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Biomedical subjects

O Hockwin

Publications and source records attributed to O Hockwin.

At least 19 recordsLinked to original sources
PubMed1994

Ocular drug safety and HMG-CoA-reductase inhibitors.

150 patients suffering from primary hypercholesterolemia were divided into three different groups receiving (1) lovastatin, (2) simvastatin, or (3) fenofibrate as controls. The aim of the study was to detect possible drug-induced ocular side effects, especially in the lens. The study period was 2 years. Ophthalmological examination and Scheimpflug photography were performed at the beginning and every 6 months. Increases or decreases in the visual acuity were distributed very similarly in the three groups. Definite evidence of side effects was not found, nor was there evidence of deleterious effects on refraction. The intraocular pressure revealed intraindividual fluctuations without clinical significance. Many changes were observed in the lens, all were minimal, including those of the extreme lens periphery which had no effect on visual acuity. The present study shows the great value of Scheimpflug photography with densitometric image analyses because of its objectivity when compared with other methods. Our observations provide good evidence that lovastatin and simvastatin have no undesirable toxic effects on the lens and other ocular tissues, compared with fenofibrate.

Color Perception↗
PubMed1993

Histological changes of rat lenses after UV-irradiation and D-penicillamine treatment.

The aim of the study was to investigate the effects of local treatment of rat eyes with D-penicillamine (PE) or D-penicillamine disulfide eye drops and their influence on the development of UV-induced lens opacities. 126 Brown Norway rats were divided into 14 groups to test the efficacy of different concentrations of the drugs. During the investigation period, slitlamp examinations and Scheimpflug measurements were performed. The post-mortem analysis comprised biochemical and histological investigations. This paper deals with the histological part of the study. A generally beneficial effect of the substances in question could not be found by means of histological methods. The best effect in relative terms was obtained by the use of 3.0% PE after a pretreatment of 7 days before starting UV irradiation. This result is in agreement with the evaluation of the Scheimpflug photography by microdensitometric image analysis.

Animals↗
PubMed1992

[Ocular side effects of drugs].

Drug-induced side effects manifested by the human eye are characterised by the specific anatomical, histological and functional features of the eye. Such ocular changes may arise after local or systemic drug application. The following article outlines the clinically relevant common drug-related side effect on the lids, cornea, conjunctiva, lens, retina, uvea, and the optic nerve, as well as effects on the intraocular pressure, refraction and accommodation.

Administration, Topical↗
PubMed1992

[Objectified measurement of eye lens transparency in elderly probands. Results of a Scheimpflug photography study over the course of three and a half years].

Lens density has been followed-up in 32 healthy volunteers (mean age 65 years) over a period of 3.5 years. The negatives of Scheimpflug-photos (Topcon SL-45) were evaluated by linear microdensitometry in three measure planes (Joyce Loebl 3 CS). Correlation coefficients, curves of regression as well as calculations of the percentage of density change made obvious, that a minimal increase in lens density occurred in the anterior cortical region.

Age Factors↗
PubMed1992

Biochemical and morphological changes in rat lenses after long-term UV B irradiation.

The aim of the present study was to investigate biochemical and morphological changes in rat lenses following long-term UV B irradiation. After an irradiation period of 156 days with follow-up documentation by means of Scheimpflug photography, section-related biochemical analyses of the lenses as well as histological investigations were performed. The video-based Scheimpflug photography (Zeiss SLC) again proved to be an excellent method for the documentation of the UV cataract induced in rats. The biochemical analyses provided indications to potential damaging mechanisms; the section-related technique used allows more precise analyses than the processing of whole lenses in a cataract type restricted to a certain layer, as is the case with UV B damage. The most prominent biochemical findings were a significant decrease in glyceraldehyde-3-phosphate dehydrogenase in the equatorial region in the group with the highest irradiation dosage and a decrease in lactate dehydrogenase in the nuclear region. The histological results reflect the local extent of the UV damage as well as its progression after a prolonged irradiation period.

Animals↗
PubMed1992

Objectified measurements of eye lens transparency in a volunteer group of advanced age, carried out over a period of 3.5 years. Results of a Scheimpflug-photographic study.

The present study deals with a prospective investigation on the optical density of the eye lenses of 32 volunteers with initially normal eyes (mean age 65 years) over a period of 3.5 years. The negatives of the Scheimpflug photographs (Topcon SL-45) were evaluated by linear densitometry in 3 measure planes (Joyce Loebl 3CS). The evaluation of the coefficient of correlation, the representation of the regression straight line as well as the evaluation of the percent changes in lens density showed that during the observation period of 3.5 years a minimum increase in density took place mainly in the anterior cortex.

Aged↗
PubMed1992

Scheimpflug photography in clinical ophthalmology. A review.

The development of a slitlamp camera system based on the Scheimpflug principle with image analysis has been a major improvement in lens and cataract research. Since its introduction into ophthalmology by Brown and Niesel in the sixties of this century and further technical amelioration by Hockwin, Dragomirescu and Sasaki it has been applied in various experimental and clinical investigations. The purpose of this paper is to summarize and review the application of Scheimpflug photography in clinical ophthalmology and to show possibilities and indications for the use of the Scheimpflug technique in clinical studies.

Anthropometry↗
PubMed1992

Comparison of the Nidek EAS 1000 system and the Topcon SL-45 in clinical application.

Some years ago, Nidek developed a new imaging system for the anterior eye segment, which offers the possibility of recording Scheimpflug and retroillumination images. The system consists of 2 different technical units, a camera unit for image recording and a computer unit for storage, system operation and image analysis. To evaluate the clinical use of the system and its reproducibility, a study with 31 volunteers/patients was performed that were photographed with the Nidek EAS 1000 at the meridians 0 degree, 45 degrees and 180 degrees. Two examinations with a 1-week interval were performed. In addition, a direct comparison of the EAS 1000 with the Topcon SL-45 was carried out with 32 volunteers that were photographed at 0 degree and 45 degrees; a retroillumination photo was additionally recorded. The video images were evaluated with the computer software, the SL-45 negatives were standardly measured with a Joyce-Loebl densitometer. The handling of the EAS 1000 in clinical use was found to be easy and comfortable for the patient, as the alignment is done with infrared light. Difficulties occur only with the retroillumination photography in that the infrared light for imaging may outshine the red fixation light during exposure. However, shadowing problems due to the eyelashes occur in oblique slit positions, especially in those patients with a pronounced front head. In studying the reproducibility, the mean values of the individual coefficients of variation for light scattering (density) were in a range between 3.6 and 5.06%, but more than 35% of the single values show a variation coefficient above 5% (maximum 20.3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

A new approach to drug penetration study.

To investigate the route of drug penetration into the eye and drug distribution patterns in the lens, the distribution of aldose reductase inhibitor (AL-04114) in the lens was measured in short term bovine lens organ cultures and topical administration to rabbit eyes. A micro lens sectioning technique was applied to determine drug localization within the lens. Freshly enucleated bovine lenses were incubated with different concentrations of an ARI (AL-04114)-containing medium for 3 hours. For the in vivo study, 40 microliters of 0.3% AL-04114 (ophthalmic solution) were administered into the cul de sacs of rabbits 3 times at 3 hour intervals. After the incubation and final instillation, the lenses were divided into an equatorial ring and several layered sections. Drug concentration was measured by a reversed-phase HPLC system. The drug concentration was highest within the layer of the posterior shallow cortex > equator > anterior shallow cortex. No drug penetration was observed in the anterior/posterior deeper cortex or nucleus in vitro. The in vivo experiment revealed drug penetration in the equator and anterior shallow cortex, but not in any other lens layers. Drug penetration was detected within the serum and aqueous humor, but not in the vitreous.

Absorption↗
PubMed1992

[Aspects of physiology, pathology and epidemiology of cataract].

World Health Organization estimates that 23 million people have a visual acuity of 0.05 or less. For 12-15 million people cataract is the cause of poor visual acuity or blindness and the majority of those afflicted live in Third World countries. It is estimated that in the year 2025 around 40 million people will become blind due to cataract. The therapeutic procedure of choice is surgical removal of the lens. The high success rate of this procedure in highly industrialized countries has been achieved by the constant improvement in technology and operative technique. This, however, does not hold true for Third World countries. The etiology and pathogenesis of cataract are not yet completely understood. This paper reports on the clinical findings and epidemiology of cataract and deals with the physiology and pathology of the lens. The aim of the study was to recognize possible cataractogenic risk factors. A decrease in the blindness rate caused by cataract in Third World countries can best be achieved through prevention.

Cataract↗
PubMed1991

[Lens changes following pneumatic retinopexy: preliminary results of linear densitometry image analysis of Scheimpflug photographs two months after operation].

The small degree of morbidity and a better postoperative visual acuity are the advantages of pneumatic retinopexy in comparison to encircling procedures in the treatment of retinal detachment. The injection of air or gas into the vitreous cavity can theoretically induce a cataract postoperatively. Two months after pneumatic retinopexy (SF6-gas) Scheimpflug photography and microdensitometric evaluation of the negative were performed on 22 pairs of phacic eyes showing changes in the transparency of the lens. The deterioration of transparency in the operated eye was small but higher than that of the non-operated eye. Due to the short follow up period no prognosis is possible as to the future lens transparency changes.

Cataract↗
PubMed1991

[Lens changes following intraocular tamponade in vitrectomy. Linear densitometric image analysis of Scheimpflug photographs 6 months after operation].

A complication arising from vitrectomy is the formation of cataract. As a result of an intra- and postoperative tamponade chosen (BSS, air, SF6-gas, silicon oil) the size and frequency of the cataract varies accordingly. 6 months after vitrectomy Scheimpflug photography and microdensitometric evaluation of the negatives were performed on 30 pairs of phacic eyes showing changes in the transparency of the lens. Following silicon oil tamponade a significant deterioration of transparency (t-test) was observed in the lens nucleus of the operated eye; in the area of the lens in front of the nucleus a marked but not significant deterioration of transparency was discovered following both silicon oil and SF6-gas tamponade. In the case of the area in front of the nucleus following SF6-gas tamponade as well as the whole of the lens following BSS or air tamponade a small but not at all significant difference in lens transparency was apparent after comparison of the operated to the non-operated eyes.

Cataract↗