Cataracts
What are cataracts and who is affected?
Cataracts are caused by a loss of transparency in the crystalline lens of the eye which causes interference in the transmission of light to the retina. They most commonly occur in people over 55, however it is not unusual for cataracts to occur in younger people and, rarely, newborns.
What causes cataracts to develop?
Cataracts can develop from chemical changes within the protein material of the lens. As a result, clouding and yellowish or brownish discoloration occurs. The chemical changes are a result of the natural aging process, however cataracts can also develop from injury, inherited tendencies, certain diseases, or birth defects. Factors that may contribute to the development of cataracts are exposure to ultraviolet light, poor nutrition, cigarette smoking, and certain drugs.
How do cataracts effect vision?
Loss of transparency means that the lens becomes opaque and the ability for light to pass through and create a sharp image on the retina is hindered. With an opaque lens, images cast on the retina are blurred and vision is foggy.
The formation of a cataract may have little to no effect on vision, however some people may experience a decrease in vision that requires surgery. Severe cataracts may result in complete loss of functional vision.
The effect on vision depends on the location and degree of clouding of the cataract. For example if the cataract is located on the side of the lens, a person may not notice a change in his/her vision for many years since peripheral vision is not used as much as the central area. The rate of progression of a cataract varies with each eye and the formation may be gradual or rapid.
The top picture illustrates how light passes through the lens to the retina for a clear, sharp image. When a cataract is present the light cannot pass through completely, causing vision to be foggy and blurred.
Common misperceptions about cataracts
- Cataracts are not the result of over-using eyes
- Cataracts are not contagious or related to cance
- There is no known way to reverse clouding once it has begun
- Cataracts are not a film or coating over the eye
Cataract prevention
Cataracts occur as a natural part of aging and therefore cannot be prevented. However, there is evidence that exposure to ultraviolet light (sunlight) and cigarette smoking can speed the development of cataracts. Two preventable measures are to not smoke and avoid excessive exposure to sunlight.
How are cataracts diagnosed?
In order to detect cataract formation, a comprehensive eye exam is necessary. Once diagnosed, regular follow-up exams are needed to determine the best possible glasses correction for the level of impairment.
What is the treatment?
Prescription glasses can help give better vision, however if the clouding is very dense surgery may be the best option to restore vision. The decision to have cataract surgery is made between the patient and his/her eye care professional and includes many factors, such as the location and density of the clouding and how daily activities are affected by the cataract.
What does cataract surgery involve?
Technological advancements have made cataract surgery a relatively painless and rapid procedure with few complications and a quick recovery time. Surgery is done one eye at a time with the more impaired eye being done first.
Cataract surgery involves the removal of the clouded lens immediately followed by the implant of an artificial lens known as an IOL (intraocular lens). Other forms of the lens replacement are prescription glasses and contact lenses, however they are not within the eye and vision is not as natural. Sight is dependent on many other factors and as a result cataract surgery may not produce complete improvement in vision. In such cases, prescriptive eye wear may enhance vision.
