Retina

Age Related Macular Degeneration

macular degeneration | Eye Clinic & Laser Centre | Navi Mumbai

What is Age-Related Macular Degeneration (ARMD)?

It is a medical condition which usually affects older adults and results in a loss of vision in the centre of the visual field, due to degeneration of receptor cells in the macula (the central area of retina). It is a major cause of blindness and visual impairment in older adults (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities.

Types

Age-related macular degeneration begins with characteristic yellow deposits (related to deposits of cholesterol) in the macula. No medical or surgical treatment is available for this condition. Vitamin supplements with high doses of lutein and zeaxanthin (both antioxidants) have been shown to slow the progression of the condition.

Caused by abnormal blood vessel growth in the eye, it can lead to bleeding, leaking and scarring causing irreversible damage to the photoreceptors and rapid vision loss if left untreated.

It can be treated with laser coagulation, and with medication that stops and sometimes reverses the growth of blood vessels. Only about 10% of patients suffering from macular degeneration have the wet type.

Symptoms of Macular Degeneration

Since the condition is not painful, it may go unnoticed for some time.
Symptoms of macular degeneration include:

  • Those with non-exudative (dry) macular degeneration may be asymptomatic or notice a gradual loss of central vision, whereas those with exudative (wet) macular degeneration often notice a rapid onset of vision loss.
  • Central missing areas of vision, also called scotomas.
  • In certain cases, patients may complain that straight lines appear wavy. This form of distorted vision is called metamorphopsia.
  • Patients may have trouble differentiating between colours and have low contrast sensitivity.
  • Patients may complain about slow recovery of visual function after exposure to bright light.

Causes

Approximately 10% of patients 66 to 74 years of age will have findings of macular degeneration. The prevalence increases to 30% in patients 75 to 85 years of age.

The lifetime risk of developing late-stage macular degeneration is 50% for people that have a relative with macular degeneration, versus 12% for people that do not have relatives with macular degeneration.

High cholesterol, obesity, high fat intake is associated with an increased risk of AMD in both women and men. A diet that derives closer to 20-25% of total food energy from fat is probably healthier.

Evidence is conflicting as to whether exposure to sunlight contributes to the development of macular degeneration. A recent study on 446 subjects found it does not. Other research, however, has shown high-energy visible

Smoking tobacco increases the risk of AMD by two to three times than that of someone who has never smoked, and may be the most important modifiable factor in its prevention. Cigarette smoking is likely to have toxic effects on the retina.

Does macular degeneration lead to total blindness?

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In almost all cases, some vision remains. The area of the macula comprises only about 2.1% of the retina, and the remaining 97.9% (the peripheral field) remains unaffected by the disease. Interestingly, even though the macula provides such a small fraction of the visual field, almost half of the visual cortex is devoted to processing macular information.
 

Diagnosis

There are various tests and investigations to diagnose the condition:

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  • The Amsler grid test is one of the simplest and most effective methods for patients to monitor the health of their maculae. The Amsler grid is, in essence, a pattern of intersecting lines (identical to graph paper) with a black dot in the middle. The central black dot is used for fixation (a place for the eye to focus). With normal vision, all lines surrounding the black dot will look straight and evenly spaced, with no missing or odd-looking areas when fixating on the grid's central black dot. In macular degeneration, the lines can look bent, distorted and/or missing.
  • Fluorescein angiography allows for the identification and localization of abnormal vascular processes.
  • Optical coherence tomography is now used in the diagnosis and the follow-up evaluation of the response to treatment by using either Avastin or Lucentis, which are injected into the vitreous humor of the eye at various intervals.

Treatment

Drugs approved for some variety of macular degeneration include Ranibizumab  and Bevacizumab.

Treatments for wet ARMD:

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  • Certain injectable drugs containing anti-angiogenics or anti-VEGF agents can cause regression of the abnormal blood vessels and improve vision when injected directly into the vitreous humor of the eye. The injections must be repeated monthly or bimonthly. Several anti-angiogenic drugs have been approved for use in the eye by the U.S. Food and Drug Administration and regulatory agencies in other countries.
  • Photodynamic therapy has also been used to treat wet AMD.
  • Some evidence supports a reduction in the risk of AMD with increasing intake of two carotenoids, lutein and zeaxanthin.
  • Consuming omega-3 fatty acids (docosahexaenoic acid and eicosapentaenoic acid) has been correlated with a reduced progression of early AMD, in conjunction with low glycemic index foods.
  • Adaptive devices can help people affected with ARMD use their peripheral vision better and compensate for their lack of central vision. These include magnifying glasses, special eyeglass lenses, computer screen readers, and TV systems that enlarge reading material.
  • Computer screen readers such as JAWS or Thunder that work with standard Windows computers can also help.
  • Video cameras can be fed into standard or special-purpose computer monitors, and the image can be zoomed in and magnified. These systems often include a movable table to move the written material.

Diabetic Retinopathy

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What is diabetic retinopathy?

Diabetic retinopathy is damage to the eye's retina that occurs with long-term diabetes.

Causes

Diabetic retinopathy is caused by damage to blood vessels of the retina. The retina is the layer of tissue at the back of the inner eye. It changes light and images that enter the eye into nerve signals that are sent to the brain. There are two types, or stages of diabetic retinopathy: Non-proliferative type develops first Proliferative is the more advanced and severe form of the disease Having more severe diabetes for a longer period of time increases the chance of getting retinopathy.

Retinopathy is also more likely to occur earlier and be more severe if diabetes has been poorly controlled. Almost everyone who has had diabetes for more than 30 years will show signs of diabetic retinopathy.

Symptoms of Diabetic Retinopathy

Most often, diabetic retinopathy has no symptoms until the damage to your eye is severe. In some cases, there may be certain symptoms like:

Blurred vision and slow vision loss over time Floaters (dark spots floating in front of the eyes) Shadows or missing areas of vision Trouble seeing at night Many people with early diabetic retinopathy have no symptoms before major bleeding occurs in the eye. This is why everyone with diabetes should have regular eye exams.

Diagnosis

The ophthalmologist can diagnose diabetic retinopathy by dilating the pupils with eye drops and then carefully examining the retina. A retinal photography or fluorescein angiography test may also be used.
 

Treatment

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People with the earlier form of diabetic retinopathy may not need treatment. However, they should be closely followed by an eye doctor. Treatment usually does not reverse damage that has already occurred. However, it can help keep the disease from getting worse. Once there are new blood vessels growing in the retina (neovascularization) or there is macular edema, treatment is usually needed. Treatment is done with laser photo-coagulation or in advanced stages with surgery. Injection of Triamcinolone a steroid in the eye is given to reduce macular oedema. Also anti- VEGF factors are given to regress new blood vessels.

Laser eye surgery creates small burns in the retina where there are abnormal blood vessels. This process is called photocoagulation. It is used to keep vessels from leaking or to get rid of abnormal, fragile vessels. Focal laser photocoagulation is used to treat macular edema. Scatter laser treatment or panretinal photocoagulation treats a large area of your retina. Often two or more sessions are needed. A surgical procedure called vitrectomy is used when there is bleeding (hemorrhage) into the eye. It may also be used to repair retinal detachment. Drugs that prevent abnormal blood vessels from growing, and corticosteroids injected into the eyeball are given if considered necessary.

Prevention

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A good control over your blood sugar levels, blood pressure and cholesterol levels go a long way in delaying the eventual onset of diabetic retinopathy. Quitting smoking also helps.
 

Complications If Left Untreated

Untreated diabetic retinopathy can lead to development of:

A dense cloudy area in the eye lens.

Increased pressure in the eye that can lead to blindness

If fluid leaks into the area of the retina that provides sharp vision straight in front of you, your vision becomes more blurry.

Scarring may cause part of the retina to pull away from the back of your eyeball.

Complications | Eye Clinic & Laser Centre | Navi Mumbai

Tips to live with diabetic retinopathy:

  • Keep good control of blood sugar and blood pressure.
  • Treatments can reduce vision loss but do not cure diabetic retinopathy or reverse the changes that have already occurred. Once proliferative retinopathy occurs, there is always a risk for bleeding. You will need to be monitored regularly, and may need more treatment.
  • If you are beginning a new exercise program or are planning to get pregnant, have your eyes examined. Avoid resistance or high-impact exercises, which can strain already weakened blood vessels in the eyes.
  • If you are at low risk, you may need follow-up exams only every 2 - 3 years. The eye exam should include dilation to check for signs of retinal disease (retinopathy).
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