AMD causes problems with your central vision, but does not lead to total loss of sight and is not painful. AMD affects the vision you use when you're looking directly at something, for example when you're reading, looking at photos or watching television. AMD may make this central vision distorted or blurry and, over a period of time, it may cause a blank patch in the centre of your vision.

There are two types of Age Related Macular Degeneration, Dry and Wet.

Dry Age Related Macular Degeneration

The macular is the part of the retina with which we get our detailed central vision. The macula area has a very high metabolic rate and as we get older waste products can begin to be left under the macula forming what are called drusen, when you are shown your retinal photo these show up as yellow spots. These yellow spots can sometimes coalesce together and areas of the macula can die off and degenerate, this happens very gradually over many years.

Occuvite Eye vitamins

There is no treatment for dry ARMD however there is some evidence that certain vitamins and eating green vegetables can reduce the rate of progression.

Wet Age Related Macular Degeneration

Sometimes the eye responds to the degeneration by producing new blood vessels under the macula these blood vessels are leaky and they may cause a leak of fluid or a bleed under the retina. This can lead to sudden loss of vision and/or your vision may look wavy.

How things might appear to someone with macula degeneration

If this happens it is important to contact us so we can refer you or your ophthalmologist as soon as possible as there is a treatment that needs to be given quite soon. The treatment may involve an injection of a drug into the eye by an ophthalmologist that stops the new vessels from growing and leaking. Wet ARMD is the leading cause of blindness in the United Kingdom.

If we suspect ARMD we may advice you to have an OCT performed which takes a picture with a laser of the layers of the retina and shows up any fluid underneath.

We may also ask you to look at an Amsler chart – a chart of horizontal and vertical lines to see if any of them are wavy. We may also give you an amsler chart to take home and look at with each eye once a week.

Sometimes we describe it as the eye being shaped like a rugby ball instead of a football. A lens must be used the brings the two foci onto the same point on the retina. In your prescription this is the second number with a minus sign in front of it. The number after this - the axis, tells us the direction the distortion is occurring in.

Astigmatism is caused by light being focussed at two points instead of one, a lens to bring the two foci together must be used

Vision through a clear lens

Vision through a cloudy lens

Light being focussed on one part of the retina

Light being obscurred

Cataracts are a very common eye condition. As we get older the lens inside our eye gradually changes and becomes less transparent (clear). A lens that has turned misty, or cloudy, is said to have a cataract. Over time a cataract can get worse, gradually making your vision mistier. A straightforward operation can usually remove the misty lens and replace it with an artificial lens to enable you to see more clearly again. Cataracts can be caused by a number of things, but by far the most common reason is growing older . Most people over the age of 65 have some changes in their lens and most of us will develop a cataract in time.

The tear film at the front of the eye is actually the most important for being able to see clearly it provides a smooth film over the front of the eye and allows the light to pass through easily. Tears are actually made up of several components and when on the eye they form into three layers. The lipid layer is the outermost layer, made up of oils produced by the meibomian glands on the lids. This layer stops the watery layers underneath from evaporating too quickly. The next layer is the aqueous (or watery) layer that keeps the eye well lubricated and supplies oxygen to the front of the eye, it is released by the lacrimal glands (which are also stimulated when we cry). The layer closest the eye is the mucin layer. Mucins are sticky substances released by the goblet cells of the lids and conjunctiva, they help stick the tears to the front of the eye. A deficiency in any of these three layers can cause dry eye.

The Tear Film has three layers, the lipid layer, aqueous later and mucin layer

Diagnosing dry eye

Tear Break Up Time

Dry eye can be diagnosed using your symptoms and also by looking at the tear quality using the slit lamp and flourescein dye. A normal tear film will not break up on the eye for at least ten seconds, in dry eye the tear film breaks up (leaving uncovered areas) in less than five seconds. The dye will also show up any areas of the eye that are not getting enough tears on them and are drying up. The glands that release the oil onto the eye will be inspected to see if there are any blockages.

The Tearscope from TearLab measures the osmorality of the eye

The tearscope can be used to measure the osmolarity of the tears which gives a good indication of whether the eye is dry even if there appear to be a lot of tears.

Treating Dry Eyes

Eye drops can be used to soothe dry eyes

Once dry eye has been diagnosed it can be treated in several ways. It is usual to start with artificial tear drops, such as Theratears, Systane, Clinitas Soothe, which replace the tear fluid on the eye. It is better to choose a non-preserved drop as these can be used with contact lenses and are a little bit better for the eye. Artificial tears can be used many times a day as necessary. If the oily layer of the tears is deficient there are now sprays such as Clarimyst which replace the lipid layer specifically.

Eye gels to lubricate dry eyes

If there is staining often a gel will be given as well such as Lacrilube or Viscotears, that can be used at night (the gel blurs the vision temporarily so it is best to use it just before bed).

In rare cases the dry eye is severe and caused by a syndrome called Sjögren’s syndrome. In this syndrome the body has an immune response against its own tear glands which reduces the watery layer of the eye and causes the front of the eye to dry out. This is a very painful condition and usually the saliva glands of the mouth are affected too, giving a very dry mouth. Sjögren’s syndrome is more common in middle aged women.

Blepharitis

Often dry eye is caused by a condition called Blepharitis. Blepharitis is an inflammation of the eyelids usually caused by a reaction to toxins released by the bacteria that live on the skin – usually Stapphylococcus Aureus. Blepharitis can be diagnosed using the slit lamp by the observation of crusting on the eye lids, red eye lid margins, this is called anterior blepharitis.

Blocked glands

If there are blocked meibomian glands (the little glands that release the oil onto the eye) then this is called posterior blepharitis.

Blepharitis can give symptoms like those of dry eye and if the meibomian glands are blocked may reduce the quality of the tears.

Treating Blepharitis

Supranettes

Unfortunately blepharitis cannot be cured but the symptoms can be alleviated. For anterior blepharitis the easiest way to do this is by taking lid hygiene measures. This involves cleaning the margins of the eye lids with either a cotton bud dipped in a mild solution of baby shampoo or using eye lid scrubs such as Supranettes.

To use the cotton bud method you will need a clean dish containing one part of baby shampoo diluted in ten parts of cool, boiled water. Try to gently remove all the crusts from the eye lid edges and from between the eye lashes -

• Using a cotton bud, dip the bud into the shampoo then gently but firmly, rub the soaked tip of the bud along the lid edges and between the lashes.
• Repeat this on upper and lower lid edges. Rinse your face with clean water and dry gently.
• Carry out this procedure twice daily at first - as the condition improves it can be done less often. Use a clean cotton bud for each eye.

If the anterior blepharitis is severe then a course of antibiotics may help. People with Acne Rosacea are unfortunately more likely to suffer from blepharitis.

If you have posterior blepharitis – otherwise known as meibomian gland dysfunction then hot compresses are the first line of treatment. Hot compresses help to melt the oil that is blocking the glands.

• Take a flannel and dip in clean hot (but comfortable on the skin) water.
• Hold the compress against each eye for two minutes.
• Then, if you can, squeeze the lids gently to help express the oil.
• Repeat this twice a day until symptoms improve then periodically to maintain comfort.

Aqueous fluid is produced behind the iris and flows through to the anterior chamber where it drains away at the angle

In the eye aqueous fluid, that baths the cornea and the iris, is produced behind the iris and flows forward where it is drained away at the trabecular meshwork in the angle of the anterior chamber. It is when the ability of the eye to drain away this fluid is reduced that the pressure in the eye rises and damage occurs to the optic nerve leading to visual field defects.

Raised pressure in the eye damages the optic nerve leading to glaucoma

There are two types of glaucoma, open angle and closed angle. Open angle is the most common form of glaucoma and it is believed that is caused by a reduction in the ability of the eye to drain away aqueous fluid even though the angle is not blocked i.e.the angle is open. The pressure rise is gradual and there are no symptoms.

There are many effective treatments for open angle glaucoma therefore it is important to catch it early so treatment can begin before too much damage occurs hence it is important to have regular eye exams. Some of the treatments involve putting drops into the eyes whilst others involve minor surgery or laser treatment to the front of the eye.

Risk factors for open angle glaucoma include: having a high pressure in the eye, old age, ethnicity (afro-caribbeans are more commonly affected) and having a family history of glaucoma. People with a first degree relative with open angle glaucoma should have an eye examination every year after the age of 45.

Closed angle glaucoma is much less common and is caused when the angle where the aqeous fluid becomes blocked or closed. This is more likely to occur in long sighted people and people of Asian oriental ethnicity as they often have smaller angles to start with. Common early symptoms are haloes around lights especially at night and if the glaucoma becomes acute then a red and extremely painful eye, blurred vision, nausea and vomiting. If you have these symptoms you should go straight to eye casualty. Treatments usually include drops and minor surgery to the iris of the eye.

Glaucoma can also be brought on by certain medications such as long term use of strong steroids and also by diseases such as diabetes and uveitis.

The Heidelberg Retinal Tomographer

If you are over 45 then you will usually have the pressure of the aqueous in the eye measured using the puff of air test (non-contact tonometry) or sometimes using applanation tonometry where is a little probe is placed against the eye to measure the pressure. We will also look at the optic disc at the back of the eye for signs of glaucoma using retinal photography and the Heidelberg Retinal Tomographer. In glaucoma the optic disc becomes more cupped as nerve tissue is lost.

The HRT ticks show a normal disc on the left and the crosses indicate a glaucomatous disc on the right

A field being taken and a plot showing a glaucomatous defect

If the pressure is of concern we will usually advise you to have your visual fields measured using the Humprhreys Field Analyser and we may refer you to an ophthalmologist for further investigation and treatment.

When we are young we are able to put extra power into our eyes by changing the shape of our lens (as we do when we look at things that are near) hence we may be able to bring things into focus without the need of a correcting lens. We may prescribe glasses to relax the extra effort. However in middle age the lens loses this ability and long sighted people will need glasses with positive lenses especially for close work.

In order to give a clear image a lens that reduces the power of the eye is used to bring the image onto the retina. As the lens reduces the power if the eye it is a negative lens hence the minus sign in front of the number.

The layers of the cornea. In keratoconus the stroma is affected

The cornea is at the front of the eye and it is performs a lot of the focussing of the eye. The cornea is made up of several layers, the middle and thickest layer called the stroma.

In keratoconus the cornea looks like a cone

In keratoconus – which literally means “cornea like a cone” the stroma thins leading to a loss in structural integrity of the cornea. This causes the cornea to bend over time into a cone shape.

Corneal topography in keratoconus does not show the normal bowtie astigmatism

Keratoconus usually appears before in the late teens or twenties. The first sign of keratoconus is an astigmatism that increases or changes frequently and which doesn’t have the regular bow tie shape when looking with corneal topography.

In the early stages glasses can be used to correct the vision. Eventually contact lenses are needed to give good vision, initially soft lenses can be used e.g. Kerasofts , however it is usual to progress to Rigid Gas Permeable lenses such as Quasar K lenses. The Synergeyes lens and the So2Clear lens are new more comfortable lenses that have designs for keratoconus.

As the disease progresses sometimes the cornea loses its ability to keep water out and what is called hydrops occurs. The scarring from hydrops can lead to loss of vision, however sometimes it improves vision as it can reduce the size of the cone. If severe a corneal graft may be required.

INTACS are plastic semi-circular segments inserted into the cornea to flatten it

There are surgical treatments for keratoconus that may be able to stabilise the degeneration (contact lenses will still be needed) such as cross linking and INTACS. INTACS are plastic semi-circular segments that are inserted into the cornea in an attempt to flatten it, reducing the astigmatism and improving contact lens comfort.

Cross linking is a relatively new treatment for keratoconus, riboflavin (vitamin B2) and ultraviolet light are used to link together the collagen fibres of the cornea leading to increased strength.

In crosslinking Riboflavin and Ultraviolet light are used to crosslink the collagen fibres and strengthen the cornea

In order to give a clear image a lens that reduces the power of the eye is used to bring the image onto the retina. As the lens reduces the power if the eye it is a negative lens hence the minus sign in front of the number.

In presbyopia the lens loses its ability to change shape stopping us focussing things close to us

As we go presbyopic we need to hold things further away to read

When this begins you may notice that you need to hold things further away to be able to read them but after a while things have to be held so far away that they are too small to be read.

In order to give the eye extra power reading, glasses need to be worn. There are several choices: separate reading glasses, bifocal lenses or varifocal lenses. There are also specific contact lenses for presbyopes.

Retinitis means disease or inflammation of the retina. Pigmentosa refers to how the retina appears in this condition, as the retina can have dark spots of pigment. The parts of the retina affected can by the rod or cone receptors. These sometimes are affected from birth or slowly stop over time. Sight loss is gradual but progressive.