POAG

Primary open-angle glaucoma (POAG) is a chronic optic neuropathy characterized by progressive loss of retinal ganglion cells and their axons, leading to cupping of the optic disc and corresponding visual field loss. The disease features open anterior chamber angles and impaired outflow of aqueous humor through the trabecular meshwork. In POAG, intraocular pressure is often elevated, though some individuals have normal pressures (normal tension glaucoma). The condition is typically asymptomatic in early stages and progresses gradually.

Pathophysiology involves increased resistance to aqueous humor outflow, which raises intraocular pressure in many patients and damages the optic nerve. The resulting retinal nerve fiber layer loss is irreversible, usually beginning with peripheral vision. Risk factors include aging, family history, African descent, thinner central corneal thickness, and myopia; vascular factors and nocturnal IOP fluctuations may contribute to progression in some cases.

Diagnosis relies on detecting glaucoma-related changes before significant vision loss. Assessments include intraocular pressure measurement, examination of the optic nerve head and retinal nerve fiber layer, and standard automated perimetry to map visual fields. Central corneal thickness may be measured because it affects IOP readings. POAG is distinguished from angle-closure glaucoma by the open angle on gonioscopy.

Management aims to lower intraocular pressure to slow or halt progression. First-line treatments are typically topical medications, with prostaglandin analogs commonly used. Alternatives include beta blockers, alpha agonists, and carbonic anhydrase inhibitors. Laser therapies such as selective laser trabeculoplasty and surgical options (trabeculectomy or glaucoma drainage devices) are considered when medications are insufficient.

Prognosis varies with baseline damage, pressure levels, adherence, and access to care. POAG is a leading cause of irreversible vision loss worldwide, especially among older adults and some ethnic groups. Regular screening and long-term management can reduce vision loss risk.