🔍 Refraction is the bending of light as it passes through different mediums (e.g., air, lens, cornea). In the eye, it focuses light onto the retina.

Types:

1. Emmetropia: Normal vision.
2. Myopia (nearsightedness): Blurred distance vision.
3. Hyperopia (farsightedness): Blurred near vision.
4. Astigmatism: Distorted vision.
5. Presbyopia: Age-related near vision loss.

Tests:

• Visual acuity: Snellen chart.
• Autorefraction: Objective measurement.
• Subjective tests: Lens power adjustment.

Corrections:

• Glasses/contact lenses: Adjust refractive power.
• Surgery: LASIK, PRK, etc.