This is a beta course, so its structure, chapters, and examples may continue to change.
Myopia
The essence of myopia: after parallel light enters the eye, it focuses in front of the retina, so distant objects form a blurry image.
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.
- Axial myopia: the axial length of the eye grows (the most common case).
- Refractive myopia: the curvature of the cornea or lens is too strong, or its refractive index is too high.
- Pseudomyopia: caused by spasm of accommodation; it can be relieved by rest or medication.
- Distance vision is blurry and you squint; near vision stays clear.
- Glare and starbursts at night may become more noticeable.
- Correction: a concave lens in glasses or a contact lens moves the focal point back onto the retina.
- Control: increase outdoor light exposure and keep a sensible viewing distance and duration; for adolescents, consider defocus lenses, orthokeratology lenses, or low-dose atropine.