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The experience of eye strain when reading in dim light has given rise to the common misconception that such an activity causes permanent eye damage. [3] When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the ciliary muscles and the extraocular muscles are strained. This causes discomfort ...
The eye includes a lens similar to lenses found in optical instruments such as cameras and the same physics principles can be applied. The pupil of the human eye is its aperture ; the iris is the diaphragm that serves as the aperture stop.
Pseudomyopia may be either organic, through stimulation of the parasympathetic nervous system, or functional in origin, through eye strain or fatigue of ocular systems. It is common in young adults who have active accommodation , and classically occurs after a change in visual requirements, such as students preparing for an exam, or a change in ...
The ciliary muscle is an intrinsic muscle of the eye formed as a ring of smooth muscle [3] [4] in the eye's middle layer, the uvea (vascular layer).It controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humor into Schlemm's canal.
The visual system is the physiological basis of visual perception (the ability to detect and process light).The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment.
Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.
Myopia, also known as near-sightedness and short-sightedness, [5] is an eye disease [6] [7] [8] where light from distant objects focuses in front of, instead of on, the retina. [ 1 ] [ 2 ] [ 7 ] As a result, distant objects appear blurry while close objects appear normal. [ 1 ]
Other types of refractive errors may exist at the same time as presbyopia. [1] This condition is similar to hypermetropia or far-sightedness, which starts in childhood and exhibits similar symptoms of blur in the vision for close objects. Presbyopia is a typical part of the aging process. [4]