Eye Care Services
Visual Fields Machine
Any condition that affects the nerve of the eye or the brain, like strokes or trauma, can result in a loss of areas of peripheral vision. This is clearly a dangerous thing for drivers or even pedestrians crossing the road if, for example, the left side of both eyes is missing. Therefore, we do carry out checks on people who are potentially at risk of loss of peripheral vision.
The front of the eye may look like a clear window and although it is just half a millimetre thick it has in fact many layers which are impossible to see with the naked eye. The slit lamp is a high powered microscope with a very intense light source that provides a very detailed examination of these layers. Since there are many conditions which result in a “red eye”, only by detailed examination with this equipment can an accurate diagnosis be made. Using a special lens called a Volk lens, this machine can also be used for a detailed look at the back of the eyes.
This is the one thing that everyone associates with an opticians. The classic letter chart that starts of with large letters and reduce in size as you read down it.
A common question is ‘at what age should I bring my children in for an examination?’ Our answer is ‘any age’. For children who cannot read or even respond to any question we use a Retinoscope which gives us an objective assessment of the prescription. This tells us whether there is any significant error that needs early correction and in most cases reassures us everything is within normal limits.
As children get older they can match letters on a card to different sized letters we show them. Older still and we can show them pictures of common objects – cars, yachts, aeroplanes and so on. On top of all that there are other sensitive tests to check both eyes work together and that colour vision is within normal limits.
The eye is kept ‘blown up’ by fluid that comes in at the back of the eye and out near the front. Sometimes the drain gets blocked up for unknown reasons and the pressure inside the eye rises. If it rises too high it can compress the small nerves in the eye resulting in a loss of side vision (see 'visual fields' for how this is tested). We are able to test the pressure with various instruments. The 'puff of air' machine is one commonly used, but we also have an iCare tonometer for people who find this machine difficult to sit at. Another technique requires us to anaesthetize the eye with drops before touching the surface with a very sensitive probe - we generally only use this method if we need to double check a high reading taken using the other methods.