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Pupillary light reflex. Variation in the size of the pupil in bright (left) and dim (right) environments. In this case the pupil is 3 mm in diameter on the left, and 9 mm on the right. The pupillary light reflex ( PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity ( luminance) of ...
Retinal scan. A retinal scan is a biometric technique that uses unique patterns on a person's retina blood vessels. It is not to be confused with other ocular-based technologies: iris recognition, commonly called an "iris scan", and eye vein verification that uses scleral veins.
Photophobia is a medical symptom of abnormal intolerance to visual perception of light. [1] As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, [2] though the term is sometimes additionally applied to abnormal or irrational fear of light, such as ...
Optical illusion is also used in film by the technique of forced perspective . Op art is a style of art that uses optical illusions to create an impression of movement, or hidden images and patterns. Trompe-l'œil uses realistic imagery to create the optical illusion that depicted objects exist in three dimensions.
Scleral tattooing is the practice of tattooing the sclera, or white part, of the human eye. Rather than being injected into the tissue, the dye is injected between two layers of the eye, then gradually spreads. The process remains uncommon due to professionals' discomfort performing the procedure [ 1] and is illegal in the American states ...
Abundant visible light to the eyes gives health benefits through its association with the timing of melatonin synthesis, maintenance of normal and robust circadian rhythms, and reduced risk of seasonal affective disorder. [10] On the negative side, UV is a mutagen and carcinogen for skin.
Monocular vision impairment refers to having no vision in one eye with adequate vision in the other. [ 2] Monopsia is a medical condition in humans who cannot perceive depth even though their two eyes are medically normal, healthy, and spaced apart in a normal way. Vision that perceives three-dimensional depth requires more than parallax.
These reflections are used to determine the size and shape of a ring in the retina which is located in the posterior part of the eye. By measuring this zone, the autorefractor can determine when a patient's eye properly focuses an image. The instrument changes its magnification until the image comes into focus.