Laser Treatment for diabetic retinopathy
Laser light (shown in yellow) is shone into the eye through a small contact lens, and makes small burns on the retina.
Laser treatment was the main treatment for retinopathy, although increasingly anti-VEGF injections are taking over.
Laser is usually carried out in a darkened room in clinic. Anaesthetic drops are dropped into your eye, a contact lens is placed on your eye, and you have to sit at a laser slit lamp. This is virtually the same machine as that used for the regular examination, but a laser has been added on. It is naturally uncomfortable having to keep still whilst a doctor flashes a very bright light into the eye.
Each treatment is slightly different, depending on the condition of the eye. Laser is simply a highly focused and powerful light, where the light rays are all of the same type. Therefore it can be pointed at one spot on the retina very accurately. Each bright flash lasts for about 0.02 seconds. The commonest laser is Argon Green, wavelength 530nm, but other wavelengths can be used and most are equally effective. Other types of light were used before laser was introduced.
Enlarge a common type of laser for maculopathy (burns are shown white for illustration)
Anti-VEGF injections are taking over in the treatment of maculopathy, but this treatment is still needed occasionally or when injections are not possible.
Laser for diabetic maculopathy is also discussed here. An average of 300 burns are needed. This type of laser is not particularly painful, and you notice a bright sting. You will be asked to look in a certain position at different times.
After each session your sight may be dim or blurred, and this improves over the next dew hours. After this treatment, some people, those with healthier eyes, may notice little black marks in their vision if they look at a white background, and this starts to fade months after the laser. It can take 3-6 months before for the leakage in the retina to reduce; sometimes proliferative retinopathy may develop as well, which will also need a lot more laser .
Just as important as the laser is controlling the blood pressure to below 130/80 if possible, control of the diabetes (fasting blood sugars of about 6mmol/l, HbA1c of 6.5% or below), and not smoking. See below.
Here is a patient 2006 (left photo) treated with laser the next week, who at the same time started to improve his diabetic control, lose weight, and lower his blood pressure. The right photo is after treatment in 2007. Below is same photo a little smaller.
before laser (left), and one year after laser (right)...the exudates (white areas) have disappeared
- they do not seem to have a significant permanent benefit for most patients.
- Regular anti-VEGF injections usually reduce macular oedema and improve vision in ~50% of patientsa. Looclly, an injection is given every month for 3 months, and after that there are regular OCT scans, and if the fluid is increases more injections are offered. Usually treatment is continued unitl there is no imporvement, and when the retinal thinkness is stable, the regular treatment is stopped and patients are asked to adttend for the reguolar OCT scans. On average 5- 8 injections may be needed the first year, and fewer after that.
Laser for proliferative retinopathy or severe pre-proliferative: PRP laser (peripheral laser photocoagulatioin)
enlarge laser for proliferative retinopathy (white for illustration)
The laser is applied the same way, usually through a slit lamp in the clinic. Each treatment is often 1-3000 burns or more. Much more in one session may cause inflammation of the eye, and too little too little an effect.
The side or 'peripheral' retina is lasered, not the centre; this is the main difference of laser for proliferative retinopathy as opposed to maculopathy above. NEJM 11
The downside of PRP laser includes the discomfort. At first the treatment sessions are unpleasant, with stinging flashes.
After the laser
- the sight may be blurred, and the eye may ache for days after the treatment. If the eye still aches after a week, anti-inflammatory drops may be helpful.
- in weeks after the laser: some people notice spots in their side vision if they look at anything with a white background. This fades (you are 'seeing' the tiny burns). Other people notice flashes of light at night.
- If a lot of laser is needed it does affect your sight. You may notice glare, that is difficulty seeing in sunlight. You may also notice difficulty seeing and driving at night. These are particular problems everyone who has had a lot of laser notices. Wearing a peaked hat may be helpful, as may tinted glasses, or glasses that change colour in bright weather.
As time goes on and more laser sessions are needed, the treatment can become extremely painful. There is no entirely effective way of reducing all the pain, except a general anaesthetic.
Local anaesthetic injections in the operating theatre, or tablets that aid relaxation, may help a little. Sometimes the local anaesthetic injection takes away all the pain, sometimes it just reduces the pain slightly. The injection is not into the eye, but under it, at one side.
For patients where the treatment is extremely painful larger departments offer general anaesthetics, as these also have the advantage of allowing laser treatment to both eyes. To do this the department must have a laser that can be used in an operating theatre.
The 'up' side of this laser is that the treatment nearly always works, although several treatments may be needed, and further treatments may be needed over the following months and years. An individual laser session only has a very marginal effect on vision.
A 30 year old person with a lot of new vessels may need 18000 smaller laser burns per eye, or even more, to prevent the new vessels growing. Other people usually need less. In patients with very severe disease so much laser may be required that the side vision becomes poor and driving unsafe: the aim of the treatment is to keep good central sight, that is sight looking straight ahead, which is need to read, work, and watch television.
If the proliferation is very aggressive, intravitreal anti-VEGF will help, in addition to laser. It always shrinks the new vessels, but unless there has been a lot of laser treatment given, the new vessels always recur. We are learning how to use anti-VEGF treatment, and each ophthalmologist uses it differently. (At present at Good Hope we have no funding so cannot use it.).
Without laser proliferative retinopathy is often blinding, so both patients and doctors may be left with little alternative to enduring and carrying out this often unpleasant treatment. Again, control of diabetes as for maculopathy above is very helpful where possible in the long term.
However, the improved control is still needed in the long term, and most people are advised to achieve good control even if that means extra laser in the next 2 years, because in the longer term (after 2-3 years) research has shown good control reduces eye and other problems.
Sometimes laser is needed for pre-proliferative retinopathy: the treatment is similar to that of maculopathy and proliferative retinopathy. Nearly all eyes with severe pre-proliferative retinopathy needed laser, but increasingly anti-VEGF injections are taking over.
Eyes with mild pre-proliferative do not need laser; eyes in between often do need laser. Ideally laser will be carried out before there is macular oedema.
The Anti=VEGF injections Avastin, Lucentis, Eylea are proving very helpful. These will have to be given on a monthly basis for most patients, certainly for a few months. After that, in none-smokers with good control, he interval between injections can be extended, and not many injections will be need in the second year.
In none-smokers with poor control, injections will be needed on a regular basis for a few years, but the interval will vary according to the retinal ischaemia
In cigarette smokers, the condition will continue to progress and ischaemic optic neuropathy may intervene, causing severe loss of sight . Vaping/electronic cigarettes are much less harmful causing 1/12 th of the damage of regular cigarettes.
By keeping to these levels as much as possible (or lower still) you will be doing your best to stop your eyes getting worse. Occasionally by sticking to these targets your retinopathy will improve, even without laser. Review BMJ17 Eye 17
- 30-120 minutes exercise a day ,
- moderate alcohol consumption only,
- avoid obesity if possible,
- balanced diet including
- 9 portions of vegetables or fruit a day (9 for men, 7 for women), Lowers BP
- minimal of animal or 'hard' vegetable fats,
salt, see the evidence
Alcohol should be limited to one drink or unit a day, six days a week (Mukamal 2004). More than this leads to brain damage.
- Oily fish such as sardine, salmon, tuna, trout, at least twice a week (small amounts are fine...not a whole salmon!).
- Fibre and healthy fats in the diet slows down retinopathy. No transfats and minimal saturated fat.
- no (ultra) processed food
- generally 130/80 (see graph) or preferably less BMJ 16. Even less if well <120 BMJ17
- (120/75 ..home monitoring)
- 125/75 or less if protein in urine present (115/70.. home monitor)
- ACE inhibitors or Angiotensin Receptor Antagonists unless young/pregnant/very low blood pressure/poorly tolerated
- The lower the better in macular oedema, as long as you feel well.
- An ideal pressure is below 115 (systolic, first number) for healthy people. <120 is is only suitable for new/well diabetes patients 2012. Otherwise slightly higher as above.
- Home monitoring blood pressures should be 10mmHg (systolic) and 5mmHg (diastolic) lower see than these 'clinic' pressures.
- Depression & anxiety increase BP.
- 48-58 mmol/mol (6.5%-7.5%) or less (see graph) with very few or preferably no hypos. These (or slightly lower) levels are the best to prevent complications
- <58 mmol/mol (7.5%) for insulin users; <48 mmol/mol (6.5%) if not using insulin and have good health. Problems with intensive control. Target should be adjusted according to health and age. If you are a type 1 patient and cannot achieve good control, you need to checked for other conditions such as coeliac disease (anti-TTG antibodies), addisons, and thyroid.
- If hypos develop, seek expert advice from your diabetes nurse/doctor.
- if your HbA1c is high (say 97mmol/mol / 11%), then the next step may be to achieve 75 (9%)....in other words, and any improvement is helpful, gradually reaching lower levels above.
sudden decrease in HbA1c
- A sudden improvement in control (HbA1c drop of 33 mmol/mol/3% ) will lead to a temporary rapid increase in progression of retinopathy: laser may be needed.
- Good control is important in the longer term, that is after about 2 years. When people who control their diabetes well will be better off after this period. See
- A temporary increase in retinopathy is most common when starting insulin for the first time, especially if the diabetes is very badly controlled when you start the insulin.
- Individual targets Nice 16
- <4.0mmol/l, and statins recommended for most adult patients with diabetes whatever the cholesterol.
- statins are recommended whatever the cholesterol, if well tolerated age>40y
- A fibrate such as fenofibrate is advisable in nearly every person with retinopathy. They reduce retinopathy progression 40% (Fenofibrate 200mg od) Field Study. We now recommend these for all adult patients, and they can be used in addition to a statin.
- LDL <2
- Avoid if pregnant, GFR <15, pancreatitis
- If GFR low but still >15, need a lower dose.
- smoking 20 a day triples/quadruples retinopathy
- passive smoking may double retinopathy: room-mates inhale at least 25%
- electronic cigarettes are much much safer and probably have a negligible effect on retinopathy debate BMJ 18
- even 'Just one cigarette a day seriously elevates cardiovascular risk ' BMJ18, so it is best to stop completely.
- multiple dose insulin, using a protocol such as using lantus (long acting) and rapid acting (novarapid/humalog) is normally superior to twice daily. (This is controversial.)
- Insulin pumps generally produce better control still, but are harder to use.
- everyone with diabetes should attend an education course, such as DAFNE (insulin) , DESMOND (type 2 at diagnosis), or XPERT (type 2). Primary Care Trusts are obliged to send you on such a course, but very few patients have ever attended one. If you have not been on one, discuss this with your diabetic team. Get a diabetes buddy.
- this contributes to macular oedema and loss of sight (Schwartz, 2006), and many serious problems.
- It is common in diabetes, particularly if you are overweight. Do you have sleep apnoea?
- see 15
- 5.0-7.2 mmol/l before meals
- <10.0 mmol/l after meals
- no serious hypos
- for patients who test their glucose levels and adjust insulin doses, the new glucose sensor is highly recommended and has transformed the lives of many patients. The cost is about £30/week).
- Rosiglitazone and pioglitazone should not be used if there is significant retinopathy, and certainly not if macular oedema is present, as they increase macular oedema and fluid retention. Case 49. Lirglutadite and Exenatide are drugs that can be used instead low also lower weight (they are injections.)
- insulin users need to avoid serious hypoglycaemia. Expert help is usually needed if episodes are severe/frequent. See
- many patients receive totally inadequate care BMJ 11. Some call this 'institutionalised neglect'.
- 10% compliance if multiple treatment,
? 60% one tablets
type 2 at diagnosis
- need a test for Haemochromatosis