(41) Diabetes
Facts About Diabetic Eye Disease
Eye conditions related to Diabetes
Eyes
I had a tendency towards short-sightedness before being diagnosed as having diabetes. Is this likely to increase my chances of developing eye complications later on?
Short-sightedness makes not the slightest difference to developing diabetic eye complications – it has been said that those with severe short-sightedness may actually be less, rather than more, prone to retinopathy.
Vision may vary with changes in diabetes control. Severe changes in blood glucose levels can alter the shape of the lens in the eye and thus alter its focusing capacity. It is therefore common for those people with high blood glucose levels (i.e. with poor control) to have difficulty with distance vision - a situation that changes completely when their diabetes is controlled and their blood glucose reduced. When this occurs, vision changes again, so that a person experiences difficulty with near vision and therefore with reading. This can be very frightening, at least until it is understood. After 2 or 3 weeks, vision always returns to thesame state as before diabetes developed.
As someone with diabetes, I know I should have my eyes checked, but how often should this be?
If your diabetes is well controlled and your vision is normal and you have no signs of complications, then once a year is generally sufficient. It is important that you do have your eyes checked once a year by someone trained in this examination, since after many years diabetes can affect the back of the eye (the retina). The routine eye checks are aimed at picking this up at an early stage before it seriously affects your vision and at a stage where it can be effectively treated.
I have just been discovered to have diabetes and the glasses that I have had for several years seem no longer suitable, but my doctor tells me not to get them changed until my diabetes has been brought under control – is this right?
Yes. When the glucose concentration in the body rises, this affects the focusing ability of the eyes, but it is only a temporary effect, and things go back to normal once the glucose has been brought under control. If you change your glasses now you will be able to see better than but as soon as your diabetes is brought under control you will need to change them yet again. It is better to follow your doctor’s advice and wait until your diabetes has been controlled for at least a month before going to the optician again.
Who is the best person to check my eyes once a year?
This can be done by either the specialist in your diabetes clinic, the specialist in the hospital’s eye clinic, your general practitioner or your local ophthalmic optician if they are sufficiently well trained to do this.
You need to undergo two examinations. The first is to test your visual acuity, which is basically your ability to read the letters on the chart down to the correct line. The second is to have the back of your eyes looked at with an ophthalmoscope: this is the more difficult of the two examinations and can be done only by somebody with special training. These days some clinics offer a service to GPs that enables people to have the backs of the eyes photographed: the photographs are then examined by a specialist, and the results are sent to the doctor
.Last time I was having my eyes checked from the chart, the nurse made me look through a small pinhole. Why was this?
The pinhole acts as a universal correcting lens. If your vision was improved when looking through the hole, it indicates that you may need spectacles for distance vision.
When I was last at the optician’s, she put drops in my eyes. Why did she do that?
These drops enlarge the pupil and make it easier for the doctor to examine the back of your eye with an ophthalmoscope. It is sometimes not possible to examine the eye properly without dilating the pupil to get a clearer view. As these drops also paralyse the lens, which allows your sight to focus properly, you should not drive immediately after leaving the clinic. The effect of the drops may last as long as 12 hours. It is worthwhile taking sunglasses with you to the clinic if they are likely to put drops in your eyes, as otherwise bright sunlight can be very uncomfortable until the drops have worn off.
Why does diabetes affect the eyes?
A simple question but difficult to answer. Current research indicates strongly that it is the excess glucose in the bloodstream that directly damages the eyes, mainly by affecting the lining of the small blood vessels that carry blood to the retina. The damage to these vessels seems to be directly proportional to how high the blood glucose is and how long it has been raised. This is the reason why we all believe that it can be avoided by bringing the blood glucose down to normal.
I have had diabetes for 20 years and seem to be quite well. When the doctor looked in my eyes at my last visit he said he could see some mild diabetic changes and referred me to a clinic called the Retinopathy Clinic. Am I about to go blind?
There is no need for alarm. It would be surprising if, after 20 years of diabetes, there were not some changes in your eyes. He probably considers it appropriate that you should be seen by an eye specialist and maybe have some special photographs taken of your eyes in order to examine them in more detail and which will be of use for future reference.
I have been diagnosed with retinopathy. Can you explain more what this is?
Retinopathy is a condition affecting the back of the eye (the retina). It may occur in people with long-standing diabetes, particularly those in whom control has not been very good. There is a gradual change in the blood vessels (arteries and veins) to the back of the eye that can lead to deterioration of vision. This may be due either to deposits in a vital area at the back of the eye or to bleeding into the eye from abnormal blood vessels.
Retinopathy is usually diagnosed by examination of the eye with an ophthalmoscope, and it can usually be picked up a long time before it leads to any disturbance in vision. Treatment at this stage with a laser usually arrests the process and slows or stops further deterioration.
On a recent TV programme it was stated that people with diabetes over 40 years of age were likely to become blind. This has horrified me because my 9-year-old son has diabetes and unfortunately some of his school friends have told him about the programme. What can I say to reassure him?
Some damage to the eyes (retinopathy) occurs quite commonly after more than 20 years of diabetes. Retinopathy is, however, usually slight and does not affect vision. Only a very small proportion of people actually go blind, probably no more than 7% of those who have had diabetes for 30 years or more. Because of the tremendous advances that have occurred in diabetes over the last 20 or 30 years, this proportion will be much less when your son has had diabetes for 30 years. The figure is likely to be smaller in people with well-controlled diabetes and larger in those who are always badly controlled.
Can I wear contact lenses and if so would you recommend hard or soft ones?
The fact that you have diabetes should not interfere with your use of contact lenses or influence the sort of lens that you are given. Of greater importance in the choice of type would be local factors affecting your eyes and vision, and the correct person to advise you would be an ophthalmologist or qualified optician specialising in prescribing and fitting contact lenses. It would be sensible to let him or her know that you have diabetes and you must follow the advice given, particularly to prevent infection-but this applies to everyone, whether or not they have diabetes.
I get flashes of light and specks across my vision. Are they symptoms of serious eye trouble?
Although people with diabetes do get eye trouble, flashing lights and specks are not usually symptoms of this particular problem. You should discuss it with your own doctor who will want to examine your eyes in case there is any problem.
My father who has diabetes now has developed cataracts. Is this too with his diabetes?
Cataracts occur in people who do not have diabetes as well as in those who do, and as such are not a specific diabetic complication, although they are more common in people with diabetes. There is a very rare form of cataract that can occur in childhood with very badly controlled diabetes, known as a ‘snowstorm’ cataract from its characteristic appearance to the specialist. The normal common variety of cataract seen in diabetes is exactly the same as that occurring in people without diabetes but is found at an earlier age. It is really due to the ageing process affecting the substance that makes up the lens of the eye. It develops wrinkles and becomes less transparent than normal.
Eventually, it becomes so opaque that it becomes difficult to see properly through it. His doctor should arrange for your father to see an eye specialist.
The last time I was tested at the clinic, I was told that I had developed microaneurysms. What on earth are these?
Microaneurysms are little balloon-like dilatations (swellings) in the very small capillaries (blood vessels) supplying the retina at the back of the eye. They are one of the earliest signs that the high blood glucose levels seen in poorly controlled diabetes have damaged the lining to these capillaries. They do not interfere with vision as such but give an early warning that retinopathy has begun to develop. There is some evidence to suggest that these can get better with the introduction of perfect control whereas, at later stages of diabetic retinopathy, reversal is not usually possible. Anyone who has microaneurysms must have regular eye checks so that any serious developments are detected at an early stage. You have picked up early so now is the time to make sure that your glucose level control is impeccable!
I shall be going to have laser treatment soon in my eyes.What will this involve?
Laser treatment is a form of treatment with a narrow beam of intense light used to cause very small burns on the back of the eye (retina). It is used in the treatment of many eye conditions including diabetic retinopathy. The laser burns are made in parts of the retina not used for detailed vision, sparing the important areas required for reading, etc. This form of treatment has been shown to arrest or delay the progress of retinopathy; provided that it is given in adequate amounts at an early stage before useful vision is lost. It is sometimes necessary to give small doses of laser treatment intermittently over many years, although occasionally it can all be dealt with over a relatively short period.
Your eyes will need continuous assessment thereafter, as it is possible that further treatment may be needed at any stage.
My doctor used the term ‘photocoagulation’ the other day. Is this the same as laser treatment? Will it damage my eyes at all?
Photocoagulation is indeed treatment of retinopathy by lasers. The strict answer as to whether it can damage your eyes is yes, but uncommonly. Occasionally the lesion produced by photo-coagulation can spread and involve vital parts of the retina so that vision is affected. Normally treatment is confined to the parts of the retina that have no noticeable effect on vision other than perhaps to narrow the field of view slightly. Photocoagulation can also occasionally result in rupture of a blood vessel and haemorrhage. After a great deal of photocoagulation, there is a slight risk of damage to the lens causing a type of cataract.
I have glaucoma. Is this related to diabetes?
Yes. Although glaucoma can occur quite commonly in people who do not have diabetes, there is a slightly increased risk in those who do. This is usually confined to those who have advanced diabetic eye problems (proliferative retinopathy).
Occasionally the eye drops that are put in your eyes to dilate the pupil to allow a proper view of the retina can precipitate an attack of glaucoma (increased pressure inside the eye). The signs of this would be the pain in the affected eye together with a blurring of vision coming on some hours after the drops have been put in.
Should this occur you must seek urgent medical advice either from your own doctor or from the accident and emergency department of your local hospital. It is reversible with rapid treatment but can cause serious damage if ignored.
Every time I receive my copy of Balance, Diabetes UK’s magazine, I have the impression that the print gets smaller. Is this true or is there something wrong with my eyes?
Eyesight tends to deteriorate with age, whether or not someone has diabetes. First, you should visit your optician and get your eyesight checked to see whether it can be improved with glasses, as this may be all that is required. You should mention the fact that you have diabetes to your optician. For people with severe retinopathy to the degree that reading becomes impossible, there are ways of helping. Balance, for example, is available to members of Diabetes UK as a cassette recording and this service is free of charge although, to satisfy Post Office regulations, you have to have a certificate of blindness before the cassette can be sent to you. Public libraries can also help – most carry a wide selection of books in large type and most also lend books on cassette. Some larger libraries now have Kurtzweil machines, which can translate printed material into speech. So, in effect, they can read to you, although the ‘voice’ sounds a little mechanical. This can be useful for any material that you feel is confidential, such as letters, where you might not want another person to read them to you. Libraries usually have these machines in rooms of their own so, once you have been shown how to use them, you can be quite private.
The Royal National Institute for the Blind also has an excellent talking book service. Diabetes - the ‘at your fingertips’ guide is available as a talking book from the RNIB.
