Biomedical subjects
Publications and source records attributed to C Ohrloff.
The authors present an extremely pronounced involvement of the orbita in malignant uveal melanoma with a ten-year course of disease. The results of imaging diagnostics (ultrasound, computed tomography, magnetic resonance tomography) are discussed.
Explore the source record for details and available documents.
Whereas specular microscopy yields mostly qualitative information, fluorophotometry furnishes quantitative data of endothelial cell function. Determination of fluorescein permeability of the endothelial cell layer reflects the function of the endothelial barrier. Following topical application of fluorescein, the time-dependent change in the fluorescein concentration in corneal stroma and aqueous yields the transfer coefficient (Kc) of the corneal endothelium. With the Fluorotron Master, Kc was 3.77 +/- 0.57 X 10(-3)/min. for normal eyes; patients with cornea guttata or Fuchs's dystrophy had a significantly higher transfer coefficient (Kc = 7.9 +/- 2.88 X 10(-3)/min.). Normal Kc values were found 6-63 months (average 33.5 months) after phacoemulsification with implantation of a posterior chamber lens.
Increased blood sugar levels may influence the refractive power of the lens in juvenile diabetics, and can lead to the rare true diabetic cataract ("snow-storm cataract"). Surplus glucose induces accumulation of the sugar alcohol within the cells, thus generating disturbances of the osmotic balance and finally causing cataract. The enzyme aldose reductase catalyzes the formation of sorbitol. Experiments with animals have shown that aldose reductase inhibitors can prevent the formation of such opacities with streptozotocin-induced diabetes in rats. Numerous aldose reductase inhibitors are now known, but we still have insufficient knowledge to determine whether systemic or local administration is preferable. The mechanisms reported here are not relevant with respect to the frequent occurrence of senile cataract in older diabetics, which has often been described.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Fifty patients with senile cataract were treated consecutively by phacoemulsification in the posterior chamber or pupillary plane using a bimanual technique followed by implantation of a Kratz posterior chamber lens. Central endothelial cell density was determined both before and after surgery. The average central endothelial cell loss was 4.1 +/- 3.02%. Follow-up examinations of a small number of patients 27 months after phacoemulsification and posterior chamber lens implantation showed no additional lens-induced endothelial cell loss.
The inhibition constants of several aldose reductase inhibitors were determined using water-soluble extracts of bovine and rat lenses. The most potent inhibitor was the Alcon compound AL-1576; the inhibitory effects of AL-1567 and Sorbinil were about equal, but both were less effective than AL-1576, and the least effective inhibitor was the calcium antagonist verapamil. There was no general difference between inhibition constants for the inhibitors in question between bovine or rat extracts. Age of bovine lenses has no effect on the IC50 of the investigated aldose reductase inhibitor compounds.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Fourteen hydrogel lamellar implants were placed in rabbit corneal stroma. Within six months of implantation, all the rabbit eyes showed some opacification of the cornea, and several of the rabbits had vascularization along the lamellar interface with signs of chronic inflammation. Opacification and vascularization eventually appeared in all 14 eyes, regardless of the water content or oxygen permeability of the lens material. One rabbit was killed, and a histopathologic examination showed evidence of chronic inflammation and scarring. Because the rabbit's sensitivity to an inflammatory nidus makes it a good laboratory test animal, these rabbits' inability to tolerate some of the currently available hydrogel corneal lamellar implants may indicate that such material is unsuitable as a permanent implant for cosmetic refractive surgery in humans.
Progressive, bilateral corneal clouding was noted at birth in an otherwise healthy infant. There was no evidence of an infectious or hereditary cause. A trial of corticosteroids was unsuccessful, and the opacification in both corneas increased during the course of a few months, necessitating penetrating keratoplasty. However, reopacification of both grafts ensued within two to four months, and a second graft was done on the right eye. Histologic examination of both the original corneal buttons and the failed graft from the right eye showed a thickening of Bowman's layer that was three to four times greater than that of normal controls. This was associated with an increased number of keratocytes producing pools of collagen bundles within Bowman's layer. This report documents a unique form of corneal opacification unassociated with other ocular or systemic diseases. This process may be interpreted as a phenomenon in which the cells that contribute to the intrauterine formation of Bowman's layer continue to proliferate in an abnormal and exuberant fashion beyond fetal life, leading to corneal opacification.
Normal human lenses removed from eye bank eyes and cataractous lenses were assayed for superoxide dismutase (SOD) activity. In normal whole human lenses, SOD shows no marked difference in activity during aging. When comparing the activity in the nucleus with that in the equator, one finds that the activity in both lens parts has decreased with increasing age. The mean values of SOD are significantly lower in human lenses with mature cataract than in clear lenses. Interestingly, no residual activity could be proved in mature cataracts, whereas the activity in posterior subcapsular cataracts lay within normal limits.
The ophthalmic examination of patients with hypertrophic cardiomyopathy treated with high doses of verapamil over a considerable period of time showed no evidence of a side effect of the drug, thus proving its ocular safety. This could be verified by densitometric image analysis of Scheimpflug photographs of the eyes. The data were used for statistical tests on lens transparency. Changes in lens transparency, i.e. a probable drug-induced cataract were found in none of the patients.
During the aging process, the lens is subjected to changes of its pertinent properties which condition the transmission of light of different wavelengths. Between the second and the third decade, for instance, wavelengths below 400 nm are almost completely absorbed. The increase in lens thickness, effected by the appositional growth during life, might be considered responsible for this phenomenon, if the newly developing lens fibers in the outer periphery would synthesize proteins which, with respect to light transmission, differ from those formed during the embryonic phase. For such a phenomenon, however, no indication was found either by clinical observations or biochemical research. -Microdensitometric analysis of Scheimpflug-photographs of the anterior eye segment allows measurements of lens transparency in the single lens which directly depend on the respective wavelengths used in the photographic procedure. Investigations performed with this method on a normal age-grouped population, show that the changes in light transmission are most evident in two of the lens segments. The lens nucleus shows a continuous increase in light scatter during aging. Also the anterior cortex - particularly in the deeper layers - shows changes in light transmission. With advancing age (beginning between 30 and 40 years of age), increased lens fluorescence is found in the region of the deeper anterior cortex, which can be excited by UV wavelengths of 330-380 nm. This phenomenon is not found in the lens nucleus. The localization of the changes within the lens clearly shows that they are due to age-related modifications of the protein properties earlier designated as posttranslational or postsynthetic molecular modifications.(ABSTRACT TRUNCATED AT 250 WORDS)
Glutathione reductase (GR) and glutathione peroxidase (GPx) show in bovine lenses a decrease in specific activity; furthermore, the heat lability of both enzymes increases with age monitoring structural changes of the molecules. GR activity was correlated with type of cataract in human lenses. Its decrease is significantly connected with cortical opacities. Superoxide dismutase activity declines in aging and cataractous lenses. These results support the assumption that in old lens tissue the capacity of the antioxidative scavanger system is diminished.
We tested the Hessburg-Barron vacuum trephine on 23 human cadaver eyes for accuracy and quality of cut. The trephine was found to make accurate, spherical cuts in the anterior corneal stroma. With penetration, the cut became beveled, leaving the posterior corneal button diameter larger than the anterior diameter especially if the trephine was lifted. The results are discussed relative to conventional techniques.
Explore the source record for details and available documents.