Category: Bk-Bl

A collection of fluid underneath the top layer of skin (epidermis). There are many causes of blisters, including burns, friction forces, and diseases of the skin. Also known as bleb and bulla.

Impaired vision in dim light and in the dark, due to impaired function of specific vision cells (namely, the rods) in the retina. The ability of our eyes to quickly view objects as they shift from light to dark areas and the ability to see in dim light or at night is an important part…

The criteria used to determine eligibility for government disability benefits and which do not necessarily indicate a person’s ability to function. In the US, the criteria for legal blindness are: Visual acuity of 20/200 or worse in the better eye with corrective lenses (20/200 means that a person at 20 feet from an eye chart can see…

Loss of useful sight. Blindness can be temporary or permanent. Damage to any portion of the eye, the optic nerve, or the area of the brain responsible for vision can lead to blindness. There are numerous (actually, innumerable) causes of blindness. The current politically correct terms for blindness include visually handicapped and visually challenged.

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).

In ophthalmology, a blind spot is: A small area of the retina where the optic nerve enters the eye; this type of blind spot occurs normally in all eyes. Any gap in the visual field corresponding to an area of the retina where no visual cells are present; this type of blind spot is associated with eye…

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.

A fertilized ovum (egg) that did not develop or whose development ceased at an early stage, before 6 or 7 weeks of gestation. On the ultrasound examination of a blighted ovum, only the gestational sac that normally surrounds the embryo can be seen. There is usually no embryo inside the gestational sac. A blighted ovum is a…

The involuntary, forcible closure of the eyelids. The first symptoms may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed, causing functional blindness even though the eyes and vision are normal. Blepharospasm is a form of focal dystonia.

An abnormal, low-lying upper eyelid margin. Drooping eyelids may occur on both sides (bilateral) or on one side only (unilateral), in which case it is more easily noticed. Congenital ptosis is eyelid drooping that is present at birth; when it develops later, it is referred to as acquired ptosis. Blepharoptosis may be barely noticeable or quite prominent.…