Presbyopia is a visual condition caused by the gradual loss of the ability to focus on near objects. Presbyopia is a natural part of the aging process of the eye which usually becomes noticeable after age 40-45.
The main causes of presbyopia are the progressive decrease of plasticity of the crystalline lens and the reduced functional capacity of the ciliary muscle.
Symptoms
At the beginning, the far-sighted subject will perceive a sense of blurry vision and visual fatigue, especially at night and in dim light conditions, while reading or in other activities that involve near vision.
As presbyopia progresses, the patient will tend to position the book or the newspaper that he/she wants to read further and further away, to try to get it into focus, until an arm's length will not suffice to compensate for the visual impairment.
In short-sighted subjects presbyopia develops later or, at least outwardly, does not arise at all, because the short-sighted subjects very often have got used to taking off their glasses for long distance viewing.
In contrast, for the subject affected by hyperopia the process starts before and has a faster evolution since presbyopia is combined with the basic refractive error.
Presbyopia tends to progress from the age of 40 up to the age of 60-65.
Diagnosis and treatment
Presbyopia is diagnosed by a basic eye exam, which includes a refraction assessment and an eye health exam.
Treatments for presbyopia correction include wearing eyeglasses or contact lenses, undergoing refractive surgery, or getting lens implants for presbyopia. All types of spectacle lenses for presbyopia must be checked often and possibly replaced to ensure optimal correction as visual impairment progresses.
Another approach in the correction of presbyopia is represented by laser eye surgery and cataract surgery, in which multifocal or EDOF intraocular lenses (IOLs) are put in place of the natural crystalline lens.
Multifocal IOLs consist of multiple zones of lens power that produce more than one focal point, allowing for enhanced vision at both near and far. The multifocal IOLs can be further subdivided into bifocal, trifocal and EDOF IOLs. Bifocal IOLs create two primary focal points and then provide the patient with both near and far vision. Trifocal IOLs, compared to bifocal IOLs, improve intermediate vision by providing a third focus. EDOF IOLs, differently from bifocal and trifocal IOLs, have a single elongated focal point which provides uninterrupted vision without gaps between foci.
A thorough evaluation is required by an ophthalmologist to identify patients who can effectively benefit from this type of intraocular lens.
