What is retina?
Retina is the photosensitive or a light sensitive layer of the eye, which acts as negative film of camera.
What can go wrong in the retina?
You can have problems in the retina, which are congenital (i.e. right from the birth) or acquired (i.e. acquired at a later age). There are conditions, where either the full retina or the central part is involved.
What are the common retinal disorders?
The common retinal disorders are as follows:
- Diabetic retinopathy – caused by long standing diabetes.
- Age related macular degeneration ( ARMD )
Diabetic Eye Disease
Diabetes and Eye
Diabetes is a disease that affects many organs of the body like eyes, kidney, nervous system, heart, limbs etc. Diabetes causes many changes in the eye. The most significant vision threatening consequence of diabetes in the eye is diabetic retinopathy and its complications. Untreated, it may cause blindness. However, timely diagnosis and proper management of this condition can help the patients maintain a useful vision.
How does diabetes affect the eye?
Diabetes, may lead to frequent fluctuations in vision and change in glasses power. It may also lead to cataract at a younger age, glaucoma, decreased vision due to involvement of the optic nerve, temporary paralysis of the eye muscles and thus double vision, Diabetic Retinopathy etc.
What is diabetic retinopathy?
Retina is the innermost layer at the back of the eye. The images of what we see are formed on this light sensitive layer and are then transmitted to the brain by optic nerve. Long standing Diabetes, especially after 5 years of disease, causes some changes in the retina and thus decreasing the vision.
Initially the small vessels of the retina are affected. They leak fluid and blood in the retina causing tiny hemorrhages and swelling of the retina, and thus decrease vision. In the later stages, the small blood vessels of retina close and lead to formation of new blood vessels. These new vessels are very fragile and bleed very easily to cause bleeding into the eye (vitreous hemorrhage). This bleeding causes severe vision loss, and many a times leads to secondary changes in the retina and eye to damage it beyond repair.These changes may result in total vision loss or blindness in adults
What are the risk factors for diabetic retinopathy?
Though any patient with diabetes may develop Diabetic Retinopathy, the longer the person has diabetes, the greater are his/her chances to develop diabetic retinopathy. Majority of the patients who have had diabetes for more than 5 years do have some changes of diabetic retinopathy. The other risk factors are high blood pressure, anemia, kidney diseases, and pregnancy.
Why is Early Detection important?
The vision lost due to Diabetic Retinopathy is not regained, and the aim of the treatment is to preserve the vision and not to improve the vision. In the earlier stages of the disease when the vision is not affected, there may be no symptoms perceived by the patient. It is best to detect the disease at this early stage before significant vision loss has occurred, and perform a timely treatment. This early detection can only be achieved by periodic evaluation (every 6 months) of the eyes of every diabetic patient, even if they have no eye related symptoms.
What are its symptoms?
Often there are no symptoms in the early stages of the disease. Vision may not change until the disease becomes severe. Nor is there any pain.
Blurred vision may occur when the macula the part of the retina that provides sharp, central visions swells from the leaking fluid. This condition is called macular edema. If new vessels have grown on the surface of the retina, they can bleed into the eye, blocking vision. But, even in more advanced cases, the disease my progress a long way without symptoms. That is why regular eye examinations for people with diabetes are so important.
How is it detected?
By Eye examination in which eyes are dilated i.e. eyedrops are used to enlarge your pupils. This permits a detailed & better eye check-up for signs of the disease.
Can diabetic retinopathy be treated?
Yes. Laser ( green laser ) procedure aims a strong light beam onto the retina to shrink the abnormal vessels, thus laser beam seals the leaking blood vessels.However, laser often cannot restore vision that has already been lost. Laser has been proved to reduce the risk of severe vision by 90 percent That is why early diagnosis of diabetic retinopathy is the best way to prevent vision loss.
Other treatments are Intravitreal Injections of Triamcinolone( steroid) and Avastin( anti-VEGF). These medicines reduces the swelling in macula and new blood vessels formation. Multiple injections may be required depending on OCT scan evaluation. Regular follow up & check up of eye pressure is very important.
Can diabetic retinopathy be prevented?
Not totally, but risk can be greatly reduced. Better control of blood sugar level slows the onset and progression of retinopathy and lessens the need for laser surgery for severe retinopathy.There is no treatment that can prevent diabetic retinopathy altogether. Besides a good control of blood sugar, one must exercise regularly, keep the blood pressure under control, and avoid smoking.
What can you do to protect your vision?
Finding and treating the disease early, before it causes vision loss or blindness is the best way to control diabetic eye disease.
So, if you have diabetes, make sure you get dilated & Detailed eye examination.
Age related macular degeneration ( ARMD )
The macula is the part of the retina, which provides us with central vision and allows us to see the fine details, such as recognizing a face, reading, or watching television. Macular Degeneration is a condition in which the macula gets damaged. It is often related to aging, and is commonly referred to as Age-related Macular Degeneration (ARMD). The late stage, associated with vision loss, is the most common cause of irreversible blindness in people over the age of 50. It affects the central vision, especially while reading.
Most often vision loss starts in one eye. Because the healthy eye compensates for the loss of vision in the damaged eye, macular degeneration may initially go unnoticed. In many cases it will ultimately affect vision in the other eye as well.
What are the types of Age-related Macular Degeneration (ARMD)?
There are two forms of macular degeneration: dry macular degeneration and wet macular degeneration.
Dry ARMD: The dry form, in which the cells of the macula slowly begin to break down, is diagnosed in 85 percent of macular degeneration cases. It may occur in one eye or both The retina becomes thinner and stops functioning. This may cause some people to detect “blank” areas in their central vision. The vision loss due to this Dry ARMD is less severe than wet ARMD. While there is no treatment available for people with dry ARMD, various low vision aids are available to help these people see well and perform daily activities.
Wet ARMD: The wet form, only accounts for 15 percent of the cases, results in 90 percent of the blindness caused by macular degeneration by developing abnormal blood vessels growing behind the macula. These fragile vessels will leak fluid & blood (hence ‘wet’ macular degeneration), cause swelling and scar tissue formation, causing rapid damage to the macula ,and thus leading to distorted vision and severe vision loss.
Can younger people get macular degeneration?
Yes. It can manifest at birth,in children upto 7, young people up tp 20, and up to 30 & 40 years . These are genetic disease & are inherited. Macular degeneration can occur in people who are severely nearsighted due to extreme elongation of the eyeball. This condition can result in tears in the macula and bleeding beneath the retina.
What causes macular degeneration?
These risk factors include:
- Gender (women appear to be at slightly higher risk)
- Family history
- High cholesterol
- Low consumption of fruits and vegetables
Can diet prevent macular degeneration?
Fruits and vegetables, especially those high in lutein and zeaxanthin, appear to provide the best protection. Lutein can be found in spinach, collard greens, kale, broccoli, papaya, oranges, kiwi, mango, green beans, peaches, sweet potatoes, lima beans, squash, red grapes and green bell peppers. Zeaxanthin can be found in yellow corn, honeydew melon, squash, oranges, mango, kale, apricots, peaches and orange bell peppers.
Why is Early Detection important?
The vision lost due to ARMD is generally irreversible, and the treatment methods try to preserve vision but can not improve vision. Hence it is important to detect this disease at an early stage, before it has caused significant vision loss.
How is ARMD detected?
In the early stages of ARMD, a person’s vision may become blurred or distorted.In late stages central patch is seen in the vision which is very disturbing.
A detailed retinal examination can detect it. Since many times the patient may not notice the initial distortion or blurring of vision, the key to preventing vision loss due to ARMD is regular eye examinations for patients above 40 years of age.
Latest Investigations like 3D OCT confirms the diagnosis
What are the Treatments available?
Untreated, ARMD progress and lead to further loss of vision,faster in the wet type. There is no current treatment for dry macular degeneration. However, vision that is already lost will not be restored by these treatments. If vision is already lost, low vision aids exist that can help improve the quality of life.
The most popular and established modes of treatment are:
Anti-VEGF therapy: Intravitreal injections
Vascular endothelial growth factor (VEGF) causes new blood vessels to develop and increases leakage and inflammation of blood vessels.The anti – VEGF injections available today,are administred directly into the eye with a very fine needle. These injection procedures should be performed only by an expert ophthalmologist.
These medicines include the following :
Avastin is an anti-VEGF drug that is currently approved for cancer of the colon or rectum, but is widely used in India as it is effective and economical.It is anti-growth factor which reduces macular oedema & new vessels growth.
Lucentis & Macugen are other two approved anti-VEGF medicines for the treatment of wet age-related macular degeneration. They are very costly. It takes one month for drug to be effective.Further injections may be required depending upon OCT scan evaluation.
What is the best defense against blindness from macular degeneration?
The best defense is having:
- Comprehensive eye exams on a regular basis
- Maintaining a one-on-one relationship with a qualified eye specialist
- Healthy diet high in antioxidants, zinc, lutein and zeaxanthin
- Protecting your eyes from UV rays
- No smoking & weight control.
Other retinal diseases
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Dr Rajesh Kapoor
Dr Aniruddha Mahindrakar ( Retinal Consultant )