![]() Your pupil can range in diameter from 1/16 inch (1.5 mm) to more than 1/3 inch (8 mm). In dim light, your pupil expands to allow more light to enter your eye. Since most of the light entering your eye does not escape, your pupil appears black. The pupil is an opening that lets light into your eye. In a dimly lit room, open and close one eye while observing the pupil of the other eye in the mirror. Observe changes in the size of one pupil while you, or a partner, shine a light into and away from the other eye. You can see it shrink down too far, and then reopen slightly. Notice also that the pupil sometimes overshoots its mark. ![]() ![]() Notice that it takes longer for your pupil to dilate than it does to contract. If you are using a large mirror, bounce the flashlight beam off the mirror into your eye. If you are using a small mirror, hold the flashlight behind the mirror and shine the light around the edge of the mirror into your eye. Notice the white of your eye, the colored disk of your iris, and your pupil, the black hole in the center of your iris. You may need to adjust the position of the magnifier to get the clearest image of your eye. If you wear contact lenses or glasses, you may either leave them on or remove them.Īdjust your distance from the mirror until you see a sharply focused and enlarged image of your eye. Look into the center of the magnifying glass with one eye. Royal Victorian Eye and Ear Hospital Tel.Place the magnifying glass on the surface of the mirror.vision problems – like long-sightedness or short- sightedness.glaucoma – a build-up of fluid inside the eyeball.conjunctivitis – inflammation of the membrane covering the eye.cataracts – the lens of the eye becomes cloudy.Some common complaints of the eye include: Stray eyelashes and particles of dust are also collected by the tears and flushed out of the eyes. A thin film of tears is swept over the eye surface every time you blink. Tears lubricate the eye and stop the surface from drying out. Move the paper back and forth until the dot on the left seems to disappear. Close your right eye and look at the dot on the right. You can ‘see’ your blind spot by drawing two dots on a piece of paper, around 10 centimetres apart. It processes the image surrounding the blind spot then fills in the blanks accordingly. This tiny patch of blindness in both eyes is compensated for by the brain. Where the optic nerve enters the back of the retina, there are no rods or cones. In bright light, the iris causes the pupil to constrict (get smaller). It causes the pupil to dilate (get bigger) in darkness so as to let in more light. The coloured part of the eye, the iris, is a muscular ring or sphincter which controls the amount of light entering the eye. It has tiny muscles that change its shape according to how far or near the eye needs to focus. Adjustments in focus are made by the lens that sits just behind the iris. The brain combines the two views and the result is a three-dimensional image. The right and left eye each see a slightly different view. optic nerve – sends information from the retina to the brain.retina – the curved back layer of the eye covered in light sensitive cells, called rods and cones, that can ‘see’ shape, colour and pattern. ![]()
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