Often symptomless. A comprehensive eye examination including a dilated funduscopic examination is essential to diagnosing glaucoma. Additional testing thereafter, if indicated, would also be performed. Many people diagnosed with glaucoma have no symptoms. A positive family history, traumatic eye injury, steroid medication use, inflammatory eye disease, congenital abnormalities, aging are among some instigators.
Loss in vision. By the time you can tell you are suffering from glaucoma by loss in vision, its already too late. Optic nerve damage is irreversible. If there's any suspicion, best to get screened by an ophthalmologist.
Blind spots. Hard to determine by yourself unless you have extensive field of vision damage that is noticeable. Acute angle closure glaucoma is associated with pain redness decrease in vision and halos.
Eye exam. You need a screening eye exam since typically glaucoma is asymptomatic except in special cases when the pressure rises very quickly, and the eye becomes, red, painful, with blurry vision due to swollen cornea.
Usually not. Open angle glaucoma has no early symptoms! Closed angle glaucoma can be painful and acute - but it's relatively rare. Only with very advanced glaucoma is the vision noticeably compromised.