I was wondering what are early signs of glaucoma?

Glaucoma: Is a disorder of the optic nerve in the back of the eye. Most people with it also have elevated pressure in the eyes. In early glaucoma, there are changes to the nerve and loss of the peripheral vision. These changes can generally only be detected by careful examination and testing. Vision loss in glaucoma is permanent and irreversible.

Usually none: "The (silent) thief of sight" is aptly applied to the most common form of glaucoma called open angle. There is no early warning sign or pain to give you concern. A family history of the disease, as well as high intraocular pressure, African or Hispanic ethnicity, steroid use, eye injury, thin cornea, high myopia, hypertension are important risk factors. A dilated exam is essential for diagnosis.