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Nyctalopia (/ ˌ n ɪ k t ə ˈ l oʊ p i ə /; from Ancient Greek νύκτ-(núkt-) 'night' ἀλαός (alaós) 'blind, invisible' and ὄψ (óps) 'eye'), [1] also called night-blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases.
Presbyopia, like other focal imperfections, becomes less noticeable in bright sunlight when the pupil becomes smaller. [8] As with any lens, increasing the focal ratio of the lens increases depth of field by reducing the level of blur of out-of-focus objects (compare the effect of aperture on depth of field in photography ).
Glare is difficulty of seeing in the presence of bright light such as direct or reflected sunlight or artificial light such as car headlamps at night. Because of this, some cars include mirrors with automatic anti-glare functions and in buildings, blinds or louvers are often used to protect occupants.
What’s important is that the child is exposed to natural light. Outdoor time is not just the parents’ responsibility, experts say. Schools and day cares should be making sure students get ...
Symptoms may include faded colours, blurry or double vision, halos around light, trouble with bright lights, and difficulty seeing at night. [1] This may result in trouble driving, reading, or recognizing faces. [8] Poor vision caused by cataracts may also result in an increased risk of falling and depression. [2]
Flash blindness is an either temporary or permanent visual impairment during and following exposure of a varying length of time to a light flash of extremely high intensity, such as a nuclear explosion, flash photograph, lightning strike, or extremely bright light, i.e. a searchlight, laser pointer, landing lights or ultraviolet light. [1] The ...
Days later, he had trouble seeing bright lights. He developed a stiff neck, which he thought could be meningitis, a symptom of the neuroinvasive form of West Nile. The West Nile expert, strangely ...
The opposite problem, known as hemeralopia, that is, inability to see clearly in bright light, is much rarer. The fovea is blind to dim light (due to its cone-only array) and the rods are more sensitive, so a dim star on a moonless night must be viewed from the side, so it stimulates the rods. This is not due to pupil width since an artificial ...