Damage of the optic nerve caused by elevated eye-pressure is called "glaucoma".
In the first stage of the disease, the pressure is not elevated the whole day through, as it will be the case later on, because the pressure will gradually heighten when not properly treated.

Glaucoma is usually a disease of both eyes, though one of them can be affected more seriously than the other.
Glaucoma is an affection of the eye only, not of the whole body; it is neither a cancer, nor an infection nor a contagious disease.
It is not perilous to life and there is no connection with the blood pressure.