Birefringent multifocal lenses: theory and application to the correction of refractive error.

Light passing through birefringent materials experiences two indices of refraction, and lenses made of or incorporating birefringent materials will therefore exhibit two focal points. The optics of birefringence are summarized, and their application to lenses is described. Prototype lenses based on these principles were produced, and the bifocal effect was observed. Multifocal lenses based on these principles have numerous uses, including contact and intraocular lenses.

Multifocal intraocular lenses fabricated from media exhibiting tuned birefringence.

Birefringent lenses provide two simultaneous powers. One power is provided by ordinary rays, the other by extraordinary rays through the lens. Because the difference between the reading and distance powers of intraocular lenses is small when compared to the average lens power, the difference between the extraordinary and the ordinary index of refraction of birefringent intraocular lenses can also be small. It is shown that a single birefringent intraocular lens which is manufactured from a properly oriented polymeric lens material provides the two powers needed for distant viewing and reading. Compound lenses consisting of M birefringent lens components provide up to 2M powers within a desired interval. Degrees of freedom exist for the choice of power values inside the desired interval and for the intensities associated with the individual powers.

Billing basics: a review course.

Each year, practice management should thoroughly examine the billing and collections operation and set goals. This review course, while not all-inclusive, should serve as a guide, reminder and perhaps catalyst to that process.

[Heart metastasis of malignant tumors. An autopsy study]. / Herzmetastasen maligner Tumoren. Eine Autopsie-Studie.

In contrast to their clinical manifestation, metastases to the heart are not rare findings at autopsy. In one of five patients dying from metastatic cancer, spread to the heart is found. The incidence of metastatic involvement of the heart depends on the type of cancer, malignant melanoma and leukemia being the most frequent and metastases of carcinoma less so. The primary carcinomas metastasizing to the heart are most often situated near it, which may indicate that lymphatic channels are infiltrated in a retrograde manner from metastatic deposits in mediastinal lymph nodes. The fact that metastasis of primary carcinoma in the vicinity of the heart lodge predominantly in the epicardium supports this concept. On the other hand, it appears easier to explain the frequency and distribution of cardiac metastases from carcinomas of the abdominal cavity by assuming that they are bloodborne. Hence it is assumed that the routes of disseminated of tumor cells to the heart are through lymphatic as well as blood vessels.

[A case of syphilitic uveitis simulating Harada disease]. / Ein Fall von luischer Uveitis unter dem Bild des Morbus Harada.

On the basis of clinical findings and fluorescein angiography the authors diagnosed Harada's disease in a 30-year-old Caucasian woman. A drastic deterioration occurred under treatment with corticosteroids and immunosuppressive agents. Another cause of the uveitis was looked for and a reactive serology for lues was found in the blood and the cerebrospinal fluid. The severe inflammation was then treated successfully with high doses of penicillin, intravenously administered; visual acuity also improved as a result this treatment. The differential diagnosis of the two conditions is discussed.

[Pyrazinamide versus ethambutol in short-term therapy of lung tuberculosis. A randomized study]. / Pyrazinamid versus Ethambutol bei der Kurzzeittherapie der Lungentuberkulose. Eine randomisierte Studie.

Recent experience suggests that the duration of chemotherapy of tuberculosis can be shortened to 6-9 months, without an increase in the relapse rate, if the treatment if started with 3 or 4 drugs including isoniazid (INH), rifampicin (RMP) and pyrazinamide (PZA). In a controlled study of culture-positive advanced pulmonary tuberculosis we have compared treatment regimens with PZA in a dosage of less than 2 g and with ethambutol (EMB). 113 patients were given, in random order for 2-3 months, either PZA (25 mg/kg body weight) or EMB (25 mg/kg) together with RMP (450 or 600 mg) and INH (5 mg/kg). The last two drugs were given for a total of 9 months. Patients treated with PZA showed a (not significantly) earlier conversion to negative cultures after an average of 7 weeks. After 18 months follow-up there have been no relapses on these regimens. 2 patients, both treated with EMB, did not respond to therapy. Drug-induced hepatitis was seen in 5 patients with PZA and in 2 patients with EMB. The hepatitis was always observed during the first month of therapy and was fully reversible. Three of the 4 patients with clinically apparent hepatitis were over 70 years of age. Three patients with elevated uric acid levels had arthralgia which led in one of them to termination of therapy. The preliminary results of our study show that the treatment regimen with PZA does not lead to a higher rate of side effects if used with particular moderation in older patients.

[Effect of a fixed betablocker diuretic combination in hypertension compared with the effect of the single components (author's transl)]. / Wirkung einer fixen Beta-Blocker-Thiazid-Kombination bei der Behandlung der Hypertonie, verglichen mit der Wirkung der Einzelkomponenten.

In a double blind designed treatment trial with three randomized groups of patients the effect of a fixed betablocker diuretic combination (Torrat, Boehringer Mannheim GmbH) was compared with the effect of the single components. 66 patients with essential and renal hypertension stage I and II according to the WHO definition were evaluated. 27 patients were treated with 1 tablet, 32 with 2 X 1 tablet, and 7 patients with 3 X 1 tablet daily. Besides of the blood pressure lowering effect over an observation period of 10 weeks the influence on pulse rate, potassium, blood sugar and uric acid were investigated. It could be shown that the blood pressure lowering effect was highest under the combination-drug. The treatment with the single components showed a less pronounced influence on the blood pressure, thus hinting at an additive effect of the 2 components metipranolol and butizide when given together. The combination exerts few side effects and does not influence the investigated parameters of metabolism over a longer period of time.