The Dubbelman eye model analysed by ray tracing through aspheric surfaces

Dubbelman and co-workers have determined intraocular spacings and surface shapes in living eyes by means of corrected Scheimpflug images in a large number of subjects of different age at several levels of accommodation. They give relationships for key anterior segment parameters as a function of age and level of accommodation. These are used in this paper to build a schematic eye incorporating aspheric surfaces. This eye model is analysed by means of ray tracing with a technique developed for use with a common spreadsheet computer program. The Dubbelman eye model appears to be well corrected for spherical aberration. Compared with measurements on real eyes it agrees well in general, but spherical aberration is negative, while in real eyes it tends to be positive.     

A Systematic Overview of Radiation Therapy Effects in Urinary Bladder Cancer

A systematic review of radiation therapy trials in several tumour types was performed by The Swedish Council of Technology Assessment in Health Care (SBU). The procedures for evaluation of the scientific literature are described separately (Acta Oncol 2003; 42: 357-365). This synthesis of the literature on radiation therapy for urinary bladder cancer is based on data from 3 meta-analyses and 33 randomized trials. The studies include 4 333 patients. The results were compared with those of a similar overview from 1996 including 15 042 patients. The conclusions reached can be summarized as these points: There is moderate evidence for an overall survival benefit with preoperative radiotherapy followed by cystectomy compared to curative radiotherapy based on early studies (1964-1986). Since that time surgical as well as radiation techniques have developed considerably. Therefore, the conclusion may not be relevant to modern treatment of invasive urinary bladder carcinoma.There is only one small study reporting on curative radiotherapy where increased dose per fraction is compared with conventionally fractionated radiotherapy to the same total dose. Thus, no conclusions can be drawn concerning optimal fraction dose.A meta-analysis based on two studies on hyperfractionated radiotherapy gives moderate evidence of a survival benefit at 5 and 10 years and an increased local control rate compared with conventional fractionation.The documentation of local control and overall survival rate after split-course radiation treatment compared to continuous therapy is conflicting. No firm conclusions can be drawn.Four small and early studies have compared radiation treatment using neutrons with photon treatment. The reports favour therapy with photons with respect to overall treatment results. There is moderate evidence for this conclusion.There is fairly strong evidence in early studies that radiation treatment in combination with hyperbaric oxygen does not confer a treatment benefit compared to radiation in normal atmosphere.There is no indication of a treatment benefit with the addition of either hyperthermia or misonidazole.A large number of phase II studies, suggesting an increased possibility for bladder preservation with concomitant chemoradiotherapy compared to radiotherapy alone, have been reviewed in a previous SBU report on chemotherapy. Only one small randomized study has been reported where concomitant chemoradiotherapy with cisplatin is compared to radiation alone. No conclusion on the therapeutic benefit of combined treatment can be drawn. Large randomized studies are needed.There is some evidence that preoperative radiotherapy followed by cystectomy does not confer any significant survival benefit compared to cystectomy alone.There is moderate evidence that palliative radiotherapy of invasive bladder carcinoma can rapidly induce tumour-related symptom relief.There is moderate evidence that palliative hypofractionated radiotherapy, 3 fractions during one week, gives the same relief of symptoms as 10 fractions during 2 weeks.     

A new intraocular lens design to reduce spherical aberration of pseudophakic eyes

PURPOSE: The aim of this study was to design and evaluate in the laboratory a new intraocular lens (IOL) intended to provide superior ocular optical quality by reducing spherical aberration. METHODS: Corneal topography measurements were performed on 71 cataract patients using an Orbscan I. The measured corneal surface shapes were used to determine the wavefront aberration of each cornea. A model cornea was then designed to reproduce the measured average spherical aberration. This model cornea was used to design IOLs having a fixed amount of negative spherical aberration that partially compensates for the average positive spherical aberration of the cornea. Theoretical and physical eye models were used to assess the expected improvement in optical quality of an eye implanted with this lens. RESULTS: Measurements of optical quality provided evidence that if this modified prolate IOL was centered within 0.4 mm and tilted less than 7 degrees, it would exceed the optical performance of a conventional spherical IOL. This improvement occurred without an apparent loss in depth of focus. CONCLUSION: A new IOL with a prolate anterior surface, designed to partially compensate for the average spherical aberration of the cornea, is intended to improve the ocular optical quality of pseudophakic patients.     

Predictors for Employment Status in People With Multiple Sclerosis: A 10-Year Longitudinal Observational Study

Objective

To identify predictors for employment status after 10 years in a cohort of people with multiple sclerosis (MS), with the aim to increase knowledge concerning factors present at an early stage that are important for working life and work-life balance.

Arrhythmogenic right ventricular dysplasia in brother and sister: Is it related to myocarditis?

Summary Two cases of arrhythmogenic right ventricular dysplasia (ARVD) in siblings are reported. In the boy, 14 years old, the clinical history, ECG, echocardiography, and histopathological findings were consistent with ARVD. Premature ventricular contractions of left bundle branch block (LBBB) pattern were recorded but no ventricular tachycardia (VT). A high titer against mycoplasma and increased concentrations of immunoglobulins were found. Two years after his first admission he died suddenly. Autopsy revealed severe right ventricular (RV) myocardial damage, with fat cell infiltration and collagenous tissue. His sister presented with sustained VT of LBBB pattern 2 years later, at 12 years of age. Vaccination against rubella and signs of upper respiratory illness had preceded the symptoms. During the following 9 days ECGs and serum enzymes indicated the development of left ventricular (LV) infarction. Echocardiography revealed an enlarged RV and a normal LV. After 6 weeks both RV and LV showed akinetic areas and sacculations. We suggest that myocarditis may be a precipitating factor in ARVD, and perhaps the prerequisite for its manifestation.     

Normalized dyslipidaemia after parathyroidectomy in mild primary hyperparathyroidism: population-based study over five years

OBJECTIVE: Postmenopausal women are at increased risk of primary hyperparathyroidism (pHPT). Secondary dyslipidaemia in pHPT has attracted little attention, although morbidity and mortality associated with cardiovascular diseases have been reported to be increased in these patients. DESIGN: A population-based screening programme was used to recruit postmenopausal women with mild, asymptomatic pHPT (mean serum calcium 2.57 +/- 0.12 mmol/l) and matched controls. MEASUREMENTS AND PATIENTS: Serum lipids, lipoprotein fractions and influences of treatment for the parathyroid disease were studied in 87 case-control pairs (mean age 67 years), 69 of whom completed a 5-year follow-up period. RESULTS: pHPT was characterized by decreased serum high-density lipoprotein (HDL)-cholesterol, increased total triglycerides, very-low-density lipoprotein (VLDL)-triglycerides and VLDL-cholesterol levels and an elevated atherogenic index. The differences were more pronounced in the cases with serum parathyroid hormone levels in the normal range and were inversely correlated to the serum parathyroid hormone level. Parathyroidectomy, with or without additive hormone replacement therapy, normalized the dyslipidaemia. Five-year surveillance of pHPT without treatment was associated with a maintained increase in total triglycerides and the atherogenic index and a decrease in HDL-cholesterol levels. CONCLUSION: Proatherosclerotic dyslipidaemia characterizes mild pHPT and is effectively reversed by parathyroidectomy. As dyslipidaemia might contribute to the increased risk of cardiovascular diseases and death observed in pHPT, the findings favour operative intervention rather than conservative surveillance in mild, asymptomatic pHPT in postmenopausal females.