Presbyopia

Presbyopia is an age-related decline in the eye’s ability to focus on nearby objects, caused primarily by reduced flexibility of the crystalline lens.

Accommodation: The eye’s adjustment of optical power to focus objects at different distances on the retina. Presbyopia is the gradual loss of this focusing ability, especially for near objects.
Bifocal glasses: Eyeglasses with distinct lens regions for distance and near vision. Their near segment compensates for presbyopia while the upper region supports distance vision.
Optics: The study of light and its interactions with materials and optical systems. The eye’s loss of near focusing power is an optical problem.
Reading: The process of interpreting written symbols and language. Small print is often among the first tasks to become difficult with presbyopia.
Crystalline lens: The transparent, flexible structure inside the eye that changes shape to help focus light on the retina. Age-related stiffening of this lens is the main cause of presbyopia.
Progressive lenses: Eyeglass lenses with a gradual change in optical power from distance to near viewing. They offer presbyopia correction across viewing distances without a visible segment line.
Refraction: The bending of light as it passes between materials with different refractive indices. Clear vision depends on directing refracted light onto the retina.
Computer vision syndrome: A group of eye and visual symptoms associated with prolonged digital-device use. Uncorrected near focusing difficulty can contribute to discomfort during screen work.
Ciliary muscle: A ring-shaped muscle in the eye that changes tension on the lens through the zonular fibers. It participates in accommodation, though lens stiffening limits its effectiveness with age.
Monovision: An optical correction strategy that sets one eye primarily for distance and the other for near vision. It can reduce dependence on reading glasses by assigning near focus to one eye.

Linked from 12 pages