Some intersting facts about the human eyeball: A human eyeball is only about an inch or 25 mm in size. When further calculations were carried out, the diopter of the eye was found to be about 50 diotpers. The contact lenses have diopters with magnitudes of only about 1-5 diopters, showing that the majority of the strength comes from the eye and lenses simply act to correct the focus of our eyes.

Human eyeball obviously grows from the day a baby is born up until the baby becomes an adult. But what's interesting is that the eyeball of an infant is about two-thirds the size of an adult. Also, the eyeball growth gradually slows as the age increases and after puberty, it stops growing.

I have previously discussed about myopia (nearsightedness) and heperopia (farsightedness), however, astigmatism can accompany both myopia and hyperopia. Since astigmatism affect nearly 100% of the population, I have tried to learn about it.

Astigmatism is related to the orientation or shape of the cornea. If the curvature of the cornea is not perfectly spheircal in shape then there is no rotational symmetry. Due to this abnormal shape, the light rays in two perpendicular planes focus at different distances.