Conditions

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Cataract

WHAT IS A CATARACT

A cataract is a condition in which the lens of the eye becomes progressively opaque resulting in reduced vision.

LENS

The crystalline lens of the eye is present inside the eye and is part of the focusing system.  Movement and changes in shape of the lens helps the eye focus on objects.

When we are born the lens of the eye is perfectly and optically clear.  When the lens begins to come opaque it is known as a cataract and the vision is subsequently affected.

There are many causes of cataract formation, the main one being age related.  Other causes include trauma, medications and systemic conditions such as diabetes mellitus.

A cataract can cause differing types of symptoms including

• Cloudy or hazy vision
• Difficulty with bright lights – photophobia
• Halos and glare
• Loss of colour perception
• Becoming more short sighted

Treatment of cataract – click here

Astigmatism

Virtually everybody has some degree of astigmatism that can reduce their vision without glasses or contact lens.

Astigmatism in its simplest form is where the cornea or front of the eye is not perfectly round, like a football.  With astigmatism the cornea is perhaps shaped a little more like a rugby ball and this can degrade your vision.

At surgery we will try to reduce the amount of astigmatism, by performing relaxing incisions in the cornea to reshape it.  Unfortunately it is sometimes not possible to reshape the cornea sufficiently and therefore you may still have some residual astigmatism post operatively which may prevent best uncorrected vision, which means you may still require glasses, either for reading and distance.

Posterior Capsule Opacification

When we remove a cataract at surgery we leave a small membrane (posterior capsule) behind in the eye that supports the implant.

At the end of cataract surgery this membrane is usually perfectly clear and transparent but in some people as the months or years go by this membrane can thicken up(opacify) and start to obscure the vision again.

The YAG laser is able to make an opening in this thickened capsule or membrane.  This enables you to see through the opening and improve your vision again assuming the rest of the eye is healthy.

Glaucoma

There are various different types of glaucoma but essentially the condition arises if the pressure inside the eye (intraocular pressure) is too high for the eye.  If this occurs then damage will occur to the eye.

The damage that occurs is a reduction in the visual field of the eye or the peripheral vision.  This peripheral vision becomes less sensitive and then disappears gradually over time. The peripheral vision can slowly march towards the centre of the vision and if no treatment is undertaken the central vision of the eye can be lost resulting in blindness.

The best way to think of glaucoma is to think of the eye as a ball. Fluid is continually being pumped in to the eyeball and is continually draining out in another part of the eye.

In glaucoma either the pumping of fluid in to the eye is too fast or the drainage of fluid from the eye is too slow.

As a result of this the pressure inside the eye elevates and causes damage to the eye.

TYPES OF GLAUCOMA

There are essentially two types of acquired glaucoma.

Acute Angle Closure Glaucoma  – In this condition the pressure inside the eye elevates very rapidly and results in a painful red eye with reduced vision.  If this is not treated very quickly it can result in permanent loss of vision in the eye.

Many types of drops and tablets are required to reduce the pressure and following this the eye may require laser treatment in the form of a peripheral iridotomy.  For this treatment a small hole is made in the iris, or coloured part of your eye, with the laser to try and help the circulation of fluid in the eye and reduce the pressure.

If this does not reduce the pressure sufficiently then further surgery may be required to do so.

The surgical gold standard at present is known as a trabeculectomy.

Chronic open angle glaucoma – In this condition the pressure inside the eye gradually elevates and slowly damages the eye.

To reduce the pressure inside the eye drops are put in to the eye.  These drops can either reduce the amount of fluid being pumped in to the eye or they can increase the drainage of fluid from the eye.  Some drops are used once a day whereas others may be used up to four times a day and often multiple drops can be used.

In some patients the pressure does not reduce low enough and tablets (Diamox – Acetazolamide) can be added to the drop regime.

The intraocular pressure and the visual field damage dictate the number of drops and/or tablets required.

If the drops and/or tablets do no control the pressure inside the eye sufficiently then one has to consider further alternatives including, laser treatment to the eye (laser trabeculoplasty) and/or formal surgery (trabeculectomy).

MONITORING OF GLAUCOMA

We monitor glaucoma by:

• Measuring the intraocular pressure
• Plotting the visual fields
• Scanning the optic nerve of the eye
• Photography of the optic nerve

Intraocular pressure – This is measured with a small prism that comes near to the eye and is used with blue light and fluorescent dye.  You may have had the pressure checked at your Optometrists previously with an air puff type tonometer.

Visual Fields – The visual fields are plotted via a computerised system. You will simply be asked to press the button every time you see a light in your peripheral field and is painless.

Optic Nerve Scan – We have the latest Heidelberg Spectralis scanner.  This is able to scan the nerve fibre layer at the back of your eye and can detect changes before other methods and is a helpful test in diagnosing and monitoring glaucoma.

Photography of the optic nerve – This allows direct comparison of the nerve at the back of your eye over time.

SURGICAL TREATMENT OF GLAUCOMA

Laser trabeculoplasty and Trabeculectomy can be used to reduce the intraocular pressure of the eye and help prevent further damage.

Treatments click here

Age Related Macular Degeneration

Age related macular degeneration is one of the leading causes of visual loss in older individuals.

There are essentially two different types of AMD

1. Dry (atrophic)
2. Wet (neovascularisation)

RETINA

The retina is a fine layer of tissue that is responsible for allowing us to see.

The simplest way to think of the retina is to think of it like wallpaper.  In a room of your house the wallpaper lines the inside wall of your room.  Likewise the retina lines the inside wall of the eye as a thin film.  The macula would be an area of the retina at the back of the eye.

If there is any disturbance of the retina or macula area then vision is affected.

THE MACULA

The macula is an area of the retina that is responsible for fine vision.

DRY AMD

In this condition the retina begins to show its age by thinning and wearing out.  In the early stages this may not cause any visual symptoms but as time progresses the central vision can deteriorate.

Close vision is usually affected early, whereas distance vision may be preserved longer.

WET AMD

In wet age related macular degeneration very small blood vessels can grow under the retina for reasons we do not fully understand.  These small blood vessels distort the macula area and cause distortion of vision.

This distortion is usually in the form of straight lines appearing bent or wavy.

These small blood vessels can leak fluid or blood under the macula that causes further distortion of the macula and hence further distortion of vision.

One can sometimes get small blister-like areas in the macula that are full of fluid or blood similar to the bubbles one can get with wallpaper (one must remember that it is air present under wallpaper and not fluid).

If left untreated the central area of the retina responsible for fine vision can be permanently damaged.

Any treatment required must be received as soon as possible. The longer the disease process continues without treatment, then there is less likelihood of retaining good vision.

Retina

The retina is a fine layer of tissue that is responsible for allowing us to see.

The simplest way to think of the retina is to think of it like wallpaper.  In a room of your house the wallpaper lines the inside wall of your room.  Likewise the retina lines the inside wall of the eye as a thin film.  The macula would be an area of the retina at the back of the eye.

If there is any disturbance of the retina or macula area then vision is affected.

The retina can be affected by a variety of disease processes.

RETINAL TEAR

Occasionally a tear can develop in the retina.

This is often preceded by the patient developing flashing lights and floaters together in the same eye.  These are important symptoms and require investigation.

Using the analogy of the retina as wallpaper, if we develop a tear in the wallpaper or the retina then fluid can pass through this small tear and progress behind the wallpaper or the retina.  This causes the wallpaper to strip off from the wall or the retina to strip off from the wall of the eye. At this stage it is called a retinal detachment and if the retina detaches this can cause some loss of vision and even complete loss of vision in the eye.

We therefore try and seal any retinal tear with a laser to prevent fluid causing such a retinal detachment.

This usually requires to be done as an urgent procedure/operation.

On occasions the laser may not be applied soon enough or may not have the desired effect and a retinal detachment may still occur.

If a retinal detachment occurs then surgery to stick the retina back in place is required.

If you are very shortsighted, you are at higher risk of retinal problems.

RETINAL VEIN OCCLUSION

In this condition the major blood vessels that supply the retina can become blocked.   This can cause sudden deterioration of vision, depending on which blood vessel is affected.

It is often found in patients with high blood pressure even if the blood pressure appears to be well controlled.

When the blood vessels block, the build up of pressure behind the blockage can cause leakage of fluid and blood from the blood vessel.   This can affect your vision.  In addition, at a later date, abnormal new blood vessels can form which are very fragile and can bleed easily. This can cause further loses of vision.

The 532 nm laser can be used to prevent further deterioration of the retina.  It is unlikely that the laser will improve your vision but is used to stabilise the retina and try and prevent further complications arising.

Intravitreal antiVEGF injections can also be used in retinal vein occlusion to try and disperse the build-up of fluid (macular oedema) that may occur in the retina.

They can help prevent complications and in a small percentage of patients there may be some visual improvement.

Unfortunately most of the damage to the vision in retinal vein occlusion occurs almost immediately after the occlusion occurs.

DIABETIC RETINOPATHY

Diabetes mellitus can affect the retina at the back of your eye.   This is called diabetic retinopathy and if left untreated can affect your vision permanently.

It is more common to have diabetic retinopathy the longer that you have had diabetes mellitus.

In diabetic retinopathy some of the blood vessels can become blocked and others can leak or bleed.

Abnormal new blood vessels can form which can also bleed and this can lead to scarring and also detachment of the retina that can seriously affect the vision.

The 532nm laser is used to destroy any new blood vessels and so prevent them bleeding.   It can also seal leaking blood vessels.

The aim of the laser treatment is to stabilise the retina and to try and prevent it deteriorating.

In some cases the laser can beneficially affect the retina and improve vision, particularly when it prevents leakage from blood vessels.

If left untreated the retinopathy may deteriorate causing irreversible damage to your eye and your vision.

Diabetic retinopathy usually affects both eyes and both eyes will often require laser.

It is still very important for you to obtain good and consistent control of your diabetes and also good control of your blood pressure otherwise laser will have very little effect.

Intravitreal antiVEGF injections can also be used in diabetic retinopathy/maculopathy to try and disperse some of the fluid (macular oedema) in the retina.

Laser

LASER

LASER stands for Light Amplification by Stimulated Emission of Radiation.

A laser is a machine that produces an intense beam of light that can be focused on certain tissues in the eye to produce a controlled thermal burn or cutting effect.

Indications for laser treatment include:

Retina

Diabetic retinopathy/maculopathy

Retinal vein occlusion

Retinal tear

Age related macular degeneration

Glaucoma

Laser trabeculoplasty

Ciliary body diode laser

YAG laser peripheral iridotomy

Posterior Capsule Opacification

YAG laser capsulotomy