Retina, AMD & Diabetes

  • Macular Degeneration

    Age-related macular degeneration (AMD) is an eye condition that affects a tiny part of the retina called the macula, which is located at the back of your eye. AMD causes problems with your central vision, but does not lead to total loss of sight and is not painful.

    AMD affects the vision you use when you are looking directly at something, for example when you are reading, looking at photos or watching television. AMD may make this central vision distorted or blurry and, over a period of time, it may cause a blank patch in the centre of your vision.

    You should have your eyes tested if:

    • you notice any difficulty with reading small print with your reading glasses,
    • straight lines start to look wavy or distorted
    • your vision isn’t as clear as it used to be

    Types of AMD

    There are two main types of AMD – “wet” AMD and “dry” AMD. They are called “wet” and “dry” because of what happens inside your eye and what the ophthalmologist sees when examining the inside of your eye, not because of how your eye feels or whether you have a watery or dry eye.

    Dry AMD

    Dry AMD is the more common type of AMD. It usually develops very slowly and causes a gradual change in your central vision. Dry AMD usually takes a long time, maybe a number of years to get to its final stage. At its worst, dry AMD causes a blank patch in the centre of your vision in both of your eyes. But it doesn’t affect your peripheral vision, so never leads to total blindness.

    Wet AMD

    About 10 –15 per cent of people who develop AMD have wet AMD. You develop wet AMD when the cells of the macula stop working correctly and the body starts growing new blood vessels to fix the problem.

    Unfortunately these blood vessels grow in the wrong place and cause swelling and bleeding underneath the macula.

    Wet AMD can develop very quickly, making serious changes to your central vision in a short period of time. Treatment is now available for wet AMD, which stops the new blood vessels from growing and damaging your macula. This treatment usually needs to be given quickly before the new blood vessels do too much damage to your macula. If the blood vessels are left to grow, the scarring and the sight loss it causes are usually permanent. Wet AMD doesn’t affect your peripheral vision, so it does not lead to total blindness.

    Some people diagnosed with dry AMD find that, with time, new blood vessels grow and they develop wet AMD. If you have dry AMD and your sight suddenly changes you should always have this checked by your ophthalmologist.

    Amsler Grid

    The Amsler Grid is a screening test for macular degeneration.

    1. Wear your glasses or contact lenses as usual.
    2. View the screen so that the grid is at eye level.
    3. Cover one eye and focus on the centre dot with the uncovered eye.

    If the grid lines are wavy, broken or distorted or there are blurred or missing patches, this MAY be a symptom of macular degeneration.

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    Amsler Grid

    How is AMD Diagnosed?

    Early signs of macular degeneration are usually detected during a routine retinal exam. If AMD is suspected, a graph called the Amsler grid is used to evaluate central vision and confirm vision loss. Depending on the findings Further diagnostic tests will be performed to determine the type of AMD and develop an effective treatment plan:

    Optical coherence tomography (OCT)
    OCT is advanced imaging technology that delivers cross sectional images of the retina at a much higher resolution

    Fluorescein angiography exam
    Fluorescein angiography involves injecting fluorescent dye into a vein in the arm, after which the dye travels to the blood vessels in the eye and illuminates the retina, thereby allowing high-quality images of the macula.

    Treatment

    Treating dry AMD

    Treatment of dry AMD involves prevention of progression of disease. Although research is going on to try and find out why the cells of the macula stop working, this has not yet led to a treatment.

    Preventing progression of AMD

    • Do not smoke – studies have shown that AMD is more severe and progresses more rapidly in smokers.
    • Eat deep sea fish rich in omega 3 regularly (up to 3 times per week).
    • Have a diet that is rich in green leafy vegetables that contain lutein (such as spinach, curly kale and broccoli). Other healthy fruit and vegetables include ones with Vitamin C and zeaxanthin such as corn, papaya and capsicum.
    • Anti-oxidants such as those found in blueberries, red kidney beans and green tea are thought to be beneficial.
    • Limit saturated fats.
    • There is some evidence that taking a dietary supplement may slow the progression of the disease

    Treatments for wet AMD – Anti-VEGF treatment

    A number of treatments are available for wet AMD. These mainly work by stopping the growth of new blood vessels. This means that treatments usually need to be given fairly quickly once the blood vessels start to grow in your eye. If the blood vessels are allowed to grow for too long they may scar the retina and this scarring cannot be treated.

    The most recent treatment available for wet AMD is with an anti-vascular endothelial growth factor (anti-VEGF) drug. As new blood vessels form in your eye, your body produces a chemical that stimulates further new blood vessel growth. Anti-VEGF drugs interfere with these chemicals and stop the vessels from growing. By stopping blood vessels growing and leaking, further damage to your sight is prevented.

    The medicine has to be injected into the vitreous, the gel-like substance inside your eye. This is called an intravitreal injection.

    For more information on intravitreal injections, please click here.

    1. Macular Degeneration
  • Diabetes

    Diabetic retinopathy is a common complication of diabetes. It occurs when high blood sugar levels damage the cells at the back of the eye (known as the retina). If it isn't treated, it can cause blindness.

    It's important for people with diabetes to control their blood sugar levels. Everyone with diabetes who is 12 years old or over should have their eyes examined once a year for signs of damage (see below).

    All people with diabetes are at risk of getting diabetic retinopathy, but good control of blood sugar levels, cholesterol and blood pressure minimises this risk.

    How diabetes can damage the retina

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    Diabetic retinopathy

    Hover over diagram to see real view

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    Diabetic retinopathy

    Hover over diagram to see real view

    The retina is the light-sensitive layer of cells at the back of the eye. It converts light into electrical signals.

    The signals are sent to the brain through the optic nerve and the brain interprets them to produce the images that you see.

    To work effectively, the retina needs a constant supply of blood, which it receives through a network of tiny blood vessels.

    Over time, a continuously high blood sugar level can cause the blood vessels to narrow, bleed or leak. This damages the retina and stops it from working.

    When the blood vessels in the central area of the retina (the macula) are affected, it's known as diabetic maculopathy.

    Symptoms of diabetic retinopathy

    During the initial stages, retinopathy does not cause any noticeable symptoms. You may not realise that your retina is damaged until the later stages, when your vision becomes affected. Vision loss will probably be permanent at this late stage, which is why diabetic eye screening is so important.

    Screening for diabetic retinopathy

    As severe retinopathy can cause sudden blindness, it needs to be identified and treated as soon as possible.

    This is done by identifying retinopathy at an early stage and ensuring that treatment is given to reduce or prevent sight damage. Everyone with diabetes who is 12 years old or over should be screened once a year.

    The screening test involves examining the back of the eyes and taking photographs of the retina. Screening can detect diabetic retinopathy before you notice any changes to your vision.

    Preventing diabetic retinopathy

    To reduce your risk of developing retinopathy, it's important to control your blood sugar level, blood pressure and cholesterol level. Good control will prevent diabetic complications in almost everyone.

    Other steps that you can take to help prevent retinopathy include:

    • attending your annual screening appointment
    • informing your GP/Optometrist if you notice any changes to your vision (do not wait until your next screening appointment)
    • taking your medication as prescribed
    • losing weight (if you're overweight) and eating
      healthy, balanced diet
    • exercising regularly
    • giving up smoking
    • controlling your blood pressure and cholesterol levels

    Treating diabetic retinopathy

    Early-stage retinopathy may not need treatment, but more advanced retinopathy may require laser treatment or injections of medicine into the eye.

    Immediate treatment may not be necessary if you have:

    • stage one (background) retinopathy
    • stage two (pre-proliferative) retinopathy
    • maculopathy with no symptoms

    However, you should still attend your annual screening check to monitor the progress of your retinopathy.

    If maculopathy is detected, you may need more frequent specialised testing (called optical coherence tomography). Additional tests may include a fluorescein angiography, which uses a camera and dye to examine blood flow in the back of the eye.

    When treatment is necessary

    • Laser treatment is offered for proliferative (stage three or four) diabetic retinopathy and some cases of maculopathy.
    • Intravitreal injections may be recommended if you have maculopathy.
    • Vitreoretinal surgery may be needed if laser treatment is not possible because retinopathy is too advanced.

    2. Diabetes
  • Vein Occlusion (RVO)

    If the flow of blood in the veins stops or slows for any reason, spots of blood and protein may leak out of the vein and into the retina and this can affect vision. The symptoms are variable and range from mild to severe visual loss depending on the size and site of the blocked vein. Leakage of fluid from the blocked vein causes swelling of the surrounding retina thus blurring the vision. Sometimes the flow of blood stops completely and then parts of the retina die so that vision is severely affected.

    Loss of vision may happen suddenly or gradually. Sometimes the problem is not noted until the good eye is covered for some reason or until a doctor or looks into the eye.

    Sometimes it is the main (central) vein that is affected, sometimes only one of its branches.

    Retinal Vein Occlusion
    Retinal Vein Occlusion

    What causes RVOs?

    Anything that makes the blood too thick or sticky are factors that can cause an occlusion in the retinal vein. These include:

    • smoking cigarettes
    • Pressure on the vein from a hardened retinal artery due to high blood pressure
    • High pressure in the eye
    • High cholesterol or lipids
    • Diabetes
    • Inflammation in the eye

    What treatment is available?

    It is very important to prevent another episode of vein blockage in either eye so your blood pressure will be measured and you will be asked to have blood tests to identify any cause of the vein occlusion.

    If new blood vessels are growing on the iris or retina then laser treatment is necessary to try and help shrink these vessels.

    If there is swelling of the central retina (macula) then laser treatment to this area may reduce the swelling.

    Trials of newer treatments such as injections of steroids or other drugs are being tried to see if they improve the longer-term outcomes in vein occlusions.

    3. Vein Occlusion
  • Flashes and Floaters

    The back of the eye is full of a gel known as vitreous. With time this gel breaks down and becomes liquefied. This is a normal process and can occur at anytime. As the vitreous liquefies it breaks away from the retina. This is known as a Posterior Vitreous Detachment (PVD).

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    How are PVDs treated?

    Patients usually present with a sudden onset of floaters in front of their vision. A floater moves with the patient and occasionally disappears from view. A PVD is a normal event that occurs with age and does not need to be treated.

    Patients become accustomed to the floater and often the brain ‘adapts’ so it is rarely seen. Rarely a floater can become very bothersome.

    What are the complications of a PVD?

    In a small percentage of patients with PVDs as the vitreous pulls away from the retina a small tear is formed. If a retinal tear occurs patients will usually notice and increase in floaters, flashing lights to the side or a curtain over their visual field.

    A small retinal tear is treated with laser in the rooms to seal the break. Topical anaesthetic is instilled into the eye and a contact lens inserted to visualise the break. Laser is then applied. Patients tolerate this very well. Follow up is required to check the tear is sealed.

    Occasionally a retinal tear results in a retinal detachment if fluid tracks beneath the retina at the point of the break. This is more common in myopic or short sighted people. This requires surgery to repair. This has a very high success rate with modern techniques.

    4. Flashes and Floaters
  • Central Serous Chorioretinopathy (CSCR or CSR)

    Central Serous Chorioretinopathy (CSCR or CSR) is a common condition that affects young people between the ages of 20-50. It is more common in males.

    Fluid accumulates underneath the retina and if this occurs at the central macular it results in blurred vision.

    Patients usually present with central distortion or blurred vision in one eye. Colours may appear washed out and there can be a central scotoma. Symptoms are usually unilateral. Metamorphopsia and image size distortion are common. There is a 5% prevalence in Cushing's syndrome.

    Central Serous Chorioretinopathy
    Central Serous Chorioretinopathy

    What causes CSCR?

    In most cases, a cause is never identified. However, stress and use of steroid medications are thought to be associated in certain cases.

    How is CSCR treated?

    In most cases CSCR resolves spontaneously and no treatment is required. Over 90% of patients return to normal or near normal vision within 3-4 months. Occasionally patients continue to have reduced colour vision, night vision or distortion.

    Some patients with non-resolving CSCR require laser treatment after 4-6 months. Photodynamic therapy is also emerging as a possible treatment option in certain patients.

    Other newer treatments that can be considered for some patients include oral medications that block mineralocorticoid receptors such as spironolactone or eplerenone.

    5. CSR