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Biomedical subjects

O Wichterle

Publications and source records attributed to O Wichterle.

14 recordsLinked to original sources
PubMed1992

[The first stage of clinical trials of hydrogel lenses manufactured in Czechoslovakia].

The authors give an account of the results of the first stage of clinical trials of Czechoslovak disc-shaped hydrogel lenses made from the copolymer HEMA and methacrylic acid. Hitherto assembled experience provided evidence that the envelope technique for opening of the anterior capsule does not ensure sufficient stability of these lenses in the later stage and their decentration may cause serious complications. Therefore the optimal solution is to place the implant in the capsule after circular capsulorhexy. Improvement of the geometrical and optic properties of the lenses during the subsequent follow-up and their perfect harmony with the surgical technique will produce even better functional results in operated patients.

Aged↗
PubMed1991

Shape of the cornea and conjunctiva.

An apparatus for investigating the surface shape of the eye, including the region beyond the limbus, has been developed. Formerly, we applied a three-parameter model to describe the eye profile. Recently we have found that two parameters, e.g., the keratometric radius, KE, and the slope, beta E, of the conjunctiva are sufficient for this purpose. The measurement of 690 unselected human eyes indicates that variation of both these values is statistically significant and that both of them may be useful in contact lens fitting.

Anthropometry↗
PubMed1988

Hydron gel implants in vocal cords.

A new operation for the correction of insufficient closure of the glottis is described. A Hydron rod is implanted while the patient is under general anesthesia at direct laryngoscopy; the operative microscope is used for visualization and illumination. The implant was introduced into a submucosal tunnel made by special instruments after a transverse incision was made of the vocal mucosa, 1 or 2 mm in front of the insertion of the processus vocalis. A spindle-form implant made from dry Hydron gel was used. This swells in the tissue within a short time. The results of the operation, which was performed successfully on 40 patients, reflects an improvement in the quality of the voice, as demonstrated by sound analysis and a considerable subjective decrease in symptoms--especially voice fatiguability.

Adolescent↗
PubMed1975

The experience with clinical application of hydron pouches in tumor chemotherapy.

Hydron pouches were applied in three cases of embryonal hepatomas in infants. Cyclophosphamide (one case) and methotrexate (two cases) were used for filling of pouches in order to accomplish local chemotherapeutical effect directly on the tumor. Histopathological examination showed good compatibility of pouches to the liver tissue. No therapeutical effect was observed in a set of experiments due to a small size of pouches as compared to big masses of tumor. Some suggestions for further development of this method are presented.

Autopsy↗
PubMed1974

Diffusion of anti-tumor drugs through membranes from hydrophilic methacrylate gels.

Permeation parameters of four anti-tumor drugs across membranes prepared from hydrophilic methacrylate gels were measured and compared with the permeation of NaCl. It was found that by increasing the ratio of butyl methacrylate (BMA) to hydroxyethyl methacrylate (HEMA), the rate of diffusion can be lowered to practically zero at 20% BMA. However, this decrease is different with various drugs due to the interaction of the drug with the gel. Differences by a factor of two were found in our set of drugs. Therefore, each new drug should be tested in this way. In addition a routine testing of dialysing devices by an NaCl solution is suggested as a method for detecting technological imperfections and calibrating the deviations from standard parameters. A chemical modification of the membrane is recommended as the best way for controlling the permeation rate.

Acrylates↗