may be prescription or nonprescription, are sometimes monocular (one eye), sometimes binocular (two eyes); lower powers may be mounted on eyeglasses; used to magnify and promote a better visual response by concentrating the image on a greater area of the eye; telescopic spectacles are particularly effective for watching TV; close focus are good for viewing at intermediate distances, i.e., piano music or hobbies; hand held are good for sightseeing and reading signs, etc.