a substance secreted in a glandular sac under the skin of the abdomen of the male musk deer, having a strong odor, and used in perfumery. 2. an artificial imitation of the substance. 3. a similar secretion of other animals, as the civet, muskrat, and otter. 4. the odor of musk or some similar odor.
Lens: The lens is a clear part of the eye behind the iris that helps to focus light, or an image, on the retina. Macula: The macula is the small, sensitive area of the retina that gives central. vision. It is located in the center of the retina. Optic nerve: The optic nerve is the largest sensory nerve of the eye. It. carries impulses for sight from the retina to the brain. Pupil: The pupil is the opening at the center of the iris. The iris adjusts the size. of the pupil and controls the amount of light that can enter the eye.
The cornea also plays a key role in vision by helping focus the light that comes into the eye. The cornea is responsible for 65Â­-75 percent of the eyeâs total focusing power. The cornea and lens of the eye are built to focus light on the retina, which is the light-sensitive tissue at the back of the eye. When light strikes the cornea, it bendsâor refractsâthe incoming light onto the lens. The lens refocuses that light onto the retina, which starts the translation of light into vision.