The macula or macula lutea is an oval-shaped pigmented area near the center of the retina of the human eye. It is responsible for the central, high-resolution, color vision that is
possible in good light; and this kind of vision is impaired if the
macula is damaged, for example in macular degeneration.
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field which typically occurs in older people. It is due to damage to the macula of the retina.
The severity is divided into early, intermediate, and late types. The
late type is additionally divided into "dry" and "wet" forms with the
dry form making up 90% of cases.
In the dry (nonexudative and 80%) form, yellowish extracellular debris called drusen accumulates between the retina and the choroid causing atrophy and scarring to the retina with gradual loss in vision.
While it does not result in complete blindness, loss of central vision can make it hard to recognize faces, drive, read, or perform other activities of daily life. Visual hallucinations may also occur and these do not represent a mental illness.
Fundus photo of the back of eye
with intermediate macular degeneration
photo: National Eye Institute, National Institutes of Health
There
are many risk factors that contribute to the condition, aging and
family history are the main ones, however, environment and lifestyle
enter into it as well.
- Smoking: Smoking tobacco increases the risk of AMD by two to three times that of someone who has never smoked, and may be the most important modifiable factor in its prevention. A review of previous studies found "a strong association between current smoking and AMD. ... Cigarette smoking is likely to have toxic effects on the retina."
- Hypertension (high blood pressure): In the ALIENOR study 2013, early and late AMD were not significantly associated with systolic or diastolic BP, hypertension, or use of antihypertensive medications, but elevated pulse pressure ((PP) systolic BP minus diastolic BP) was significantly associated with an increased risk of late AMD.
- Atherosclerosis
- High cholesterol: Elevated cholesterol may increase the risk of AMD
- Obesity: Abdominal obesity is a risk factor, especially among men
- Fat intake: Consuming high amounts of certain fats including saturated fats, trans fats and omega-6 fatty acids likely contributes to AMD, while monounsaturated fats are potentially protective. In particular, omega-3 fatty acids may decrease the risk of AMD.
- Exposure to UV light from the sun or blue light from the sun or LEDs
As of 2018, there are no medical or surgical treatments to reverse the effects of dry macular degeneration.
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