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Biomedical subjects

J Draeger

Publications and source records attributed to J Draeger.

At least 127 records · Page 7Linked to original sources
PubMed1986

[Current status of PMMA intraocular lens sterilization].

One possible reason for the "toxic lens syndrome" may be the method of IOL sterilization used. Advantages and disadvantages of wet and dry sterilization techniques are discussed. Ethylene oxide remnants in IOL optics were measured using headspace chromatography. The influence of gamma radiation on PMMA lens optics was studied by spectrometry.

Ethylene Oxide↗
PubMed1986

[Topography of the corneal endothelium following surgical trauma].

In a prospective study preoperative and postoperative endothelial cell densities were determined after intracapsular cataract extraction with and without implantation of intraocular lenses. There was a characteristic disparity in cell densities measured at different points--near the corneal wound, at the center, and below the center. The cell loss measured near the corneal wound is partly compensated for by elongation of the cells below the center. Consequently, the cell loss is not only made good in the immediate postoperative period; cell migration also continues for prolonged periods of time until homogeneity of the cell pattern is almost completely restored.

Cataract Extraction↗
PubMed1986

[Side effects of YAG laser treatment].

In enucleated pig eyes endothelial cell damage was demonstrated after YAG laser coagulation. The extent of the damage can be correlated to the distance between the laser focus and the endothelium, and to the energy. Similar effects and correlations can be demonstrated on intraocular implant lenses in an experimental model.

Animals↗
PubMed1986

[Instrument requirements for lens implantation in the capsule sac].

The more accurate the positioning and fixation of the intraocular lens has to be, the more important the process of gentle, but nevertheless reliable introduction of the lens into the posterior chamber becomes. New types of instruments are required for this. The special instruments needed for intracapsular implantation are discussed and their use demonstrated. Newly developed implantation forceps are described for the first time.

Cataract Extraction↗
PubMed1986

[Ophthalmologic implants--a risk at high altitudes?].

In the course of an experimental study typical ophthalmological implant materials were transported to altitudes of up to 48,000 feet. Spherical prostheses manifested practically no changes in volume, while scleral sponge material for detachment surgery released death bubbles during decompression. It is pointed out that less severe effects are likely to occur in this respect under clinical conditions, and likewise that the measured values are only of consequence for the patient in cases of rapid decompression.

Altitude↗
PubMed1986

Postural variations of intraocular pressure--preflight experiments for the D1-mission.

Specific alterations in systemic circulation due to fluid shift in microgravity may lead to a rise in intraocular pressure (IOP). This situation can be simulated by head-down tilt. Several series of tonometry were performed using a handheld applanation tonometer: (1) Short time postural changes up to -90 degrees head down and back. (2) A period of 2 h in -10 degrees head down. (3) Repetition of series 2 after dehydration of the subjects. (4) Seven-day bedrest study in -7 degrees head-down tilt. (5) A period of lower body negative pressure (LBNP). (6) Valsalva maneuver. Immediately on tilting, the IOP rises with hydrostatic pressure and returns to normal again after about 1 h. The IOP seems to change parallel to venous pressure. Further experiments are planned for Spacelab missions.

Adult↗
PubMed1986

A simple method for controlled freezing of human donor corneae.

A simple method for freezing cultured human donor material with dimethyl sulfoxide (DMSO) was developed empirically in a commercially available microcomputer-controlled apparatus allowing reproducible freezing curves to be made. The optimum cooling rate was found to be 1.0 degrees C/min down to -40 degrees C and then 5.0 degrees C/min to -80 degrees C. Total cell loss rates were 36.9 +/- (SD) 19.8% of postmortem endothelial cell counts. An improved method for evaluating endothelial viability was applied, which enabled us to observe definite cell survival after a postculture period.

Cornea↗
PubMed1985

[Needs and technical prerequisites of an improved supply of donor material for penetrating keratoplasty].

The supply of donor material for keratoplasty is still considered a problem in many clinics. Preservation of donor tissue makes it possible to improve material selection. As far as the grafting of typed corneas is concerned, corneal organ culture offers a valuable time interval for planning the operation. In these preservation techniques the transplanted tissue is trephined from the endothelial side. With an optimal trephining technique the number of viable endothelial cells transplanted can be increased.

Corneal Transplantation↗
PubMed1985

[Endothelium protective effect of hyaluronic acid].

In an experimental study the endothelia of porcine corneas were exposed to mechanical trauma under controlled conditions. Endothelial damage was caused by a polymethylmethacrylate (PMMA) plastic sphere shaped like the optical part of an intraocular implant. Two power settings were investigated. At the high power setting an average damage of 4.63 mm2 (+/- 1.33) was observed under saline, whereas application of hyaluronic acid 1% reduced the endothelial cell loss to 3.006 mm2 (+/- 0.87). At a low power setting the endothelial cell loss under saline was 2.18 mm2 (+/- 0.65); the average damage under hyaluronic acid was 0.55 mm3 (+/- 0.29). The results were statistically significant. The cell protective effect of a viscous substance against a mechanically shearing force was thus demonstrated in a biomechanical model.

Animals↗
PubMed1985

[Experimental studies on the correction of presbyopia].

As a consequence of the changing population structure the number of older, i.e., presbyopic people in work will increase in the future. At the same time the demands made on vision at work will also increase, as new technologies are introduced. Both of these factors will have to be taken into account by ophthalmologists and the optical industry. As accommodation deteriorates, special glasses become necessary which are suited to requirements for highly qualified work. With this in mind the authors conducted a joint investigation at a precision assembly workplace together with the manufacturing technology laboratory of Duisburg University. The results show that if bifocal or respectively trifocal glasses are prescribed at the right time efficiency can be improved both quantitatively and qualitatively. The specific requirements with regard to spectacles worn at such workplaces result in particular from the fact that, for ergonomic and technical reasons, operating devices and controls are being mounted ever more frequently above the horizontal line of gaze. Therefore, when prescribing the glasses, it is important that not only the correction for close and mid-range vision, but also the size and location of this portion of the lens should be taken into consideration. This is illustrated with a number of examples.

Adult↗
PubMed1985

[Effect of the culture technic on results following corneal preservation].

Organ culture of human donor material extends post mortem storage times up to 4 weeks. If dextrane is omitted from the medium, as in the authors' current technique, a stromal swelling occurs which can be reserved preoperatively. The authors also report on their experience with organ culture of donor material in a culture medium containing dextrane. Short-term incubation of donor tissue in culture medium at 32 degrees C containing dextrane may be possible as an alternative to the MK technique, in which the donor tissue is kept at 4 degrees C. All methods have specific advantages and disadvantages, not only in laboratory handling but also in the postoperative development of the graft.

Cornea↗