How is presbyopia different from hyperopia (farsightedness)?

Hyperopia is a refractive error from a mismatch between optical power and eye length present independent of age, whereas presbyopia is the age-related loss of the lens's ability to change shape for near focus; a person can have one, the other, or both.

Why does presbyopia affect almost everyone?

Because it results from the normal age-related stiffening of the crystalline lens, the loss of near-focusing ability develops in essentially all people as they reach middle age.

Presbyopia

Presbyopia is the gradual, age-related loss of the eye's ability to focus on near objects, caused by a progressive decline in accommodation. It is a near-universal change of mid-adult life and, when uncorrected, is a leading cause of near-vision impairment worldwide.

Definition

Presbyopia is the age-related reduction in accommodative amplitude in which the eye progressively loses its ability to increase optical power for near focus, so that clear near vision is no longer possible without optical assistance.

Scope

The entry covers the concept of accommodation and its age-related decline, the symptoms that define presbyopia as near-vision difficulty, and the global burden of uncorrected presbyopia. It treats presbyopia as a reference clinical topic and is not a guide to prescribing reading correction.

Key concepts

Accommodation
Accommodative amplitude and its age-related decline
Near point of focus
Crystalline lens stiffening
Near-vision impairment
Uncorrected presbyopia as avoidable impairment

Mechanisms

Accommodation is the process by which the eye increases its optical power to focus on near objects: contraction of the ciliary muscle releases tension on the lens, which becomes more curved and more powerful. With age the crystalline lens progressively loses the capacity to change shape in response to this effort, so the accommodative amplitude declines and the near point of clear focus recedes. The dominant explanation attributes this to age-related stiffening and growth-related changes of the crystalline lens, although the precise contributions of the lens and surrounding structures continue to be studied. The result is the characteristic difficulty with near tasks that becomes noticeable in middle age.

Clinical relevance

Presbyopia affects essentially everyone who lives long enough and is the usual reason adults begin to need help with near tasks; it is correctable optically. This entry describes the underlying change and its population burden as reference material and is not a basis for prescribing near correction for an individual.

Epidemiology

Presbyopia is essentially universal with advancing age, and global estimates identify uncorrected presbyopia as a major cause of near-vision impairment affecting a very large number of people, with the burden concentrated where access to simple near correction is limited.

Debates

What is the precise mechanism of age-related accommodative loss?: The leading account attributes presbyopia chiefly to age-related stiffening and continued growth of the crystalline lens, but the relative roles of the lens substance, capsule, and ciliary structures remain a subject of investigation.

Seminal works

fricke-2018
bourne-2021

Frequently asked questions

How is presbyopia different from hyperopia (farsightedness)?: Hyperopia is a refractive error from a mismatch between optical power and eye length present independent of age, whereas presbyopia is the age-related loss of the lens's ability to change shape for near focus; a person can have one, the other, or both.
Why does presbyopia affect almost everyone?: Because it results from the normal age-related stiffening of the crystalline lens, the loss of near-focusing ability develops in essentially all people as they reach middle age.