Which condition is defined by an irregular curvature of the cornea?

Which condition is defined by an irregular curvature of the cornea?

• A. Myopia
• B. Hyperopia
• C. Cataract
• D. Astigmatism

Answer: (D)

Irregular curvature of the cornea causes astigmatism, a refractive error where light does not converge to a single point on the retina. When the cornea isn’t equally curved in all directions, one meridian bends light more than another, so images are blurred or distorted at all distances because the eye ends up focusing light at two different points rather than one. This differs from myopia, where the eye is too long or the cornea too steep causing focus in front of the retina, and hyperopia, where focus falls behind the retina due to a too-flat cornea or a short eyeball. Cataract is a clouding of the lens inside the eye, not a problem with corneal shape. Astigmatism is often corrected with toric lenses (glasses or contacts) or with laser refractive surgery to restore even curvatures and single, clear focus on the retina.

Irregular curvature of the cornea causes astigmatism, a refractive error where light does not converge to a single point on the retina. When the cornea isn’t equally curved in all directions, one meridian bends light more than another, so images are blurred or distorted at all distances because the eye ends up focusing light at two different points rather than one. This differs from myopia, where the eye is too long or the cornea too steep causing focus in front of the retina, and hyperopia, where focus falls behind the retina due to a too-flat cornea or a short eyeball. Cataract is a clouding of the lens inside the eye, not a problem with corneal shape. Astigmatism is often corrected with toric lenses (glasses or contacts) or with laser refractive surgery to restore even curvatures and single, clear focus on the retina.