Behind the iris, we distinguish the lens that due to its transparency determines largely the sharpness of
our vision. Decreasing its pupil and changing the shape of the lens, our eye can focus at close
distances (through accommodation) just like an automatic photo camera. At older ages, this ability is
reduced and we need glasses for near vision (presbyopia). Getting even older ,the transparency of the
lens is reduced and it gradually blurs - causing cataract - significantly reducing our vision (fig.5).
Behind the lens, we distinguish the vitreous cavity of the eye that keeps its shape thanks to the
gelly vitreous humor uniformly attached to the retina. This transparent and gelatinous mass under
certain circumstances can either be detached from the retina (developing 'floaters' for the patient),
or cause retinal holes which require urgent treatment.