Something that causes a response in a body part or organism. A stimulus may be internal or external. Sense organs, such as the ear, and sensory receptors, such as those in the skin, are sensitive to external stimuli such as sound and touch.
Just curious...given my insurance plan I can get a new pair of frames and lenses once every 2 years, but I realllly love glasses so I tend to purchase about 2 pair per year...Gotta have my style...oh and of course the added benefit of sight is a nice plus:)
This is usually when people -- even those with excellent eyesight -- begin to need reading glasses. â¢ People ages 40 to 64 should have an eye assessment every two to four years, depending on whether they notice a change in vision or experience symptoms of illness.