Entoptic phenomenon
Entoptic Phenomenon
Entoptic Phenomenon (/ɛnˈtɒptɪk/; from the Greek words entos, meaning "within", and optikos, meaning "of sight") refers to visual effects whose source is within the eye itself. In particular, these are visual effects that are caused by structures within the observer's own eye.
Etymology
The term "Entoptic Phenomenon" is derived from the Greek words entos ("within") and optikos ("of sight"). It was first used in the 19th century to describe visual phenomena that originate within the eye itself, as opposed to those that are caused by light entering the eye from the external environment.
Types of Entoptic Phenomena
There are several types of entoptic phenomena, including:
- Floaters: These are small, dark, shadowy shapes that float across your field of vision. They are caused by tiny pieces of the eye's gel-like vitreous breaking loose within the inner back portion of the eye.
- Phosphenes: These are the sensation of seeing light when light is not actually entering the eye, such as when you rub your eyes or apply pressure to them.
- Blue field entoptic phenomenon: This is the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into bright blue light such as a clear sky.
- Haidinger's brush: This is a subtle visual effect that is seen as a yellowish-brown or purplish-blue bow-tie or hourglass shape, and is associated with the perception of polarized light.
Related Terms
- Visual snow: This is a condition that causes people to see snow or static, similar to the noise of an analogue television, in parts or the whole of their visual fields.
- Afterimage: This is a non-specific term that refers to an image continuing to appear in one's vision after the exposure to the original image has ceased.
- Purkinje images: These are reflections of objects from the structure of the eye, named after the Czech anatomist who first described them, Jan Evangelista Purkinje.
See Also
References
External links
- Medical encyclopedia article on Entoptic phenomenon
- Wikipedia's article - Entoptic phenomenon
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