If you are nearsighted or myopic, distant objects are blurred while near objects are seen clearly. The reason for this is too much focusing power, either because your cornea is excessively curved, or the eyeball is abnormally elongated. To have normal vision, the light rays entering the eye must be focused on the retina. However, in the case of myopia, the light rays are focused in front of the retina. The brain then receives blurry images of objects, which leads to blurry vision when looking at the distance.

Farsightedness, also known as hyperopia, is when near objects are blurred, while distant objects are seen clearly. You have either a smaller shaped eyeball or insufficient curvature of the cornea, leading to decreased focusing power of the eye. Light rays entering your eye come into focus behind the retina, instead of focusing on the retina, where normal vision are retrieved, sending blurred messages to the brain. The brain interpreter the near objects now as blurred, and distant objects as clear.

Astigmatism is the inability of your eye to focus clearly at any distance because your cornea is not symmetrical. The cornea is the transparent round central surface that covers the coloured iris and the black pupil. It is shaped like a rugby ball instead of a soccer ball, thus the one meridian is more curved than the other. Blurry messages are send to the brain at any distance, leading to headaches, eyestrain, red eyes and fatigue if not corrected. Astigmatism is often associated with hyperopia or myopia, and can be corrected either with spectacle lenses or contact lenses.

The crystalline lens, situated inside the eye, is the focusing mechanism of the eye. As we age, this clear lens becomes cloudy and yellow and loses its ability to change focus. This condition is called a cataract, and cannot be seen with the naked eye. The result is a general dimming of vision. A cataract may be slow to develop but once it appears, it almost always continues to become cloudier.

There is no known treatment such as diet, exercise, eye drops or laser technology to prevent formation or to cure a cataract. When it has developed, the only way to restore normal vision is surgical removal of the lens, through a small surgical stab incision and replacement with a permanent implant. Once a cataract has been removed, it will not come back.

Cataract removal is probably one of the most successful operations done on the human body, and no person should feel frightened if they are developing cataracts. For the first few days after cataract surgery, the eye may be red and sensitive, but full recovery usually takes about four weeks. For more information visit www.eyesite.co.za

A pterygium is the pinkish yellow growth on the conjunctiva, which can be seen with the naked eye. The conjunctiva is transparent and covers the white sclera of the eyeball. The cornea is the round central transparent area that covers the coloured iris and black pupil. A pterygium can grow towards and onto the cornea, inducing astigmatism and loss of vision. When this happens, it needs to be surgically removed.

Pterygiums are fairly common in areas where people live mostly outdoors, and where they are more exposed to ultra-violet rays, wind and dust. When a pterygium is irritated by above factors it can become inflamed, red and uncomfortable. Therefore it is always wise to wear a good pare of sunglasses and use a moisture drop, to relieve discomfort.

Floaters are a condition characterized by cloudy particles within the eye that seem to float about in the field of vision. As we age, the fluid in the eye becomes more compact, forming these cloudy particles. Due to gravity, these particles lay at the bottom of the eye and only on movement of the eye we seem to notice them. A good exercise is to stand facing a white wall, keeping the eyes very still. Upon movement of you eye, notice the shape and amount of floaters moving. Almost everyone has some floaters; they are quite common and are usually harmless.

When to consult your optometrist:

• When floaters increase drastically in a short period of time
• When you see a bright flashing of light

During pregnancy, a woman's body changes drastically to prepare for the birth of her child. Temporary eye conditions, due to an increase in hormones, can occur but vision returns almost to normal after delivery. Symptoms can include:

• Reduced tolerance for wearing contact lenses
• Increases dryness
• Blurred and distorted vision
• Tunnel vision

Drugs, and mostly drug combinations, where it improves one condition, can cause side effects in another part of the body. Taking these medications may have a drastic effect on your vision, due to the eye's blood vessels that are very sensitive and physiologically different from the rest of the body. These visual changes may be symptomatic of a reaction to medication: it includes dry or teary eyes, blurred, yellow or double vision, sensitivity to light, puffy eyelids, increased pupil sizes, poor night vision, and change in your normal eye color. Consult your GP before reducing any intake of medication.