Stories of stubborn grit in the eye

A middle aged man was on his way to Bangkok from Singapore when he felt something blow into his eye at the airport. Trying to clear the irritation, he rubbed his eyes. The irritation persisted and while in Bangkok a doctor could not find anything wrong and patched the eye up. Unfortunately, this did not help much.

He returned to Singapore the next day at the end of the work trip and when I saw him the eye was obviously red and tearing. The picture below shows a green area with surrounding green dots and lines. These represent raw areas on the surface of the eye where the surface cells (epithelium) have been scratched away. 

(Note: I have put some fluorescein drops into the eye-this vegetable based dye tends to stick to raw areas, and gives off a green light when blue light is shone onto it. This makes it very valuable for highlighting abrasions/scratches ont he eye. )

Even before I did anything else, I knew there was something still in the eye. The green lines indicated that very fresh scratches were occurring at the time itself by blinking and eye movements. I automatically 'everted' the eyelid (turned it so that the inner surface faces outwards-some small children like my youngest daughter can do it as a trick to look like a ghoul [below]!)

The picture below shows a tiny yellow spot just to the left of center. The yellowness is actually from the fluorescein dye-if I had not put fluorescein in, it would have been invisible as it was transparent.

Having found the culprit, it was a simple thing to get a pair of jeweller's forceps (mini tweezers) to grab and remove the foreign body. Most of the time when we remove such things, it is impossible to say what it was or where it came from. The picture below shows the offending object at the end of the forceps-a nondescript, fluorescein stained stiff strand-I suspect some little bit of plastic.

When looking for such things, I am fortunate enough to have a slit lamp microscope and of course, the good ol' fluorescein. Very few things escape such scrutiny. Except...

There was a similar case that initially flummoxed me a couple of years ago. A Japanese lady went to the Accident and Emergency Department of a local hospital and I was called to see her. She similarly complained of a stubborn, persisting scratchy sensation in her eye. I did my usual, but try as I might, I could not see a foreign body. She certainly did have scratches on the cornea, but with no sign of a foreign body even with fluorescein eyedrops instilled, I thought the foreign body had been washed out by her tears. I inserted a bandage contact lens and she felt better.

I checked on her a couple of days later and she said she was feeling fine, so I removed the bandage contact lens. Almost immediately, she started tearing and as I looked, scratches were starting to appear on the cornea again! (See pic below) So I everted the eyelid at the slit lamp, but still could not see anything. OK, this calls for plan B...

I brought her to our small treatment room and used an operating microscope this time. With her lying down I could 'double evert' the eyelid-lo and behold-there was a small stitch protruding from the inner surface of the upper eyelid!
NB: In double eversion we evert the eyelid a second time to expose things even higher up in the little pocket called the 'conjunctival fornix'. This stitch was at the upper end of the stiff 'skeleton' of the eyelid, the tarsus.

It turned out that she had double eyelid surgery some years ago, and the person doing it had used a method utilising just stitches. These stitches are often permanent, and do not dissolve on their own. Over time, it had slowly eroded out through the inner surface of the eyelid and the ends of the stitch were now poking the cornea. With that, it was a simple matter to cut the stitch and remove it-problem solved.

Did the double eyelid disappear? No, because after some months collagenous 'scar' tissue forms around the stitch and anchors the skin around the eyelid fold down to the underlying tissues, thus creating a permanent effect that persists even if the stitch is taken out.

I guess the message is, if there is any stubborn grit/irritation in the eye, firstly don't rub the eye, and secondly don't hesitate to visit your friendly eye doctor!

Floaters, flashes of light and retina detachments

One of the most common reasons people seek an eye consult is the sudden onset of floaters or flashes of light.

Those of us who've never experienced this might be scratching our heads wondering if these people were hallucinating...:)

In actual fact, this series of symptoms are natural phenomena which will affect most if not all people at some point in their life.

What our eyes contain

Most of our eyeball is filled with a jelly like substance called the vitreous, and this is a solid blob at the time we are born. It is made of a number of molecules including hyaluronic acid (the substance that lubricates our joints) interspersed in a collagen matrix.

With age, these molecules separate out from the collagen, leading to the formation of liquid filled cavities within the vitreous. Usually, a thin layer of the vitreous gel continues to line the retina of the eyeball for many years, even though the centre has turned into liquid. For some people at this stage, floaters are noted already. These are generally perceived as 'transparent', and look like little bubbles/circles that may be arranged in string like patterns. I've even sometimes had children of 9 or 10 years old tell me that they see these things.

As a person gets older, even more of the jelly in the center liquefies. At some point, the remaining solid vitreous lining the retina at the sides collapses inwards towards the fluid filled center-this is called a 'posterior vitreous detachment' or PVD. When this happens, there is a dramatic change in the floaters. Instead of transparent bubbles in clumps or a string, more obvious gray or black floaters like a cobweb or mosquito can appear. Sometimes these are associated with flashing streaks of light at the side especially in the dark, when turning the head. That's why the term 'floaters and flashes' came about.

As the layer of vitreous jelly peels away from the retina, nothing happens most of the time. However, if that layer happens to be stuck firmly at some point to the retina, this area of retina can get torn as the jelly peels away. Imagine peeling the skin of an onion. If the layers are not stuck together, they can come off nicely layer by layer. However, if the layers are stuck together, peeling one layer off will tear the underlying layer.

In the pictures above you can see a retinal hole before and after it is lasered. The white blob floating to the right of the arrow is the piece of retina that has been torn off. In the bottom picture, there is a white circle around the hole. This is retina that has been treated with laser, which causes the retina to stick to the wall of the eye. Even though the hole is still there and cannot be closed, the retina is now much less likely to detach.

The picture above shows a large U shaped tear on the right but no retinal detachment yet, while the picture below shows 2 retinal breaks (one oval hole and one curvy tear on the right) with most of the retina already detached (greyish areas).

Treatment

How do we treat these problems? As with all the things we deal with, some things we can treat well, and other things-well, are still looking for a solution. Unfortunately for many people, the annoying floaters continue to be a problem for many months or even years, although they do generally get less obvious with time as they drift out to the periphery somewhere. They are more obvious in bright situations, so I tell my patients to wear sunglasses when they go outdoors and perhaps to dim their computer screens. But there is no medication to clear them. Some surgeons do 'floaterectomy' operations, but these are generally frowned upon by most eye doctors because manipulating the vitreous gel confers a risk in itself of retinal tears and retinal detachment. Plus a risk of early onset cataracts associated with removing the vitreous gel.

Wherever a retinal break (hole or tear) is seen and the retina is not yet detached, laser treatment is done. This takes 5-10 minutes, and the chance of future problems is very significantly reduced. Unfortunately by the time some patients arrive at the doctor's office, the retina is already detached, by which stage it is too late to solve the problem with laser treatment alone.

There are basically 2 ways to repair detached retinas. The first involves stitching and fixing a band of plastic around the circumference of the eye like a belt. This presses the wall of the eye inwards, and by doing so brings it closer to the detached retina. It also reduces the pull of the vitreous on the retinal tear. This can be combined with drainage of the fluid under the detached retina, and also freezing or laser treatment to form a permanent seal around the laser tear. In the picture below, the ridge at the top part of the picture is the view from inside the eye of the band pressing inwards.

From: Myhealth.alberta.ca

The second method involves removing the vitreous gel (vitrectomy) and then replacing the gel with a gas or silicone oil. This second method can actually also be combined with the first in complicated cases.

There are pros and cons with each type of surgery, which perhaps should be addressed in a later post. Suffice to say that wherever possible, most surgeons in Singapore prefer to do the first method (Scleral buckling) as it is an external procedure, with no requirement to posture face down (as the patient would have to do if it was vitrectomy with gas) and no need for a second operation to remove silicone oil (as is sometimes done with vitrectomy and silicone oil). 

Soft contact lenses or hard contact lenses?

Contact lenses are a very popular form of vision correction. In Singapore, it is estimated that 600000 people wear them (ST, Sep 1 2012 'Contact lenses safe, provided proper care is taken'), with a very low risk of complications.

Generally, contact lenses can be divided into soft and hard varieties. Soft lenses tend to be large in diameter and are flexible, so they can be folded. They are much more comfortable to wear, and currently the most commonly used ones are of the disposable type. Although soft contact lenses first became available in 1971, the disposable type only became available from 1987 onwards.

Nowadays, there are daily disposable, 2 weekly disposable, and monthly disposable types. And of course, there are the longer term, permanent lenses which actually are used for about 1 year before they need to be replaced. Daily disposable lenses are expensive, but they are least likely among soft contact lenses to cause problems such as allergies or infections, unless the user does not wear them according to instructions. Daily disposable lenses also are thinner, and so less likely to cause or exacerbate dry eye situations. Even 2 weekly or monthly disposable types are worn successfully by many people, and are most cost efficient for those who wear lenses on a daily basis.

Current 'hard' or 'semi-hard' lenses usually refer to corneal rigid gas permeable lenses (RGP), and these were first introduced in 1978. In actual fact there are other types of hard lenses, such as scleral lenses, and there are even hybrid hard lenses with a soft skirt at the edge, but these are more rarely used.

In 2012, RGP lenses made up 9% of contact lenses worn in the US. Source: Contact Lens Spectrum, January 2013. 

They are less widely used than soft lenses, because there is an initial period when RGP wearers will feel the lens in their eye. This uncomfortable sensation is akin to having an eyelash in the eye-ie it is not very painful but in the initial stages can cause tearing and bother the wearer. Once over this period (up to 2-3 weeks), the lens is as comfortable as soft lenses, and the RGP lens really begins to shine. Occasionally, if a bit of dust gets under the contact lens, that can cause eye pain, but a quick rinse with even tap water will clear this easily.

The benefits of RGP lens wear are many, among which are sharp vision (usually sharper than soft contact lenses or spectacles), very good oxygen permeability (yes, your cornea needs to breathe oxygen in the air!), less tendency to be affected by dry eyes, and very good durability.

One reason why some young children used to be started on RGP lenses was a belief that wearing them could slow the progression of shortsightedness (Myopia). However, a study done 10 years ago (Arch Ophthalmol. 2004;122(12):1760-1766) showed that there was no difference in growth of eyeball length between the soft contact lens wearers vs the RGP lens wearers. This suggests that RGP lenses have no real ability to  retard the progression of shortsightedness.

There is a special class of RGP lenses called orthokeratology lenses which are worn to sleep, and are worn with the intention to flatten an area of the cornea. I will cover these lenses in a future post as they are used in a radically different way compared to other contact lenses.

Should one go for soft lenses or hard lenses? I would say that for the majority of people, soft contact lenses are best because of the comfort, ease of wear and care. They are good for occasional wearers and those with otherwise healthy eyes.

RGP lenses would be especially useful for those with the desire or need to see with very sharp vision, and those for whom the extra thickness of soft contact lenses might give rise to problems eg those with very high spectacle power, or those with dry eyes.

I guess I am partial to RGP lenses, having worn them myself for over 30 years. The only thing I avoid doing with any regularity is swimming, even though it is possible to wear goggles with them on. I have gotten so used to them that I actually find it easier to wear them than soft contact lenses.

Blood is thicker than water

Mr C is an old patient of mine. I first met him 3 years ago, soon after moving to Singapore from Penang.

His is a story of survival, of successfully battling leukemia and unfortunately then losing vision in one eye from complications of graft vs host disease. At the time of his leukemia treatment, he was fortunate enough to receive a bone marrow transplant from one of his sisters, and he subsequently went into remission. The bone marrow unfortunately produced cells which started attacking parts of his body. Some scarring developed in his mouth, but it was his right eye which bore the brunt of it. Treatment with high doses of steroids produced steroid induced glaucoma in the eye, for which he underwent transscleral cyclodiode laser treatment. Unfortunately, that eye became phthisical.

When I first met him, he was just starting to develop inflammation in his other eye. We managed to control that with oral steroids at the beginning, but soon a tongue of fibrovascular tissue started growing inexorably towards the centre of his cornea from under his upper eyelid.

We got him a haematology referral, put him on other immunosuppressants, searched the literature for graft vs host disease, and got nowhere. His vision was soon obscured by the fibrovascular ingrowth. At first, I did a simple excision of this tissue, but ominously it grew back within a matter of months.

I had read reports of oral mucosal transplantation to the ocular surface, but had up to this time been somewhat skeptical of the reported benefits. For this patient, there were not many alternatives. The superior fibrovascular tissue had obliterated the superior conjunctival fornix, and at a minimum I would need some tissue to resurface that. There was no significant tissue to take from his other, phthisical eye. I got my plastic surgeon brother and together we worked on Mr C. He harvested a rectangle of oral mucosa, following which I dissected Mr C's upper lid free of the cornea. I then transplanted the oral mucosa to the uppermost part of the tarsal surface of the upper lid. The surface of the eyeball I covered with a layer of amniotic membrane.

It was with dismay that I noticed fibrovascular tissue creeping across the amniotic membrane a few weeks after surgery. Before long we would be back to square one!

I took Mr C to the treatment room, and slightly out of desperation took a very thin layer (split thickness, see pic below) of the transplanted oral mucosa from the superior forniceal area and retransplanted this to his superior limbal area, hoping that this would act as a barrier to further fibrovascular ingrowth. Amazingly, it did just that! The fibrous tissue regressed into a small red granuloma (see below), which I easily excised in clinic. Epithelium from the oral mucosa in the limbal area also started growing over the cornea, which was soon epithelialised. Amazing, and here we are with so much research done trying to grow oral mucosal epithelium in the lab.

And we all live happily forever after? Unfortunately, no.

After about a year, it became apparent that things were still unstable. Firstly, blood vessels started growing into the superior part of the cornea (see below). Obviously, the oral mucosal cells do nothing to stop blood vessels from growing in. Anytime I tried to reduce his oral steroids and immunosuppression, his conjunctiva and even cornea would get inflamed, with epithelial defects and even more alarmingly, slowly progressive corneal thinning. Secondly, his long term usage of oral steroids had caused a very dense posterior subcapsular cataract. We got by, by keeping him dilated with atropine so he could still see out of the less affected peripheral lens.

But we knew that things were not getting any better. And I was worried that one day his cornea would melt and perforate (as has happened to one of my Stevens Johnson patients before). What he really needed was limbal stem cells that were immune to attack from the transplanted bone marrow. A light bulb went off-I would use limbal tissue from the sister who had donated the bone marrow in the first place! As the immune cells and the limbal tissue are from the same donor, the limbal tissue would naturally be immune from attack!

We discussed this a number of times, and finally about a month ago I sat down and spoke to quite a few of the siblings (they are a large family). As expected, the sister involved wanted to know how the limbal stem cell harvest would affect her. I replied that it was a very safe procedure that would cause very temporary and mild discomfort, although it could cause some changes in spectacle power/astigmatism.

Last week I performed the operation to remove the cataract as well as transplant the limbal stem cells from the sister to Mr C. Both are doing great. The limbal stem cells are taking well and today donor corneal epithelium had grown to cover most of the corneal stroma. Hopefully this is the last operation I have to do for Mr C!

Even though Mr C was unfortunate to get leukemia and then graft vs host disease, he was very lucky to have such a supportive family and sister. You really know who are the people you can count on when the going gets tough!

Update (13 August 2014)
Mr C continues to do well with clear corneas and vision of 6/12 unaided. Driving vision!

Can spectacle power return after LASIK?

LASIK changes the power of the eye by changing the shape of the cornea, the clear window at the front of the eye. Besides transmitting light, this window is also responsible for much of the focusing power of the eye, giving doctors a great opportunity to 'build a contact lens' into the eye itself.

LASIK works by removing minute amounts of corneal tissue from the surface of the eye. By doing so, certain parts of the cornea can be flattened, and other parts steepened. For example, in shortsighted patients the central part of the cornea is flattened, the amount of flattening corresponding to the spectacle power of the patient.

Back to the question: Can spectacle power return after LASIK? The short answer is yes. This can happen for a few reasons:
1. The corneal shape slowly regresses towards its original shape (It can never regain its original shape, but the 'healing' process sometimes causes the corneal curvature to become a little more like how it was before the LASIK)
2. The eyeball changes in length, usually by becoming longer in very shortsighted people
3. Some other unrelated eye disease, such as cataract

The higher the spectacle power of the eye to begin with, the more likely this is to happen. However, overall the risk is low as has been shown in a number of studies.

Am J Ophthalmol 2008;145:46–54. 

The above graph from an article in the American Journal of Ophthalmology shows that even after 10 years, the average spectacle power of the eyes of a group of patients was only about 50 degrees, or 0.50 dioptre of shortsightedness.

If the spectacle power returns, what next?

It depends on how much power has come back, how much cornea is left, and how keen the patient is on having a LASIK enhancement/adjustment.

Generally speaking, an enhancement is not recommended if the residual spectacle power is 50 degrees or less than targeted. Some patients are also quite happy if the power is higher than that, and there is no need to repeat surgery for all these patients.

When the power gets to 75 degrees or higher though, more and more people find that it affects their daily activities. They may need glasses, for example, when driving. If so, the inconvenience may drive them to seek an enhancement. This can be considered if the remaining cornea is thick enough.

In recent times it has been found that a LASIK flap can be lifted again many years after the original surgery. As such, an enhancement surgery is very much 'half an original LASIK operation', since it does not involve making another flap. Using topography guided techniques, enhancements can be done not only to correct residual short/long sightedness and astigmatism, but also aberrations like spherical aberration and coma. The picture below shows topographies (corneal maps) of a patient who had coma and residual shortsightedness before (left most map) and the subsequent healing after enhancement. Note how the blue area has shifted from the right side (left map), over to the centre (right map).

If the cornea under a LASIK flap is already too thin for further treatments, alternative techniques would include PRK on the flap, or even ICL surgery if the anterior chamber of the eye is deep enough.

Atropine eyedrops for the control of shortsightedness

Shortsightedness is a huge problem in Singapore and many big cities around the world. More than half of Singapore schoolchildren are already wearing glasses for shortsightedness by the age of 12 years. What is worrying is that the earlier one starts out becoming shortsighted, the higher the final spectacle degree tends to be. Very highly shortsighted people are at increased risk of eye problems like cataract and retinal problems at a younger than average age.

It is important therefore that we try to slow down the increase of shortsightedness as much as possible. Ensure that a child spends 1-2 hours outdoors in sunlight each day. Take regular breaks from near work when reading or with computer use. Apart from these, using Atropine eyedrops is the only method proven in big studies (randomised controlled trials) to slow down the rate at which shortsightedness increases.

What is Atropine?

This is a chemical obtained from plants in the same family as the nightshade plant. Owing to the presence of extremely high levels of atropine and other chemicals, the berries and leaves of the plant are poisonous. 

Interestingly, the nightshade plant is also called ‘belladonna’ (meaning beautiful woman in Italian) as people in the past used atropine to dilate the eyes for a cosmetic effect! It achieves its effects in the body by blocking a special receptor molecule that among other things controls the action of muscles as well as the growth of the eyeball.

Atropine is available in many forms, but for eye conditions it is used as an eyedrop. Various concentrations have been tried but the commonly available concentrations are 1%, 0.125% and 0.01%.

Traditional treatment (Atropine 1%)

Traditionally, to reduce the rate at which shortsightedness increases, 1% Atropine eyedrops were used once a day or even once a week. In a study at the Singapore National Eye Centre, 1% eyedrops used once a day reduced the progression of shortsightedness from an average of 100 degrees a year to less than 25 degrees a year. Our experience suggests that using it even once a week has a very similar effect.

Side effects of traditional Atropine treatment

Atropine 1% dilates the pupil and relaxes the muscle used for near focusing inside the eye. As a result patients feel very sensitive to bright lights and with normal glasses on have difficulty with close up work such as reading. If this concentration is used, special glasses which turn dark outdoors (‘Transitions’ lenses) and which have progressive lenses (having a near section below for near focus) are required. All of these side effects are temporary and disappear when the patient stops using the drops.

Newer treatments (Atropine 0.125% and 0.01%)

In an effort to do away with the side effects of Atropine, lower concentrations of Atropine were tried. When used once every day, 61% of those using 0.1% and only 6% of those using 0.01% Atropine felt a need for special ‘Transitions’ and progressive lenses. Therefore, normal glasses or contact lenses can usually be worn while the 0.01% Atropine concentration is used.

However, the lower concentrations are not as effective as the 1% concentration at slowing progression of shortsightedness. On average, the myopia progression over 2 years for 1% Atropine was 28 degrees, for 0.1% 38 degrees, and for 0.01% 49 degrees. This was still better than the 120 degree increase seen in those who were not using the Atropine eyedrops.

General pointers about using Atropine for shortsightedness

Whether 1% or 0.01% Atropine is used, the eyedrops must be used for a long period of time. Although the shortsightedness increases at a slower rate while Atropine is used, the rate increases again when it is stopped. The idea is therefore to use the Atropine during the period of time when the shortsightedness is increasing fastest. Usually by about 18 years of age, the rate of increase of shortsightedness would have already slowed down naturally.

This means that on average, most children who use the eyedrops would be using them for several years. The longer the eyedrop is used, the bigger its potential effect. For example, if a child had shortsightedness that was increasing by 100 degrees every year, using the 1% eyedrop for 3 years would reduce the final power by 300 degrees. This might mean that instead of having 500 degrees of shortsightedness as an adult, he/she would only have 200 degrees of shortsightedness finally.

In trying to slow the progression of shortsightedness, a number of decisions have to be made. Should Atropine be used or not? Should the 1%, 0.125% or 0.01% concentration be used? How long should the child continue with the eyedrops?

These decisions should be made after a discussion of the pros and cons of each decision with your eye doctor. For example, if the shortsightedness is increasing very fast and is already of a high degree, one would favour using the 1% eyedrop despite the side effects. On the other hand, if the side effects cannot be tolerated and one is willing to give up some of the stabilizing effect of the 1% eyedrop, then the 0.01% concentration is a good option.

EDIT 7 MAY 2018
Please note that I do not run an online pharmacy, and these are illegal in many parts of the world. Do not request Atropine from myself, or any other doctor, unless you or your child have seen the particular doctor and it has been determined after a proper consultation that Atropine is necessary. Requests for Atropine will be deleted in the future to avoid cluttering up the comments section in this post.

P/S.
Have you ever seen pinhole glasses? I heard that they are available at Watsons. Do NOT waste your money on these gimmicks. They do nothing to help the eyes or vision. Have a look at this link: Case Watch report on settlement of charges of misleading claims

How is glaucoma treated?

As was discussed earlier, glaucoma refers to damage to the optic nerve cells. There may be many factors important in causing this, but the biggest factor shown in studies is the level of pressure in the eye. (IntraOcular Pressure, or IOP)

Hence, the main aim of treatment in glaucoma is to lower the eye pressure. Sometimes, the eye pressure may be in the ‘normal’ range of 10-21mmHg, but the nerve continues to deteriorate. In such cases, the eye pressure is lowered further still. Lowering the eye pressure of most glaucoma patients starts with eyedrops (right).

Fortunately there are many medicines available now to reduce eye pressures. If using one does not lower the pressure enough, the doctor may change the eyedrop to a different one, or a second eyedrop may be added. In patients with very high pressures, an oral medicine called Diamox may also be used.

Medicines used to lower the eye pressure either reduce the production of fluid inside the eyeball, or they help the fluid to drain out of the eye more easily. Medicines that do the former include beta blockers such as Timolol, Brimonidine (Alphagan), and Dorzolamide (Trusopt). Others that help with drainage include the prostaglandin analogues Latanoprost (Xalatan), Travaprost (Travatan) and Bimatoprost (Lumigan).

In most cases of glaucoma, long term use of the medication is required. When the medication is stopped, the pressure starts to rise again, and optic nerve damage gets worse with enlargement of blind spots. It is very important therefore, that glaucoma patients do not stop using their eyedrop unless their doctor says it is OK to do so.

As with any medication, glaucoma medicines may have side effects. The most interesting concern the prostaglandin analogues. They do not cause any serious life or sight threatening side effects, but often make the eye redder than normal. This effect can persist for some months, and then often gets better by itself. They also make the eyelashes longer, an effect which has been exploited in the eyelash lengthening treatment called Latisse.

Another cosmetic side effect that is often undesirable is the changing of the iris colour, usually from a lighter blue or green colour to a browner colour, as seen below.

In cases of glaucoma where the front of the eye is narrow, a laser procedure called a laser peripheral iridotomy may be performed (See figure below-the two black dots are small holes in the iris made by a laser; the video below shows the procedure being performed with an Nd:YAG laser). This is a simple procedure performed in the clinic and may take 15 minutes to complete. It helps to improve fluid flow out of the eye despite the narrowness of the anterior chamber.

In some patients, medical or laser treatment fails to lower the eye pressure, necessitating surgery. In the most common operation, a new channel is created for fluid to drain out of the eyeball. This operation is called a ‘trabeculectomy’. To facilitate drainage, sometimes a metal tube (called the ExPRESS shunt) is used as well. In some patients where trabeculectomies have previously been performed but eye pressures have increased again, silicone drainage tubes may be implanted for better fluid flow out of the eye and pressure control.

Glaucoma in the long term

Many people with glaucoma are worried about blindness. However, most glaucoma patients do not become blind. The most important factor is control of the eye pressure, which is achieved either with the use of eyedrops or surgery. If eyedrops are regularly instilled, and eye pressures are well controlled, vision is usually well preserved.

However, patients should realise that damage to the nerve before treatment was started cannot be reversed. The aim in glaucoma treatment is to stabilise the condition, and in most patients vision is maintained for life.