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The epidemiology of microbial keratitis has been investigated in several studies by analysis of organisms cultured from corneal scrapes. However, a comparison of the frequency of different organisms causing keratitis in different parts of the world is lacking. The authors present a review incorporating an analysis of data from studies worldwide. The data provide a comparison of the frequency of culture-positive organisms found in different parts of the world. Associations between a country's gross national income and types of causative organism are explored. The highest proportion of bacterial corneal ulcers was reported in studies from North America, Australia, The Netherlands and Singapore. The highest proportion of staphylococcal ulcers was found in a study from Paraguay, while the highest proportion of pseudomonas ulcers was reported in a study from Bangkok. The highest proportions of fungal infections were found in studies from India and Nepal. The Spearman correlation coefficient demonstrated statistically significant correlations between gross national income and percentages of bacterial (0.85 (95% CI 0.68 to 0.91, p<0.0001)), fungal (-0.81 (95% CI -0.90 to -0.66, p<0.0001)) and streptococcal (-0.43 (95% CI -0.66 to -0.12, p=0.009)) isolates.

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P ulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling, right heart failure, and reduced survival.1 Both symptoms and extent of right heart failure predict mortality. [2][3][4] Measures of RV filling pressure and systolic function have been shown to correlate with clinical disease progression and survival. 5-8 Clinical Perspective on p 755Right ventricular (RV) contraction is a complex process related to a variety of actions, the predominant being longitudinal motion because of the arrangement of ventricular myofibrils.9-12 RV systolic strain assessment by speckle-tracking echocardiography is an angle-independent sensitive measure of RV contraction shown to correlate with clinical symptoms and invasive hemodynamic measures and is predictive of disease progression and mortality. [13][14][15][16][17] PAH is a disease of the pulmonary circulation with resultant effects on the right heart. Conceptually, left heart anatomy and function should be normal in patients with PAH. However, the RV and left ventricle (LV) do not function in isolation, sharing a common pericardial sac and interventricular septum. 18 A delayed relaxation mitral inflow Doppler pattern on echocardiography (a feature seen in normal or low filling pressures and diastolic dysfunction) has been linked to severity of disease in PAH; however, it is unclear whether this Doppler pattern reflects impaired LV filling because of reduced RV output or intrinsic LV dysfunction. 19 We sought to define the clinical and prognostic significance of ventricular interdependence Background-Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling and right heart failure. The right (RV) and left ventricles (LV) do not function in isolation, sharing a common pericardial sac and interventricular septum. We sought to define the clinical and prognostic significance of ventricular interdependence in PAH and its association with LV filling patterns through speckle-tracking strain echocardiography. Methods and Results-Echocardiography was performed in 71 adults with a new diagnosis of PAH. To analyze LV and RV function separately, we measured peak systolic longitudinal and circumferential strain of the LV and RV. Survival was assessed >2 years. Patients had dilated right-sided chambers (right atrial volume index, 44±19 mL/m 2 ; RV end-diastolic area, 34±9 cm 2 ), and reduced RV function (RV fractional area change, 28±12%). Speckle-tracking echocardiography revealed significant reductions in RV free wall peak systolic strain (−15±3%). Despite normal LV size and normal conventional measures of LV systolic function (end-diastolic dimension, 42±6 mm; ejection fraction, 65±8%; cardiac index, 2.6±0.8 L/min per m 2 ), patients had reduced LV free wall systolic strain (−15±3%). Decreased LV free wall systolic strain was associated with a delayed relaxation mitral inflow Doppler pattern, P=0.0002. During 2-year follow-up, 19 patients (27%) died. LV strain was associated with increased mortality (unadjusted hazard ratio, 2...