Blindness
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  Blindness



Blindness

    Legal blindness is defined as: 1) visual acuity of 20/200 (only being able to see the big E on the eye chart) or less in the best eye even with the eyes corrected by glasses or contact lenses; or, 2) The peripheral visual field is reduced to 20 degrees of visual angle or less. Twenty degrees of visual angle is about the size of a one foot ruler held at arms length.

RELATED TERMS
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Blindness
Legal blindness is defined as: 1) visual acuity of 20/200 (only being able to see the big E on the eye chart) or less in the best eye even with the eyes corrected by glasses or contact lenses; or, 2) The peripheral visual field is reduced to 20 degrees of visual angle or less. Twenty degrees of visual angle is about the size of a one foot ruler held at arms length.

Acuity
The highest spatial frequency rsolvable with a grating of unity contrast (i.e. the maximum possibly contrast).

Glasses
A pair of ophthalmic lenses in a frame or mounting which is supported by the nose and ears. The purpose is to aid or improve vision. It does not include goggles or nonprescription sun glasses for which EYE PROTECTIVE DEVICES is available.

Peripheral
At or near the surface of the body. Located away from the center structure.

Foot
The distal portion of the leg, upon which an individual stands and walks. It consists, in man, of the tarsus, metatarsus, and phalanges and the tissues encompassing them.

Arms
An appendage in anatomy and in clinical trials. See: Arm.



SIMILAR TERMS
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Blind
1. Unable to see. Without part or all of the sense of sight.2. In a clinical trial, not to know the treatment given or received. The participant is not told whether they are in the experimental or control arm of the study. Also called masked.

Blind review
The checking and assessment of data during the period of time between trial completion (the last observation on the last subject) and the breaking of the blind, for the purpose of finalising the planned analysis.

Blind spot
The location where optic nerve fibers leave the retina. This area has no photoreceptors and therefore no visual input. The cortex appears to fill-in this missing information so we are not conscious of the blind spot.

Blind study
One in which the subject or the investigator (or both) are unaware of what trial product a subject is taking. See also double-blind study, single-blind study, triple-blind study.

Blinded medications
Products that appear identical in size, shape, colour, flavour, and other attributes to make it very difficult for subjects and investigators to determine which medication is being administered.

Blinded study
A study done in such a way that the patients or subjects do not know (is blinded as to) what treatment they are receiving to ensure that the results are not affected by a placebo effect (the power of suggestion).

Blinding/masking
A procedure in which one or more parties to the trial are kept unaware of the treatment assignments. Single-blinding usually refers to the subject(s) being unaware, and doubleblinding usually refers to the subject(s), investigators, monitor, and, in some cases, data analyst(s) being unaware of the treatment assignments.

Blindness, legal
See: Legal blindness.

Blindness, night
Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina.

Blindsight
A phenomenon reported in individuals suffering from cortical blindness (i.e. damage to the primary visual cortex resulting in blindness). Individuals with blindsight report that they are unable to see, yet under forced choice conditions are able to indicate the presence and location of visually presented objects.

Blink rate
The number of times per minute that the eyelid automatically closes -- normally 10 to 30 per minute.



PREVIOUS AND NEXT TERMS
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Billing medical software
A specific type of software addressed to medical charging and billing needs.

Brinerdin
An antihypertensive agent produced by Novartis and based on reserpine, clopamide, dihydroergocristine, and hydralazin.

Butazolidin
A non-steroidal anti-inflammatory drug manufactured by Novartis and based in phenylbutazone.

Best's disease
Also called Vitelliform macular dystrophy. Causes atrophy of the RPE and photoreceptors in the macula. Late in the disease there is a loss of visual acuity to legal blindness and a blind spot in central vision. No treatment is available.

Blepharitis
An inflammation of the eyelids or lid margins. It is often caused by an infection. A chronic form produces a scaling or crusting of the lid margins. This is treatable by an eye doctor.

Blindness

Biltricide
Biltricide (praziquantel) is a medication for the treatment of infections caused by various schistosoma species. Produced by Bayer.

Baycip
A potent broad spectrum oral antibiotic that, when first introduced, represented a breakthrough in fighting infectious diseases. Made by Bayer.

Baymycard RR
Baymycard RR(nisoldipine) is a Bayer treatment for migraine pain.

Bayer
A German-based multinational pharmaceutical corporation developing many medical devices and drugs.

Bromvalerylurea
A hypnotic substance.

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