Glaucoma

What it is

A group of optic-nerve diseases, typically related to pressure, but damage can occur at statistically “normal” pressure. Lost field and nerve fibres do not return. The aim is to slow worsening, not to cure. Angle-closure is more common in Chinese people than in many Western groups.

1. Primary open-angle glaucoma

The angle is open; outflow resistance is high; pressure is often raised. Early disease is silent. Age, family history, high myopia and a thin cornea raise risk. A doctor may discuss pressure-lowering drops, selective laser trabeculoplasty (SLT; the LiGHT trial supports SLT as one first-line option for suitable people — not mandatory for everyone, and not a personal guarantee), then surgery classes if drops or laser are not enough or not tolerated. Monitoring needs pressure, field and OCT — not a single pressure reading.

2. Normal-tension glaucoma

Glaucomatous disc and field with pressures repeatedly in the statistically normal range (often cited around 21 mmHg — not a personal cut-off). Common in East Asia. Disc haemorrhage, nocturnal hypotension, sleep apnoea or migraine may be discussed. CNTGS showed that, after cataract effects were removed, the group whose pressure was lowered a further 30% or so worsened less; the intention-to-treat analysis showed no significant difference, and many untreated people did not worsen either, so whether to lower pressure actively is for the doctor to assess individually. Atypical nerves may need the doctor to exclude compression — that is not a DIY MRI.

3. Ocular hypertension

Pressure above the usual cut-off with a still-normal disc and field. Not everyone needs drops at once. OHTS showed that some convert to open-angle glaucoma over years; thin cornea and higher pressure matter. Observation or about a 20% pressure drop may be discussed. Today’s normal field does not guarantee five years from now.

4. Angle closure and an acute attack

The iris blocks access to the trabecular meshwork. Hyperopia, a shallow chamber, an ageing lens and Chinese ancestry are associated. Stages such as suspect closure, angle closure and angle-closure glaucoma are research and teaching labels — not for self-diagnosis. Chronic closure can be painless, with repeated pressure rises and slow field loss.

Public research linked to Zhongshan Ophthalmic Center helps frame how common “narrow angles” are in Chinese populations — not your personal risk, and not a clinic outcome guarantee. In the Guangzhou Liwan Eye Study (Zhongshan team), among urban Chinese aged ≥50 with open angles at baseline, about one in five developed some form of primary angle closure over ten years (any stage cumulative about 20.5%; most were suspect closure / PACS, with lower numbers progressing to angle-closure glaucoma / PACG). A thicker lens, shallower anterior chamber and narrower angles were associated with higher incidence. In the Zhongshan Angle-Closure Prevention (ZAP) Trial, community-screened people with bilateral primary angle-closure suspect (PACS) status received laser peripheral iridotomy (LPI) in one eye with the fellow eye as control: LPI reduced later progression to angle-closure–related endpoints, but overall progression and acute attacks remained relatively uncommon in that community PACS group — whether to offer preventive laser is an individual risk decision by a doctor; this page does not guarantee that everyone must or must not have it.

Dilating drops and medicines: why they may trigger an acute attack (education, not a prescription)

When the pupil is mid-dilated, peripheral iris can block aqueous outflow (pupillary block); in an already narrow or shallow front of the eye this can precipitate acute angle closure. People at higher risk are usually those with known narrow angles or angle-closure history, hyperopia / a shallow chamber, and older Chinese adults (especially women) — these are population and anatomy ballparks, not personal probability guarantees.

Topical dilating drops (for eye exams): clinics commonly use short-acting mydriatic drops to dilate the pupil for a fundus exam. Most people are fine; if you already know you have narrow angles, had an acute attack, or were told “do not dilate,” tell the examiner before dilation. Do not buy dilating drops yourself to “clear the eyes.”

Systemic / over-the-counter medicines: some cold or cough remedies, antihistamines, anticholinergic or sympathomimetic ingredients, and some psychiatric or anti-Parkinson medicines can dilate the pupil or shift the ciliary body and precipitate an attack (mechanism summarised in medication-induced angle-closure reviews; this page lists no brand names). A Hong Kong prospective series reported that some people with acute primary angle closure had a recent upper respiratory infection or had taken cough medicine — an observation from that study, not that a cold always causes an attack, and not a brand comparison. If you have a narrow-angle history: tell the doctor or pharmacist before getting medicines; if you get a red painful eye, rainbows, nausea or vomiting, or a sudden vision drop → A&E / 999 now; do not add more dilating drops or “wait one more night.”

Staying in the dark for long periods or emotional arousal can also dilate the pupil — the same physiological pathway as education on triggers, not a claim that turning off the lights will inevitably cause an attack.

• A&E may use several pressure-lowering routes (topical drops, oral or intravenous carbonic-anhydrase inhibitors, hyperosmotic agents) chosen by the duty doctor for the kidneys and allergy history
• Laser iridotomy when the cornea clears; later early lens extraction only in selected people — EAGLE had strict entry criteria (see the hyperopia / shallow-chamber page); not for every narrow angle

Three care directions a doctor may discuss (education overview, not a prescription)

Glaucoma care usually centres on three paths that can be used alone or in sequence. Which fits depends on type (open-angle / angle-closure / normal-tension and so on), target pressure, field and nerve change, side effects, and whether drops can be taken on schedule — only an ophthalmologist decides. This page does not rank “which is best” or quote any clinic’s success rate.

• Pressure-lowering drops (long-term medicine): the long-term backbone for most open-angle disease and ocular hypertension. Taking them on time and reducing missed doses is one improvable reason for worsening. Mechanisms, cautions and technique for five topical classes are on the glaucoma drops page. No product names here. Do not stop on your own or lend leftover bottles.
• Laser: for open-angle / ocular hypertension, selective laser trabeculoplasty (SLT) and similar — the LiGHT randomised trial (Gazzard et al., Lancet 2019) supports SLT as one first-line option for suitable people; a later six-year visual-field progression analysis (Montesano et al.) also found slower average field worsening in the SLT-first group. Those figures are from public trials / analyses — not your personal prognosis, not a brand comparison, and not something everyone must have; field already lost cannot be restored. Whether it fits and whether drops can be reduced is the doctor’s call. For angle-closure–related care, laser peripheral iridotomy (LPI) and similar — see the angle-closure / ZAP education above; preventive laser is not “everyone must” or “everyone must not.” Drops or further surgery may still be needed after laser.
• Surgery (more often discussed when drops / laser are not enough or not tolerated): conceptually includes traditional filtering surgery (e.g. trabeculectomy-class), aqueous drainage devices, and several minimally invasive glaucoma surgery (MIGS) classes — indications, risks and aftercare differ widely. The aim is still to lower pressure to slow worsening; lost field does not return. This page quotes no success rates, lists no device or implant brand names, and has no DIY postoperative drop timetable.

Personalised target pressure and how to read OCT / visual-field reports: see the glaucoma-monitoring hub (target IOP, OCT / visual field and reports).

Seeking care and what a doctor may discuss

• Personalised target pressure, OCT / visual field and how reports look: see the glaucoma-monitoring hub; lost field does not return
• Pressure-lowering drops must be used on schedule; missed doses are a preventable reason for worsening — five classes on the glaucoma drops page
• Laser (iridotomy, trabeculoplasty) and surgery classes need individual assessment; this page does not quote clinic success rates