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Visual snow syndrome (VSS) is an uncommon neurological condition in which the primary symptom is that affected individuals see persistent flickering white, black, transparent, or colored dots across the whole visual field. [7] [4] Other common symptoms are palinopsia, enhanced entoptic phenomena, photophobia, and tension headaches.
Entoptic phenomena (from Ancient Greek ἐντός (entós) 'within' and ὀπτικός (optikós) 'visual') are visual effects whose source is within the human eye itself. (Occasionally, these are called entopic phenomena, which is probably a typographical mistake.) In Helmholtz 's words: "Under suitable conditions light falling on the eye ...
The sclera, [ note 1] also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective outer layer of the eye containing mainly collagen and some crucial elastic fiber. [ 2] In the development of the embryo, the sclera is derived from the neural crest. [ 3]
Some mental control can be exerted over these closed-eye visualizations, but it usually requires a bit of relaxation and concentration to achieve. [1] [2] When properly relaxed, it is possible to cause regions of intense black, bright white or even colors such as yellow, green, or pink to appear in the noise. These regions can span the entire ...
We've all grown up thinking that sitting too close to the television is damaging to our eyes ... but that might not be the case. Technology spawns lots of confusion ... and a few affectionately ...
Contrast (vision) Six renditions of a rocky shore photo with incremental contrast levels, clockwise from bottom left. Contrast is the difference in luminance or color that makes an object (or its representation in an image or display) visible against a background of different luminance or color. The human visual system is more sensitive to ...
Cone cell. Cone cells or cones are photoreceptor cells in the retinas of vertebrates' eyes. They respond differently to light of different wavelengths, and the combination of their responses is responsible for color vision. Cones function best in relatively bright light, called the photopic region, as opposed to rod cells, which work better in ...
Environmental Exposure. Drastic weather changes are a common cause of dry skin. Extremely cold weather can make it more difficult for your skin to retain moisture. Low humidity in the air creates ...