Accuracy Assessment of the ESA CCI 20M Land Cover Map: Kenya, Gabon, Ivory Coast and South Africa

This working paper presents the overall and spatial accuracy assessment of the European Space Agency (ESA) 20 m prototype land cover map for Africa for four countries: Kenya, Gabon, Ivory Coast and South Africa. This accuracy assessment was undertaken as part of the ESA-funded CrowdVal project. The results varied from 44% (for South Africa) to 91% (for Gabon). In the case of Kenya (56% overall accuracy) and South Africa, these values are largely caused by the confusion between grassland and shrubland. However, if a weighted confusion matrix is used, which diminishes the importance of the confusion between grassland and shrubs, the overall accuracy for Kenya increases to 79% and for South Africa, 75%. The overall accuracy for Ivory Coast (47%) is a result of a highly fragmented land cover, which makes it a difficult country to map with remote sensing. The exception was Gabon with a high overall accuracy of 91%, but this can be explained by the high amount of tree cover across the country, which is a relatively easy class to map

Anxiety and depression prevalence rates in age-related macular degeneration

PURPOSE. To estimate the prevalence rates of depression and anxiety in patients with wet age-related macular degeneration (AMD) and the relationship with visual acuity and to develop a simple algorithm for depression screening. METHODS. This cross-sectional, prospective, observational, multicenter study was performed in France, Germany, and Italy. Retina specialists at 10 centers per country each enrolled 12 consecutive patients with wet ARMD. Patients were stratified into four severity groups by using best eye (BE) and worst eye (WE) visual acuity (VA) thresholds (BE:VA 20/40 and WE:VA 20/200). Patients rated themselves on the Hospital Anxiety and Depression Scale (HADS). Analysis of variance was performed to estimate the effect of VA severity levels on HADS scores adjusted on age, gender, and country. RESULTS. Patients (females 60%) were recruited, with a mean age of 77 years and 2.3 years' disease duration. Mean BE:VA at inclusion was 0.49 logMar (logarithm of the minimum angled of resolution) and WE:VA 1.0 logMar. The prevalence of severe depression increased from 0% (BE:VA ≥ 20/40+WE:VA ≥ 20/200) to 7.6% (BE:VA < 20/40+WE:VA < 20/200), whereas anxiety was unrelated to VA loss. Moreover, total depression scores were strongly associated with VA severity (P = 0.006), but not total anxiety scores (P = 0.840). Responses to two HADS items ("I still enjoy things I used to enjoy"; "I can enjoy a good book or radio or television program") identified 95% of severely to moderately depressed patients. CONCLUSIONS. Self-rated depression in patients with AMD was associated with VA severity level. It should, therefore, be relatively easy for ophthalmologists to implement the screening procedure and refer identified patients to psychiatrists for proper assessment and treatment. Copyright © Association for Research in Vision and Ophthalmology