ABSTRACT
The vitreous fills the internal space of the eye posterior to the lens and its zonular fibres and has a volume in emmetropia of about 4 mL, which increases to 10 mL in highly myopic eyes. The cortical part of the vitreous gel has a higher content of hyaluronic acid and collagen compared with the less dense central gel. There are anterior and posterior hyaloid membranes and a central tubular condensation called Cloquet's canal. The retina is divided into regions. The macula between the temporal vascular arcades serves approximately 20° of visual field. The fovea is a central darkened area with a pit called the foveola. Cones provide high-resolution colour vision in photopic conditions. They react quickly and recover rapidly to different light stimuli. The nerve fibres of the ganglion cells on the inner surface of the retina pass tangentially towards the optic nerve.
