Diabetic Retinopathy

Retinopathy is one of the several eye diseases caused by sub-optimal control of diabetes and other co-existing vascular risk factors. There are a variety of less common, but in some instances more severe, eye disease that can result from diabetes. It is worth knowing that well controlled diabetes rarely ever causes eye disease no matter how long a patient has had it for. Problems with focussing, pre-mature cataracts together with accelerated progression, optic nerve disease, major retinal vascular disease and eye movement disorders are some other problems caused by poor diabetic control. Early detection of retinopathy thanks to the national screening programme, vastly improved diagnostic technology and the use of targeted intra-ocular therapy have bolstered the time-tested efficacy of Argon laser photocoagulation treatment.

Role of Eye Screening Programme

The English National Screening Programme for Diabetic Retinopathy is responsible for overseeing the National Service Framework recommendation that all diabetic patients are screened for diabetic retinopathy. The Diabetes Eye Screening Service (DESS) for Northamptonshire provides screening appointments for all diabetic patients in the county (approx 30,000). Screening appointments are offered once annually with the exception of patients already in care of the hospital. The photographs of the retina taken during the screening examination are graded by 2 qualified graders and should there be a discrepancy, ruled by a further arbitration grader. If there were evidence of referable disease, they are sent to the hospital to see the Consultant. Referral to the hospital does not on its own mean that there is a serious eye problem as there may be instances where the severity of the disease may not be accurately gradable on the basis of a photograph. Sometimes there is not adequate detail on the picture owing to opacities in the media of the eye or simply a technical failure to obtain a good quality photograph.

Investigations

Ocular Coherence Tomograph (OCT)

OCT is a relatively new technology that has changed the landscape of retinal investigation in the recent years. It is a non invasive imaging modality that uses a special light to scan the layers of the retina and finds its use in the management of Glaucoma, AMD, diabetic retinopathy and other macular diseases. The images take only a few minutes to acquire and the latest generation of OCT machines offer unsurpassed 3-D resolution to accurately identify the anatomy at different layers inside the human retina.

Fundus Fluorescein Angiography (FFA)

FFA has been around for a few decades providing valuable information for retinal specialist on the blood circulation of the retina. It involves an injection of a fluorescent dye through a vein in the arm. Within a few seconds the dye enters the general circulation of the body including the retinal circulation. Photographs of the retina are taken using special filters in rapid sequence, so that the blood vessels are observed as they fill up with the dye. Upon evaluating the series of photographs, your consultant is able to identify abnormal vessels as in AMD, leakage from vessels or absence of circulation in conditions such as diabetes or retinal vein occlusion.

From a patient’s perspective, the photographs would be taken for 5-10 minutes following the injection. They are then asked to be seated for a further hour for observation. The cannula that had been inserted into the vein for the purpose of injecting the drug, would then be removed and the patient sent off home.

Fluorescein also colours the skin (often with a lovely tan!) which fades away over a few days. Fluorescein is excreted by the kidneys and patients are asked not to be concerned to see a change in the colour (a bright yellow) of their urine for a few days afterwards as it is one of the ways by which the dye leaves the body. It is quite a safe drug although as with any drug that is being injected into the body it can be allergic to some people. A transient nauseating feeling is common and rarely patients experience a more severe allergic response. Although is possible in theory, a serious anaphylactic reaction resulting in death has not been observed in one large reported series of 100,000 patients who had FFA.

Treatments

Treatment of diabetic retinopathy is quite simply the treatment of the cause of retinopathy. Good control of diabetes, hypertension (raised blood pressure), hyperlipidemia (raised blood fats), anaemia, stopping smoking besides having a sensible diet and healthy lifestyle are essential.

Retinopathy varies in severity from mild to the extreme end of proliferative retinopathy where abnormal blood vessels (that sprout in response to the retina sensing a lack of oxygen) cause bleeding inside the eye or result in Glaucoma. Retinopathy is entirely reversible up the point of proliferative retinopathy. Maculopathy which is retinopathy that involves the central retina (and therefore central vision) is also fully reversible in the early stages. It therefore would be imperative to a address all the risk factors to avoid the need for Argon laser photocoagulation or the need for repeated laser and intravitreal treatments.

It is important to remember that the laser or intravitreal treatments do not treat i.e. reverse the damage caused to blood vessels. At best they play a supportive role in prevention of visual loss rather than a standalone cure for the disease. Just as diabetes is a dynamic disease, where the control can vary, so can the severity of eye involvement. Treatments offered for eyes are therefore not one-off and may have to be repeated should the retinopathy get worse. Sadly the outcomes following repeated treatments are poor, often as a reflection of the underlying state of vasculature rather than the treatments themselves. The eye treatments include:

Argon laser macular photocoagulation
Your Condition

Your diabetic eye disease (maculopathy) has now progressed to a stage that there has been some “water logging” of the central retina due to leakage from weakened blood vessels. This has either caused or has the ability to cause, a reduction in central vision and your near vision (eyesight for reading).

The Procedure

Laser is a focussed beam of light energy of a specified wavelength. It is applied as spots on the back of your eye (the retina). After dilating the pupil, the surface of your eye will be made numb with local anaesthetic drops after which a contact lens will be applied. You will not have to worry about keeping your eyes open but it would help if you co-operate by looking in the direction that your consultant asks you to. You will be seeing bright flashes of light in quick succession as the laser is applied. The procedure will be completed in about 10 minutes time.

These bright flashes of light (together with the fact that your pupils have been made large) will leave you dazzled for a while. We recommend that you go home straight away and have a good rest. Should you experience any headache afterwards you can take a couple of Paracetamol tablets (2 X 500mg) or other painkillers that you are used to taking.

Laser treatment for Maculopathy is a painless procedure. It is important that you remain still during the procedure. Movement can be dangerous as it may direct the laser to a wrong part of the eye. Should you wish to draw attention, please knock on the table and your consultant will stop immediately.

Alternative treatment options

Intravitreal therapy involving injections into the eye can be given in certain situations.

What happens if you don’t have this treatment?

There is an increased risk of severe and permanent loss of vision especially for reading (central vision).

The Benefit

Laser treatment is done, because without treatment, there is a much higher risk of you losing your eyesight in the long run. It may not improve your eyesight. The serious or frequently occurring risks:

  • Laser treatment may cause deterioration in central vision, which is usually transient but rarely can be permanent.
  • Laser treatment is not a “one-off” procedure. Re-treatments may be needed in future.
Argon Laser Scatter Photocoagulation
Your Condition

Your diabetic eye disease (retinopathy) has now progressed to a stage that the retina has sensed a lack of oxygen and started to develop new blood vessels on its surface. This unfortunately is not good news, as these new vessels serve no useful purpose. Being fragile, they rupture and bleed inside the eye. This will cause a sudden loss of vision.

Should the new vessels grow on the surface of the iris (the coloured part of the eye) they can block the drainage of fluid out of the eye and can cause the pressure inside to build up to high levels fairly quickly. This is very painful and can also cause irreparable loss of vision. Laser treatment is done to cause regression of these vessels. The treatment is performed over 1 to 3 sittings.

The Procedure

Laser is a focussed beam of light energy of a specified wavelength. It is applied as spots on the back part of your eye (the retina). After dilating your pupil, the surface of your eye will be made numb with local anaesthetic drops after which a contact lens will be applied. You will not have to worry about keeping your eyes open but it would help if you co-operate by looking in the direction that your doctor asks you to. You will be seeing bright flashes of light in quick succession as the laser is applied. These spots can number up to a thousand in each sitting and will be completed in approximately 15 minutes time. These flashes of light (together with the fact that your pupils have been made big) will leave you dazzled for a few hours. We recommend that you go home straight away and have a good rest. Should you experience any headache afterwards, you can take a couple of Paracetamol tablets (2 X 500mg) or other painkillers that you are used to taking.

Laser treatment for retinopathy is not a painless procedure. You will ‘feel’ the laser each time that it is applied. However, the sensation of a ‘thump’ at the back of your eye which most people experience is not intolerable. Re-treatments can be more painful at times. It is important that you remain still during the procedure, as movement can be dangerous as it may direct the laser to a wrong part of the eye. Should you wish to draw attention, please knock on the table and the doctor will stop immediately.

Alternative Treatment Options

Intravitreal therapy (injection of special drugs into the eye) could help shrink these vessels in certain situations.

What happens if you don’t have this treatment?

The new blood vessels will continue to grow and cause severe and persistent bleeding, scarring and retinal detachment together with irreversible loss of vision.

The Benefit

The treatment should help regress the new vessels and reduce the risk of bleeding in future. It is not done to improve your eyesight.

The serious or frequently occurring risks
  • Laser treatment can cause deterioration in central vision, which is usually transient.
  • This treatment reduces your visual field (side vision/peripheral vision). This can affect your fitness to drive. You are obliged to inform the DVLA, especially if you have this treatment in both eyes.
  • It can impair your night vision and you may take longer to adapt in darkness. Again this has implications on your driving at night. You are expected to use your judgement in these circumstances.
Intravitreal therapy (Lucentis, Eylea, Ozurdex or Iluvien)
Background

Intravitreal injections like Lucentis (Ranibizumab) or Eylea (Aflibercept) are used offering short term benefits while intravitreal implants like Ozurdex (Dexamethasone) or Iluvien (Flucinalone) are slow release implants. Treatment with intravitreal injections involves a series of injections of the drug into the eye using a very fine needle. The injections often start off at monthly intervals for the first few months and tailored to response following that period.  Implants can deliver the drug from inside the eye for periods ranging from 6 months to three years. The treatment procedure is the same for both and careful patient selection and informed choice determine the suitability of a patient to particular treatment type.

The Procedure

The procedure is done under strict aseptic conditions. The surface of the eye is made quite numb with local anaesthetic drops. The skin around the eye is then cleaned with antiseptic and drapes are applied. A speculum (a thin metal clip) is used to keep the eyelids apart. Further antibiotic/antiseptic solutions are applied on the eye surface. A very fine needle is used to inject the drug into the eyeball. This is followed by a retinal examination after which antibiotics are instilled and a sterile dressing applied.

Alternative Treatment Options

Argon laser photocoagulation is an option in appropriate circumstances.

What happens if you don’t have this treatment?

The disease is likely to worsen, often leading to an irreversible loss of vision.

The Benefit

The treatment is likely to improve the retinal disease and result in a better chance of retaining good or better vision.

The serious or frequently occurring risks
  • Infection, bleeding or severe inflammation inside the eye leading to visual loss.
  • Increased eye pressure.
  • Closure of the blood circulation of the nerve of sight.
  • Retinal detachment.
  • Cataract formation.

The ETDRS (Early Treatment Diabetic Retinopathy Study) was a landmark clinical trial which enrolled 3711 participants and reported its findings in the eighties, provided robust evidence in support of treatment with Argon laser photocoagulation. After nearly two decades, thanks to our improved understanding of the molecular mechanisms that influence vascular permeability and growth, we are able to improve on our results by expanding the tool-kit to include anti-VEGF (Lucentis) treatment which is a newly licensed drug for the treatment of diabetic maculopathy. READ-2, RISE & RIDE, RESOLVE and RESTORE clinical trials, all of which have been published very recently have found evidence to confirm the efficacy of this new treatment modality.

Mr Ashwin’s choice for Argon laser is the Pascal photocoagulator (TOPCON Medical Laser Systems, California, USA) being the most advanced pattern laser delivery system that offers unparalleled accuracy in laser delivery and found to be the best tolerated amongst patients.

External Resources

English National Screening Programme – Diabetic Retinopathy (ENSPDR)

The website of the ENSPDR has filterable content made specifically available for patients and public outlining their role and providing an insight into how the screening programme works. Their document “Diabetic retinopathy-the facts” is a useful read.
http://www.retinalscreening.nhs.uk/pages

National Eye Institute (NEI)

NEI is a part of National Institutes for Health which is a US governmental organisation funded to promote high quality research into sight-saving treatment. They have a very high profile amongst the ophthalmic community owing to the landmark clinical trials that they have set-up and funded.

https://ww.nei.nih.gov/health/diabetic/retinopathy

NHS Choices

A comprehensive website offering a detailed overview on this condition.
http://www.nhs.uk/conditions/diabetic-retinopathy…

Royal National Institute of Blind People (RNIB)

RNIB is a leading UK charity founded in 1824 and their website is the largest source of information available on the internet on blindness and partial sightedness. They also run a useful helpline.
http://www.rnib.org.uk/eyehealth/eyeconditions/eyeconditionsdn…

Drivers and Vehicle Licensing Authority (DVLA)

This webpage of the DVLA details information for patients who have diabetes and other medical conditions that may impact on their ability to drive safely.
http://www.dft.gov.uk/dvla/medical.aspx