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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 ...
So far, two lighting methods have been shown to improve nighttime sleep in AD patients: (1) exposure to bright white light (at least 2500 lx and as high as 8000 lx at the cornea) for at least one hour in the morning, for two weeks and (2) exposure to 30 lx of blue light from LEDs, peaking at 470 nm at the eye for two hours.
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.
Light sensitivity or photosensitivity refers to a notable or increased reactivity to light. Apart from vision , human beings have many physiological and psychological responses to light. In rare individuals an atypical response may result in serious discomfort, disease, or injury.
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Most older adult humans lose photopic spatial contrast sensitivity. Adults in their 70s tend to require about 30–60% more contrast to detect high spatial frequencies than adults in their 20s. [3] The human eye uses scotopic vision under low-light conditions (luminance level 10 −6 to 10 −3.5 cd/m 2), and mesopic vision in intermediate ...
The duration and recurrence of symptoms depend on the underlying cause and the individual’s age or stage of life. Cyanopsia is most commonly reported in older adults after cataract surgery, where symptoms typically subside within a few days to weeks as the eyes adapt to the synthetic lens.
There are two luminous efficiency functions in common use. For everyday light levels, the photopic luminosity function best approximates the response of the human eye. For low light levels, the response of the human eye changes, and the scotopic curve applies. The photopic curve is the CIE standard curve used in the CIE 1931 color space.