About Glaucoma

The eye is similar to a ball, like a Squash ball, filled with clear fluid. This fluid has a pressure, just like a car tyre has an air pressure. The fluid is not a constant thing, but is constantly being renewed: - in the same way that the air in an air-conditioned room is constantly being renewed, so the fluid in the eye is constantly being produced in one part of the eye. Once the fluid has circulated inside the eye for a while, it is drained away. If the amount of fluid being produced exactly matches the amount being drained away, then the pressure of the fluid remains constant. However, if the amount of fluid being drained away is reduced whilst the amount being created is the same, then the fluid pressure will rise. If the pressure rises high enough, it will start to press against the delicate nerve fibres of the retina so much that the nerve fibres become irreversibly damaged. This is what happens with Glaucoma.

There are 2 main forms of Glaucoma: Firstly ACUTE Glaucoma, which has a sudden onset, is very painful, and causes the eye to go red and the vision to go misty. The pain alone is usually enough to make the person seek medical help.

Secondly CHRONIC Glaucoma, which is a slow, insidious disease. The pressure is only slightly too high, and the retinal nerves are slowly damaged over a period of many years. The patient will normally only be aware that there is a deterioration of sight when the disease is well progressed, and treatment cannot restore what sight has been lost. Modern Optician/Optometrist's testing routines are specially tuned to detect Glaucoma well before it causes symptoms, using a variety of techniques from visual Optic Nerve head examination, Intra Ocular Pressure measurement (the "air-puff" test, as it is commonly known), and examination of the Visual Field.

Early detection and treatment will almost always prevent further deterioration towards blindness.

About Cateract

The Crystalline lens of the eye lies just behind the coloured Iris, and is responsible for focusing light when we want to look at things up close.

The lens is normally clear, but a variety of situations from trauma to Ultra-Violet light exposure, side effects of medication to old age, can cause the lens to lose its clarity and become cloudy and opaque. The eye is then said to have a Cateract.
The symptoms of Cateract are connected with the feeling of looking through a haze, and people will say that the world seems misty, or they feel as if their spectacles need cleaning when they are really fine.

For most people with Cateract, whose general health is otherwise reasonably good, treatment is a fairly simple surgical procedure. Most hospital procedures will not require an overnight stay in hospital, and the Cateract is removed and replaced with a clear plastic substitute.

Improvement in sight is usually fairly instant, with the best results occurring after the eye has settled down for 3 or 4 weeks.
Occasionally a thin film of cells can grow over the surface of the implant, causing symptoms very similar to the original Cateract. The treatment for this is usually even simpler than the original Cateract operation, and involves the use of a Laser to remove the extra cells and restore clear vision.

About Retinal Degeneration

The Retina is the fine layer of light-sensitive nerve fibres at the back of the eye, which react to images focused by the Cornea and the Crystalline lens. The Retina is similar in function to the film in a camera.
Normally, one would expect nerve cells to last a lifetime - they normally do not regenerate. If damaged, the effects are permanent.

The Retinal nerves are pretty durable, but they can be damaged by things like poor circulation/ high blood pressure, Diabetes, Glaucoma, exposure to excess Ultra-Violet light, arterial blockages, trauma etc.

One of the most common causes of loss of sight/ blindness in the Western world is Age Related Macula Degeneration (ARMD). This mostly affects people in the 60+ age group, and happens because the micro-circulation behind the Macula (which is the centre of the Retina) begins to fail, leading to the loss of Retinal nerve fibres.

This causes the central vision to become poor, even though the peripheral vision remains good. Strangely, the person affected will often feel as if their sight is almost O.K., except that they cannot read, and find faces difficult to recognise (these are two of the most important tasks that the Macula undertakes).

The Optometrist will try to make reading glasses as strong as possible, much stronger than for use by people without any eye disease, and advise the patient to hold the paper/ book etc. as close as possible whilst using as strong a light as possible. Magnifying glasses can sometimes be used, but if the patient is elderly (as is usually the case), then the holding and positioning that is required with a magnifying glass usually is too much trouble.

Unfortunately there is no treatment for this condition. There has been some reporting in the press recently about new advances with ARMD, but these are trials to do with a small percentage of people with an unusual form of the disease, where the results, though encouraging, are not anything like restoring normal sight to previously blind eyes.

About Diabetic Eye Disease

Diabetes is high on the list of causes of blindness in the Western world. The reason is that Diabetes that is long-standing and/ or severe can cause damage to the blood vessels that nourish the Retina.

The Retinal blood vessels (Arteries & Veins) are supposed to be 'leak-proof', unlike most of the other blood vessels in the body which are prone to a bit of leaking in the normal course of events. Similarly the blood vessels in the Brain, Kidneys and a few other organs are built to be 'leak-proof'. The Diabetic condition can cause the leak-proofing to break down, which can cause blood plasma to leak into the Retina, or even a hemorrhage to occur. These sorts of occurrences can damage the Retinal nerve fibres, causing a situation similar to Macula Degeneration (above).

Just as bad, the Retinal blood vessels can sometimes begin to sprout new branches in an attempt to nourish areas of the Retina that have been damaged. The new blood vessels are very delicate and easily ruptured, which can cause a lot of damage.

The key to successfully avoiding these problems lies in very tight control of the Diabetic condition - i.e. making sure that the blood sugar levels are kept consistently at their normal level. If there is a Retinal problem, it should be monitored very carefully so that preventative laser treatment can be carried out when appropriate.