Corrective lenses and contact lenses function through the principle of refraction, bending light to correct vision. In individuals with normal vision, light is focused onto the retina, where it is converted into signals for the brain. Refractive errors can prevent proper focus, necessitating the use of lenses to redirect light accurately onto the retina. The design of these lenses varies according to the specific vision issues being addressed, with their strength measured in diopters. Higher diopter values indicate stronger lenses for more significant corrections.