Vision Problems

How your eye works

Your eye works like a camera.  The front of your eye, the cornea, iris, pupil, and lens focus the image onto your retina, which lines the inside of your eye.  The retina is sensitive to light and acts like the film in a camera, capturing images and then sending them via the optic nerve to your brain where the images are interpreted.

Seeing the images clearly

There are two factors at work in seeing clearly.  The first is proper focus.  Just like a camera your eye needs to be focussed properly to send clear images to your brain.  The second is healthy eye tissue.  Any damage or disease to the cells within your eye has the potential to remove your ability to see fully – sometimes damage can be permanent.

Early detection prevents serious eye damage.

If you have any problems with your eyes or with seeing clearly then you need to see an optometrist.

Any change in vision should be checked,  It may be normal, or it could be the result of a more serious condition. Changes in vision could be related to vascular, neurological, or other medical conditions such as high blood pressure or diabetes.

Eye exams and vision screening

Vision screening (or sight testing) will only tell you if you would benefit from glasses. Vision Screening will not tell if your eyes are healthy. Not being able to see well is the most common sign of eye problems including eye disease that can cause blindness. This is why it is always necessary for an optometrist to examine your eyes thoroughly to make a diagnosis before prescribing a treatment.

A comprehensive eye exam will measure any refractive error that you have and will also investigate for signs of eye diseases that have the potential to make you blind.

You can tell you are having a comprehensive eye exam if it includes assessment of:

  • medical history
  • slit-lamp examination
  • glaucoma
  • retinoscopy
  • external eye
  • internal eye
  • visual fields
  • subjective refraction
  • eye muscles
  • colour perception
  • peripheral fundus
  • macular health

It takes a while so you should expect to be in the chair for at least 30 minutes and maybe more.  For many people the news will be that they have great eye health.  Only around sixty percent of people examined need to be prescribed glasses or contact lenses for refractive error.

Read more about the comprehensive eye exam

Refractive error

Refractive error is the term used to describe poor focus. It may be caused by the shape of the eye and is resolved by applying a prescription lens in front of the eye to ensure a clear image reaches the retina. There are a number of specific refractive problems which cause poor vision including myopia, hyperopia, and astigmatism.

Myopia (means "short sight")

Myopia causes blurred vision. The most common problem for those who are shortsighted is difficulty seeing distant objects clearly. Some myopic children have never had clear distance vision and so are not aware of what they are missing. School vision screening will often detect myopia. Frowning and screwing up the eyes in an effort to see better is common and this may cause headaches. Shortsighted children will sometimes hold reading material quite close. In their mid to late forties most people with perfect distance vision need reading spectacles, however many people with myopia can see close work clearly without them. …. read more

Hyperopia (means "longsight")

A young "normal" eye looking into the far distance sees clearly without making any focussing effort. A hyperopic (longsighted) young eye looking into the far distance can only see clearly if the muscular focussing system inside the eye is used.

A normal eye begins to use its focussing system as an object comes closer. A longsighted eye has to make the same focussing effort for near work as a normal eye, but this is in addition to the effort it makes to keep distance vision clear. With hyperopia, a long sighted eye has to "work harder" than a normal eye at all distances. …. read more

Astigmatism - Blurred Vision and Tired Eyes

Astigmatism is a very common focussing error of the eyes which causes blur. It is caused by the shape of the eye, usually due to the cornea's surface or occasionally due to the eye's lens being tilted. Sometimes astigmatism can be inherited but it often happens as a normal characteristic of growth.

Blur from astigmatism is not like that from myopia where all of an image is equally blurred, because some parts of the image are more out of focus than others. If you look at the line diagrams, you can see the effect of astigmatism by tilting the tip the page down and facing away from you the lines running across the page are less distinct than those running away from you. The blur of astigmatism makes things uncomfortable to look at, difficult to focus and may cause headaches, tiredness and poor concentration. …. read more


Normal healthy, young eyes have a wide range of focus from far distance to a few centimetres. In a young eye the lenses very flexible. Muscles within the eye have the ability to change the shape of the lens and by doing so, change its focus. This change happens so quickly that we don't even know our eye is refocusing!

As we get older, the lens of the eye thickens and slowly loses its flexibility, making it difficult to hold objects very close and see clearly. Around the age of 40 to 45, vision at our normal reading distance becomes blurry. We have to hold print further away to avoid tired eyes.

This loss of focusing ability is called presbyopia. It is not a disease, but a normal change which affects everyone. Presbyopia doesn't occur suddenly. It doesn't affect distance vision. It is a change which begins in adolescence and cannot be prevented. …. read more

Good light helps your vision

Eyes need light. Eyes adapt to different levels of light very well. From the brightest light on a sunny day to the extremely low levels of light at night, we can still see. ...Read more about glare, the correct positioning of lights and the impact of poor lighting on your vision.

Children's Eye Health

Ninety percent of learning in young children comes through the senses. Eighty percent of all information processed by the brain is collected by the eyes, so having good vision is important for learning and improving poor vision can have a large impact on learning difficulties. Early detection of long-sightedness (hyperopia) is important in young children who are learning to read and optometrists are equipped to carry out the exams. Eye exams and glasses are subsidised in some cases for low income families.…. read more

Spectacle Care

If you do wear spectacles then we do have a word of advice: handle your spectacles carefully. Your spectacles are custom made, high-tech appliances that serve a very important function - they help you see. If they become maladjusted, your ability to see clearly or comfortably may be compromised. It is common sense to suggest that you take special care of your glasses, both on and off your nose. …. read more

Driving - Your Vision Warrant of Fitness

Just as your car needs regular checks to ensure that it is functioning normally, your eyes need examining to ensure that your vision meets the LTSA eyesight standards. Most drivers can reach the standard necessary for safe driving with spectacles or contact lenses. ... read more

Colour Vision

A person with 'normal' colour vision sees approximately six bands of colour (red, orange, yellow, green, blue and violet). A person with colour deficiency will possibly only see four colour bands (yellow-orange, grey, blue and violet). Distinguishing pastel colours may prove difficult for someone with colour deficiency. Blue-green and red-purple shades can be confused with grey, while yellow, brown and green may also be confused for each other. …. read more

Do you need sunglasses?

Sunglasses are bought and worn for many reasons. Some people buy sunglasses purely as a fashion accessory while others have special lenses made specifically to suit their vision needs. Whatever the reason for purchase, sunglasses must provide protection against UV (ultra-violet) radiation which can seriously damage your eyes …. read more

Floaters and Flashing Lights

Floaters (or spots) are particles which float inside the eye and cast shadows on the light sensitive tissue at the back of the eye (the Retina) reducing vision. Usually nothing more than a nuisance, floaters can result from eye disease or injury and need to be assessed by your optometrist. …. read more

The Ageing Eye

Eye health and vision are hugely important for general health and independence as we age. Cataracts macular degeneration and glaucoma are common eye conditions conditions affecting an older people. New treatments are being developed and we now have ways to detect these conditions earlier so vision can be protected for longer. Compared to people with good vision, people with low vision are less able to live independently, have poorer quality of life, rank their health as worse, are more likely to get depressed, and have more falls and fractures....cataracts , glaucoma , and macular degeneration

What is Glaucoma?

Glaucoma usually comes without any warning. Glaucoma is an eye disorder in which the fluid pressure inside the eye causes progressive damage to parts of the optic nerve. The pressure usually increases when there is inadequate drainage of fluid from inside the eye. A gradual but permanent loss of vision occurs unless the condition is treated. …. read more