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Biomedical subjects

T Seiler

Publications and source records attributed to T Seiler.

At least 145 records · Page 8Linked to original sources
PubMed1986

[Hypotension syndrome caused by shrinkage of the lens capsule].

Two cases of ocular hypotony in myopic eyes following extracapsular surgery are described. A trampoline-like shrinkage of the posterior capsule and severe hypotony developed four and eight weeks after cataract extraction without IOL implantation. After discussion of the capsule by YAG-laser an IOP overshoot to more than 50 mmHg occurred, but three weeks later the IOP had dropped to normal values without further medical treatment. All transition stages to hypotony seem to be possible, thus explaining the well-known pressure-lowering effect of extracapsular cataract surgery can be understood.

Aged↗
PubMed1986

[NMR-tomography of the human eye].

The NMR relaxation data of tissue are the basis of an appropriate adjustment of NMR imaging parameters. The relaxation data of ocular tissues are presented, and the relaxation behaviour of the eye is discussed. NMR imaging of eyes with intraocular silicone and pseudophakia are shown. Up to the present time, neuritis of the optic nerve is not detectable by NMR tomography whereas intraocular melanoma are clearly distinguishable.

Eye↗
PubMed1986

In vivo experiments with the excimer laser--technical parameters and healing processes.

In vivo experiments on rabbit corneae with the excimer laser (lambda = 193 nm) are presented. A new delivery system using total-reflecting prisms is described. For corneal surgery a repetition rate of about 50 Hz seems to be optimal. Healing processes of the cornea are demonstrated. It is supposed that the corneal incisions by excimer laser have not to be as deep as those induced by knives to change corneal curvature.

Animals↗
PubMed1985

The resistance of the trabecular meshwork to aqueous humor outflow.

A theoretical model is presented that is able to explain for the first time the pressure drop across the trabecular meshwork. The ramified flow paths in the subendothelial region of the trabecular meshwork can be interpreted as a filter bed. Data from transmission electron microscope (TEM) photographs are the starting point of the theoretical consideration. Taking shrinkage of the sections into account, the pressure gradient across the subendothelial region amounts to 0.05 mm Hg. As these canaliculi are coated by a film of glycosaminoglycans (GAGs), the pressure drop is presumably a function of the film thickness. Only film thicknesses of 0.35 micron led to pressure gradients in the experimentally verified magnitude. As the whole filter bed probably does not contribute to the filtration but only about 10%, the pressure drop specified is reached when the GAG coating is 0.25 micron. As these values seem to be fairly realistic, it can be concluded that the subendothelial region of the juxtacanalicular meshwork (about 2 micron thickness) can be regarded as the "locus generis" of aqueous humor outflow resistance.

Aqueous Humor↗
PubMed1985

[Equivalency of different methods of measuring lens power].

Mathematical error analysis shows that the prognosis of IOL powers on the basis of theoretical optical formulas for calculating lens power is no more accurate than the regression (SRK) formula. The minimum error in a recommended lens power is at present between +/- 0.6 and +/- 1.0 D. As a result of this range of error there is a range of equivalence of the two formulas, and the vast majority of cataract patients (85%) are within this range. However, in hyperopic eyes the SRK formula is clearly superior to the theoretical optical formulas for a clinically useful prognosis.

Aphakia, Postcataract↗
PubMed1985

[Corneal astigmatism following a 2-step scleral incision in cataract operations with implantation of posterior chamber lenses].

The postoperative astigmatism of 987 eyes after cataract extraction was studied with reference to behavior in the course of time, axis, and amount. The late post-operative distribution (6 months) of astigmatism approximates the preoperative values. Using Euler's method, the influence of surgical technique and surgeon on the refractive power of the cornea was investigated. The standard deviation of refractive power is more than twice the influence of surgeon and different surgical technique (extracapsular cataract extraction versus phakoemulsification).

Astigmatism↗
PubMed1984

[Linearity of applanation tonometry].

A method has been developed for measuring intraocular pressure continuously. By comparing the results with theoretical models it has been established that only viscoelasticity of the sclera and cornea is able to compensate for rapid pressure fluctuations, whereas facility does this only to a minor degree.

Animals↗
PubMed1984

[Berlin dye laser].

The conditions for an optimal ophthalmic coagulating system are derived from the absorption spectra of xanthophyll, melanin and hemoglobin. Coagulation is effected by a dye laser with two dyes. The continuously tunable range of 570 nm to 680 nm opens up new horizons in photocoagulation of the retina.

Diabetic Retinopathy↗
PubMed1983

Phase transitions in ocular tissue - NMR and temperature measurements.

The human cornea, sclera and lens is studied by nuclear magnetic resonance (NMR) measurements and temperature curves. The bound water fractions of these tissues have been determined as 3% in the cornea, 20% in the sclera and 17% in the lens. In contrast to other investigations we found freezing intervals near -1 degree C.

Body Water↗