Fit & Proper: Learning more about glaucoma

What is glaucoma? How does it affect the eyes?
Glaucoma is a disease that affects the optic nerve, the nerve that is responsible for vision. It is often associated with raised intraocular pressure (IOP) which is the pressure of the eye, independent of blood pressure. Each eye has millions of nerves, and glaucoma causes destruction of the nerves, that first causes visual field defects, and later on affects vision per se.
 
What can one do to prevent vision loss in glaucoma?
Glaucoma is often diagnosed late as defective vision occurs after almost 80% of the nerve fibres are lost.