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Ocular accommodation
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Ocular accommodation is what your eye does when you shift from looking far away to looking at something close, like your phone. It is a reflex: you do not decide it, it just happens.
Three things happen at the same time. Both eyes turn inward to aim at the same point; the ciliary muscle, which surrounds the lens, contracts and changes the lens's shape; and the pupil narrows a little. The lens is the focusing element you carry inside your eye, and it does not shift position: it changes curvature, like a water droplet bulging.
Over the years the lens gets harder and the tension in that muscle drops. This is called presbyopia, and it is why the closest point you can focus on keeps moving farther away: your arm starts coming up short.
In brief
Ocular accommodation is the reflex the eye uses to focus on nearby objects.
Three things happen together in this reflex: both eyes converge, the ciliary muscle contracts and changes the shape of the lens, and the pupil narrows.
The lens does not move: it changes curvature, like a water droplet bulging.
With age the lens stiffens and ciliary muscle tension drops: this is presbyopia, and the near point of focus moves farther away.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Accommodation, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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