Biomedical subjects
Publications and source records attributed to J Draeger.
The larger the corneal graft, the more difficult is the excision of the button and especially suturing of the graft. The instruments and microsurgical unit are adapted to size and dimensions of animal surgery. The mathematical correlation between the diameter of the graft, the thickness of the cornea, and the length of the wound edges and suturing material can be calculated.
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By means of an electronic optical esthesiometer corneal sensitivity was examined in 91 volunteers of different age groups. Additionally, the anesthetic duration of the local anesthetic benoxinate was investigated. Corneal sensitivity decreases with advancing age. Comparing male and female subjects, we can suppose that there are age and sex specific differences of corneal sensitivity. There might be additional genetic factors. There are great interindividual differences in the anesthetic duration of benoxinate. It can be assumed that benoxinate is metabolized by pseudocholinesterase. One possible explanation for the great differences in the anesthetic duration of benoxinate can be seen in the genetically determined variants of pseudocholinesterase.
The mean endothelial cell count of 282 donated corneas was 2,665 cells/mm2, and the mean donor age was 56.01 years. The majority of the donors were over the age of 40 years, and the major causes of death were malignancies and myocardial infarction. Vital staining of the endothelium and direct evaluation of cells with an inverted phase contrast microscope were used in assessing the viability of this monocell layer. Evaluation of endothelial photomicrographs revealed that the cell count falls in the first three decades of life and eventually stabilizes around 2,600 cells/mm2. It is therefore suggested that patient age should not be the primary criterion for donor corneal selection.
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The toxicity of different procedures utilized for the sterilization of intraocular implant material was assessed on the endothelium of organ-cultured porcine corneas. Polymethylmethacrylate lenses sterilized by treatment with sodium hydroxide (NaOH), ethylene oxide, formaldehyde, and gamma radiation were added to a culture medium containing normal porcine corneas. Considering the viability of endothelial cells, appearance of intracellular degenerative vacuoles, and denudation of corneal Descemet's membrane as criterion for the evaluation of toxicity of different methods of sterilization, the NaOH-treated lenses were found to be the least toxic to porcine corneal endothelium. Phase-contrast microscopy and vital staining of the endothelium permitted direct viewing of the endothelium aiding in the assessment of toxicity.
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As the demand for donor corneas increases, not only fresh donor material but also increasing numbers of preserved corneas are being transplanted. The simple eye-banking procedures such as the moist chamber and the McCarey-Kaufman medium provide sufficient endothelial cell viability for short periods. The methods of organ culture of corneoscleral disks extend storage periods to up to four weeks. Cryopreservation as a method of long-term storage has not come to be widely used owing to the complicated procedure involved and the considerable damage thus caused to endothelial cells. Thus, the organ culture method may represent a compromise between extended storage periods and good endothelial cell viability.
The consideration for the choice of intracapsular lens-implantation are presented, and the surgical technique of the implantation of the new Binkhorst "all in the bag" lens is described in detail.
Between 1961 and 1983, 544 goniotomies were performed at the Department of Ophthalmology of the University of Hamburg and Bremen General Hospital. Of these 227 were performed in 130 eyes with congenital glaucoma between 1961 and 1983. Pressure regulation was achieved in 72% of the eyes examined 3-22 years postoperatively. The prognosis is not related to the preoperative corneal diameter or IOP, but the patient's age at the first goniotomy is of prognostic importance. Very poor results are achieved in cases of manifestation during the first 2 months of life. Of the regulated eyes, 56% achieved a visual acuity of over 0.4. If only one eye is affected, visual acuity attained is poorer. Results of surgical techniques and methods of goniotomy are compared and discussed.
By means of a recently developed electronical optical esthesiometer the efficacy of five different topical anaesthetics was compared. The influence of vehicle and concentration was also investigated. From the results it can be concluded that the drugs currently available are of suitable local anaesthetic effect with little influence of the vehicle or preservative agent used.
In various states of refraction axial eye length and thickness of the posterior ocular coats were measured echographically. As proved in previously performed experimental studies, retina, choroid and sclera were resolved in a considerable percentage of cases by combining the A- and B-mode techniques of modern ultrasonic equipment. The supposed close negative correlation between length of the globe and ocular coat dimensions was confirmed by statistical analysis of our data. This result should provide additional help, when interpreting the reflections of the ocular wall under normal and pathological conditions.
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