Eye conditions

How the eye works

The eye is shaped like a ball, and is protected by a tough white covering called the sclera. The cornea is a clear window in the sclera in front of the iris, and lets light inside the eye. The iris is the coloured part of the eye and contracts and expands the pupil to control the amount of light that the eye lets in. Light passes through the pupil, through the lens. The lens and cornea focus light on the retina at the back of the eye. Nerves and blood vessels in the retina form the optic nerve, which then sends these images to the brain.

The eye is filled with liquid which keeps the eye's shape and size. The space in front of the lens is filled with a watery fluid called the aqueous humour, which nourishes the lens, iris and cornea. Behind the lens, the eye is filled with a clear jelly-like fluid, call the vitreous humour.

The ciliary body is behind the iris and around the lens and produces the aqueous humour. In 'normal' eye pressure, the amount of fluid produced is balanced by the amount of fluid draining away. If there is a blockage in the eye's drainage system, fluid in the eye does not drain away properly and the pressure inside the eye increases.

Glaucoma

a condition in which pressure builds up inside the eye damaging the optic nerve.

Glaucoma is a disease that gradually gets worse and it happens when the pressure of the fluid inside the eye is too high, resulting in gradual loss of sight.

Glaucoma cannot be cured but it can be controlled and blindness can be prevented if it is diagnosed and treated early enough.

How common is glaucoma?

Glaucoma is one of the most common causes of blindness that can be prevented. In the UK, 2% of people over the age of 40 have glaucoma.

What is glaucoma?

The eye produces a nourishing fluid called the aqueous humour, which continually flows in and out of the eye, bathing the eye and helping the eye keep its shape.

A certain minimum pressure inside the eye is important to keep the eye's shape and size. In 'normal' eye pressure, the amount of fluid produced is balanced by the amount of fluid draining away. In glaucoma, the excess fluid cannot drain away as it should do because the eye's drainage system is not working properly. This means that the fluid pressure inside the eye increases, leading to increased pressure on the optic nerve. Over time, this increased pressure can damage the small blood vessels supplying the optic nerve. This means that the optic nerve does not receive enough blood supply to work properly. Long-term sight is affected because the optic nerve sends sight images to the brain and if the optic nerve is damaged, sight will also be damaged.

Different types of glaucoma

Primary open-angle (chronic glaucoma

Primary open-angle (chronic) glaucoma is the most common type of glaucoma. It is one of the main reasons for blindness in middle-aged and elderly people. This type of glaucoma is dangerous because often there are no symptoms until late in the disease, by which time permanent damage has already happened.

Primary open-angle (chronic) glaucoma happens when the eye's fluid can drain to

some extent (open angle), but slowly becomes blocked over many years. As the blockage gradually grows, the pressure within the eye gradually increases. The field of vision gradually becomes affected.

Primary closed-angle (acute) glaucoma

In Europe and North America, primary closed-angle (acute) glaucoma is much less common. It happens when there is a sudden and more complete blockage in the flow of fluid from the eye (closed-angle).

Primary closed-angle (acute) glaucoma is often accompanied by severe symptoms as the pressure inside the eye rises rapidly (such as feeling sick, vomiting, sever pain, redness of the eye and losing vision quickly).

There are two other types of glaucoma

When the eye pressure increases because of another eye condition (for example, inflammation or other problems which obstruct the normal drainage of fluid), this is called secondary glaucoma.

There is also a rare condition in babies called developmental glaucoma or buphthalmos, which is caused if the eye does not form properly.

What is a cataract?

So, you may be wondering exactly what a cataract is and why you’ve got one.

A cataract is a clouding of the lens in your eye. As you age, proteins in your natural lens begin to break down and the lens becomes clouded. Some people don’t even realise they have a cataract because it usually grows very slowly and may not impede vision early on.

Cataracts Symptoms

You may experience one or more of the following cataracts symptoms:

A decrease in vision clarity that can’t be corrected with glasses
Colours appear faded or washed out, sometimes with a yellow haze
Sensitivity to light, glare, and seeing halos around lights
Frequent changes to glasses or contact lens prescriptions

Book an appointment

It’s best to see an optician if you think you have cataracts, they will perform a thorough eye check and be able to confirm whether what you’re experiencing are indeed cataracts symptoms and if they’re present in either, or both, of your eyes.

Cataract treatment

Cataracts are pretty common in adults, about 30% of adults aged 65+ will have a cataract that is affecting their vision and requires treatment.

Cataract surgery (which is a relatively straightforward procedure) is the only reliable cataract treatment. It is the most common operation performed today in the UK, with about 450,000 surgeries performed each year. For most individuals this is a straightforward operation, which lasts about 10 minutes, without the need for any needles or injections, as the local anaesthetic is administered using eye drops.

During cataract lens replacement surgery, the cloudy lens is removed and replaced with a new lens implant (called an intraocular lens, or IOL for short). Your new intraocular lens implant will be chosen specifically to match the prescription required for each eye and can help correct long or short-sighted vision if required.

With the NHS, you will usually be offered monofocal lenses, which have a single point of focus. This means the intraocular lens will be fixed for either near or distance vision, but not both. If you go private, you may be able to choose either a multifocal or an accommodating lens, which allows the eye to focus on both near and distant objects.

Dry Eye

Dry eye or more correctly Kerato-conjunctivitis sicca is common amongst the forty plus age group. Affecting females more than males it causes general discomfort, gritty hot eyes, often watery and sometimes difficult to open in the morning.

In the absence of discharge it is best treated with a combination of simple eye ointment at night and hypromellose drops or viscotears gel three times during the day.

What may start initially as a relatively trivial condition, it can cause a great deal of distress and can lead, if ignored or mismanaged, to serious corneal damage and visual loss.