Having 20/20 vision is a North American term. In Europe we say 6/6 as a notation. A Snellen chart (the traditional letter chart used in sight testing) is used in an eye test to determine your vision (what you can see without glasses or contact lenses) and visual acuity (what you can see with glasses or contact lenses)
The top number in the fraction denotes the distance which the chart is viewed. 20m in North America, 6 metres in Europe. The bottom number denotes the distance at which a person can see a line on the chart clearly.
If you have 6/12 visual acuity, this means you can see something from a distance of 12 metres, what a person with perfect eyesight can see at 6 metres.
I have astigmatism, do I need to wear glasses?
Firstly, what is astigmatism?
Astigmatism is when you have an irregular shaped cornea (front surface of the eye) and/or an irregular shaped lens inside the eye. This is nothing to be concerned about in most people, as it is very common. It is only a cause for concern if the amount of astigmatism increase), in a short space of time. This could be a sign of Keratoconus.
You may have heard astigmatism being explained as your eyes being the shape of a rugby ball. Which could be interpreted as, your eyeball having a steeper curvature in one meridian than the other.
Astigmatism can be corrected by wearing glasses or contact lenses. There are soft contact lenses that will correct a certain amount of astigmatism, or gas permeable lenses which can correct higher amounts of astigmatism. These lens types are otherwise known as toric lenses.
What is kerataconus
Keratoconus is a condition where the cornea (the front surface of the eye) becomes conical in shape and thins in the middle. This causes eye sight to deteriorate. It can normally be corrected by glasses and soft contact lenses at the beginning stages, but as it progresses, a special type of contact lens may be required.
My reading used to be perfect, why am I now having to hold things further back?
This is the natural process as we age, our eyes also age, you have entered a stage called Presbyopia.
What is Presbyopia? Presbyopia is the process where the lens in our eye loses its elasticity. This means that when we focus on close up tasks such as trying to read small print, this becomes increasingly difficult as the lens cannot focus itself like it used to. This can also result in eye strain and headaches. Presbyopia usually occurs after the age of 40. Holding print further away and having better lighting conditions helps for a little while but this does not cure the eyestrain and headaches. Reading glasses are prescribed at this point to make close up tasks easier to manage.
What is Glaucoma
Glaucoma is an eye condition where the optic nerve which is responsible for the connection between the eye and the brain, becomes damaged. This is caused by the pressure in the eye getting too high. When untreated, Glaucoma can cause vision loss. The affect of Glaucoma on vision can be loss of peripheral vision, but as this can be very gradual, it can go unnoticed for a while. Regular eye examinations are important for the detection of Glaucoma early.
Other symptoms you may notice include blurred vision and seeing rainbow coloured circles around lights.
Occasionally, Glaucoma may develop very suddenly. This will cause a number of symptoms:
Intense eye pain
Tenderness around the eye
Seeing rings around lights
If you are concerned about any of the above, click here to contact us for an appointment.