BRITISH BROADCASTING CORPORATION
RADIO SCIENCE UNIT
CASE NOTES
Programme no. 8 - Ageing Eyes
RADIO 4
TUESDAY 20/03/07 2100-2130
PRESENTER:
MARK PORTER
CONTRIBUTORS:
SEEMA VERMA
FAZ HOV
ANDREW LOTERY
PRODUCER:
ERIKA WRIGHT
NOT CHECKED AS BROADCAST
PORTER
Hello. In today's programme I'll be exploring how our eyes change as we get older. I'll be finding out why, after nearly 45 years of perfect vision, I now need specs to read a newspaper. I will be getting checked for glaucoma - one of the most common, yet treatable, causes of blindness in the UK. And I meet a man undergoing a new form of treatment for another common cause of blindness - age related macular degeneration.
HAMMOND
I close my right eye and look with the left eye only, there was a darkish blob underneath, a shadow.
PORTER
Had you heard of macular degeneration before?
HAMMOND
No, everybody else seems to except me.
LOTERY
It's estimated that one in three people have some signs of macular degeneration in their eyes and that figure goes up to one in two by age 85. So it's really a hidden epidemic that's becoming much more of a problem as the population ages.
PORTER
More from Professor Lotery later.
My guest today is Miss Seema Verma who is a consultant ophthalmologist at Moorfield's Eye Hospital in London.
Seema, let's start with some basic anatomy. Take me through the passage of a ray of light as it travels through the eye, so imagine I'm looking at a tree on a distant hill, how does that get to the part of the brain that actually sees it?
VERMA
When you look at somebody's eye most of us look at the coloured part of the eye and then you see a black hole, which is the pupil. But in front of that structure is a clear structure known as the cornea. And the cornea together with another structure called the lens bend the light and focus it in the eye. So what happens is light travels, hits the cornea, it's bent a little bit, it then travels into the eye through the pupil - the little dark hole - and then hits the lens where it's further bent and then comes to a focus at the back of the eye on the retina.
PORTER
So the retina, you often hear the analogy that it's a sort of photographic plate, it doesn't quite work that way - it's electrical isn't it, I mean essentially it's sending a signal from the retina through to the brain and that gets there how?
VERMA
Basically what you have is lots of cells and you're quite right - electrical cells - in the retina which then form a bundle of nerve fibres which then go into the optic nerve through the optic tract and then hit an area in the brain known as the occipital cortex where all the imagery is done.
PORTER
And going back to the lens - the lens is not a fixed lens, we can adjust it, I mean if you look in a telescope it has a fixed lens in there but we can actually change the shape of our lens to look at things for different distances.
VERMA
Absolutely right. The lens is a structure in the eye - when you're young it is able to change its shape quite a lot but as you get older it changes less so. And so depending on where you're looking automatically your lens is able to change its shape to focus the object that you're looking at.
PORTER
Now we talked about those light rays travelling through those structures but what's in between them, it's not air is it, it's fluid in the eye?
VERMA
Absolutely right. Between the cornea and the iris - the coloured part of the eye - you have a fluid known as the aqueous humour and behind the lens in the cavity, the major part of the eye between the lens and the retina, you've got another fluid known as the vitreous humour. So absolutely right - it's not a vacuum, it's full of fluid.
PORTER
What happens to the eye as we get older in terms of size, I mean compare a baby's eye to an adult's eye does the eye grow?
VERMA
It does indeed. Children are born with small eyes and as we grow the growth of that eye also occurs. And you will find that a number of children need spectacles when they're younger but as they grow older they actually can shed those spectacles away. And so the small eye then becomes a normal sized eye by the age of about 8 to 10.
PORTER
Well not every part of the eye stops growing at 8 or 10, if you are in your mid 40s like me or beyond you will almost certainly have noticed that your near vision isn't what it used to be, and you will probably need glasses for reading. It's an age related condition called presbyopia and it happens to all of us as I discovered at an appointment with ophthalmologist Mr Faz Hove at Southampton General Hospital.
HOVE
Right how can I help you today?
PORTER
Well my problem, like many people of my age - I'm in the mid 40s - is that I've just got to that stage where I'm noticing I'm struggling to read things that I normally wouldn't have had any trouble with. It seems to worse in the evenings - I mean if I go out and I'm reading a menu in a restaurant that's not well lit it's a real problem and I suspect that, like everybody my age, that I'm heading that way. So I'm probably going to need some specs I think.
HOVE
Alright fine, so what I normally want to do in checking that is first of all what we would normally do is we check your distance vision okay? But today just as you say you're worried about your reading vision what we would normally do is we get some reading print, okay, and then we'll start with the print that's a bit larger, so that you're not going to just tell me you can't see it at all. Start with something that's relatively big and then what I do is I say to you have a look at that, can you read it?
PORTER
Yeah I mean that's normal text size from a book and I can read that there yeah.
HOVE
Not a problem? Now the question I say to you is - I want you to hold the text, take it forwards or backwards and bring it until it gets a comfortable distance for you to read.
PORTER
Right, well that's comfortable there, which is nearly with my arms outstretched.
HOVE
Exactly and that's what happens as people get older. So what happens is as people get older is that your lens - the lens is the one tissue - some people say the ears as well, I'm not so convinced about the ears - but they say it's the one tissue that never stops growing, so as you grow older and older the lens gets fatter and fatter and fatter, right, and then the capsule, which is the elastic which allows the lens to change size, as all tissues in your body has become less elastic. So what happens is your lens is less able to change size to allow you to focus at different distances.
PORTER
So effectively it's thicker and stiffer?
HOVE
Yes. So what we then do is make the text smaller, so just to see if it's not just the distance. So if I said to you - this is quite small text, it's N8, it's quite small, can you read that?
PORTER
I can read that yes - in the middle of winter when the broad flakes of snow were falling around.
HOVE
Fine, check again, what's comfortable - what distance would you get it?
PORTER
Well about the same actually.
HOVE
About the same.
PORTER
It has to be - yeah - I could probably get away with that yeah.
HOVE
Yeah so that's about 50-60 centimetres?
PORTER
Now one of the things that people - you often hear people say is that the minute they start wearing their reading glasses their eyes get weaker and weaker and they get more and more trouble, presumably that's because the lens carries on growing?
HOVE
The lens carries on growing - I think it's just, what happens is that they've really, really been putting up with it and the moment they acknowledge the problem they realise the depth of the problem, so they say oh the moment I started wearing reading glasses I was now stuck but in reality they had got to the point where they were just - they were really, really trying not to and then now they just have to wear the glasses.
PORTER
And there's nothing about wearing the glasses that accelerates that process in any way?
HOVE
Not at all. Okay. Another thing just to mention is as they continue to get older the strength of those glasses needs to get stronger because that lens is becoming more stiff and fatter. So what we give you when you're 45 will be different to what we give you when you're 50, it'll be different to what we give you when you're 60 and it'll be different to what we give you when you're 70.
PORTER
And presumably both eyes can progress at slightly different rates.
HOVE
Yeah I know but when it comes to reading on the whole you tend to give much the same for both eyes, but yeah there is - there is some slight difference but it's normally quite minimal.
PORTER
Mr Faz Hove explaining why I am now the proud owner of my first pair of specs.
You are listening to Case Notes, I'm Dr Mark Porter and I am discussing the ageing eye with my guest Miss Seema Verma.
Seema, We've heard there how the lens gets bigger and stiffer as we get older, but it also become cloudy too doesn't it - cataracts.
VERMA
Yeah I mean if you wanted a definition of cataract - any opacity in a clear lens is a cataract. And they come in different patterns, different diseases will cause certain types of cataracts, so for example, if you're diabetic or you're on steroids your cataract comes on earlier and will be in a particular position of the lens. Whereas if it's a naturally ageing process then there are two main types of cataracts that people get - one is the one where the colour changes and there is a nuclear sclerosis - it's just a change in the protein of the lenses. There's another kind of cataract which is a cortical, so you get spokes perhaps of opacity within the lens and as a result patients will describe different symptoms and it gives you an idea of what kind of lens they've got.
PORTER
Looking at the purely age related ones how common are they, I mean if you look in the eyes of a 50 year old or a 60 year old what sort of proportion of people are likely to have them?
VERMA
I think that is quite a difficult figure to put but what is certain is that if you look at somebody at the age of 60 you will definitely see some changes, some cataractous changes.
PORTER
And do we know what's actually causing those - it's just simple exposure to UV light and just get older that does it or do we not know?
VERMA
There's lot of theories, for example people in India tend to have cataracts at an earlier age - dehydration is a theory. So there are lots of theories but I don't really think that there is one factor that causes cataracts.
PORTER
Short of somebody like you looking in my eye how might I know that I was developing cataracts, what would you notice?
VERMA
Okay, again depending on the kind of cataract one of the things people say is when they're driving they get glare, so light is scattered.
PORTER
Almost like looking through the opaque glass in a bathroom window that you might use, you get that sort of ...
VERMA
Yeah and just blurred vision or perhaps that you find things that were - that you were able to read quite clearly you've either got to bring them closer to read it. Other symptoms people will describe is that just generally everything looks darker.
PORTER
Which presumably it is because less light's getting through to the back of the eye.
VERMA
Yeah.
PORTER
Now I was an anaesthetist when I first started my training over 20 years ago now and we used to - I used to anaesthetise people for cataracts and it was a general anaesthetic and it was quite a palaver then, but I've got patients as a GP who are going in and having their lenses replaced, which is the treatment for cataract, in 15 minutes.
VERMA
Absolutely right. I think one of the things that ophthalmology has got a lot of advantage is from techniques, getting better and better. And so with the result that a cataract operation can be done in 20 minutes or it can be done in half an hour. But actually the ...
PORTER
Just using drops in the eye?
VERMA
Just using - you can have drops in the eye and you can do the operation.
PORTER
So you're removing the old lens and slipping in a replacement?
VERMA
In a replacement. Or you can have a small injection around the eye, which will also numb the eye and prevent it from moving.
PORTER
And it's a pretty successful procedure isn't it.
VERMA
In the hands of good surgeons it is a fantastic procedure with, I would say, something like 95-98% success rate.
PORTER
And briefly at what stage would you recommend that somebody has the surgery?
VERMA
I think when they're quality of life is affected by their vision, so just because your optician says - Oh Mr Smith you've got a cataract - does not mean that Mr Smith has to go and have that cataract operated upon.
PORTER
But if he's got a hobby that involves tying flies for fly fishing or something that requires fine sight he might go in earlier?
VERMA
Absolutely, if you've got to shoot that golf ball and see where it's going and it's important that you see it then I think the time for cataract operation has occurred.
PORTER
I never know where mine have gone.
Well another change that can occur as we get older is a rise in pressure within the eye - an increase which often comes on slowly and goes unnoticed. It's called glaucoma and left untreated results in a gradual and irreversible loss of vision . And it's common - around a half a million people in the UK are thought to have the condition. Back to the eye unit at Southampton General for another test.
OPHTHALMOLOGIST
Would you like to have a seat then, we're just going to check the pressure in your eye using this instrument here. Okay it does it by firing a puff of air at your eye. If I just demonstrate on your hand what it feels like, okay, so there's no pain. If you look straight into the red light there.
PORTER
Oh I was anticipating - it was good.
OPHTHALMOLOGIST
Okay, it does make you jump. Okay and the same for the left eye. Okay, so it gives me a reading here, gives me the pressure inside your eye. And that's quite normal.
PORTER
It was following a similar test as part of a routine eye check in 1994 that Mike Sage's high pressures were picked up. He was 51 and blissfully unaware that he had developed glaucoma.
SAGE
When that word is used then alarm bells start to ring and I think a lot of people will start to feel very anxious, I mean all sorts of thoughts go through your mind. But it was explained and an attempt was given to reassure and say that we're in the business of helping you retain maximum sight for as long as you're on this earth. And so it was all put across in a very positive way.
PORTER
And practically what has it meant for you in terms of treatment and follow up?
SAGE
I had trabeculectomies which are surgical procedures, as you will know Mark, creating a channel to help reduce the pressure in your eye. And then I was into, like most people, you're then into a regime of eye drops. My eye pressures have stabilised.
PORTER
It's been 13 odd years since you were diagnosed, has it had any effect on your vision?
SAGE
When the checks are done each time I've lost sight gradually in various parts of my vision. But I mean the brain compensates miraculously for this and for the most part I'm not aware of it having any serious effect on my day-to-day living.
PORTER
Has anyone else in your family been affected?
SAGE
My mother was diagnosed after me, interestingly, and of course my family now, as is recommended, my family all have regular check ups.
PORTER
Mike Sage talking to me earlier.
Seema Verma, what's actually happening inside the eye in glaucoma, why does the pressure rise?
VERMA
The front surface compartment in fact of the eye was filled with this fluid called aqueous humour.
PORTER
So this is the bit between the front of the eye and the lens?
VERMA
And the lens. Now there's a steady production of aqueous humour and there's a steady drainage of aqueous humour, so if you take an analogy of the sink - one of the theories is that the drainage, there's a resistance, there's an increased resistance to drainage and therefore the pressure builds up. Too much coming in or the normal amount coming in but not enough getting out is one of the theories as to why there is this very insidious and slow increase in pressure.
PORTER
But it's not always slow and insidious, there's another type of glaucoma that presents in a very different way.
VERMA
Yeah, the one that you're referring to is acute angle closure glaucoma. Now in that what happens is - and it presents very differently - in that a person will get a sudden rise of pressure, the eye becomes very painful and the pressure suddenly goes up, the vision becomes hazy. And the pain is such that people feel quite sick with it. Now if that happens that's an ophthalmic emergency, you really need to get to your A&E department as soon as possible.
PORTER
Well let's go back to the type that's more often missed because of its insidious onset. What's the pressure actually doing to the eye that can result in blindness?
VERMA
If you think of the eye as a closed entity, there's obviously some stretch factor in it - the eye can expand a little bit, I mean after all the tissue has some tensile strength. But after that as the pressure goes up the main effect is on the optic nerves - the nerves - and you get death of these nerves occurring. And as a result the visual field of the eye begins to go. And so if somebody has had raised pressure for a very long time they may be unaware because their vision may be very good but if they closed one eye and looked out of the other eye they wouldn't get the good field of vision that you get, you start to get tunnel vision.
PORTER
So they get preservation of basically what they're looking at - central vision - it's the periphery that's going. Looking at treatment, we heard there Mike talking about surgery, you mentioned an operation, and that's presumably to improve the drainage?
VERMA
That's right.
PORTER
And then the drops - what are the drops doing?
VERMA
The drops work in different ways - some are to reduce the production of the fluid, others are to help in the drainage of the fluid. So - and sometimes you might be on both as a combination.
PORTER
And presumably they're a lifelong treatment?
VERMA
Absolutely.
PORTER
Looking at the implications, I mean the only way you're going to pick this up if the onset is that insidious, as in Mike's case, is to have a regular eye check. I mean at what stage does glaucoma become common enough to warrant regular eye checks?
VERMA
I think that people over the age of 40, I think would be reasonable to say that you should - if you've never been to an optician it would be a good idea to go and have a screening test done.
PORTER
Of course glaucoma's not the only thing that can get picked up of course.
VERMA
Absolutely. And the other thing of course is that if you have a family history then I think you should be screened earlier.
PORTER
And if you have a family history you get free eye checks anyway, don't you, I think over the age of 36 or something.
VERMA
Absolutely.
PORTER
Looking at who else is at risk, besides somebody with a family history, is there anything else that might put you at an increased risk of developing glaucoma?
VERMA
There are - there are certain races that are at a slightly increased risk of glaucoma, so, for example, Afro Caribbean patients are at a risk. We also find that myopia ...
PORTER
Short-sightedness.
VERMA
Short-sightedness can also be a risk factor.
PORTER
I want to leave glaucoma now and move on to another very common cause of sight problems in older people - and that's age related macular degeneration or AMD. The macula is the most important part of the retina - it's the area responsible for central vision. And there are two types of AMD - the more common dry version, which can't be treated. And the aggressive, but less common, wet version that, if caught early enough, can be halted or slowed and, using the very latest drugs, sometimes even reversed.
Andrew Lotery is Professor of Opthalmology at the University of Southampton and has a special interest in AMD - and the new drugs, known as anti-VEGF therapies.
David Hammond is currently undergoing treatment for wet AMD at the Eye Unit at Southampton and he first noticed something was awry while watching a musical just over four weeks ago.
MUSIC - CHICAGO
HAMMOND
I was in the Mayflower Theatre in Southampton to see Chicago and I noticed verticals were wobbling, it was a strange effect. I mentioned it to my wife and she said well better go and have your eyes tested again.
PORTER
Because she presumably - the verticals were standing stationary for her?
HAMMOND
Oh yeah, yeah. I closed my right eye and looked with a left eye only, there was a darkish blob underneath, a shadow.
LOTERY
Patients often report that they notice distortion, for example, if they look at the lines in the centre of the road that they would have a kink or a curve in them. So blurred central vision, distorted central vision are key features.
PORTER
And when you, as an ophthalmologist, are looking in the back of the eye what do you actually see?
LOTERY
Dry macular degeneration, which is the commonest type, is where the tissue is actually - the retinal tissue that senses light has actually thinned and worn away, it's a little bit like having a bald patch in your carpet. Wet macular degeneration is more like weeds growing through cracks in the pavement, these are new blood vessels growing into the retina from the normal blood supply layer beneath the retina.
PORTER
It's called age related macular degeneration but what's actually causing it - is it simply that the retina's ageing?
LOTERY
Well this has been a debate running for the last hundred years, in the last four years we're starting to get answers. We know that in most people now the cause is due to a fault in one of two genes and so in most people the main reason that they develop macular degeneration is because they've got an in built weakness in genes that they've been born with. There are environmental factors that can contribute as well and the biggest risk factor that's not well known is actually smoking and so if you have a faulty gene you don't necessarily get the disease but you may just be tipped over the threshold for getting the disease if you smoke or have a bad diet as well. The majority of patients are over the age of 50 and I would say most patients that we see are in their 70s or older.
PORTER
And the intervention that you can offer them - I mean somebody comes into you, you make a diagnosis of wet AMD, what's the first thing that you need to do and on what sort of timescale?
LOTERY
The first thing's a meeting to confirm that there is a new blood vessel and the reason that people are losing vision is because of the fluid leaking out of these fragile vessels. And then depending on where the blood vessel is the options would either be to cauterise them, leaky blood vessel, with a hot laser. Unfortunately that's only a small number of patients who benefit from that. What has become available much more recently are drugs that we can inject into the eye that can actually recover vision that was lost and we see spectacular results, such as people who would be legally blind regaining driving vision and we've never had any treatment like that before.
HAMMOND
They decided it was macular degeneration and I had to have laser treatment and Avastin injections.
PORTER
So what does that practically involve? Let's start with the laser - how does that work?
HAMMOND
Well they anaesthetise the eye ...
PORTER
With some drops.
HAMMOND
... with drops and I sat in front of the machine and I didn't even know anything was going on until he said it's finished. And I suppose because the eye was anaesthetised I couldn't feel it.
PORTER
Could you see the laser?
HAMMOND
No I could just see a slight line, it sort of blurred all my vision, so I didn't really see what was going on, I couldn't see.
PORTER
And the injections?
HAMMOND
The injection was done yesterday. That again was a quickie - 10 minutes at the most.
PORTER
And an injection went into where?
HAMMOND
The injection went into my eyeball, that was done in another hospital because it's a private injection.
PORTER
Injections like Avastin are not widely available on the NHS. Their use is currently being assessed by NICE - the National Institute for Health and Clinical Excellence - and most primary care trusts are awaiting the watchdog's approval before agreeing to fund treatment. Which is why David Hammond, and many other patients like him, have decided to pay for the drugs privately. Time is of the essence in treating wet AMD and waiting for a decision from NICE could cost them their sight.
HAMMOND
I've got another injection in six weeks.
PORTER
Into the eye again.
HAMMOND
Into the eye again.
PORTER
When the subject of this new treatment was first raised when did you find out that you'd have to pay for it?
HAMMOND
At the same time.
PORTER
And that's cost you how much?
HAMMOND
Five hundred pound to start with and I've got another one in three months - in six weeks I should say.
PORTER
A thousand pounds - a lot of money.
HAMMOND
It is a lot of money but I've either got to have it done or forget it and go blind. I mean I was told originally that within three weeks you can go blind. And I have spoken to other people since that know people that this has happened to. So at the moment ...
PORTER
You thought that a thousand pounds was a gamble worth ...
HAMMOND
Gamble worth taking.
PORTER
The odds were in your favour.
HAMMOND
Yeah definitely.
LOTERY
There's some recent research I've been involved in that estimates that the cost to the NHS of blindness related to AMD is approximately 拢350 million a year. So in a way you'd be making a profit if you introduced these drugs because offsetting the costs of blindness, patients who are blind lose their independence and are more likely to have falls, have fractures, it makes sound economic sense.
PORTER
If we pick the condition up early does it make it easier to save somebody's sight?
LOTERY
Absolutely. The hope is that with this new genetic knowledge that eventually that we might be able to pick up people at risk, even before there's any signs in their eyes, for example, in their 20s, and that we may develop a simple intervention that would prevent them ever getting the disease and that's an area of current research.
PORTER
Professor Andrew Lotery. And we'll have links to more information on AMD and those new drugs on our website, bbc.co.uk/radio4.
Seema, we haven't mentioned floaters - these little black dots that people often see in their vision more common problem the older you get.
VERMA
Floaters can be a symptom of many conditions but commonly what we find is that most people will arrive and say I see these cobwebs or these tadpoles flying around as I move the eye and for the vast majority of people it's an innocuous thing.
PORTER
And what's actually causing it - bits of debris in the fluid or ...?
VERMA
Well if you remember we talked about the vitreous filling most of the eye, well the vitreous is sort of a jelly like substance in the back of the eye and with age it sort of alters its consistency and with that it produces blobs and bits in it and you see them as black floaters. One of the problems is that as it condenses it's attached to the retina at several points and so as it condenses it can pull on the retina and occasionally tear the retina. And what people might see are flashes of light.
PORTER
So floaters on their own - a few floaters - is rarely anything to worry about.
VERMA
Usually but unless somebody does a full examination you can't be sure.
PORTER
So that's the idea of presenting promptly so something can be done about it urgently.
I am afraid we are out of time. Miss Seema Verma, thank you very much.
If you want more information on the subjects we have discussed then, as I said, you can visit the website, that's bbc.co.uk/radio4, where you can also listen to any part of the programme again. And if you have difficulty using a computer, or don't have access to the internet, then do try our Action Line on 0800 044 044.
Next week's Case Notes will be the last in the current series and we'll be looking at the latest developments in the world of palliative medicine - a fast expanding speciality that is helping to transform the care of people in the latter stages of a wide range of different illnesses.
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