What is age-related macular degeneration?
Eye is an important sensory organ that helps in vision, one of the important parts of the eye is the retina which has a vital role in visual recognition and receiving light. Macula is a part of the retina of the eye which contains the highest number of photoreceptors that detects light and then sends signals to the brain. AMD or ARMD is a disease of the eye in which the macula gets deteriorated with progression of age and it is one of the leading causes of vision loss in older people. It is also known as Age related Maculopathy. There are two types of age-related macular degeneration i.e. Dry AMD and Wet AMD.
Types of age-related macular degeneration
Dry AMD (non-exudative type) is the most common form in which people have yellow deposits in the macula called drusen, which are extracellular deposits between the layers of the retina. Dry AMD may also progress into wet AMD but it’s not very common.
Wet AMD (exudative type) is characterized by growth of blood vessels under the macula and then there is bleeding into the retina leading to rapid loss of vision and it is a lesser common type.
AMD is a disease that usually affects people above 60 years of age and its prevalence increases with age. It is seen that females are more affected than males. In AMD there is no sudden blindness but gradually and slowly there is visual impairment, and it is one of the common causes of irreversible visual loss in industrial countries. It is more common in the Caucasians and lesser in black population.
What causes age-related macular degeneration?
There are multiple etiologies and it involves many genetic and environmental factors which lead to Age related Macular Degeneration that includes some of the following mentioned below:
Age-People over the age of 60 years are affected the most as this is an age-related disease.
Race– Affects Caucasians more than Hispanic and lesser in Black population.
Heredity-There is a strong possibility of getting this disease if there is a family history of this disease. If any of the parents had this disease, there are more chances that the off springs might get this disease when they get older. There are various genes which show protection against any damage to the eye such as the chromosome 1q32 protects the cells of the eye from any damage and same goes for ABCR gene. If these genes go missing in individuals, they will be at higher risk of getting AMD.
Smoking– It increases the risk of AMD by narrowing blood vessels of the eye and resulting in decreased blood supply to the macula which then causes activation of the Immune component hence resulting in inflammation of the retina and gradually in impaired vision.
Hypertension– Including other cardiovascular diseases, hypertension is another important factor that can be associated with the risk of getting AMD. Hypertensive retinopathy is the most feared complication with increasing age and in hypertensive and diabetic patients. When there is reduced blood flow to the eye it becomes more prone to damage to the blood vessels of the retina and it can also lead to macular degeneration in the older population.
Dietary factors- High intake of fats or oily foods can result in obesity and other diseases such as hypertension and cardiovascular diseases which than contribute to cause age related macular degeneration. Those who have diabetes are also at higher risk as their sugar control is not good and high sugar diet also needs to be avoided. Low intake of fats and good intake of green vegetables and fruits are suggested. One more factor that can contribute in the worsening of this disease can be the lack of exercise; those who exercise daily can reduce the risk of getting this disease.
Cataract surgery– People who undergo cataract surgery do not come with complication of AMD immediately but some studies have shown that those who underwent cataract surgeries, a good proportion of them later developed neo-vascularization of the macula which then caused macular degeneration with increasing age.
Blue color iris- Iris is another important part of the eye which helps in protection of the eye by maintaining the balance between red and blue light which enters the eye. If there is too much blue light entering the eye it can be dangerous as it can cause macular degeneration. Ultraviolet lights are even more harmful for the eye as the iris cannot balance it with the red light and it can reach the macula and damage it overtime. Those who have blue colored iris are at higher risk as the amount of blue light entering the eye becomes even more and severe and can cause damage to the macula of the eye.
High Sunlight Exposure– Normally the sunlight is a natural and protective source of light for the eye and it cannot damage the eye but overexposure can result in damage of the eye as there are other dangerous rays which come out of the sun such as the ultraviolet rays which can cause cataract formation and even macular degeneration.
Symptoms of age-related macular degeneration
The signs and symptoms of Age-related Macular Degeneration varies according to its types that are Dry and Wet AMD. Dry type is also called Atrophic type and it is the most common one.
Dry AMD- impairment of vision is gradual and takes over months to years. There is often fluctuation in vision and they can see better when they are in bright light. Symptoms such as reduction in central vision in one or both eyes and straight lines seem to be bent and visual deterioration without pain. Other features include difficulty recognizing faces, blurry vision and it is difficult for them to adjust themselves in dim light.
Some of the important signs that your ophthalmologist can see during an eye exam include:
- Large and soft drusen deposits in the macula which become confluent
- Hyper pigmentation of the layers of the retina
- Atrophic areas of the retina become enlarged, drusen deposits disappear and choroidal vessels become visible
- Visual acuity (vision) is impaired and fovea is also involved
Wet AMD- is a less common type but it can rapidly progress to visual loss. The symptoms include the following:
- Blurriness in vision
- A blurry spot in the field of vision
- Symptoms worsen immediately
- Visual disturbances such as straight lines seem to be bent
AMD affects the central vision but doesn’t affect the peripheral vision that is why the patients of macular degeneration do not present with complete blindness.
How is age-related macular degeneration diagnosed?
Apart from routine examination of the eye, your ophthalmologist may perform diagnostic testing to evaluate age-related macular degeneration. The important investigative procedures that are suggested in AMD are:
- Fluorescein Angiography
- Ocular Coherence Tomography (OCT)
Treatment of age-related macular degeneration
It is always said that prevention is better than cure and there are various preventative measures that need to be taken before starting treatment of this disease. The daily routine measures include daily exercise, intake of less fat and more vegetables and fruits, cessation of smoking, less usage of mobiles and electronic devices at night and doing a routine eye checkup after every 6 months. Your eye doctor may also recommend antioxidant supplementation which include vitamins and minerals that reduce the risk of AMD progression.
The other treatment options include:
- Rehabilitation of low vision
- Experimental surgery that includes retinal translocation surgery and miniature intraocular telescope implantation.
- Laser Photocoagulation-used to coagulate the abnormal blood vessels under the macula
- Photodynamic therapy- used to treat the abnormal the blood vessels under the macula that supply the macula by stopping the leakage.
- Medications- drugs that stop the growth of new blood vessels such as bevacizumab and ranibizumab can be used.