presbyopia

(redirected from old sight)
Also found in: Dictionary, Thesaurus, Medical, Legal.

presbyopia

a progressively diminishing ability of the eye to focus, noticeable from middle to old age, caused by loss of elasticity of the crystalline lens

Presbyopia

 

diminution of the power of accommodation of the eye due to advancing years. Presbyopia occurs as a result of sclerosing of the crystalline lens, which is unable to increase its curvature to the limit when there is a maximum tension (accommodation); the result is that its refractive power decreases, and the ability to see objects close to the eye is impaired.

Presbyopia begins at age 40 to 45 when eye refraction is normal. When myopia is present, it begins later, and with hyperopia, it comes on earlier. Treatment consists in appropriate selection of glasses for reading and close work. Persons 40 to 45 years of age with normal refraction need a plus lens of 1.0 to 1.5 diopters for reading at a distance of 33 cm. Every five years the refractive power of the lens is increased by 0.5 to 1 diopter. Corresponding corrections in the lens power are made for myopia and hyperopia.

presbyopia

[‚prez·bē′ō·pē·ə]
(medicine)
Diminished ability to focus the eye on near objects due to gradual loss of elasticity of the crystalline lens with age.
References in periodicals archive ?
In fact old sights have become a collecting field of their own.
She had left with her friends in 1956 as an 11-year-old girl and suddenly, despite many changes at the school, all the old sights, sounds and smells came back to her.
We went to Eastbourne many, many years ago so it will be nice to see the old sights again.