Glaucoma

Glaucoma is damage to the optic nerve, usually but not always associated with raised pressure inside the eye. It destroys peripheral vision first, and it does so slowly and symmetrically enough that the brain fills in the gaps. People routinely lose a substantial part of their field before noticing anything.

The damage is permanent. Treatment stops it progressing; it cannot restore what has gone. That asymmetry — nothing to feel, nothing to recover — is the entire argument for regular exams.

• Usually none at all in the common open-angle form, until late
• Gradual loss of peripheral vision, often noticed first as bumping into things
• Difficulty adapting to dim light
• In advanced disease, tunnel vision
• Acute angle-closure is the exception: sudden severe pain, haloes, nausea, a red eye and rapid vision loss

• Raised intraocular pressure, though it can occur at normal pressure
• Age over 60
• Family history — a first-degree relative raises risk several-fold
• African, Caribbean or Hispanic ancestry for open-angle; East Asian ancestry for angle-closure
• High myopia, diabetes, and long-term steroid use
• Previous eye injury

The goal is to lower pressure enough to stop further nerve damage, then keep it there for life.

• Pressure-lowering eye drops, used daily and indefinitely — adherence is the single biggest determinant of outcome
• Selective laser trabeculoplasty, increasingly used as a first-line option
• Surgery, including trabeculectomy, tubes and minimally invasive stents
• Regular field tests and optic nerve imaging to detect progression
• Urgent treatment for acute angle-closure