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Fossil records show the first living creature to evolve an eye was a tiny trilobite that lived over 500 million years ago. With vision, that creature had an advantage over its blind prey. Dr Andrew Parker, an Australian biologist, describes it as a "monumental event" in the course of evolution.

How can I take care of my eyes for better eyesight?

Today, although we have lost the predatory advantage of vision, we have retained the eye as an extremely useful tool for day to day life. About 80% of the sensory information we take in comes from vision, so it's vital to care for the health of our eyes. Here are some top tips for improving eyesight:

• Have regular check-ups for your eyes: have a professional NZ optometrist check your eyes every two years to catch any problems at an early stage.
• Protect your eyes from UV rays: sunlight can cause damage to the delicate eye; overexposure to UV light can bring about eyesight problems such as macular degeneration, cataracts, pterygium and cancer. Wear sunglasses if you're outdoors between 10:00am and 2:00pm. Check that your sunglasses are 100% UV resistant!
• Exercise regularly: this will help you avoid high blood pressure, which can cause retina damage and vision loss.
• Eat well: fruits and vegetables are good for your general health, but they also contain antioxidants which are great for your retina! Eat plenty of green leafy vegetables, carrots, celery, corn, tomatoes, blueberries, kiwifruit and lemons.
• Quit smoking: the thousands of chemicals in tobacco cigarettes accumulate in your body and cause damage to the delicate retina (as well as many other organs in your body), so give up the habit for better eyesight.

Are there exercises for improving eyesight?

Yes, some people have found these exercises effective when done on a regular basis. Remove glasses and contact lenses before doing these exercises:

• Clock gazing: improve your eye muscles by visualising a clock face in front of you. Keeping your head still, look upwards as far as you can towards the 12 o'clock position on the clock face. Hold for 2 seconds, then return your gaze straight ahead. Repeat for 1 o'clock, 2 o'clock and so on; then do the same counter-clockwise.
• Near and far focus: to reduce strain from too much close-focus work, hold you finger up about 15cm in front of you and find a still object about 6 metres away. Alternate your focus between the near and far points, holding each for 2 seconds.
• Eye rolls: slowly roll your eyes in a clockwise direction, then back in a counter-clockwise rotation. Repeat several times.
• Blinking: to cleanse your eyes and keep them moist, blink hard (squeezing your eyes shut tightly), release, blink normally and then blink hard again. Repeat several times.

So, how does the eye work?
Vision is all about light. Rays of light are reflected off objects and colours surrounding us, forming a coherent shape as they are processed by our eyes and brain. Parts of our eye include:

• The cornea, a clear covering over the eye and the first point of contact for rays of light entering the eye. The curvature of the cornea is important in refracting (bending) the rays at the correct angle to provide a focused, clear image.
• The pupil, located at the centre of the eye. The pupil regulates the amount of light that can enter the eye. In low light levels, the pupil dilates (becomes large) to allow as much light in as possible, while in bright light conditions it contracts (becomes small) to prevent too much light entering the eye.
• The iris, the coloured part of the eye, containing a large portion of the muscle that controls the dilation and contraction of the pupil.
• The crystalline lens, the lens within the eye which sits just behind the iris. The lens is crucial for focusing images as they are transmitted to the retina, at the back of the eye.
• The retina, the area at the back of the eye that transmits impulses through the optic nerve to the brain. There, the brain interprets the image and we 'see' the world around us.

What are some of the most common eyesight problems?

Around 81,500 people in New Zealand are blind or live with a sight limitation that cannot be corrected with glasses or contact lenses. Some simply experience poor eyesight, while 11,500 are completely blind. If you experience any of the following symptoms, get immediate help from a professional:

• Loss of peripheral vision: this can be a gradually developing condition indicating damage to your optic nerve, the onset of glaucoma or optic atrophy.
• Loss of central vision: this can develop over a period of years and may indicate macular degeneration, a condition that affects us as we age. The condition occurs when blood vessels grow abnormally on the retina. Permanent loss of sight can result.
• Irritated or red eyes: may be caused by minor conditions, such as allergies, but can also be a symptom of infections, which can lead to blindness if left untreated. You may be susceptible if you wear contact lenses.
• Seeing black: can indicate a detachment of the retina. Visit the emergency department or an ophthalmologist immediately.
• Sudden vision problems: when the onset of vision symptoms is very sudden, it may signal a major problem. Go to your ophthalmologist immediately if you experience sudden blurring of vision, sensitivity to light, loss of colour or contrast, or any other severe change in your sight. These problems are not always directly related to your eye health.

Looking for more information? Find New Zealand optometrists in the NZS.com directory.

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Lifestyle images from Flickr: Glasses, Yoga and Wine.