupil was studied by the reaction following local instillation of one drop of 1% adrenaline solution (comparison with other eye). The results found in 2 patients are described.
[Diagnostic ultrasonography and X-ray computer tomography in space-occupying orbital lesions--a joint effort (author's transl)].
Diagnostic ultrasonography (A-and B-scans) and X-ray computer tomography are completely different in their physical bases. The yield, therefore, different informations in the examination of space-space-occupying lesions in the orbit. The informations which can be recorded from normal and pathologic tissues in the orbit are described in this paper. The value, but also the limitations, of the various diagnostic methods are demonstrated in clinical cases. The reliable diagnosis of unilateral, progressive pseudoprotrusion in high myopia by ultrasound exophthalmometry is described. Facilities and diagnostic value of ultrasonography and X-ray computer tomography in the localisation of orbital tumours and in the determination of their relationship to the orbital walls are discussed. The diagnostic management in intermittent exophthalmos, in orbital abscess and in Grave's disease is reported. The complete ophthalmic examination is followed by ultrasound exophthalmometry and--if indicated--A- and B-scan ultrasonography of orbital tissues. Computed X-ray tomography is indicated in all tumour-suspicious lesions within the orbit. The results of diagnostic ultrasonography and computed X-ray tomography may complete each other in a very helpful manner. The combined evaluation yields better results than the use of only one of these methods. In orbital varices we recommend, to supplement ultrasonography by venography and eventually arteriography. In diagnoses of orbital abscesses resulting from paranasal sinusitis it may usually suffice to combine ultrasound diagnosis with native X-ray examinations. Good interdisciplinary cooperation in diagnosis and therapy is mandatory in all patients with space-occupying orbital lesions.
[Ophthalmological operations in retrobulbar space-occupying processes].
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Visualization of orbital tissues using various echographic techniques.
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[Ophthalmologic after-examinations in fractures of the middle face].
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[Peripheral retinal detachment--ultrasonic diagnosis and therapeutic consequences].
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[Unrecognized paralyses of accommodation and their importance in diagnostics and expertise (author's transl)].
Paralyses of accommodation are safely diagnosticizable even in patients over 45 years of age provided there is no complete presbyopia. The identification can be a key to diagnosing the entire disease pattern. In one case a suspected Adie's syndrome with amblyopia and without any connection with internment and damage due to malnutrition was identified as ophthalmoplegia interna with partial atrophy of the n. opticus, most probably caused by malnutrition encephalopathy or encephalitis. In another patient, a bilateral isolated accommodation paralysis indicated damage of the accommodation center during concussion of the brain (possibly only a functional damage).
[Checking and clinical application of time gain compensation (TGC) in diagnostic ultrasonography (author's transl)].
The usefulness of TGC depends on the scanning technique. The A- and B-scan echograms of the orbit can show much more detailed information of the orbital structures, if TGC and a corresponding scanning technique are applied. The sound beam should be directed preferably through the center of the eyeball to keep the length of vitreous within the sound beam constant. The external eye muscles, orbital fat and optic nerve can much better be identified and localized. Radiolucent orbital foreign bodies (wood splinters) were experimentally examined and could also be shown much better using TGC. The TGC characteristic must be measured for reproducible adjustments. The scale readings of the apparatus are insufficient. Even in apparatus supplied with an indication of the TGC characteristic on the screen checking of the real TGC characteristic proved necessary. A simple measurement technique, easily applicable under hospital conditions is described. It is based on a test reflector made from material for soft corneal contact lenses (testreflector W 38, Poly-HEMA, 38% water content.
[Echography of the vitreous body in case of aphakia and malignant aphakic glaucoma (author's transl)].
The senile destructions of the vitreous body which can be seen with the slit-lamp (formation of visible fibres, vacuoles and posterior vitreous detachment) cause, if sufficiently advanced, small echoblips visible at echographic examination. We reexamined aphakic patients who had no complications during cataract cryo-extraction. In aphakic eyes without postoperative vitreous prolapse into the anterior chamber the echograms usually consisted of uninterrupted series of small amplitude echoes in the vitreous area. In aphakic eyes with postoperative vitreous prolapse into the anterior chamber echo-free parts were found in the vitreous area and also parts showing closer placing of vitreous echoes. The echo-free parts may represent fluid-filled vacuoles. In malignant aphakic glaucomas, which could not be controlled otherwise, we succeeded inaspirating aqueous humour from these echo-free parts by punction. Echography facilitated, in this way, the punction of the trapped aqueous. Echography of the senile vitreous destructions approaches the limits of present ultrasonographic facilities; artefacts may occur, and technical improvements are desirable and possible.