Eccentric photorefraction: improving the predictive value and yield in detection of refractive errors

Abstract
Eccentric photorefraction (EPR) is a simple photographic technique for detecting amblyopiogenic conditions. Previous EPR studies to detect refractive errors (RE) have demonstrated high sensitivity but poor predictive value. We have established new criteria for detecting RE involving quantifying retinoscopic reflex crescent widths, thereby achieving 67% predictive value with 100% sensitivity for detecting RE ≥+ 3.5 D in a clinical study of 69 children.
Optical analysis of EPR shows that anticrescent width (light crescent-free portion of the pupil) is independent of pupil diameter. Quantifying anti-crescent widths in the above clinical trial increased the predictive value to 85%.
Schematic eye and human eye EPR studies verify the theoretical prediction that similar ability to detect refractive errors is maintained when the working distance and eccentricity (distance of light source from lens edge) are reduced.
These improvements in EPR reduce its cost and improve its yield; both are essential for its introduction as an acceptable community screening tool.     

Constrictive pericardial disease: prognostic significance of a nonvisualized left ventricular wall

Twenty-six patients with pericardial constriction confirmed by catheterization were studied by dynamic computed tomography (CT). The posterolateral wall of the left ventricular myocardium was not detected in five patients (19.2%). None had evidence of previous myocardial infarction on electrocardiogram or levocardiogram. In 16 patients, a pericardiectomy was performed to remove pericardial constriction. All five patients with nondetectable posterolateral walls of the left ventricle died at or immediately following surgery because of acute myocardial failure. Nonvisualization of the posterolateral wall of the left ventricle in patients with constrictive pericarditis suggests the presence of myocardial fibrosis or atrophy. Surgery is an extremely high risk in these patients.     

Is adrenaline released by sympathetic nerves in man?

Radiotracer methods were used to measure the rates of regional release of adrenaline and noradrenaline into plasma in man. This was done as a partial test of a theory of essential hypertension pathogenesis which envisages an important cotransmitter function for neuronally released adrenaline. In healthy resting men no release of adrenaline could be detected from the heart, lungs or liver. Adrenaline was released into the right renal vein but an adrenal medullary source is suspected. With the relatively limited activation of the cardiac sympathetic outflow which accompanied mental challenge and isometric exercise, cardiac adrenaline release remained undetectable. During supine bicycle exercise, which increased cardiac noradrenaline release 10–30 fold, to a mean value of 197ng/min, cardiac adrenaline release averaged 2.36 ng/min. In two clinical conditions associated with persistently elevated plasma adrenaline concentrations, cardiac failure and adrenaline-secreting phaeochromocytoma, regional release of adrenaline was clearly evident. Thus, in normal man during exercise, and in patients with cardiac failure at rest, adrenaline is released from non-adrenal sources, and probably from sympathetic nerves. Whether neuronal adrenaline release of the degree found would be sufficient to facilitate noradrenaline release, augment sympathetically-mediated cardiovascular responses and contribute to the development of arterial hypertension remains to be tested.     

Cardiac dysrhythmias during oral surgery. Comparison of hyoscine and droperidol premedication

The incidence of cardiac dysrhythmias during inpatient dental anaesthesia under halothane was studied following either hyoscine or droperidol as a supplement to papaveretum for premedication. Forty-three percent of patients given hyoscine exhibited cardiac dysrhythmias compared to 23 percent of the group given droperidol (p = 0.03). The incidence of dysrhythmias bore no relationship to the age, sex or weight of the patient, nor to the end tidal carbon dioxide tension.     

Psychomotor testing of oncall anaesthetists

The critical flicker fusion frequency and choice reaction times of 16 on-call anaesthetists were measured between 1400 and 1600, at 2300 and at 0200 hours. Critical flicker fusion decreased between the afternoon and 2300; there was no further change between 2300 and 0200. No significant differences in choice reaction times were found on any of these different occasions.