What are characteristics of glaucoma in beginning stage?

No symptoms: Glaucoma has no symptoms in the early stage. It can only be diagnosed by a complete eye exam. As it progresses, it slowly takes the peripheral vision. Most people do not notice that it is taking vision until there is substantial, irreversible loss of vision.

Asymptomatic: None, depends on how early. By the time you see something like loss of contrast sensitivity, it's no longer early disease.