This is a beta course, so its structure, chapters, and examples may continue to change.
How Glasses Correct Vision
Glasses use lenses to change the light path so that the focus falls back on the retina. Myopia is corrected with a concave lens that “diverges first, then focuses,” while hyperopia is corrected with a convex lens that “focuses earlier.”
Myopia corrected with a concave lens: the focus moves forward onto the retinaMyopia
- Myopia: the light focuses in front of the retina; the concave lens diverges it first, and the eye then focuses it back onto the retina.
- Alignment: the optical center of the lens must line up with the pupillary distance, otherwise a prism effect can appear and cause dizziness.
- Full correction vs. undercorrection: myopia in adolescents is usually fully corrected to keep vision clear; adults can fine-tune under professional guidance.
- Frame choice: a small frame makes the edges thinner and reduces aberration; adjusting the nose pads and temples determines comfort and stability.
If dizziness, double vision, or distorted vision appears after putting the glasses on, have the prescription and pupillary distance rechecked, and ask the optometrist to adjust the frame if needed.