Near point

Definition

The near point is the closest distance at which the eye can focus on an object clearly. It varies with age and eye health, typically being around 25 cm for a young adult with normal vision.

5 Must Know Facts For Your Next Test

1. The near point tends to recede with age due to the decreasing elasticity of the eye's lens, a condition known as presbyopia.
2. For a young adult with normal vision, the near point is approximately 25 cm from the eye.
3. Corrective lenses, such as reading glasses or contact lenses, can help bring closer objects into focus by adjusting the focal length of the eyes.
4. The near point can be measured using a simple ruler and an object to determine at what distance it becomes blurred.
5. A shorter near point than average can indicate myopia (nearsightedness), where distant objects are blurry.

Review Questions

• What is the typical near point distance for a young adult with normal vision?
• How does presbyopia affect the near point as one ages?
• What role do corrective lenses play in adjusting someone's near point?

Related terms

Focal Length: The distance between the lens and its focus. In optics, it determines how strongly light rays are converged or diverged by a lens.

Presbyopia: An age-related condition in which the eye's lens loses its elasticity, making it difficult to focus on close objects.

Accommodation: The process by which the eye's lens changes shape to focus on objects at various distances.