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The fovea centralis is a small, central pit composed of closely packed cones in the eye.It is located in the center of the macula lutea of the retina. [1] [2]The fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for activities for which visual detail is of primary importance, such as reading and driving.
Humans have a slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements), [4] [5] [6] (with eye movements included it is slightly larger, as you can try for yourself by wiggling a finger on the side), while some birds have a complete or nearly complete 360-degree visual field. The vertical range of ...
The macula corresponds to the central 17 degrees diameter of the visual field; the fovea to the central 5.2 degrees, and the foveola to 1–1.2 degrees diameter. [10] [11] [12] Note that in the clinical literature the fovea can refer to the central 1–1.2 deg, i.e. what is otherwise known as the foveola, and can be referred to as the "clinical ...
The pupil of the human eye can range in size from 2 mm to over 8 mm to adapt to the environment The human eye can detect a luminance from 10 −6 cd/m 2 , or one millionth (0.000001) of a candela per square meter to 10 8 cd/m 2 or one hundred million (100,000,000) candelas per square meter.
This article features a BMI chart for women 18 and older. Skip to main content. 24/7 Help. For premium support please call: 800-290-4726 more ways to reach us. Sign in. Mail. 24/7 Help. For ...
What is a normal blood pressure reading? Updated May 17, 2019 at 1:19 PM. ... "Your blood pressure is supposed to be under 140 over 90, optimally closer to 120 over 80."
Normal individuals have an acuity of 6/4 or better (depending on age and other factors). In the expression 6/x vision, the numerator (6) is the distance in metres between the subject and the chart and the denominator (x) the distance at which a person with 6/6 acuity would discern the same optotype. Thus, 6/12 means that a person with 6/6 ...
It most commonly occurs in people over the age of fifty and in the United States is the most common cause of vision loss in this age group. [1] [3] About 0.4% of people between 50 and 60 have the disease, while it occurs in 0.7% of people 60 to 70, 2.3% of those 70 to 80, and nearly 12% of people over 80 years old. [3]