Astigmatism (for Class 10 level) is a defect of vision in which a person cannot see all parts of an object clearly at the same time because the cornea or lens of the eye is not perfectly spherical, so light does not focus at a single point on the retina.

Simple Class 10 Definition

  • In astigmatism, the surface of the cornea or lens is irregularly curved (football‑like instead of perfectly round), so light rays coming from an object do not converge to one common focus on the retina.
  • Because of this, one direction (say vertical lines) may appear clear while the perpendicular direction (horizontal lines) appears blurred or distorted.

A Class 10‑style answer could be written as:

Astigmatism is a defect of vision in which, due to irregular curvature of the cornea or lens, light rays from an object do not focus at a single point on the retina, so different parts or directions of the object cannot be seen clearly at the same time.

Cause (Class 10 explanation)

  • Normal eye: Cornea and lens are almost perfectly spherical, so all rays from a point meet at one focus on the retina.
  • Astigmatic eye: Cornea or lens is more curved in one meridian and less in the perpendicular meridian, so there are effectively two different focal points instead of one.

Symptoms (what the person feels)

  • Blurred or distorted vision at all distances (near and far).
  • Eyestrain and headaches, especially after reading or using screens.
  • Difficulty seeing fine details and sometimes squinting to see clearly.

Type of defect (in exam language)

  • Astigmatism is a type of refractive error of the eye, like myopia (short‑sightedness) and hypermetropia (long‑sightedness).
  • It can be:
    • Corneal astigmatism – due to irregular shape of the cornea.
* Lenticular astigmatism – due to irregular shape of the lens.

Correction (how it is corrected – Class 10 point)

  • Astigmatism is mainly corrected by using cylindrical lenses in spectacles or special contact lenses (toric lenses) which provide different powers in different meridians to bring all rays to a single focus on the retina.
  • In some cases, laser surgery like LASIK can also be used to reshape the cornea and reduce or remove astigmatism.

One‑line exam answer (ready to write)

If you want a very short Class 10 board‑style answer:

Astigmatism is a defect of vision in which, due to unequal curvature of the cornea or lens, light from an object does not converge to a single point on the retina, so different directions of the object cannot be seen clearly at the same time; it is corrected by using suitable cylindrical lenses.

Meta description (SEO style):
Astigmatism is a common refractive error explained in Class 10 as a defect of vision caused by irregular curvature of the cornea or lens, leading to blurred or distorted vision, usually corrected by cylindrical lenses.

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