Physiology · Special Senses

Accommodation and near vision

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Definition

  • Accommodation is the process by which the eye increases its refractive power, by increasing lens curvature, to focus on near objects within 6 m.
  • Near point is the nearest point at which an object can be seen clearly, with accommodation exerted to its maximum.

Functional Basis of Accommodation

  • The cornea has fixed curvature, so its refractive power is constant; only the malleable lens can vary curvature via ciliary muscle contraction, giving the eye a variable focal point.
  • A resting (unaccommodated) eye focuses objects at more than 6 m away; ciliary muscles are relaxed and the lens is at its flattest curvature.

Mechanism of Accommodation