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ABC of Eye Diseases and Disorders

Firstly, what’s the difference between a disease and a disorder? […]

By Published On: 7 February 20125.3 min read

Firstly, what’s the difference between a disease and a disorder?

The two are relatively interchangeable, especially in the media, but the two terms do have different connotations.

A disease is something that destroys or damages a part of the body, whereas a disorder is something that does NOT necessarily do that. Disorder implies that something is “not in order” or different from what is considered normal and it’s often used when a condition has no known causes or cure.

So for example conjunctivitis is a disease that affects the eye, whereas myopia is a disorder in that sight is not considered to be standard or average.

Acanthamoeba Keratitis

Keratitis is an inflammation of the eye cornea, and there are four types of which acanthamoeba keratitis is one – the others being viral, bacterial and fungal.

Wearers of contact lenses not following a strict hygiene regime often contract the disease.  The key risk factor is rinsing contact lenses in tap water or worse still storing them in tap water overnight.

Allergic Conjunctivitis

Symptoms of pink eye, watery eyes, as well as itchiness cause by a reaction to:
•    materials such as fur, fabric softener on clothes
•    seasonal events from pollen and grass cutting as in hay fever.

Not contagious and can be treated effectively with antihistamines

Amblyopia (Lazy Eye)

Is when one eye effectively does not contribute to sight. If it is caused by the eyes having different visual capacity, with one eye being either near or farsighted (called a refractive eye error) then it can be treated by optometrist prescription glasses or even contact lenses.

In almost all cases however the use of a cover up patch over the good eye to let the less developed eye catch up in development is a feature of treatment. The covering up process needs to be prolonged for a period up to a couple of months, but luckily only a couple of hours a day.


A disorder of both the cornea and the lens of the eye, astigmatism affects some 25% of people, with light from objects not being correctly focussed on to the retina.

People with astigmatism, which is not easily detected, especially in younger children, may not see clearly both distant nor near objects.

Bacterial Conjunctivitis

Symptoms are pink eye, itchiness, grittiness and pus like discharge. It is highly contagious but readily treated with antibiotics.

It can easily be contracted from touching others infected, as well as surfaces and by sharing items such as face cloths and towels.

Bacterial Keratitis

Keratitis is an inflammation of the cornea and can lead to the development of corneal ulcers.

Bacterial keratitis is a particular form of keratitis that has some dangerous sounding bacteria at work – streptococcus, staphylococcus and pseudomonas to name but a few. Antibiotics are prescribed, occasionally steroids with careful monitoring.

Bell’s Palsy

Bell’s palsy is the name given to a disorder that can happen overnight and leaves a person with muscle weakness on one side of the face. This often severely affects facial movements, particularly smiling and eye opening and closing. A viral infection is thought to be the cause.

Protecting the eye during sleep is particularly important as it can be subjected to continual aggravation by sheets and pillows. 95% of sufferers make a complete recovery.


Blepharitis is an inflammatory eyelid infection, often with dandruff like flaking, and can affect people of all ages. It can appear outside the eyelid or on the underside.

The main cause is infectious bacteria on the eyelids, also allergies and dust mites. There is no real cure, but management through disciplined eye cleanliness is effective.


Cataracts are simply part of growing old!

It is the formation of a cloudy area in the eye lens, which slowly affects vision and requires more frequent visits to the optometrist for a new prescription, and any cataracts will be diagnosed during visits.

Cataract surgery is required once vision is not acceptable for every day activity or driving a car.  Because cataracts usually occur later in life it is important to develop them otherwise it can be said that you have not lived long enough!

Seriously though cataracts can occur even from birth and is the leading cause of blindness in undeveloped countries.  Luckily for us in Australia it is a very routine and successful procedure.


A chalazion is similar to a stye in that it is a small red bump on the eye, but it’s not infectious.

Caused by the oil glands not working properly or becoming blocked, a chalazion will clear up with home treatment and only rarely needs minor surgery. If they become too regular then some sort of serious hygiene regime needs implementing.

Fish oil supplementation seems to be protective.

Closed Angle Glaucoma

If the iris comes into permanent contact with the lens of the eye, and the mesh through which the internal excess fluid escapes is blocked off, then eye pressure increases and the optic nerve is damaged leading to glaucoma.

Treatment is by relieving the blockage, either with eye drops or laser surgery. The glaucoma cannot be reversed but it can be halted and managed. Symptoms include eye pain that can lead to nausea.  Often though it is symptomless so regular eye examinations with the optometrist will discover whether you are at risk.

Colour Blindness

A term that does not really describe the disorder – people aren’t blind in any way – they simple can’t distinguish between colours, especially reds and greens.

It’s inherited and there’s not much that can be done about it – except for educating the general public about how to use colour in everything from school books to the internet to make it easier for those with “Defective Colour Vision”.


Is a general term to describe a family of diseases with symptoms of pink eye, watery and itchy eyes.

The diseases can be infectious as in the bacterial or viral types or reactive as in the case of an allergic type.

Corneal Ulcer

Generally ulcers that develop throughout various parts of the body and the mouth are annoying and go away after a while – ulcers on the cornea on the other hand are serious.

They can be fungal, bacterial, viral or parasitic and are all readily treatable with medication, although in extreme cases a procedure called collagen cross-linking or corneal transplantation might be required.


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