blur

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blur

 
lack of sharpness in an x-ray image, usually due to patient motion.

blur 

1. Degradation of an image formed by an optical system as a result of lack of focusing, aberrations, diffusion of light, etc.
2. A pattern in which the border is indistinct. See lens flare; blurred vision.
blur back test See plus 1.00 D blur test.
blur circle A circular patch of light formed on the retina resulting from a point object whose image is focused either in front of, or behind the retina, or due to excessive aberrations of the optical system of the eye. The size of the blur circle increases with the distance of the ocular image from the retina and with the diameter of the pupil. Its diameter can be expressed in angular terms (in min arc) as
α = 3.48 ✕ ΧFd
where ΧF is the defocus (in dioptres) with respect to the object point, and d the pupil diameter (in mm) (Figs. B4 and B5). Example: An object at infinity is viewed by a 2 D uncorrected myope with a 4.0 mm pupil diameter, i.e. α = 3.48 ✕ 2 ✕ 4 = 28 min arc. Syn. circle of confusion; circle of diffusion. See aberration; depth of field.
plus 1.00D blur test See plus 1.00 D blur test.
blur point See blur point.
spectacle blur Reduction in visual acuity noticed with spectacles after removal of hard contact lenses (PMMA). This may be due to corneal oedema, alteration of the corneal index of refraction, surface distortion of the cornea, etc. Refitting the patient with gas permeable lenses usually relieves this symptom.
Fig. B4 Blur circle corresponding to an image formed in front of the retinaenlarge picture
Fig. B4 Blur circle corresponding to an image formed in front of the retina
Fig. B5 Effect of pupil size on the blur circle. O9 is the image of object O formed by the optics of the eyeenlarge picture
Fig. B5 Effect of pupil size on the blur circle. O9 is the image of object O formed by the optics of the eye

Patient discussion about blur

Q. My vision is blurry and I see zigzag lines, what is it from? Every now and again, usually after sitting a few hours in front of the computer or not sleeping enough at night, I start getting blurry vision. I see zigzag lines in front of my eyes and it can take sometimes an hour to go away. What is this from?

A. It sounds like you have a migraine. A migraine that comes with blurry vision and zigzags (an aura) is called a classic migraine. The aura of migraine typically lasts from 20 minutes to an hour. Some patients have prolonged aura symptoms that can last hours to days. The aura also typically ends before the headache itself begins. When migraine aura symptoms are prolonged or last into or through the headache phase these types of migraine are commonly referred to as complicated migraines.

Q. I have fibromyalgia and am having terrible vision problems...double, blurred, feel off blance.Is this common?

A. Blurry vision is not a usual symptom in fibromyalgia. If you are experiencing this on a permenant basis you should see a doctor- either a neurologist or an ophthalmologist to rule out other vision conditions that might be causing this.

Q. What are the sides effects of alcoholism beside dizziness and blur?

A. In the short term, excessive alcohol consumption may cause vomiting and metabolic disturbances, seizures and coma. In the long term, alcohol may damage the pancreas, liver and other organs, and expose to cancer of the mouth.

You may read more here:
www.nlm.nih.gov/medlineplus/alcoholism.html

More discussions about blur
References in periodicals archive ?
It'll be blurrier than an actual pinhole but much brighter, so you can cast its light a lot farther and get a bigger image.
But the new study demonstrates that the distinction between wave and particle is blurrier. Quantum physicist Shi-Liang Zhu of Nanjing University in China and colleagues used the delayed-choice apparatus to measure the specially prepared light pulse of a single photon.
Nothing in this Article denies that courts have significant creative authority to flesh out the blurrier contours of congressional legislation and that they can appropriately pursue coherence when doing so.
Precisely because the line is growing blurrier by the day, those who define themselves as professional journalists need more than ever to maintain standards and report with seriousness and objectivity.
Adding to the discussion about how the terms "structural" and "cyclical" should be defined, she opined that the line between what could be affected by the monetary policy and what could not was blurrier than implied in the paper.
Although laws passed in the 1970s technically guaranteed workers the right to refuse unsafe work, the line between safety and danger was often a blurry one, made blurrier still by confusion over the dangers posed (or not posed) by particular substances.
Due to the continuous innovation in this industry the line between professional athletes and recreational exercisers are becoming blurrier therefore the market registers a continuous growth.
Thus, even though the existence of probable cause may trigger a formal rule of reasonableness (and a corresponding safe harbor for the exercise of arrest discretion), the determination about whether probable cause exists in the first instance is blurrier and may admit qualitative balancing.
The line separating children and adults is never blurrier than on national signing day, when middle-aged men feverishly refresh their computer screens while teenagers pick hats off of tables.
The line between fine art and illustration is blurrier than the art world acknowledged just a few decades ago.
Not intervening in Syria -- letting Bashar Assad cross Obama's red line of using chemical weapons on civilians -- makes any red lines regarding Iran's nuclear progress blurrier. When Obama originally set his red line back in August 2012, he caught his advisers completely off guard.