Raphaela will look at how the iris and the pupil work together, controlling the amount of light that enters the eye. While practicing surf, depending on the weather and the period of the day, we will be exposed to different light intensities.
Eduardo will be investigating the processes know as accommodation, when the ciliary muscle contracts or relaxes to change the shape of the eye lens so that we see in the right focus. When a wave is near or far from a person, the shape of the lens changes, so that we see in the correct focus.
For the biological part of the experiment, two aspects of the eye will be investigated. Raphaela Altit was in charge of finding out about the pupil reflex.
The change in size of the pupil is controlled by involuntary contraction and dilatation of the iris, to regulate the light entering the eye and reaching the retina (back part of eye, as shown in diagram below).
In bright light, the pupil will decrease in size, to allow less light to enter, so that the sensitive cells in the retina are not damaged. When the lights are dimmed, the pupil increases in size, thus increasing the amount of light entering the eye and reaching the retina. This change in size is also shown in one of the diagrams below.
In the sunlight, the pupil can be of a very small size, reaching 1.5mm in diameter, and when the lights are down, it can increase a lot, reaching 8mm.
For the Group 4 experiment, the 3D model of the eye will be used to show where the pupil is, and where the iris and the muscles that contract to control the pupil’s size are found in the eye. We will also show where the retina is, to show where the light would damage the eye if it reached it with a greater intensity then what is adequate.
Change in size of the pupil depending on the light intensity
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