Glaucoma is an eye disease that affects the optic nerve that takes the messages received by the retina and transmits them to the brain.

Open angle glaucoma is an insidious form of glaucoma in that it develops extremely slowly, with few obvious signs or symptoms, and can proceed to a state where vision is severely affected, even lost altogether.

What is scary is that for a patient to realise that their vision is affected by glaucoma, they will need to lose approximately 60% of the optic nerve for it to make an impact on their perception.  THIS IS TOO LATE!  Regular eye testing will find glaucoma in the early stages when treatment is the most effective.

The eye has many components working in harmony to give us sight.

Behind the cornea at the very front of the eye is an aqueous fluid that fills the gap between it and the iris. The fluid needs to be replenished meaning that it also has to drain away – it does this by passing through a very fine strip of mesh called the trabecular meshwork. The mesh is located at the join between the inside of the cornea and the ciliary muscles holding the eye lens.

It’s the angle between the cornea and the iris being up to 45 degrees where the mesh is located that gives this particular type of glaucoma its name. (If the angle is reduced to the state where the iris comes in to contact the cornea, thereby preventing drainage and immediate and painful increase in pressure, then that type of glaucoma is called a closed angle glaucoma)

If the fluid does not drain away correctly, then there is a build up of pressure (called intra ocular pressure or IOP) in the eye, which leads to degeneration of the optic nerve.

How to detect open angle glaucoma

It’s not easy!

It’s not called the “silent thief of sight” for nothing – an open angle glaucoma, since it doesn’t produce the pain that the closed angle glaucoma does, may go entirely unnoticed as it develops, to the stage where vision is seriously under threat.

The most effective way to detect an open angle glaucoma is by means of regular eye examinations carried out by an eye doctor such as an optometrist or ophthalmologist.
Both professionals carry out screening for glaucoma by measuring intra ocular pressure (IOP) with a tonometer, one type of which introduces a puff of air on to the eye. The machine measures the eye pressure by ascertaining how light reflections are changed by the air hitting the eye.  Another type of tonometer is called the Goldmann – this requires an anaesthetic as the instrument very gently touches the front of the eye.
In addition the rear of the eye and particularly the optic nerve will be examined to check for rim appearance and changes in blood vessels.

Treatment

Management rather than treatment is the course of action to be undertaken, beginning with taking steps to reduce intra ocular pressure. Eye drops, sometimes more than one type will control up to 90% of glaucoma.

Inevitably the use of medications can produce side effects, which on occasion persuade the patient to forego treatment, which is a serious overall problem in the management process – it’s important that the patient discuss any side effects with their practitioners as it is often a simple matter of change of prescription or mode of application.

Increasingly surgery is being utilised to perform very small changes to drainage of the meshwork to alleviate eye pressure.

Overall early diagnosis means early treatment, which means better outcomes.

The way that glaucoma creeps up on you without you knowing is one of the reasons it’s called “the silent thief of sight”.

To understand how glaucoma develops and how it affects sight it’s useful to know something about the workings of the eye:

•    An eye works like an old fashioned (non-digital) camera where light from an image – after going through the opening shutter – is focused using a lens onto a plate or film at the rear of the camera

•    In the case of the eye the pupil and cornea form the “shutter” whilst a flexible lens focuses the image on to the retina, a light-sensitive layer at the back of the eye

•    Unlike a camera which is basically empty, the eye is filled with a liquid called an “aqueous humour” which is under a slight pressure; the pressure is called intra-ocular pressure, or IOP for short.

•    An optic nerve transmits the signal from the retina to the brain.

Now we’re ready to understand what glaucoma is.

If the intra ocular pressure becomes too much, and it’s easily measured, then it can affect the optic nerve to such an extent that it degenerates and sight is gradually lost since no image can be received by the brain.

In other cases the blood vessels that supply the optic nerve can be affected leading to the same outcome of vision loss.

Symptoms of glaucoma

One stand out symptom is of course an increase in intra ocular pressure, noting that it’s an INCREASE that’s relevant, as people have different values much in the same way as they have different blood pressure values.

It’s essential then to have regular eye examinations to pick up any increase, especially for those with a high risk:

•    Anyone taking prescribed corticosteroids – quite a few people do these days for a wide variety of conditions related to auto-immune deficiencies

•    Those with some sort of history of glaucoma in the family

•    Cardiovascular disease

•    Migraine suffers – especially females

•    Anyone having both short or long sightedness

Types of Glaucoma

There are two basic types – “open angle” and closed angle” – depending on the degree of flow of aqueous humour that is allowed to drain through a very fine mesh. Open angle glaucoma allows more flow than its closed angle counterpart

Open angle glaucoma makes up 90% of all cases, and because there are few if any signs or symptoms, apart from maybe unnoticeable vision loss, the condition may go undiagnosed.

Closed angle glaucoma can happen quite quickly, and since it’s often accompanied by some pain referral to an optometrist or ophthalmologist is usually made, leading to action to prevent vision loss.

With closed angle glaucoma accounting for 10% of cases it seems that there is no room for any other types. However there are other types caused by congenital defects, diabetes and use of corticosteroids.

Asians on the other hand are more likely to have the “closed angle” variety due to genetic differences.

What can be done?

The main thing to de done once a diagnosis has been made is to manage the condition to prevent further deterioration and importantly vision loss.

Lowering the intra ocular pressure (IOC) still remains the most effective management technique. Lowering can be achieved through use of drugs or eye drops as well as surgery.

Gradual loss of vision, especially in the elderly, can lead to increased risk of falls which will in turn exacerbate things, so re-education in balance and movement – however basic that may seem – can prevent a catastrophe!

What is key to understand is that regular eye examination will pick up glaucoma.  Studies have demonstrated that for a person to realise that there is something wrong with their vision and glaucoma ultimately is the reason – at this point of patient recognition, they have lost 60% of their vision.  This of course is way too late, so make sure you have a comprehensive eye test at least every two years.

What is to follow?

Glaucoma is a very important eye condition so will discuss it in detail over the next few posts.

Fortunately the occasions on which this happens are quite rare, but nevertheless it does happen, and it’s good to know what to look for by way of symptoms and what to do by way of seeking medical help.

Herpetic retinitis is a particularly serious variant of eye herpes.

The virus

The basic herpes virus called “Herpes Simplex Virus” (HSV) type 1 is responsible for millions of people worldwide waking up one morning and out of the blue having a tingling feeling on the top lip – it’s the beginning of a cold sore!

By the way there are over the counter proprietary medications that can stop the cold sore developing further, but you have to be quick! An easier home remedy is to hold an ice cube on the spot where the tingling sensation is for as long as you can stand the pain – it works!

The type 1 herpes virus lies dormant in a big proportion of the population, almost certainly acquired as children from being kissed on the lips by a loving family member who has the virus.

Now it’s no big deal to have a cold sore once a year as it goes away fairly quickly, and no-one seems all that perturbed looking at you – but if the virus spreads to the eyes then that’s another matter.

About 0.2% of those people who have the type 1 virus contract ocular (eye) herpes, by chance perhaps but probably by transfer through touch.

The type 2 virus is a degree worse since it affects the genital area, and fortunately it’s quite rare for transfer to the eyes.

The range of eye herpes diseases

The herpes virus can attack and inflame various parts of the eye, starting at the front surface and moving to the very back with the seriousness of the disease increasing:

•    At the very front – herpes keratitis affects the top layer (the epithelium) and is readily treated. An optometrist is sometimes able to clear up the affected area using initially only a cotton swab. It is better though to treat it with Zovirax ointment that has been made specifically for the eye.

•    Deeper into the eye, the stroma is the middle layer, and the inflammation is appropriately called “stromal keratitis”. Without treatment scarring of the cornea can be the result.

•    Even deeper into the eye “herpetic uveitis” affects the area from the iris to the choroid further to the rear. Treatment involves the prescription of corticosteroids and the problems that can arise from that medication regime.

•    To the very rear of the eye is the retina images are formed and sent to the brain – this is an extremely vulnerable area obviously so that any inflammation or infection can have serious consequences. Without effective treatment there is the possibility of retinal detachment leading to blindness.

Symptoms

Particular and unusual symptoms are “floaters” appearing to be seen by the patient – these are imaginary cobweb-like structures that are generated by changes in the internal gel of the eye.

Gradual loss of visual accuracy in one eye.

Treatment

Initially treatment is similar to those for stromal keratitis and herpetic uveitis, with acyclovir prescribed, but with higher dosage and at times even applied intravenously.

If retinal breaks do appear then laser surgery is preferred before conventional surgery, and finally a vitrectomy procedure can be carried out, which involves a lengthy process of replacing the gel inside the eye with fluid under pressure to maintain integrity of the retina.

Since 90% of cases of Uveitis are anterior they are often called by another name “iritis”, and eye-care specialists use the terms interchangeably.

Although it’s not certain what causes the various types of uveitis, if the herpes simplex virus (HSV) is thought to be responsible, then the inflammation will be given the specific description “herpetic uveitis”.

In line with most cases of uveitis being of the anterior type, accordingly most cases of herpetic uveitis are the same – anterior type.

The disease is quite rare with an incidence of only 1 in 200,000 of population.

How does the herpes virus figure in uveitis?

There are two types of herpes simplex virus – type 1 is the one that lies dormant in millions of people and gives rise to cold sores or lip blisters, and is probably contracted from being kissed as a child by family members.

The herpes virus in this case can either stimulate uveitis by itself or be contracted through firstly touching the lips and then the eyes. The vast majority of cases of herpetic uveitis stem from the type 1 virus.

The type 2 herpes simplex virus is centred in the genital area and it is quite rare for it to migrate to the eyes. Cases of transfer have been noted with babies born from mothers with the type 2 disease.

It’s fortunate that herpetic uveitis comes from the type 1 as it is readily treatable – when from type 2 the treatment is more complicated as the disease is more serious.

Signs and symptoms

General symptoms include quite a few of those found in many other eye diseases, so diagnosis is difficult without tests and examinations as there are none that point directly to the herpes association.

•    Light sensitivity

•    Migraine-like eye pain

•    “Pink eye”

•    Vision is blurry

•    Repeated infections

Symptoms found upon examination:

•    Intra ocular pressure – usually with standard uveitis it is low, but with herpes it may be higher than normal

•    Pupils may be dilated even though no dilating drops have been introduced

•    If an anaesthetic is introduced to carry out the examination and the pain associated with the general symptoms persists, then the presence of anterior uveitis itself is not probable.

Treatment

Topical corticosteroid eye drops such as prednisolone are applied, together with acyclovir taken orally (a brand name being Zovirax) and used to treat herpes.  In severe cases oral prednisolone might be required.

Care has to be taken with the use of steroids since they are used in many auto-immune deficiency situations and too quick a reduction in dosage is liable to cause recurrence or complications; a programme of tiered withdrawal needs to be drawn up.

But relax, the chances of that happening are quite rare, and in any case timely consultation with your optometrist will prevent the worse from happening.

So how does Stromal Herpetic Keratitis in the eye occur?

The simplex Herpes Virus (referred to as HSV) comes in two types, both of which can transmit infection to the eye.

Type 1 HSV is the herpes that occurs on the lips that affects millions of people each year and erupts into cold sore blisters. They normally do not need any particular medical attention, although there are proprietary treatments to prevent them from happening once they are detected.

Type 2 HSV affects the genital area and associated eye infection is rare.

A note on cold sores

Proprietary treatments are no more than remedies in the main, and it has been pointed out by the dental profession (dentists obviously see quite a few) that if a cube of ice straight from the freezer is held hard on the place where the tingling sensation of a forming cold sore is, and for as long as the pain can be endured, it will effectively stop it developing!

Why don’t you try it next time?

Who gets stromal herpetic keratitis?

Stromal keratitis occurs in people who have had type 1 HSV – it may have been dormant for years – and the immune response is low. When a new bout occurs it may be that this time it might just START in the eye.

Alternatively it can be transmitted during a cold sore outbreak by touching (so oral to eye hygiene is of paramount importance!)

The stroma part of the eye is a deeper middle layer of the corneal layer, and so any inflammation from a keratitis can be quite serious without effective treatment.

Treatment

Treatment of stromal keratitis is similar to that for epithelial keratitis (which affects the outermost layer of the cornea) except that some steroid eye drops may be prescribed in addition to the antiviral ointment and eye drops to further reduce inflammation.

With stromal keratitis it is important to closely supervise the use of the steroids in terms of frequency and strength as they can have adverse effects on treatment and recovery.

What to look for next time

Any herpes related disease is more than likely to reoccur. These reoccurrences may be anything from many months to years.

If the reoccurrences become frequent (and increasingly annoying) then your eye-care specialist might prescribe a regime of regular medication to alleviate the problem. Anecdotal evidence suggests that reoccurrences can be delayed for twice as long by taking an oral anti-viral called Acyclovir.

It should be remembered that frequent infections will gradually increase corneal scarring to the extent that vision loss will be the result, so some attention to frequency is required.

Can anything be done?

Yes.

Stay out of strong sunlight, or otherwise wear wrap around sunglasses, and avoid stress. Even if these continued actions don’t actually do anything, they won’t do any harm and is practical advice in terms of lifestyle.

Herpes keratitis is the most common of the eye herpes and also goes by the name herpetic epithelial keratitis – it affects the cornea on the top superficial layer of the surface of the cornea, and since this layer is called the epithelium the adjective epithelial is applied to it.

(If the herpes virus attacks the eye deeper than the epithelial layer and enters into the stroma, then things become more serious and a new name is given to the disease – herpetic stromal keratitis).

Eye herpes, or ocular herpes as it’s sometimes called, normally comes from type 1 herpes – the cold sore type – but on rare occasions it can come from type 2 herpes which affects the genital area and is far more serious.

Whilst herpes cold sores can be treated by oneself without resort to a visit to the doctor, any kind of eye herpes needs to be brought to the attention of therapeutic optometrist or an ophthalmologist for urgent attention.

Great care needs to be taken by the eye-care professional in determining which variation is present as treatments are specific and an inappropriate treatment can lead to aggravation.

Symptoms

A past symptom is the occurrence at some time or other of type 1 herpes – cold sores on the lips.

Eye pain, sensitivity to light, blurred vision and “pink eye” are regular symptoms with excessive tearing being an additional discomfort. All of these symptoms are indications of other eye diseases and infections, particularly conjunctivitis, so an accurate diagnosis for epithelial keratitis is often fraught with difficulty.

Diagnosis requires careful examination with a microscope specific for eyes called a biomicroscope.  This is not a diagnosis that a general practitioner can make and it is certainly not something that you would go to the pharmacist for over the counter drops.

Very often a patient has recurring bouts of the disease. It is essential in such cases that the services of an eye-care specialist such as an optometrist are sought early as loss of vision might be a long term outcome.

How prevalent is the disease?

Millions of people have a dormant herpes virus inside them from being unintentionally infected by family members kissing them as a young child on the lips.

Fortunately less than 1% of those people will ever have an episode of general herpes, and then less than 1% of those will suffer from epithelial keratitis.

Over the years the disease has become more frequently diagnosed and it’s thought that the increased acceptance and wearing of contact lenses is postulated to contribute.  In thirty years of practice I (Dr Jim Kokkinakis) have consulted with thousands and thousands of patients wearing contact lenses.  Of all the cases of epithelial keratitis that I have seen, to date I cannot remember seeing one case that has coincided with contact lens wear.  Even though this could be just a sheer coincidence it is unlikely that contact lenses a definte trigger for herpes keratitis.

Treatment

As mentioned earlier, care is needed in accurately identifying the particular epithelial keratitis as treatment is specific.

An antiviral topical ointment (Zovirax) or alternatively eye drops should be applied – not to eradicate the virus entirely but to slow its growth until nature takes its course and the infection clears up – a sound way to do things!

It’s important then that the full course of treatment is followed – many eye-care specialists complain that patients do not do this, thinking that their condition has cleared up when this is simply not the case.

The ultimate objective of any treatment is to prevent any long term damage that may occur in the cornea.  Recurrent cases are particularly dangerous to a favourable long term outcome.  In these cases oral Acyclovir or related oral antiviral called Famvir are prescribed ongoing as a prophylactic to recurrence.