What is eye disease?

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There are many different conditions that can affect the eye. Some are minor and resolve by themselves quickly (e.g. viral conjunctivitis), but others could be serious and lead to serious visual impairment (e.g. glaucoma).

Vision loss or impairment can be sudden or gradual, and some serious eye problems can lead to total loss of vision. A decrease in vision is usually one of the first presenting symptoms and should always be investigated.

Blindness can be the result of serious untreated eye problems. That said, 80% of blindness is avoidable, which is why early diagnosis and treatment of eye problems are so essential.

Problems affecting the eye can range from infections of the eye or the eyelid, genetically inherited eye problems, eye injuries or objects in the eye, and eye disorders that are the result of conditions that affect many organs (e.g. diabetes or hypertension).

Many eye diseases have no early symptoms, and changes in vision only occur when the disease is advanced, making treatment more difficult.

Many people experience a degree of age-related deterioration in their visual abilities. Blurred vision, some loss of peripheral vision, and a decrease in visual acuity can be some of the symptoms experienced later in life.

One of the most common symptoms is redness of the eyeball – a result of swollen or dilated blood vessels. This makes the eye look bloodshot, and can be caused by allergies (allergic conjunctivitis) or eye fatigue, to name but two possibilities. A painful red eye is a concerning matter and should be investigated at all times.

Genetic inheritance can increase your risk for certain eye problems (e.g. glaucoma and colour blindness).

Optometrists can examine your eyes to find out whether you might need glasses or medical treatment, while an ophthalmologist is a specialist in medical and surgical eye problems.

Four types of eye problems

1. Eye infections
These can be caused by bacteria, fungi or viruses. Infections can occur in different parts of the eye and can affect just one eye or both. In the case of a condition such as infectious conjunctivitis, the infection can spread easily from one eye to the other, or from one person to another.

Signs of an eye infection include eye pain and a discharge, a feeling that there’s a foreign body in the eye, redness of the eye or eyelids and, in some cases, decreased vision.

These are of the most common eye infections:

  • Conjunctivitis, better known as pink eye, is an infection of the mucous membrane covering the front of the eye and which lines the inside of the eyelids. These infections can be caused by both bacteria and viruses.
  • Eyelid inflammation, also known as blepharitis, is an inflammation of the follicles of the eyelashes.
  • A stye is a red, painful bump on the eyelid caused by a bacterial infection of the sebaceous glands.

Genetically inherited eye problems
Some eye problems are genetically inherited. Five out of every 10,000 children are born with eye malformations, according to the US Children’s National Health System, so it’s relatively rare. Examples include anopthalmia (where an eye or both eyes are absent) and underdeveloped optic nerves.

Other genetically inherited eye problems can include glaucoma, age-related macular degeneration and cataracts. These three conditions usually develop in older individuals, but a family history of the disease does increase a person’s risk for these eye problems. Sometimes children can also be affected by these eye diseases.

Glaucoma, a condition where the pressure inside the eye causes optic nerve damage, can lead to vision loss and permanent blindness.

A cataract is a clouding of the lens of the eye that can cause a loss of vision – and the leading cause of blindness throughout the world. Cataracts can usually be removed and replaced with an artificial lens. Although this isn’t a very complicated operation, many people around the world don’t have access to the type of medical services that can provide this procedure.

A squint (strabismus) is a condition in which the eyes point in different directions and can affect as many as one in 20 children. These can easily be corrected by surgery. So-called “refractive errors”, which include near-sightedness, far-sightedness and astigmatism, can develop with age, but sometimes children are born with these eye problems.

Eye injuries and foreign objects in the eye
Though well protected, the eyes can suffer injuries, ranging from mild (e.g. a minor corneal scratch) to severe (e.g. retinal detachment).

In the case of injury to the eye in an accident, immediate medical treatment is required to prevent permanent eye damage and vision loss.

Eye injuries can be the result of direct trauma, or the penetration of an object into the eye. These can cause corneal scratches, or far more serious injuries like severe damage or even loss of the globe.

Substances such as acids, oven cleaners and chalk dust can cause serious damage if they get into your eyes. Others, such as shampoo, can cause burning and stinging and short-term discomfort, but may not cause serious long-term injury.

A black eye can be the result of being struck in the eye or in the area around the eye, causing bruising around the eye socket. Fractures or cracks in the facial bones surrounding the eye also warrant immediate treatment. Black eyes should therefore always be examined by a doctor.

Trauma to the eye can cause retinal detachment, which is a serious condition that needs immediate medical treatment.

Eye problems related to other conditions
Some conditions affect many of the organs in the body, of which the eye could be one.

An example of this would be diabetic retinopathy, a complication of both diabetes type 1 and type 2. The blood vessels in the retina of the eye gets damaged if diabetes isn’t well controlled, which can eventually lead to blindness. In fact, diabetic retinopathy is the sixth biggest cause of blindness worldwide.

High blood pressure (hypertension) could cause hypertensive retinopathy, and multiple sclerosis could cause the eyelid muscles to droop.

Reviewed by ophthalmologist Dr Viresh Dullabh, MBBCh (Wits) FC Ophth SA (CMSA) MMED (UKZN). September 2018.

Read more:

Symptoms of eye disease

Diagnosing eye disease

Causes of eye disease

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