It is through our eyes that we learn most of what is going on around us. Our eyes allow us to see things in great detail and in a wide range of colour; they automatically adjust to bright and dim light, and by using the two eyes in conjunction we can estimate distances with great accuracy. But the eye would be useless if those areas of the brain concerned with vision were not functioning correctly. Professor W.S. Bullough explains this important partnership between eye and brain in today's programme.