Jaheed Khan: The two main concerns of diabetic retinopathy are swelling and bleeding, and the swelling is more to do with the macula. The treatment for the swelling of the macula is usually injections into the back of the eye, which are rarely delivered frequently in the first few months to reverse some of the swelling of diabetic macular oedema directly.
Jane: Tell me more about injections into the back of the eye; that sounds scary.
Jaheed Khan: It is not scary; it is not painful. Most people are a little bit concerned about that mode of treatment. The first to say is that it is delivered very quickly, it is done as an outpatient procedure. It is a procedure that is sterile and the risks of having a problem are very very low. What people do not like the idea of is whether it is going to hurt and whether they can see something coming towards the eye. It does not hurt because we use drops and we numb the surface of the eye, and you do not see anything coming towards you because you look to one side and we deliver it with a very very fine injection needle in the white of the eye. So it is not coming through at the front.
Jane: I think you reassured me if I had diabetic macular oedema.
Jaheed Khan: Yeah, it is a trade-off.
Jaheed Khan: But it works very well, and the most of our patients are very happy once they have had it and do not think the injection is scary after the first injection.
Jane: How many injections would someone have to have and what is the drug that you are injecting?
Jaheed Khan: That can be very variable, and if you got severe oedema then you probably will need a prolonged course of treatment. The reason being is that the drug does not tend to last as long as we would like. That is just a constraint of the technology around injection, so we on average would give people around eight injections in the first year, but that goes down each year down to about six in the second and possibly four in the third.
Jane: And with that will they get rid of oedema or will their vision get better or they just stabilise that?
Jaheed Khan: In the short term it gets better, and in the long term it stays better, so the issue here is that it was always going to be a treatment to keep giving, but it improves vision in a vast majority.
Jane: What about preventing? You know, you have got to a stage, you are 18 months down, you have improved their vision a couple of lines on the Snellen chart, they have still got their diabetes, but they stopped smoking, and their control is good, are they still at risk of new oedema.
Jaheed: Well, this is an ongoing subject of investigations and subject to research. What we have noticed is that if we keep giving injections the chance of having fluid re-form in the future goes down significantly. It is a cumulative effect after many injections, so once you have had a lot of treatment, you are less likely to have a problem. It is when you stop treatment the issue arises.
Jane: When you had the treatment of diabetic macular oedema and your vision is improved, does it need some very fine scarring there?
Jaheed: No, one of the advantages of injections is that it is a drug that is delivered into the gel of the eye and diffuses gradually into the retina. There is no direct structural affect.
Jane: So its affects function, but it does not affect the anatomy.
Jaheed: It does not affect the anatomy or structure, and you cannot tell if people have had injections or not. It is unlike laser, which is the old treatment, where there were some structural changes that you could subtly see.
Jane: Since you could see the laser scars.
Jane: You said there were two main concerns, one being swelling and the other is bleeding with diabetic retinopathy.
Jaheed: Bleeding is a concern for us because if the retina becomes damaged severely, a lack of oxygen stimulates new blood vessels to grow in the retina. Now, those blood vessels do not function normally, and they can grow forward and be prone to be cut and bleed.
Jane: How would someone know if they have got blood vessels going forward?
Jaheed: In the large majority you do not have any symptoms, so you need to be screened, or someone needs to look at the back of the eye regularly, but in the rarest circumstances they can bleed into the gel of the eye and cause blurring.
Jane: What symptoms might they get?
Jaheed: It is usually painless loss of vision. You would wake up one day, and you see a big black blob in the vision, which would be quite difficult to see through and that – in a diabetic – is a serious sign of severe diabetic retinopathy.
Jane: Let’s say I am patient that has woken up Monday morning – the day of your clinic – and I have got a black blob in my vision, and I managed to get an appointment to see you; what would you do?
Jaheed: We would do all of the other tests that we described, but we would have a look at the back of the eye to see where that blood is coming from. In a large majority of cases, it is probably sensible to do a fluorescein angiogram, which is an investigation which tells us where blood vessels are leaking and that involves injecting a dye into the arm.
Jane: You have to wait for the blood to disappear so that you can see?
Jaheed: If the blood is mild you do not have to wait too long.
Jaheed: If the blood is severe then sometimes you have to wait.
Jane: And when you found these little blood vessels, what can happen next?
Jaheed: Well, if you leave them they continue to grow. So what we try and do is when the view is clearer is apply laser treatment to the retina to cause them to shrink indirectly. We do not directly laser the blood vessels. The indirect effect is achieved by using laser shocks to the peripheral retina and through a shift in oxygen diffusion. We shrink the blood vessels indirectly, so we sacrifice the peripheral vision to maintain the central vision. Peripheral vision is rods vision and is what we use at night.
Jane: When would they notice that they did not have such good peripheral vision?
Jaheed: At night time, a certain percentage of patients who do have treatment in both eyes may have reduced fields of vision for things like driving. In the majority, that is not the case.
Jane: What proportion do you see of macular oedema against new vessel formation and bleed?
Jaheed: With the advent of screening, we see much less bleeding than we used to, partly because diabetic control has got a lot better so diabetic macular oedema is something we see a lot more of and is one of the reasons why people go blind in a working age. It is the most common reason for patients to go blind in the working age group, so we see a lot more of that because our technology is improved and we can see early signs of it.
Jane: And presumably it can affect both eyes?
Jaheed: It can affect both eyes, it can affect one eye, more so than the other. It can come and go, so you have to monitor both very carefully.
Jane: What would your advice be to a person with diabetes to avoid risk factors for their vision?
Jaheed: First and foremost – diabetic control, diabetic monitoring, being screened for diabetic eye disease is mandatory. Lifestyle changes – living a healthy lifestyle, making sure that other things such as blood pressure are controlled and stopping smoking is a big help, losing weight and all of the other things that lead to a healthier lifestyle and can reverse diabetic retinopathy.
Jane: Does it make any difference whether your diabetes is a Type 1 or Type 2. Tell me the difference between Type 1 and Type 2.
Jaheed: Traditionally, Type 1 diabetics have a deficiency of insulin from a young age, so they need insulin injections to treat that condition, and the long-term complications are if that is uncontrolled or insulin is not replaced that you have high blood sugars over a prolonged period.
Type 2 diabetics have what we call insulin resistance, where their insulin production – over time – starts to reduce. That second type of insulin type 2 diabetes is related to obesity. That is related to lifestyle factors more and genetics, so two different conditions but the same outcomes if left untreated.
Jane: And that second group, will they be more likely to be on tablets and diet?
Jaheed: They can be on a diet if it is a mild form of diabetes. They then transcend to tablets if their diabetes worsens. Some of those people go on to insulin, so it does depend on the severity of each group and how bad that is.
Jane: Next, I’d like to discuss if people with diabetes get more cataracts. Join us for our next blog post to find out more.