Final answer:
Ortho-K corrects myopia and hyperopia by temporarily reshaping the cornea through overnight lens wear, flattening it for nearsightedness and steepening it for farsightedness. LASIK is a surgical method that permanently reshapes the cornea to correct vision errors by adjusting its curvature.
Step-by-step explanation:
Ortho-K and Vision Correction Theory
The theory behind Ortho-K (orthokeratology) involves corneal reshaping through controlled overnight lens wear. The rigid gas-permeable lenses are worn while sleeping to temporarily reshape the cornea, thus improving vision. This is done to correct refractive errors such as myopia (nearsightedness) and hyperopia (farsightedness). For myopia correction, the curvature of the cornea needs to be made flatter, which decreases its power and allows light to focus correctly on the retina. In contrast, correcting hyperopia involves increasing the corneal curvature to enhance its power, similar to how a positive-power spectacle lens would function.
Laser vision correction, such as LASIK (Laser-Assisted in situ Keratomileusis), is a surgical alternative that also reshapes the cornea. This procedure uses a laser to permanently modify the corneal shape, ensuring light is correctly focused on the retina. For nearsightedness, the LASIK procedure flattens the cornea to reduce its power, while for farsightedness, it increases the curvature to heighten the eye's power.