Understanding Glaucoma

Glaucoma is the name given to a set of eye disorders caused by an increase in pressure within the eye. If left untreated, it results in damage to the optic nerve and loss of sight. A brief summary of processes that normally take place in the eye is necessary to explain how glaucoma can develop:

An aqueous fluid or humour is produced by cells located behind the iris and flows through the pupil into an anterior chamber located between the cornea and the iris. The aqueous fluid is then filtered and absorbed into the bloodstream via minute channels called the trabecular meshwork. A healthy eye maintains a balance between aqueous fluid input and its elimination into the bloodstream. The balance of this process is disturbed when too much aqueous fluid is produced and not eliminated quickly enough through the trabecular meshwork or if the latter fails to drain sufficiently due to blockage. The result of this imbalance of flow leads to pressure within the eye where the following destructive process ensues:

– The lens is pressed back against the vitreous body.
– The vitreous body presses against the retina.
– The retina presses against the choroid, thus restricting the supply of blood to the retina. – As a result, the retina cells die leading to damage of the optic nerve and ultimately blindness.

An Explanation of Glaucoma Disorders

Primary Open-Angle Glaucoma (POAG)

The most common type of glaucoma is POAG and is usually found in people over 50. People of African descent are particularly affected by this disorder and may need treatment at a younger age. Diabetes may also be a contributing factor. The symptoms include a gradual weakening of peripheral vision resulting in ‘tunnel vision’ and blindness if left untreated.

Deterioration of sight in this disorder is painless and may not be heeded for some time by the sufferer, therefore regular eye tests are advisable for early detection, treatment and resolution.

Acute-Angle Closure Glaucoma

Acute-Angle Closure Glaucoma is less common than POAG and is characterised by pain, nausea, red eye, a sudden deterioration of vision, and coloured circles around white light may be experienced. Immediate medical attention is imperative because there is a rapid increase of pressure within the eye. The aqueous fluid is unable to drain away through the channels of the trabecular meshwork due to the exterior rim of the iris and the cornea coming into contact.

Secondary Glaucoma

This type of Glaucoma is initiated by a primary cause either from an injury, an operation or side-effects induced by some medications.

Congenital Glaucoma

Congenital Glaucoma is a rare condition found in babies and children. It affects 1 in 10,000 infants and is usually detected between the ages of 3 to 6 months.

Ocular Hypertension

There is no damage to the optic nerve but there is a high eye pressure of 22mmHg and above.

Low Tension or Normal Glaucoma

The pressure within the eye is low or normal; however there is damage to the optic nerve. Treatment is the same as for POAG.

Laser Treatments Available on the NHS

The NHS is able to offer laser eye treatment for Glaucoma which includes the two commonly used types of laser eye surgery for the condition, one for POAG and the other mainly for closed-angle glaucoma, although some POAG patients may receive the latter. These operations are performed under local anaesthetic and there is no need for a hospital stay.

Laser surgery is usually a once-only procedure, although the operation can be repeated if necessary. Eye-drops are prescribed to stabilise the eye pressure during post-operative care.

The two types of laser eye surgery offered by the NHS are:

– Laser Trabeculoplasty – a treatment to improve drainage of the trabecular meshwork by creating a new channel in the white of the eye, known as the sclera.

– Laser Iridotomy – a treatment available for patients with (or at risk of) closed-angle glaucoma as well as POAG sufferers. A new drainage channel is made through the iris for the aqueous fluid to escape.

Finally, there is an another type of laser surgery called the cyclodiode laser treatment. This decreases pressure within the eye by destroying a portion of the eye tissue involved in the production of aqueous fluid, thereby reducing the amount of fluid produced.

The Cost of Private Treatment – A Rough Guide

The price of a laser eye operation on both eyes costs the NHS around £930; the cost of private treatment is about the same or may be more expensive. When having private treatment it is important to consider the added costs of initial consultation, tests, scans and post-operative reviews. Private consultations can range from £135 – £195, while tests can cost anywhere between £50 and £195 depending on which tests are required.

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