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Pindara Private Hospital Magazine - Issue Two

More than Meets the Eye Introducing the retina Everybody knows what an eye is, but do you know specifically what the retina is, or what it does? Have you heard of retinal tears or detachments? You may be surprised to learn that it’s not an all too uncommon occurrence as you start to age. Here we break it down for you and explain what to look out for. The Retina: What is it? The retina is the light-sensitive layer of tissue that lines the inside of the eye and is responsible for receiving visual stimuli from the environment and processing this information via the optic nerve to the brain. The central 5% - 10% of the retina, the macula, is responsible for clear central vision. The peripheral retina, as its name suggests, is responsible for peripheral vision. Like all tissues in the human body, it is supplied with nutrients and oxygen via arteries and is drained of waste products by veins. Beneath the retina is a supportive layer of cells called the Retinal Pigment Epithelium, the pigmented cell layer that nourishes the retina, with a further vascular layer beneath this called the choroid, a tissue layer that contains many of these vitally important blood vessels and other structures. How Does the Eye Work? Put simply, we can compare it to a camera. The cornea, which is the transparent covering on the front of the eye, acts much like a lens cover and a focusing element by bending entering light rays through the central ‘black hole’, the pupil. When combined with the coloured iris, the shutter, it acts like the aperture of a camera. The lens is the next component in line and acts like the lens in a camera by its ability to focus light onto the retina, which can be compared to the film of the camera. The retina contains many light sensitive nerve cells called photoreceptors, which transmit the light rays into electrical impulses, which are delivered to the brain via the optic nerve, where an image is perceived. Similarly to a camera, if the film is of poor quality or malfunctioning, no matter how effective the rest of the components are, the final picture will be poor. What is a Retinal Tear? The back of the eye, the posterior segment (also known as the vitreous cavity), is filled with a jelly like substance that is composed of 99% water and a protein called collagen. This substance is called the vitreous. The vitreous is closely attached to the retina and as we age, the vitreous fibres may condense and liquefy, and may cause the vitreous to pull forward from the surrounding retina. In the majority of patients, this process is uneventful and causes no problems. In some patients, the vitreous may be strongly adherent to the retina, and the separation can cause a tear in the retina. A tear may be located peripherally and thus not produce significant visual symptoms apart from flashes of light or new floaters. Anyone experiencing these symptoms should be promptly examined to ensure adequate treatment of their tear in order to prevent a retinal detachment. What are the Symptoms of a Retinal Tear? • A retinal tear may be accompanied by the General Health sensation of flashing lights in the affected eye • Floaters – small, moving spots or specks that may appear as dots, circles, lines, clouds, cobwebs • Blurry vision What is a Retinal Detachment? As discussed earlier, the retina is a multi-layered light sensitive tissue covering the inside of the eye and sends visual information to the brain. Retinal detachment refers to the separation of the inner layers of the retina from the underlying Retinal Pigment Epithelium (RPE). A retinal detachment is considered to be a medical emergency and prompt referral and treatment should be sought. What are the Symptoms of Retinal Detachment? Similarly to a retinal tear, patients may experience new onset floaters, blurred or decreased vision and peripheral bright flashing lights or sparks. • As the retina detaches – a shadow or curtain may develop in the vision that this area of retina would normally process • Some people may experience complete and sudden loss of vision. • The effect on eyesight depends on the location and severity of the detachment. For example, if the retina detaches involving the macula, central vision may be lost. pindaramagazine.com.au Pindara Magazine 25


Pindara Private Hospital Magazine - Issue Two
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