What are some examples of corrective lenses

Glasses and contacts are corrective lenses.

A corrective lens is a lens worn in front of the eye, mainly used to treat myopia, hyperopia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye. Contact lenses are worn directly on the surface of the eye. Intraocular lenses are surgically implanted most commonly after cataract removal, but recently for purely refractive purposes. Myopia (near-sightedness) requires a divergent lens, whereas hyperopia (far-sightedness) requires a convergent lens. In other words Corrective lenses are typically prescribed by an ophthalmologist or an optometrist. The prescription consists of all the specifications necessary to make the lens. Prescriptions typically include the power specifications of each lens (for each eye). Strengths are generally prescribed in quarter-diopter steps because most people cannot generally distinguish between smaller increments. I hope this helps and that you understand

Stand or kneel behind the child and wrap your arms around his or her waist. locate the navel with one or two fingers in the middle of the child’s abdomen. just above the navel and well below the lower tip of the breastbone

Children typically learn to read during preschool.