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Description

Diabetes-related sight loss describes a number of eye conditions which are caused by diabetes. These include diabetic retinopathy, glaucoma and cataracts. Diabetes-related eye conditions can lead to loss of sight and potentially blindness and are most common form of blindness in people of working age in Ireland. When these conditions are caught early, treatment may be effective at reducing or preventing damage to sight.

Diabetic Retinopathy is a condition which is characterised by damage to the blood vessels of the retina within the eye. It is a common complication of diabetes and is the leading cause of sight loss in people under the age of 65, though this has been changed in England and Wales by their diabetic retinopathy screening service. Diabetic retinopathy can be categorised into stages, dependent on the extent of damage to the retina. It may not have any symptoms or affect sight in the early stages but as the condition progresses- sight will become affected and may be lost, if left untreated.

The earliest stage of Diabetic Retinopathy is known as Background Retinopathy and presents with small bulges in the walls of blood vessels in the retina (i.e. microaneurysms), which may leak blood and fluid. At this stage, vision is rarely affected. This may then progress to pre-proliferative diabetic retinopathy, where changes in the retina occur but do not require treatment. Instead they are closely monitored. If the condition progresses, it can lead to the development of proliferative diabetic retinopathy, where abnormal, leaky blood vessels grow along the retina and along the surface of the clear (vitreous) gel that fills the inside of the eye. By themselves, these blood vessels do not cause symptoms or vision loss. However, they have thin, fragile walls. If they leak blood, severe vision loss and even blindness can result. In a small proportion of cases, diabetic macular oedema (DMO) may occur. This is where blood vessels leak their contents into the macular region of the retina, the part of the eye where sharp, central vision occurs. The fluid makes the macula swell, blurring vision. This can occur at any stage of diabetic retinopathy, although it is more likely to occur as the disease progresses. It may present as a more rapid form of vision loss.

Another complication of Diabetes is Glaucoma, a condition characterised by damage to the optic nerve, the medium for communication between the retina and the brain. Diabetes, if not managed appropriately can also affect the lens contained within the eye. Irregular blood sugar levels can cause premature cataract development.

Symptoms

The symptoms of Diabetes-related Sight Loss can vary, depending on the nature and extent of the condition.

In cases of Diabetic Retinopathy, there are often no or very few symptoms in the early stages of the disease (Background Diabetic Retinopathy), nor is there any pain. In more advanced stages of the condition where the abnormal, fragile blood vessels start to leak, vision loss can occur and it may occur suddenly. This leakage of blood and fluid within the eye may appear like “blobs” floating in your eye. The amount of vision loss will depend on the extent of damage. In some cases, the blood and fluid lost from these blood vessels may be reabsorbed (removed) and vision may improve. If more significant damage occurs, this may lead to scarring which can harm the retina and cause a more significant loss of sight.

If Diabetic Retinopathy affects the macula, this portion of the retina which is important for sharp, central vision may be affected. The macula will also be affected in cases of Diabetic Macular Oedema, where fluid abnormally collects in the macula, interfering with its normal function. Damage to the macula may lead to difficulties in reading, recognising colours or faces. However, peripheral vision is not typically affected in such cases.

Some cases of Diabetes, where blood sugar levels are highly variable, can lead to a clouding of the lens which can cause blurred vision. More significantly, if this persists over time, this clouding of the lens can lead to the development of cataracts.

If glaucoma presents as a result of diabetes, there may be very few symptoms. This makes regular eye tests very important. In some cases, blurred vision, the appearance of halos, watering eyes or eye pain may signal glaucoma.

Causes

Diabetes is characterised by either the body’s failure to have appropriate levels of functioning insulin to cope with the sugar and carbohydrates which are taken in our diet (type 1 diabetes) or resistance of the tissues to insulin in the blood (type 2 diabetes). This leads to higher than desired levels of sugar circulating within the bloodstream which causes progressive damage to blood vessels throughout the body, the smallest of which are in the eyes and kidneys.

A network of blood vessels nourishes and supports the retina’s normal function in the eye. Diabetes can affect this important network, most likely through high glucose levels. In the early stages of this condition, small bulges can appear in the walls of the blood vessels in the retina (i.e. microaneurysms). These bulges can leak blood and fluid, but do not normally cause problems to vision. Over a period of time, the blood vessels which support the macula can become damaged, potentially leading to loss of vision. This damage can worsen, leading to blockages within the blood vessels. To try and make-up for this damage, new blood vessels start to grow in this area, however they are often fragile and leak blood and fluid. The leakage of these contents into the eye can contribute to vision loss. More significantly, such damage can result in scarring. Scar tissue can affect the position of the retina within the eye and can cause it to detach if the scarring is significant.

There are a number of risk factors which can increase the risks of developing Diabetic Retinopathy. These include having poor blood glucose/sugar control, having high blood pressure or raised fat levels (triglycerides) in the blood, pregnancy (where Diabetes can worsen Diabetic Retinopathy), smoking and long duration of diabetes.

Diagnosis

Diabetes-related Sight Loss is diagnosed using a number of tests which are important for providing the correct diagnosis.

The eye doctor will ask about a person’s medical history, including any family history of eye conditions. Individuals will receive a clinical eye examination where they may be asked to read letters off a chart (Snellen chart). They may also check intraocular pressure and examine visual field and visual acuity.

The eye doctor will also dilate the pupil (make it wider) to allow them to see inside the eye. They will take a close look at the retina and the optic nerve (the main communication pathway between the eye and the brain).

An individual may receive a number of imaging tests. Information about the condition may be identified using colour or wide-field fundus photography (which essentially takes photos of the back of the eye). Fundus autofluorescence may be used to identify stress or damage to the retinal pigment epithelium. Optical coherence tomography (OCT) can also be used to assess the various layers at the back of the eye. An individual may also have an electroretinogram (known as an ERG), which is used to evaluate the functioning of the different types of photoreceptor cells (rods and cones).

Fluorescein angiograms are particularly useful in the diagnosis of diabetic retinopathy. This test examines the blood vessels at the back of the eye to check for any abnormalities.

Through regular and effective retina screening, diabetic retinopathy can be caught early and effectively treated. The national diabetic retina screening programme for diabetic retinopathy (Diabetic RetinaScreen) has been rolled out nationwide for everyone over the age of 12 who is affected by Diabetes in Ireland. If you have diabetes it is extremely important to register your interest in taking part in the eye screening. More information is available on the diabetic retina screen website  or by calling 1890 45 45 55. People with diabetes can greatly reduce the possibilities of eye complications by going to their routine examinations with an eye doctor and taking part in this national screening programme. Many problems can be treated with much greater success when caught early.

Treatment

Prevention of diabetic retinopathy is the most important step to take for anyone with diabetes. Researchers have found that individuals diagnosed with diabetes that are able to maintain appropriate blood sugar and blood pressure levels have fewer eye problems than those with poor control. Diet and exercise play important roles in the overall health of people with diabetes.

Diabetic retinopathy is treated in many ways depending on the stage of the disease and the specific problem that requires attention. The doctor relies on several tests to monitor the progression of the disease and to make decisions for the appropriate treatment.

In cases of background retinopathy and pre-proliferative retinopathy, treatment may not be necessary, but will require regular eye assessments to monitor the condition over time. In cases of proliferative diabetic retinopathy and diabetic macular oedema, treatment will be recommended.

Laser eye treatment called pan retinal photocoagulation (PRP) is one treatment choice used to prevent the blood vessels from leaking, or to get rid of the growth of abnormal, fragile vessels. This treatment option may provide benefit for cases of proliferative diabetic retinopathy and diabetic macular oedema. The treatment may be delivered over a number of visits to an outpatient clinic or sometimes in the operating theatre under sedation/anaesthetic. While laser treatment is not normally painful, some individuals may have difficulty tolerating a full treatment under local anaesthetic. Some painkillers can be given by doctors to ease any pain experienced. This treatment may initially result in blurred vision for a few hours afterwards, however, vision should return to normal.

A class of drugs known as anti-VEGF (anti-vascular endothelial growth factor) can be used to treat cases of diabetic macular oedema. Anti-VEGF drugs target the substance in the body which is responsible for the development of blood vessels. In diabetic macular oedema, too much VEGF is produced in the eye, and these drugs block the production of these new, abnormal vessels. In some instances, anti-VEGF treatments, delivered by injection into the vitreous within the eye and Anti-VEGF drugs may be used in conjunction with laser treatment to treat diabetic macular oedema.

Vitrectomy is another surgery commonly needed for diabetic patients who suffer a vitreous haemorrhage (bleeding in the gel-like substance (vitreous) that fills the centre of the eye). During a vitrectomy, the retina surgeon carefully removes blood, fibrous tissue and vitreous from the eye, relieving traction on the retina and preventing retinal detachment. If retinal detachments or tears occur, they are often sealed with laser surgery. Retinal detachment requires surgical treatment to reattach the retina to the back of the eye. The prognosis for visual recovery is dependent on the severity of the detachment.

If glaucoma develops as a result of diabetes, the ophthalmologist will select the appropriate treatment option depending on the presentation of the condition. For more information on treatments for glaucoma, please visit the Glaucoma treatment section. In cases where cataracts may develop, these can be removed and replaced with an artificial lens. More information can be found in the Cataract treatment section.

No matter what level of vision a person may have, it is important to look after the eyes. To find out more about what can be done to take care of the eyes on a daily basis, please visit our Tips for Good Eye Health.

Research

There are many approaches being pursued to learn more about the development and progression of diabetes-related sight loss and to identify improvements in diagnostics and treatments. Across the world, clinical trials are actively testing new options and evaluating new practices to improve the way by which diabetes-related sight loss is detected and treated. Some examples of these studies are included below.

Researchers are aware of the importance of early detection of the complications of diabetes to limit significant damage to the eye and loss of sight. As such, research teams are actively seeking improvements in the ways by which diabetes-related sight loss is identified and when it is detected. One such clinical trial is aiming to develop and test a new predictive technology that could improve the way in which Diabetic Retinopathy is identified. Researchers aim to analyse details about the individual’s background, medical history and laboratory test results to develop an improved means of identifying and managing the condition. Another study also seeks to test artificial intelligence to detect diabetic retinopathy. Research also underway seeks to find new molecules circulating in the bloodstream which could highlight the prognosis of people living with diabetic retinopathy; namely identifying those people for whom the condition may be mild, moderate or more severe over time.

Researchers are also seeking to better understand the mechanisms by which diabetes-related sight loss progresses. One clinical trial aims to find out more about diabetic retinopathy progression through studying the internal structures of the eye’s blood vessels using an imaging technique known as optical coherence tomography angiography (OCTA) to assess changes in the condition over time.

In terms of treatment, research teams continue to evaluate treatments already available to patients in order to improve the means of treatment but also to improve treatment outcomes. For example, one study aims to investigate whether laser treatment or peripheral retinal ischemia combined with an anti-VEGF treatment could reduce the number of anti-VEGF injections needed to control diabetic macular oedema as compared with anti-VEGF treatment alone over a 24 month period. Another trial is investigating whether an anti-VEGF treatment administration and monitoring for diabetic macular oedema is better guided with the use of optical coherence tomography or visual acuity over time. In terms of people living with diabetes who are also diagnosed with cataracts, researchers are investigating whether the timing of when anti-VEGF injections are delivered can affect the visual acuity of people.

New therapeutic approaches are also being investigated for Diabetes-related Sight Loss. These include antioxidant therapy for diabetic retinopathy, based on the suggestion that oxidative damage may be a key factor in the development of this condition. Researchers are also investigating new treatment combinations such as curcumin (extract from turmeric (ginger)) and dexamethasone (a type of steroid used to dampen down the body’s defence mechanisms) to treat diabetic macular oedema.

Information about clinical trials can be found on the clinical trials website and can be searched by condition and trial location. For further information, please contact the research department on 01 6789004 or e-mail research@fightingblindness.ie.

Support

Receiving a diagnosis can be overwhelming for anyone, but this is not a journey that you have to make alone. There are many groups and resources available to provide support for people living with Diabetes-Related sight loss.

Fighting Blindness offers a free and confidential counselling service (Insight Counselling). For further information please contact insight@fightingblindness.ie or call 01 6746496.

A mindfulness group is also available on every Wednesday at the Fighting Blindness office at 11am.

For technology support and guidance, the Dublin-based Technology Exchange Club meets every Monday at the Fighting Blindness office at 11am. Another Technology Exchange Club, based in Cork, meet every Saturday in the Cork City Library, Grand Parade, Cork City at 11am. The Cork-based club do not meet on Bank Holiday weekends or on the second Saturday of the month. For further information please contact insight@fightingblindness.ie or call 01 6746496.

Resources

Féach provides support for parents of children living with sight loss in Ireland.

ChildVision is the national education centre for children with sight loss in Ireland.

NCBI (National Council for the Blind in Ireland) provides support and services for people living with sight loss in Ireland.

Irish Guide Dogs for the blind helps individuals and their families to achieve improved mobility and independence.

 

Diabetic RetinaScreen – The National Diabetic Retinal Screening Programme.

Diabetes Ireland provides support, education and motivation to people diagnosed with Diabetes.