Lens of the eye. Coloured scanning electron micrograph (SEM) of a fractured section of the lens of the eye. The lens focuses light onto the retina. The transparency of the lens (width 4 millimetres) is due to the absence of nuclei in its cells (long thin lines, running diagonally). The transparency is also due to the crystalline precision of the cell arrangement. Where the cells have been fractured (broken off) the cells can be seen to be arranged in regular stacks. The cells of the lens are called fibres because of their dimensions, with lengths of 10 millimetres and diameters of 5 micrometres. Magnification: x285 at 5x7cm size. Magnification: x650 at 6x4.5 inch print size.