In New Zealand, glaucoma is managed by ophthalmologists. Glaucoma is a group of optic-nerve diseases that quietly destroy retinal ganglion cell axons, usually driven by intraocular pressure that the eye cannot tolerate, and is the leading cause of irreversible blindness worldwide. An estimated 76 million adults aged 40-80 were living with glaucoma in 2020, projected to reach 111.8 million by 2040 (Tham 2014).
Glaucoma (ICD-10: H40) is a chronic, progressive optic neuropathy defined by characteristic loss of retinal ganglion cells and their axons, producing a typical pattern of optic disc cupping and matching visual field defects. Elevated intraocular pressure (IOP) is the single largest modifiable risk factor, but glaucoma is no longer defined by IOP alone — up to 30-40% of patients have pressures inside the statistically normal range (normal-tension glaucoma) yet still develop nerve damage, while many people with elevated IOP never develop disease (ocular hypertension). The current pathophysiologic model centers on mechanical compression at the lamina cribrosa combined with impaired axoplasmic flow, vascular dysregulation of the optic nerve head, and downstream apoptosis of ganglion cells. Disease is classified by anterior-chamber angle anatomy (open-angle vs angle-closure) and by cause (primary vs secondary).
The key symptoms of Glaucoma are: Gradual loss of peripheral (side) vision over years — patients describe bumping into door frames, missing kerbs, or losing items in their visual field, often after central acuity is still 20/20., Increasing difficulty seeing in low light or at night, with cars and faces blending into dim backgrounds earlier than expected for age., Reduced contrast sensitivity, so that low-contrast objects (a grey car on a grey road) become harder to detect even when high-contrast reading is preserved., Late-stage tunnel vision in advanced open-angle disease, where only a small central island of clear sight remains., Severe ocular pain, blurred vision, halos around lights, headache, nausea and vomiting in an acute angle-closure attack — a true ophthalmic emergency., Mild aching around the eye and intermittent blurred vision in subacute or intermittent angle-closure, often after watching a film in a darkened room (pupil dilation worsens crowding of the angle)., Eye redness with hazy or steamy cornea during an acute pressure spike — pressures above 40 mmHg cause corneal oedema..
Diagnosis of glaucoma rests on structural evidence of optic nerve damage combined with functional evidence of corresponding visual field loss, supported by intraocular pressure and anterior segment findings. The clinical workflow begins with a focused history covering family history, ocular trauma, steroid exposure, refractive error, and prior eye surgery, followed by best-corrected visual acuity, slit-lamp examination of the anterior segment, gonioscopy to grade the drainage angle (open versus narrow versus closed), and IOP measurement with Goldmann applanation tonometry. Central corneal thickness (pachymetry) is measured because Goldmann readings under-estimate IOP in thin corneas and over-estimate in thick ones — the OHTS study showed pachymetry independently predicts conversion to glaucoma. A dilated fundus examination assesses the optic nerve head for diagnostic features: enlarged cup-to-disc ratio, thinning of the neuroretinal rim (ISN'T rule violations), disc haemorrhages, retinal nerve fibre layer defects, and inter-eye asymmetry. Optical coherence tomography of the retinal nerve fibre layer and ganglion cell complex provides reproducible quantitative measurements and detects damage earlier than perimetry in many patients. Standard automated perimetry, usually 24-2 Humphrey or equivalent Octopus protocol, maps the functional defect; SITA-Standard or SITA-Faster is the typical algorithm. Diagnosis requires reliable, repeatable defects (two consecutive abnormal fields meeting glaucoma hemifield criteria) plus structural correlation. Differential diagnoses ruled out at this stage include compressive optic neuropathy, ischaemic optic neuropathy, retinal disease that mimics field loss, and physiologic large cups in long-axial-length myopic eyes. Repeat testing every 6-12 months is needed to confirm progression and set IOP targets.
With early detection and consistent IOP-lowering therapy, the long-term prognosis for vision is excellent: most patients diagnosed before significant field loss retain functional sight throughout life. The Early Manifest Glaucoma Trial showed that treating to a meaningful IOP reduction roughly halves progression risk (Heijl 2002), and modern treatment regimens hold most newly diagnosed patients stable for decades. Outcomes are less favourable in patients diagnosed late, in those with poor adherence, in advanced disease at presentation, in normal-tension glaucoma with vascular dysregulation, and in pseudoexfoliation or neovascular glaucoma where pressures are higher and more volatile. About 10-15% of treated open-angle patients still progress to severe visual impairment in one eye over a lifetime, and an estimated 5% become bilaterally blind. The decisive prognostic factors are the IOP achieved and maintained, the stage at diagnosis, and treatment adherence — not the IOP at presentation alone.
An ophthalmologist — ideally one with glaucoma fellowship training — should evaluate any newly suspected glaucoma, any patient progressing on current therapy, anyone needing more than two pressure-lowering drops, any angle-closure spectrum disease, any pre-perimetric or normal-tension presentation, and any patient considering laser or surgical intervention. Glaucoma management is a multi-decade relationship — continuity with one specialist who can compare today's OCT and visual field with the patient's own baseline is far more valuable than any single new test.
Find specialists →There is no recovery of vision once retinal ganglion cells die — glaucoma damage is irreversible. The treatment timeline runs in years: IOP-lowering therapy takes effect within hours to days, structural OCT changes stabilise over months, and visual fields require 6-12 months of repeat testing to confirm stability. After SLT, peak IOP lowering occurs at 4-6 weeks and lasts 2-5 years before retreatment may be needed. After trabeculectomy, IOP control stabilises by 3 months; bleb health is monitored lifelong. After MIGS combined with cataract surgery, full recovery is similar to standard cataract surgery — usually 2-6 weeks.
Regular moderate aerobic exercise (walking, cycling, swimming) for at least 150 minutes per week is safe and beneficial. Avoid sustained breath-holding (Valsalva) during heavy resistance training, head-down yoga inversions (sirsasana, downward dog held long), and other manoeuvres that transiently raise IOP, especially in advanced disease. Wear polycarbonate protective eyewear during any sport with projectile risk.
Look for board certification in ophthalmology and ideally a glaucoma fellowship. Confirm the practice has up-to-date OCT, standard automated perimetry, gonioscopy capability, and access to SLT, MIGS, and traditional filtering surgery on site or by referral. Ask how often visual fields and OCT are repeated for stable patients (every 6-12 months is standard). For Black, Hispanic, or Asian patients, choose a clinician familiar with the higher progression rates and angle-anatomy issues in those populations.
Medically reviewed by AIHealz Medical Editorial Board · May 12, 2026
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