The eyes process more information than any other organ in the human body as they transmit light signals to the brain to create vision. A serious malfunction in the eyes can cause blindness. Less severe problems can be corrected with glasses, contacts and sometimes surgery. Other problems, such as colour blindness, cannot be corrected. A model eye will show the many different parts and how they interconnect.
Blow up the first round balloon to the desired size of the finished model. Tie off the end of the balloon. Tear the newspaper into strips approximately 5 cm (2 inches) wide. Mix the glue and water together in a mixing bowl. Dip each newspaper strip into the mixture and wrap around the balloon. Leave a 2.5 cm (1-inch) circle around the tied end of the balloon uncovered with the newspaper. Set aside to dry.
Paint the entire eye white and allow it to dry completely. Set the compass at 2.5 cm (1 inch) and draw a circle at the end opposite the opening in the model. This will be the pupil of the eye. Set the compass at 5 cm (2 inches) and draw a second circle around the first one. This will be the iris of the eye. Paint the pupil black and the iris blue. Paint a very thin line of black around the outside of the iris. Set aside to dry.
Use the ruler to draw a straight line from the centre of the pupil around the side of the eye to the opening at the back. Draw a duplicate line on the opposite side of the eye. Cut along the line to create two halves of the eye. Remove the balloon from inside the mould. Paint the inside of both halves of the eye mould white. Allow them to dry completely. Choose one side of the mould to work with and add the internal parts of the eye.
Review the eye diagram thoroughly. Roll the yellow clay into a thin pancake shape. This represents the cornea of the eye and it should be large enough to cover the entire front end of the eye model. Cut the pancake to shape it to fit inside the front of the eye model on one side. Glue in place. Shape the white clay into an oblong ball. Press the ball slightly with your hands to flatten it. This represents the aqueous. Press firmly onto the yellow clay cornea in the model. Glue in place if necessary. Make a pancake shape with the blue clay to represent the iris. Cut the blue clay to fit onto the white clay. Press firmly in place. Glue if necessary.
Blow up the small white balloon so its circumference is a slightly smaller size than the blue clay iris. This represents the lens of the eye. Tie off the end of the balloon. Press the balloon against the blue clay so the tied end is not visible and the balloon has an oblong shape. Add tape over the balloon to force it to keep its oblong shape and to hold it in place inside the model.
Cut a 1/2 circle from the aluminium foil that is large enough to cover the back wall of the eye model. The foil can cover the opening at the back of the model but should not extend above the edge of the half of the model being used. This foil represents the retina. Draw a half circle in the centre of the aluminium foil where the opening in the model is located with the black marker and colour in this area. This represents the macula. Glue the aluminium foil into the eye model. Insert one end of the thick pipe cleaner into the centre of the macula with the long end of the cleaner hanging out the back of the eye model. The pipe cleaner represents the optic nerve. Glue the pipe cleaner in place.
Blow up the orange balloon to a size that will fit into the model eye. Tie off the balloon. This represents the vitreous and will need to be removed to illustrate the macula and retina. Place the two halves of the eye model together to complete the model. Tape can be used to hold the two halves together when transporting the model.
Use a water balloon for the small white balloon as this type is much smaller than standard party balloons. The newspaper shell represents the sclera of the eye. Create a poster with labels to identify the various parts of the eye if necessary for a presentation.