Unit 7: Gradual Loss of Vision
3: Primary open angle glaucoma (POAG)
Pathogenesis
Aqueous humor is produced by the ciliary body and drains out through the trabecular meshwork.
With age the trabecular meshwork may not drain as effectively, and the IOP rises.
Raised IOP may damage the nerve fibres at the optic nerve head, producing a visual field defect.
Eye anatomy fluid (aqueous humor) flow
Source: Drawing of the Eye, National Eye Institute, National Institutes of Health, used under CC BY 2.0.
Ocular hypertension: Some people have above normal IOP (>21 mmHg) without optic nerve head cupping or visual field defect.
Normal tension glaucoma: Some people have optic nerve cupping and visual field loss despite normal IOP.