|Retina is a part of the central nervous system (CNS) responsible for visual perception and processing. The retina is a complex organ and, like the CNS, it is also an immune privilege site, which has a blood retinal barrier (BRB) - the inner BRB formed by tight junctions of the endothelium and the outer BRB form by the retinal pigment epithelium (RPE). Retinal capillaries are covered by pericytes at a ratio of 1:1 with endothelial cell, which is the highest pericyte coverage in the entire vascular system. Retinal neurons are arranged in three distinctive layers - the photoreceptor layer or outer nuclear layer (ONL), which anchors at RPE, the bipolar layer or inner nucler layer (INL), and the ganglion cell layer (GCL).
The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.