Take Shana in Figure 1 as an example. She is set to be \(141\,\mathrm{cm}\) tall.[1] On this set of axes her height is about 16 \(y\)-axis units.
Line segment \(a\) which approximates the diameter of the eye (approximating the eye as a circle) has length \(\approx 0.5\) \(y\)-axis units. This gives an approximation of the diameter of the eye as \( \frac{141 \times 0.5}{16} = 4.4\,\mathrm{cm} \), corresponding to an area of about \(15\,\mathrm{cm}^2\).
As a comparison, my left eye is \(3.5\,\mathrm{cm}\) long and \(1\,\mathrm{cm}\) wide. Approximating it as an ellipse, this corresponds to an area of less than \(3\,\mathrm{cm}^2\).
