The Eye is Our Window to The Brain – and There’s a Lot We Can Tell From It

The human brain is the most complex arrangement of matter in the known universe. Through our five senses it “digests” vast amounts of information that allows us to see, hear, taste, touch and balance. It commands our muscles, it learns, remembers, hungers, loves and hates.

Understanding how the brain works is a major research challenge; thousands of scientists are studying it in the expectation that through greater understanding we can eventually overcome many tragic diseases and injuries.

What goes wrong during stroke or in dementia? What are the causes and genetics of brain disease, age-related hearing loss, motor neuron disease? What treatments will improve them and will psychological interventions help? Then there are the those who want to explore the brain, to find out how it ticks and how, for example, we see and read.

The eye is the only part of the brain that can be seen directly – this happens when the optician uses an ophthalmoscope and shines a bright light into your eye as part of an eye examination. It shows the innermost layer of the eye (the retina), and the nerve carrying visual messages from the retina to the brain (along the optic nerve) are visible in the back of the eye.

In many neurological diseases, such as multiple sclerosis or stroke, we can see changes in the optic nerve that provide a direct diagnosis. And if pressure in the brain increases, perhaps due to a brain tumor, we can see this as a swelling of the optic nerve. So changes in the back of the eye can be used in the diagnosis of high blood pressure, diabetes, glaucoma, age-related macular degeneration or genetic diseases, such as retinal dystrophies

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