Presbyopia is a type of farsightedness and is caused when the center of the eye lens hardens and loses flexibility making it unable to accommodate near vision. Presbyopia leads to an inability to see fine print. To learn how to improve your vision, see Eyesight and consider using a product for better vision called Eyesight-Rx.

Visual impairment among the elderly is a major health problem. With advancing age, the normal function of eye tissues decreases and there is an increased incidence of ocular pathology. Demographic studies have shown that age is the best predictor of blindness and visual impairment. The most common causes of age related visual impairment in the elderly are presbyopia, cataracts, age related macular degeneration, primary open angle glaucoma and diabetic retinopathy. By age seventy, 21% of the people living in the United States have both vision and hearing loss.

Cause of Presbyopia
There is a marked increase in the stiffness of the human lens with age. This is most pronounced in the nucleus. Since the nucleus must change shape significantly during accommodation, it is highly likely that these measured changes in physical properties will markedly diminish the ability of the lens to accommodate, and thus may be a major contributing factor to presbyopia.

See Eye Disorder for a list of common eye conditions.

Presbyopia Research Update
The mechanism of presbyopia.
Prog Retin Eye Res. 2005 May;24(3):379-93. Epub 2004 Dec 19. Strenk SA, Strenk LM, Koretz JF.
Department of Surgery, Robert Wood Johnson Medical School-University of Medicine and Dentistry of New Jersey, Piscataway, NJ
Accommodation in humans refers to the ability of the lens to change shape in order to bring near objects into focus. Accommodative loss begins during childhood, with symptomatic presbyopia, or presbyopia that affects one's day to day activities, striking during midlife. While symptomatic presbyopia has traditionally been treated with reading glasses or contact lenses, a number of surgical interventions and devices are being actively developed in an attempt to restore at least some level of accommodation. This is occurring at a time when the underlying cause of presbyopia remains unknown, and even the mechanism of accommodation is occasionally debated. While Helmholtz' theory regarding the mechanism of accommodation is generally accepted with regard to broad issues, additional details continue to emerge. Age-related changes in anterior segment structures associated with accommodation have been documented, often through in vitro and/or rhesus monkey studies. A review of these findings suggests that presbyopia develops very differently in humans compared to non-human primates. Focusing on non-invasive in vivo human imaging technologies, including Scheimpflug photography and high-resolution magnetic resonance imaging (MRI), the data suggest that the human uveal tract acts as a unit in response to age-related increasing lens thickness and strongly implicates lifelong lens growth as the causal factor in the development of presbyopia.