Refractive

Presbyopia is the inability to focus clearly due to age. It effects everyone to some degree or another and symptoms often start in the 40+ age group.

It is caused by loss of accommodation, which is where the natural lens within the eye no longer changes shape, a function that is necessary in order for the eye to 'fine focus'.

Initially a person may be able to read by holding material some distance away. People who wear glasses to correct short sight or myopia will find they have to take their glasses off to read. Longsighted people often suffer the most, finding it difficult to focus at any distance without glasses.

Young people who require lens surgery (for trauma or early cataract) may suffer induced presbyopia if they are given monofocal lens implants. In this situation, multifocal or accommodative implants can prevent induced presbyopia. Likewise these lenses can give all round vision to those who cannot tolerate presbyopia and who wish to be free of glasses for most tasks.