Amsler grid: While conducting an eye examination, the eye care professional may ask the patient to look at an Amsler grid. This grid is a pattern that resembles a checkerboard. The patient covers one eye and stares at a black dot in the center of the grid. While staring at the dot, the patient may notice that the straight lines in the pattern appear wavy.
This kind of wavy pattern on viewing the Amsler grid is abnormal. It can be an important warning sign of what is called wet age-related macular degeneration. The macula is an area in the retina of the eye that is responsible for central (straight-ahead) vision. It deteriorates most often after age 60 resulting in age-related macular degeneration (AMD). An early sign of the dangerous “wet” type of AMD is the wavy appearance of the lines on the Amsler grid. The early diagnosis of wet AMD is critical since laser surgery is urgently needed to preserve sight.
The Amsler grids shown here are reduced in size; eye care specialists have full-size grids in their office and for the patient to use at home.
Amusia: The inability to recognize musical tones or to reproduce them. Amusia can be congenital (present at birth) or be acquired sometime later in life (as from brain damage). Amusia is composed of a- + -musia and literally means the lack of music. Also commonly called tone deafness.
Amygdaloid: Like an almond. Almond-shaped. As the amygdaloid nucleus in the brain, a structure that anatomists thought resembled an almond. Amygdaloid is pronounced in three syllables: amyg da loid. From the Greek amydale (almond) + the Greek eidos (like).
Amygdala: 1. The amygdaloid nucleus in the brain. 2. The tonsils. These structures were so named because they appeared to be shaped like an almond. From the Greek amydale (almond) + the Greek eidos (like).
- Amygdaloid nucleus
Amygdaloid nucleus: A small oval structure in the temporal lobe of the brain that is closely connected to the hypothalamus, the hippocampus, and the cingulate gyrus. The amygdaloid nucleus is part of the olefactory and limbic systems and plays a role in the sense of smell, motivation, and emotional behavior. It was named the amygdaloid […]
Amyl-: (Amylo- before a consonant.) A prefix pertaining to starch. From the Greek amylon, meaning starch.