More about the eye

Maybe we’re biased, but we think the human eye is one of the most beautiful structures in the natural world.

Part of that beauty is down to its complexity. But that complexity can also make it rather daunting if you’re new to the world of ophthalmology. In this section you can learn more about the biology of your eyes: how the different parts function and how they fit together. It’s a growing library of links and resources about all things eye-related.

Understanding the eye

The cornea is the clear window of the eye. The iris, which is the coloured part of the eye with the black pupil in the middle, is behind the cornea. The lens lies behind the iris.

In a healthy eye, the lens is clear and able to focus light onto the retina, the light-sensitive nerve layer that lines the inside of the eye. Rays of light enter the eye, passing through the cornea, pupil and lens before focusing onto the retina.

The retina contains photoreceptors, which convert light into electrical impulses. In a healthy eye these impulses are sent via the optic nerve to the brain, where sight is interpreted as clear, bright, colourful images. A useful comparison is the way that light falls onto the photographic film in a camera.

model of the eye
In a healthy eye the lens is clear and able to focus light onto the retina, the light-sensitive nerve layer that lines the inside of the eye.

The wall of the eye is formed of three layers: the retina, choroid and sclera. The choroid is the underlying vascular (blood vessel) layer of the eye, from which the retina receives oxygen and nutrients. The sclera, or “white of the eye”, forms a tough protective coat.

The macula is a small area at the centre of the retina. It is very important, as it is responsible for our central vision. It allows us to see fine detail for activities such as reading, recognising faces, watching television, and driving. It also enables us to see colour.

The vitreous is the clear, jelly-like substance which fills the hollow space behind the lens.

What is Posterior Vitreous Detachment?

Posterior Vitreous Detachment (PVD) is a very common eye condition. It can affect people of all ages, though older patients are the most like sufferers: the RNIB estimates that more than three quarters of people aged 65+ will develop the condition. PVD usually happens because of natural changes to the vitreous, the clear, jelly-like substance inside our eyes. As we age, the jelly often becomes more watery. This can cause it to lose its normal shape and separate from the retina, the thin layer of nerves at the back of our eyes. The reassuring thing about PVD is that it doesn’t cause any pain or damage to the eye, and doesn’t require treatment. That said, the condition can cause some frustrating symptoms, such as floaters (tiny dark shapes in your vision) or flashing lights; these usually decrease as your brain adjusts to the changes. However, since the symptoms of PVD are often similar to a more serious condition called Retinal Detachment, it’s very important to see an ophthalmologist or optometrist as soon as you notice them.

Concerned that you may be experiencing some of the symptoms of PVD? Contact us today to make an appointment.

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