Primary open angle glaucoma shows no symptoms until very late in the disease when extensive damage has occurred. Slow loss of peripheral vision is often not picked up by the affected person.
Cupping of the optic disc, high intra-ocular pressure and visual field defects are symptoms that may show up during medical examination
Because glaucoma may not cause any symptoms until irreversible damage has occurred, every routine eye examination – and ideally every physical examination – in all adult patients should include checking the pressure in the eye. This is called tonometry. A single normal reading does not rule out glaucoma since the eye pressure varies according to the time of day and the pressure rise in early glaucoma may be intermittent.
In addition the optic disc is examined for characteristic changes. The optic disc may appear normal or show what is called "cupping", in which the centre is depressed, indicating glaucoma. The visual fields may also be checked, and may show characteristic defects in the periphery. If glaucoma is suspected, you should have a complete assessment and frequent follow-up examinations by a specialist eye doctor (ophthalmologist) and a detailed visual field examination.