Blepharoptosis: 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. Some sagging of the skin and connective tissues occurs during the normal aging process, potentially leading to drooping of the eyelids. Other causes include conditions that affect the muscles and nerves of the eyelid as well as conditions that affect the skin and connective tissues of the eyelid.
Blepharospasm: 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.
- Blighted ovum
Blighted ovum: 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 […]
- Blind spot
Blind spot: 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 […]
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.
- Blinded study
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).