macule A circumscribed change in the color of skin that is neither raised nor depressed. Macules are completely flat and can only be appreciated by visual inspection and not by touch. Physicians refer to flat skin spots on the skin as macules, as opposed to papules.
macular vision The type of fine, sharp, straightahead vision that enables people to read, drive, and perform other activities. As light is focused onto the macula, millions of cells change the light into nerve signals that tell the brain what is being seen. This is called macular or central vision. See also maculalutea.
macular hole A hole in the macula, the area of the retina that is responsible for fine central vision. Macular holes occur mainly in women. In time, central vision tends to worsen. A surgical procedure called vitrectomy (removal of the vitreous humor) may be considered as a treatment option. See also macular vision.
macular degeneration Deterioration of the macula lutea, a common progressive disorder that causes partial or total loss of macular vision, causing difficulty in doing tasks that require fine frontal vision (such as reading and driving a car). Although some forms of macular degeneration affect young people, most macular degeneration occurs in people over 60 years…
macular 1 Referring to a macule, a circumscribed change in the color of the skin that is neither elevated nor depressed. 2 Referring to the macula lutea of the retina.
macula lutea A small area in the retina that provides the keenest vision. It is the light-sensitive layer of tissue at the back of the eye. Also known as simply macula.
macula A small spot. For example, a macula on the skin is a small flat spot. See also macula lutea.
macrosomia An overly large body. A child with macrosomia has significant overgrowth, which can represent a hormone imbalance.
macroscopic Large enough to be seen with the naked eye, as opposed to microscopic. For example, a macroscopic tumor is big enough to see without a microscope.
macrophage A type of white blood cell that ingests foreign material. Macrophages are key players in the immune response to foreign invaders of the body, such as infectious microorganisms. They are normally found in the liver, spleen, and connective tissues of the body.
macroorchidism Abnormally large testes. To determine if the testes are too large, a device called an orchidometer is used that permits a testis to be compared to a series of plastic ovals (like miniature American footballs) of differing sizes. Macroorchidism is a diagnostic feature, for example, of the fragile X syndrome, the most common inherited…
macrolide antibiotic One of a family of antibiotics produced by Streptomyces bacteria. Examples of the macrolide antibiotics include erythromycin and azithromycin. See also erythromycin.