There are many different types of eye problem, most of which can affect vision to some degree. A few of these eye conditions can also lead to blindness. One of the leading causes of blindness in the United States is macular degeneration. There are several types of macular degeneration but age-related macular degeneration is the most common type.
In fact macular degeneration is the most common cause of blindness in people over the age of 50 years. It needs to be differentiated from other eye conditions that also become common with age, such as cataracts and presbyopia. However, macular degeneration is largely irreversible and the blindness that may eventually occur cannot be corrected with surgery like in cataracts or with corrective eyewear as in presbyopia.
Read more on signs of cataracts.
What Happens in Macular Degeneration?
Macular degeneration is a condition that affects the part of the eye that is responsible for detecting light and converting it to signals that are relayed to the brain. It is this process that allows for the sense of vision. The macula is one part of the light-sensitive inner lining of the eye known as the retina. The fovea is the small area of the macular which is responsible for clarity of vision. As the name suggest, macular degeneration is where the light-sensitive region of the eye deteriorates.
There are two types – dry (non-exudative) and wet (exudative). Non-exudative or dry macular degeneration accounts for 9 in 10 cases of macular degeneration. It is more common among the elderly and is believed to be due to oxidative stress to the eye during the course of life, genetics and both lifesyle and environmental factors, such as cigarette smoking, obesity and cardiovascular diseases.
Wet macular degeneration on the other hand is where there is fluid buildup at the back of the eye or abnormal blood vessel growth behind the macula. It is more likely to occur in people who have dry macular degeneration. However, the exact cause of both dry and wet macular degeneration is not known. There is no treatment to reverse or cure macular degeneration. Prevention is advisable as far as possible although preventative measures focusing on lifestyle and environmental changes may not always mean that macular degeneration is entirely avoidable.
Read more on macular degeneration.
How to Spot Macular Degeneration
Macular degeneration affects at least 1 in 10 people over 65 years and about 1 in 4 people older than 75 years. When visual disturbances as discussed below are noticed in the elderly then macular degeneration should be suspected in the elderly. Some of the signs of macular degeneration may overlap with other eye and vision disorders like cataracts, glaucoma and refractive errors. Therefore it is important to undergo an opthalmic examination to confirm a diagnosis of macular degeneration.
One of the cardinal signs of macular degeneration is dimming vision. This is where the vision gradually becomes duller like there is less light. It is often missed at the outset due to its gradual onset. At most people with macular degeneration may complain in the early stages of needing brighter light to see when reading or doing fine work.
Eventually the dimmining vision along with the other symptoms are a clear indication of some underlying problem. This visual disturbance is often described as “someone turning off the light”. It may reach a point where a person is unable to recognize faces or differentiate objects with similar shape and size.
Dullness of Colors
Another characteristic sign of macular degeneration is the dullness of colors. As this also develops gradually, many people may not notice it in the early stages of the disease. Color perception varies among individuals and this dullness of colors may also not be easily spotted by the person with macular degeneration or close contacts such as family members. However, alongside the dimming vision there is eventually a point where a person realizes that their vision is impaired to some degree. The dullness is not the same as color blindness.
Difficulty Adapting to Light
The eyes may require a few seconds to adapt when moving from a bright room to a room with less light. However, in macular degeneration a person may experience pronounced difficulty adapting to light that may also last longer. Even stepping into a dimly lit area where most people would not have a problem adapting almost instantly can be a problem. Areas with low levels of light can affect vision significantly where a person may not be able to define any objects for seconds to minutes.
Blurring of the vision is not unique to macular degeneration. It occurs in many different eye and vision conditions. Therefore it is often mistaken for other conditions such as refractive eye disorders (nearsightedness, farsightedness, astigmatism). With macular degeneration being more common among the elderly and presbyopia developing with advancing age, it is not uncommon for this blurring to be associated with presbyopia. Along with the dimming vision, a person may have difficulty with reading and recognizing faces.
Central vision is blurred and hazy and eventually blind spots may form. These are small areas of the visual field where there is no sight. It may not be significantly noticeable when these blinds spots are small. The other eye and brain may accommodate and adapt to some extent. It is more likely to be detected during opthalmic examination. In the early stages, these blind spots may first become apparent when activities are affected due to the loss of vision in these small areas. Eventually these spots may be large and affect vision.
Visual hallucinations are a less common symptom and more likely to occur in advanced stages of macular degeneration. A person may see images that do not exist. This can occur when a person fixes their vision at an object for long periods or in duller environments, although it may alos occur spontaneously. Hallucinations can be complex and may even be as detailed as faces, animals and even scenery. These visual hallucinations in macular degeneration is also known as Charles Bonnet syndrome. It should not be confused with hallucinations in mental diseases.