Glaucoma and the ageing optic nerve
Like a fibre-optic TV cable in which the bandwidth determines the signal transmission speed and the image quality, the human eye has its own cable—the optic nerve—which connects the back of our eye (retina) to the visual cortex at the back of our brain.
Accelerated ageing in the optic nerve is a disease which we call glaucoma, or optic neuropathy. It’s a common condition that can start at any age, leading to loss of bandwidth and premature degradation of the image quality.
The optic nerve is formed during pregnancy by biological connector cells which we call ‘ganglion cells’. These cells grow long tails called ‘axons’ which combine to form the optic nerve. A normal optic nerve has about 1.2 million axons—it is living neural tissue which requires a blood supply, an energy source and nutrients.
As we grow older, the number of axons declines, affecting the composition of fibres and the complex links to the eye’s rods and cones. We progressively lose our peripheral vision before the ability to read is compromised.
Detecting glaucoma in its early stages is both difficult and critical for effective treatment.
To be able to judge the difference between normal and abnormal, an eye specialist requires extensive training and many years of clinical experience. Repeat testing is often necessary.
We check for glaucoma by testing the pressure inside your eye (a process called tonometry) and by assessing your optic nerve function with visual field tests. With powerful detection algorithms, new imaging devices and improving technological innovation, we can measure the thickness of the ganglion cell layer in the retina, the neural rim in the optic nerve head, and the nerve fibres. This provides critical data.
Fortunately, in most cases we can slow down the rate of progressive ageing of the optic nerve. With eye drops, laser treatments or drainage surgery, we can reduce the pressure inside the eye by opening outflow channels or reducing production of eye fluid.