Astigmatism

Definition

Astigmatism is a common vision condition caused by an irregular curvature of the cornea or lens, leading to blurred or distorted vision. It affects how light is focused on the retina, resulting in multiple focal points.

5 Must Know Facts For Your Next Test

1. Astigmatism results from an irregular shape of the cornea or lens rather than a perfect spherical shape.
2. This condition can cause both near and distant objects to appear blurry or wavy.
3. Astigmatism is often corrected using cylindrical lenses that compensate for the uneven curvature.
4. A combination of astigmatism with myopia (nearsightedness) or hyperopia (farsightedness) is common.
5. The severity of astigmatism is measured in diopters, and higher values indicate more significant irregularity.

Review Questions

• What causes astigmatism and how does it affect vision?
• How are cylindrical lenses used to correct astigmatism?
• Explain why someone might have both astigmatism and nearsightedness.

Related terms

Cornea: The transparent front part of the eye that covers the iris, pupil, and anterior chamber, playing a key role in focusing vision.

Diopter: A unit of measurement for the optical power of a lens; used to quantify refractive errors like myopia, hyperopia, and astigmatism.

Cylindrical Lens: A type of corrective lens designed to correct astigmatism by compensating for the uneven curvature of the cornea or lens.