Making Sense of Sensory Loss
How do your eyes work?
Acknowledgments: This section was developed using information from 'Better Health Channel Victoria' (www.betterhealthchannel.vic.gov.au), Glaucoma Australia (www.glaucoma.org.au), 'Making Sense of Sensory Loss' booklet and DVA Senior Medical Adviser.
The eye is our organ of vision. Its complicated design means that an image can pass through its many layers and end up crisply focused on the back of the eye, called the retina. The retina is covered in light sensitive cells, called rods and cones. Information on shape, colour and pattern is picked up by the retina and carried to the brain via the optic nerve.
Picture courtesy of Glaucoma Australia
To keep it light-weight for rapid movement, the eye is made from soft, but strong tissues. However, like a camera, the eye needs to maintain its shape so that it can focus light accurately.
This is achieved by keeping the eye firm, like a balloon. Clear fluid (the aqueous) is pumped into the eye from the bloodstream carrying oxygen, sugars and other essential nutrients. Circulating around the structures inside the eye, the aqueous is then drained through a meshwork back to the blood to be renewed. Drainage is against resistance, so the eye's pressure is kept higher than air pressure, but lower than the blood pressure.