Presbyopia
Growing older changes the near point.
Holding the newspaper
Many older people hold a newspaper farther from their eyes than they did when they were young.
What has happened to their near point?
What this lesson covers
The idea
In presbyopia the power of accommodation decreases with ageing and the near point recedes, owing to gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.
Holding the newspaper
Many older people hold a newspaper farther from their eyes than they did when they were young.
What has happened to their near point?
- It has moved farther away
- It has moved closer
- It is exactly the same as before
Growing older
Press Next step.
The near point recedes
As people grow older, the ciliary muscles weaken and the eye lens becomes less flexible. The power of accommodation falls, so the near point moves farther away and near work becomes hard without eye-glasses.
In presbyopia the power of accommodation decreases with ageing and the near point recedes, owing to gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens.
Notes
In presbyopia the power of accommodation decreases with ageing and the near point recedes, due to weakening ciliary muscles and a less flexible eye lens.
Check yourself
What causes presbyopia?
With ageing, the near point usually…
The power of accommodation of the eye usually…
A person with presbyopia finds it difficult to see…
- Gradual weakening of the ciliary muscles and diminishing flexibility of the eye lens — correct. Yes!
- Elongation of the eyeball. Elongation of the eyeball is a cause of myopia.
- An eyeball that has become too small. An eyeball that is too small is a cause of hypermetropia.
- comes closer to the eye. In presbyopia the near point recedes away, not closer.
- gradually recedes away — correct. Yes!
- stays at 25 cm for everyone. For most people the near point gradually recedes away with ageing.
- increases with ageing. With ageing the ciliary muscles weaken and the lens becomes less flexible, so accommodation decreases.
- does not change with ageing. The power of accommodation usually decreases with ageing.
- decreases with ageing — correct. Yes!
- nearby objects comfortably and distinctly without corrective eye-glasses — correct. Yes!
- distant objects comfortably. In presbyopia the difficulty is with nearby objects, since the near point recedes.
- anything, even with eye-glasses. Presbyopia can be corrected with suitable spherical lenses in eye-glasses.