Monday, May 22, 2006

24

Far Point of the Eye

The far point of the eye is the object point imaged by the eye onto the retina in an unaccommodated eye. If a corrective lens is used to correct for myopia, the lens has its secondary focal point coincident with the far point of the eye.

  • The far point of the emmetropic eye is at infinity.
  • Myopia exists if, without accommodation, a point at infinity is imaged in front of the retina (in the vitreous). The stimulus on the retina is therefore not a point, but a blur circle. Moving the object closer to the myopic eye, until the image is a point focus on the retina, establishes the far point of the eye.
  • Hyperopia exists, if without accommodation, an object point at infinity is imaged neither in the vitreous nor on the retina, but theoretically, behind it.


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