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The Amsler grid showing the visual perception of the left eye of a person experiencing metamorphopsia (straight lines appear bent or curved) [1] [2]. Metamorphopsia (from Ancient Greek: μεταμορφοψία, metamorphopsia, 'seeing mutated shapes') is a type of distorted vision in which a grid of straight lines appears wavy or partially blank.
In teichopsia, migraine sufferers may see patterns that look like the shape of the walls of a star fort. As the scotoma area expands, some people perceive only a bright flickering area that obstructs normal vision, while others describe seeing various patterns. Some describe seeing one or more shimmering arcs of white or colored flashing lights.
The retina lines the inside of the eye. It is light-sensitive and communicates visual messages to the brain. If the retina detaches, it moves and shifts from its normal position. This can cause photopsia, but can also cause permanent vision loss. Medical attention is needed to prevent vision loss.
Chatoyancy, cat's eye gems such as chrysoberyl cat's eye or aquamarine cat's eye; Chromatic polarization; Diffraction, the apparent bending and spreading of light waves when they meet an obstruction; Dispersion; Double refraction or birefringence of calcite and other minerals; Double-slit experiment; Electroluminescence; Evanescent wave
Diffraction spikes are lines radiating from bright light sources, causing what is known as the starburst effect [1] or sunstars [2] in photographs and in vision. They are artifacts caused by light diffracting around the support vanes of the secondary mirror in reflecting telescopes , or edges of non-circular camera apertures , and around ...
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
In a typical astronomical image of a star with an exposure time of seconds or even minutes, the different distortions average out as a filled disc called the "seeing disc". The diameter of the seeing disk, most often defined as the full width at half maximum (FWHM), is a measure of the astronomical seeing conditions.
In a dispersive prism, material dispersion (a wavelength-dependent refractive index) causes different colors to refract at different angles, splitting white light into a spectrum. A compact fluorescent lamp seen through an Amici prism. Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. [1]