THE EYE AND DIABETES
National Eye Institute, National Institutes of Health
Our eyes provide sight which is probably the most important of our 5 senses and so it is understandable that we are all a little nervous that when we have our eyes examined – the underlying fear of ‘bad news’.
It is important that everyone has regular, full eye examinations but especially so for people with diabetes. Early detection and diagnosis of many eye conditions means that treatment can start early in order to preserve sight. In the UK everyone with diabetes is entitled to a free eye test.
A review of retinopathy by the University of York NHS Centre for Reviews and Dissemination published in Effective Health Care, August 1999, provides the following information:
- Diabetic retinopathy is the leading cause of blindness in people of working age in industrialised countries. It is estimated that 12% of people who are registered blind or partially sighted in the UK have diabetic eye disease.
- Twenty years after diagnosis almost all those with Type 1 diabetes and 60% of those with Type 2 diabetes will have some degree of retinopathy.
- British screening studies suggest that around 5-10% have sight-threatening retinopathy and up to 40% of people with newly diagnosed Type 2 diabetes have some retinopathy.
ANATOMY OF THE EYE
Before considering diabetic eye disease we need to understand a little of how the anatomy of the eye and how the eye works.
- IRIS – this regulates the amount of light that enters the eye. It is the coloured part of the eye across the front of the lens. Light enters through a central opening called the pupil.
- PUPIL – is the circular opening in the centre of the iris through which light passes. The iris controls dilation and constriction of the pupil.
- CORNEA – is the clear circular part of the front of the eyeball. It refracts the light entering the eye on to the lens, which then focuses it on to the retina. The cornea is extremely sensitive to pain.
- LENS – is a transparent crystalline structure behind the pupil of the eye. It helps to refract incoming light and focus it on to the retina. A cataract is when the lens becomes cloudy, and then the lens can be removed and replaced with a plastic intra-ocular lens.
- VITREOUS – is a clear jelly-like material in the middle of the eye.
- RETINA – is a light sensitive layer that lines the interior of the eye. It is made up of light sensitive cells known as rods and cones. The rods are necessary for seeing in dim light. And the cones best in bright light and are essential for receiving a sharp accurate image. Cones can also distinguish colours. The retina works much in the same way as film in a camera.
- MACULA – Is the yellow spot on the retina at the back of the eye and is the area with the greatest concentration of cone cells. It is the area of greatest acuity of vision such as reading.
- OPTIC DISK – is the visible portion of the optic nerve on the retina. The optic disk is the start of the optic nerve where messages from cone and rod cells leave the eye and pass along nerve fibres and so transfer all the visual information to the brain. The optic disk is also known as the ‘blind spot’.
How We See
For sight to take place light must be able to pass to the retina at the back of the eye. The light passes through cornea and enters the eye through the pupil. It then passes through the lens and the vitreous to be focussed on the retina. The focussed light or images of what we have been looking at, are then passed down the optic nerve to the brain.
- If diagnosed early enough diabetic retinopathy is a treatable condition.
- The only treatment for diabetic retinopathy is laser treatment.
- Over the past 30 years laser treatment has been shown to be helpful in either stopping the progress of the condition or in maintaining sight.
- In the UK sight tests for checking for diabetic retinopathy are free.
- There are two vulnerable groups of people susceptible to retinopathy – firstly, pregnant women and secondly, children and adolescents. In the long term children and adolescents are at greater risk of microvascular and macrovascular complications of diabetes. It is recommended [ref1] that surveillance for the earliest evidence of microvascular disease [this includes retinopathy] should begin at puberty and after 3 and 5 years of diabetes.
Ref 1 Endocrin Metab Clin North Am 1999 Dec;28: 865-8
WHAT IS DIABETIC RETINOPATHY?
Retinopathy is usually classified according to its severity. This may not be the same in both eyes. There are two classifications of diabetic retinopathy:
This is the first stage of the development of retinopathy and it is rare before 8 to 10 years of diabetes duration. At this stage the vision is normal and sight is not threatened. If there are diabetic changes present such as small haemorrhages, fatty deposits [exudates] or abnormal blood vessels [microaneurysms] then this is a sign that the retinopathy is worsening and the doctor will be alerted to arrange more frequent follow ups.
This is where the blood vessels [capillaries] block and starve the retina of nutrients causing new vessels to grow. These new vessels grow either in front of the retina on to the back of the vitreous or occasionally on to the iris. These new vessels are fragile and may bleed into the vitreous. This then affects the sight and may cause floaters, dots or lines and if severe may cause clouding of the vision or loss of vision.
If the vessels grow on the iris, they can cause a rise in pressure in the eye and severe, painful glaucoma. The new vessels eventually cause scar tissue and this can lead to a retinal detachment where the retina becomes detached from the back of the eye with a resulting severe loss of sight.
Points to remember:
- If diagnosed early enough diabetic retinopathy is a treatable condition.
- Regular eye checks do not prevent retinopathy but do enable early diagnosis and early treatment and this will benefit your sight.
- Small blood vessels in the retina become blocked, swollen or leaky causing oedema and new, fragile vessels grow haphazardly in the retina. This process can continue for years without causing visual symptoms or visual impairment: during this period, retinopathy can only be detected by eye examination.
- Eye checks are free in the UK.
- In insulin treated diabetes, annual eye checks should be carried out after about 5 years of diabetes or after the onset of puberty in children and young people.
- In people with diabetes not using insulin, then eye checks should take place annually from diagnosis onwards.
WHO MAY DEVELOP DIABETIC RETINOPATHY?
Retinopathy can affect people with all types of diabetes:
- Anyone with insulin dependent diabetes, both young and old.
- People who treated with tablets
- People on diet only
- People who have well-controlled diabetes can develop retinopathy if they have had diabetes long enough.
CAN RETINOPATHY BE PREVENTED?
No, but early ‘good’ diabetic control may slow down the rate of progression of the condition. Improving diabetic control rarely has an effect on diabetic retinopathy itself, but it can prevent further deterioration. Therefore you should:
DIABETES and EYES – GUIDANCE
- Always take your diabetic treatment as not doing so is harmful.
- Control your diet.
- Avoid becoming overweight.
- Avoid smoking and alcohol.
- Have regular blood pressure checks.
RETINOPATHY and GENETICALLY PRODUCED ‘HUMAN’ INSULIN’
Two of the major insulin manufacturers have admitted that ‘human’ insulin therapy may cause serious adverse reactions. These are very much in line with the evidence from a large number of patients.
18 years after genetically engineered ‘human’ insulin was introduced, there is still no evidence of any clinical benefit for patients and patients in countries around the world have complained of adverse reactions to it. These largely regress with a change to natural animal insulin but this is being systematically withdrawn from the market for commercial reasons. Patients reporting adverse reactions have been largely ignored by regulatory bodies, doctors and healthcare professionals.
On April 24th 2000, insulin manufacturer, Aventis Pharmaceuticals, issued the following statement in a press release:
“Human insulin therapy may be associated with hypoglycaemia, worsening of diabetic retinopathy, lipodystrophy, skin reactions (such as injection-site reaction, pruritus, and rash), allergic reactions, sodium retention and oedema.”
The statement put in the public domain by the insulin manufacturer themselves, has very serious implications for people with diabetes. The risk/benefit ratio for insulin treatment may have shifted from ‘human’ insulin to animal insulin and present prescribing habits may be putting some people at risk of unnecessary and avoidable complications to which they are already susceptible. Increased risk of retinopathy is a particular worry because diabetes is the largest cause of blindness in the working population. Any increased risk of blindness or visual impairment is unacceptable to patients when there are natural insulins available that have not been said to cause such risks.
RETINOPATHY and DRIVING
You should tell the DVLA and your motor insurers, if you have retinopathy that requires treatment, that is affecting your vision or visual fields. It is a condition that should be declared under the item ‘has there been any material change that could affect your driving.’ If you were involved in an accident and you had not declared that you have retinopathy, then you may not be insured and the DVLA could take action because you have not informed them.
PYCNOGENOL – ARE WE MISSING SOMETHING? Article from IDDT’s Autumn Newsletter, October 1999
An article in Diabetes Interview [US March 1999] really made me think. We all read about miracle cures for various illnesses and I expect you, like me, treat them with some of scepticism. But this article really made me wonder if we should not treat some of these things with a more serious approach.
Apparently French people with diabetes and retinopathy are often treated with a patented pill called Pycnogenol – unheard of in the US and I don’t know about over here. Pycnogenol apparently is made up of a particular group of bioflanonoids that have been shown to improve the elasticity of the very small blood vessels [capillaries]. It has also been shown to have antioxidant powers that get rid of the free radicals – these are harmful molecules that lead to vascular and other problems. Diabetes Interview talks to a man who was diagnosed with retinopathy requiring laser treatment in 1982. He searched for a possible solution himself and found Pycnogenol in France – his retinopathy regressed and he has had no laser treatment. At this point I say to myself, well this could happen naturally but……..
- A study published in Ophthalmic Research in 1996 proved Pycnogenol’s beneficial effects on the retinas of pigs and cows.
- In the Journal of Cardiovascular Pharmacology, October 1998, it was shown to counteract the blood vessel restricting effects of adrenalin, to decrease the clogging of blood vessels by decreasing platelet clustering and adhesion.
- In the journal Free Radical Biology and Medicine, May 1998, it was shown to significantly decease nitrogen monoxide generation [this is important in many disease including diabetes].
- In Biotechnology Therapeutics, 1994-95, it was shown to protect the cells lining the lymphatic vessels and the heart from injury due to oxidation.
I feel I would like to know more about this and we should not dismiss too lightly the claims that are being made, especially if it is being used fairly widely across the Channel in France. To those that either have or are at risk of retinopathy, every avenue of possible prevention or stabilisation should be considered and explored. We now have laser treatment but this does not mean that we should be complacent and not look for other means of prevention and treatment. It surely must be worth some research funding or a review of published studies.
PYCNOGENOL -Update May 2001 Recent Research
In a recent study published in Phytotherapy Research [15;1-5:2001] 30 people with diabetes were treated with 50-mg doses of Pycnogenol 3 times a day for 2 months and 10 people in a control group were treated with a placebo [dummy pill]. The researchers found that in those who took Pycnogenol there was a slowing down of the progression of retinopathy and in some cases the progression actually halted but in the control group using the placebo, retinopathy only got worse.
This is only a small study and therefore it must be treated with caution. However, despite efforts to achieve near normal blood glucose levels, in industrialised countries diabetic retinopathy is still the leading cause of blindness in the working population emphasising a clear need to investigate all possible avenues to prevent people from becoming blind or visually impaired. Therefore IDDT welcomes the findings of this study and believes that it should not be dismissed because Pycnogenol is a herb. There needs to be further independent studies using Pycnogenol involving greater numbers of participants over a greater duration of time.
The use of Pycnogenol must not be a seen as a substitute for ‘good’ control and because of its powerful antioxidant effects should only be used in consultation with your medical adviser, as indeed should all supplements and complementary medicines. It is also essential that the use of Pycnogenol does not replace essential regular eye examinations.
Charles Bonnet Syndrome
Charles Bonnet syndrome (CBS) is a common condition among people who have lost their sight. It causes people who have lost a lot of vision to see things that aren’t really there, known as visual hallucinations.
CBS can be distressing, but the hallucinations are usually not permanent. Many people experience hallucinations for a year to eighteen months before they become a lot less frequent.
People who have CBS may have lost a lot of their vision from an eye condition, such as age-related macular degeneration, cataract, glaucoma or diabetic eye disease. Many of these conditions are more common in older people so many people who have CBS are older. However, anyone of any age, including children, may develop this condition as any eye condition that causes sight loss can trigger CBS.
There are thought to be more than 100,000 cases of CBS in the UK. Some research suggests that up to 60 per cent of individuals who are experiencing serious sight loss may develop it.
DRIVING WITH EYE CONDITIONS
The law requires that you must inform the DVLA in Swansea and your motor insurers if there are any changes in health or sight that could affect your ability to drive safely. Failure to do this could result in prosecution and your motor insurance being invalid.
Meeting the driving standards
To drive a car, you are required to be able to read a number plate at 25 yards or 20.5 metres with both eyes together, in good daylight and with glasses if worn. You must also have an adequate field of vision. The DVLA may require a report from your ophthalmologist about your eye condition. You must NOT drive until your specialist has confirmed that you meet the required standards. To drive vocational vehicles, the standards are more stringent.
Diabetes and Driving
Patients with Type 1 Diabetes treated with insulin and Type 2 Diabetes when insulin is prescribed to treat their long term condition are placed under significant pressure by clinicians to improve the HbA1c results so as to minimise the risk of long term diabetic complications. The balance is a very fine one and requires daily patient input to achieve this by controlled diet and insulin adjustment so as to avoid hypoglycaemia. Interpretation of blood glucose results by patients and clinicians requires careful scrutiny before changes can be made. The new DVLA regulations devised to conform to EC legislation places further burdens on patients with diabetes to ensure avoidance of severe hypoglycaemia. Regular twice daily blood testing with increased testing every 2 hours when driving, especially long distances, along with careful diet and driving compliance within the 20,30 or 40 mph speed limits in towns and built up areas and within 60 mph on country roads and 70 mph on motorways has over the years led to the vast majority of drivers suffering diabetes to be recognised as safe and careful drivers.
1. Diabetes UK has raised public concerns that the changed DVLA rules on driving are open to misrepresentation as people often experience hypos when asleep and such night time hypos have no medical basis of relevance to driving, Ref Balance Issue 4, 2011, page 6. Further details are available at the Diabetes UK website.
2. Likewise the IDT, InDependent Diabetes Trust, has raised similar observations in their newsletters entitled ‘Diabetes, Your Driving Licence and Insurance’ July 2010 page 8 – 9; ‘Proposed Changes To The Driving Licence Standards for Vision, Diabetes and Epilepsy’ April 2011 page 4 – 5; Updates DVLA December 2011 page 4.
3. The DVLA website features details of the consultation process which was carried out to effect implementation of the changes to the rules however not every patient with diabetes will necessarily spend hours reading all this information and furthermore not all patients with diabetes are active internet users.
4. The recommendation is that patients treated with insulin on occasion will require to have their fitness as to their ability to drive assessed by an ‘expert’ presumably a ‘clinical diabetologist’.
5. In 1999 the Act of the UK Parliament created a Scottish Parliament and passed to it the power to make laws on a range of issues known as devolved matters. These include health, justice, police and fire services, some aspects of transport including roads and buses.
6. It has been reported that a working group has been set up in November 2011 to review the definition of severe hypoglycaemia. The only experts who are really capable of identifying with the degrees of hypoglycaemia are the individual patients and their carers and their input to any working group will be essential to facilitate transparency in advice to the DVLA representative of the views of Diabetes UK and IDDT. In the meantime we are left with a debacle of a situation wide open to differing interpretations with no clear definitive rulings leaving a wide open potential Human Rights legal opportunity for the legal profession to generate massive legal costs yet again from the poor victims of diabetes in the event of a patient with diabetes being involved in an adverse motoring incident.
7. At present insulin users in the UK have to reapply at least every 3 years to have their driving licence renewed in the UK to the DVLA. In the event a patient has received treatment for retinopathy it is sometimes the case a licence is renewed for 1 year then must be reapplied for. A similar situation may apply concerning patients with hypo unawareness who lose their licence due to loss of hypo warning signs which upon return of hypo warning signs may lead to a 1 year licence being issued. Following the recommendation of the DVLA the Deregulation Bill at present before Parliament may lead to a Government change that insulin users applying for a Group 1 licence (cars and motorcycles) may be able to obtain a licence of up to 10 years.
THE HEALTH PROFESSIONALS INVOLVED IN EYE CARE
Dispensing opticians – are qualified to fit and measure for glasses and to examine conditions that affect the outside of the eye. They are not allowed to test the eyes for glasses or to examine the inside of the eye – for example with an ophthalmoscope. They are allowed to fit and supply contact lenses to a supplied prescription.
Diabetes and Eyes
Ophthalmic Opticians or Optometrists – are different titles for the same qualifications. This group is qualified to fully examine the eyes. If there are any abnormalities or suspected abnormalities then they refer the person to their GP or directly to the hospital if it is an emergency situation. They also test for glasses and to fit and supply them. They may be ‘high street’ opticians or hospital based.
NB If you have diabetes and you are having an eye check with an optician/optometrist, it is important that he/she carries out an eye examination with drops to enlarge the pupil so that he/she can observe more of the retina. If necessary, you should ask for this to be done, especially if you are not having this done at the hospital as part of your diabetes care.
Consultant Ophthalmologist – this is the hospital consultant to whom the GP refers people with suspected abnormalities and he/she carries out the necessary treatment or surgery.
Eye test are free in the UK for all people with diabetes, for people with glaucoma and their close relatives and for people over 60 years old. TIPS FOR PEOPLE WITH VISUAL IMPAIRMENT
TIPS FOR PEOPLE WITH VISUAL IMPAIRMENT
Visual difficulties can affect people with or without diabetes but the one thing that insulin-treated people have to do is be able to inject the accurate amount of insulin. While visual difficulties may not prevent many activities, not being able to do your own injections [and blood glucose tests] results in a loss of independence, especially for people who live alone. There are also many everyday things that fully sighted people take for granted but these become difficult or impossible for people with visual impairment.
Alison Blackburn has had diabetes for many years and is visually impaired as a result of diabetic retinopathy. She shares with us some of the tips she has picked up over the years that her sight was deteriorating that have enabled her to maintain her independence and ability to do many of the everyday things in life.
INSULIN INJECTING Tips for injecting your insulin
Using a Pen Injection Device
- There are a variety of pens available and they have clicking devices so that you can count the clicks to know how many units you are injecting.
- There are pre-filled disposable pens available for some brands of insulin and this means that you do not have to re-load the pen when a cartridge runs out. This can be easier for people with visual impairment [and for people with hand movement problems].
- Magnifiers are available that fit on to the pen.
While a pen injector may seem ideal, not everyone likes to use them and many people still prefer to use syringes for their injections. Here are a few of Alison’s tips:
Using a Syringe to Inject
- Syringe magnifiers that slot over a disposable syringe are available.
- If you take the same dose of insulin regularly, score the outside of the syringe at your dose and then draw up to this mark. If you take two different doses, morning and evening, score two syringes but make sure you keep them in different places.
- If seeing the clear insulin is difficult then hold a coloured card behind the syringe for a better contrast making sure that the colour is one that you can see well. If you ‘haven’t enough hands’ pin the card to the wall or a door.
- Syringes are available in different sizes, 100ml, 50ml and 30ml. If your dose is small enough choose the smallest size syringe because the markings are further apart and easier to see – 30ml are easier to see than 50ml and 50ml easier than 100ml.
- A nurse or relative can draw up a week’s supply of insulin in syringes and leave them in the fridge. Again if the dose or type of insulin is different at different times of the day, make sure that the morning syringes are stored on the top shelf and the evening ones on the bottom shelf. If using longer-acting cloudy insulin, then make sure that you roll the syringe about 20 times to ensure that the insulin is mixed properly before injecting.