Author: Claude (AI), from PubMed abstracts · Reviewed by: Dr Mina Abdelmseih · Reviewed: 2026-11-15 · Review due: 2027-11-15

Educational content only. Not personalised medical advice. Clinical decisions remain the responsibility of the treating clinician.

Normal-Tension Glaucoma

Normal-tension glaucoma (NTG) is glaucomatous optic neuropathy with open angles and intraocular pressure (IOP) within the normal range, below 21 mmHg [S3] [S5]. It is described as more prevalent in Asia than in Western countries [S5], and it is a diagnosis made by excluding other, non-glaucomatous optic neuropathies [S5].

Key points - NTG is a diagnosis of exclusion: neurological disease can mimic it on disc appearance, and ocular ischaemic syndrome can present with it [S1] [S2] [S5]. - Lowering IOP, even from "normal" levels, is the mainstay of treatment in narrative reviews; IOP-independent treatments remain unproven [S5] [S7]. - Across open-angle glaucoma including NTG, disc haemorrhage, bilateral disease and female sex were associated with progression, and treatment was protective (low to moderate certainty) [S10]. - Untreated NTG progressed more slowly on average than high-tension glaucoma or pseudoexfoliation glaucoma, but individual rates vary widely [S6].

Evidence last checked: 2026-10-17 (PubMed abstracts).

Red flags

• Signs that suggest another cause: findings of ocular ischaemic syndrome such as iris neovascularisation, asymmetric cataract, mid-peripheral retinal haemorrhages or narrowed retinal arteries point to carotid disease [S1].
• Disc appearance that may be neurological: neurological diseases may mimic NTG, and a focused systemic work-up can uncover life-threatening disease [S2].
• Disc haemorrhage: associated with progression in open-angle glaucoma (adjusted HR 2.03, low certainty) [S10].

Recognise it: features and associations

• Compared with high-pressure POAG, NTG shows larger and deeper cupping, more central field defects and more disc haemorrhages, according to a narrative review [S5].
• Proposed associations include low vascular perfusion, Raynaud phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension [S3]. In the Cochrane prognostic review, migraine, Raynaud syndrome, systemic hypertension and cardiovascular disease did not show consistent effects on progression (very low to low certainty) [S10]. These sources conflict.
• Nocturnal hypotension and sleep apnoea may contribute to progression [S2].

Confirm it

• Tools listed in a narrative review: Goldmann applanation tonometry, gonioscopy, slit-lamp examination, OCT and visual field analysis [S3].
• Exclude ocular ischaemic syndrome with carotid imaging and fluorescein angiography where suspected [S1].
• Consider a systemic work-up where features suggest a secondary or neurological cause [S2].
• Repeated follow-up examinations are needed to estimate an individual's rate of progression [S6].

Manage it

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Tier A (primary care / no specialist)

• Refer people with a suspicious optic disc even when IOP is normal.
• Review blood pressure treatment with the patient's physician: antihypertensive choice and low blood pressure may matter in NTG (expert opinion) [S4].

Tier B (general eye clinic)

1. Lower IOP. Reviews describe controlling IOP as low as possible with medication, laser trabeculoplasty or surgery as the key to management [S5]. One review states a goal of 30% reduction from baseline to 12 to 14 mmHg (expert opinion, not trial data in the abstract) [S3].
2. Drug choice. Betaxolol, brimonidine and prostaglandin analogues are listed in a narrative review [S3]. Ophthalmic beta blockers and systemic antihypertensives need balancing in patients with low blood pressure [S4].
3. Nocturnal IOP. Peak IOP often occurs at night, and many current treatments lower nighttime IOP less than daytime IOP (narrative review) [S8].

Tier C (specialist centre)

• Surgery. Trabeculectomy is listed for refractory cases [S3].
• Neuroprotection. In a 12-week crossover RCT of 53 NTG patients already on IOP-lowering therapy, oral nicotinamide (1 g/day for 6 weeks, then 2 g/day for 6 weeks, as reported in [S9]) improved electroretinogram responses but not visual field indices [S9]. Long-term data are needed [S9].
• Other IOP-independent options (vasoactive, antioxidant, anti-inflammatory) remain inconclusive [S7]. Systemic calcium channel blockers are mentioned in one review without supporting data in the abstract [S3].
• Ocular ischaemic syndrome needs referral to neurology, vascular surgery and cardiology [S1].

Refer when

Pitfalls

• Dismissing glaucoma because IOP is normal [S3] [S5].
• Labelling every pale or cupped disc as NTG without excluding other optic neuropathies [S2] [S5].
• Over-treating systemic hypertension in patients with NTG (expert opinion) [S3] [S4].
• Promising benefit from supplements or vascular drugs [S7] [S9].

Evidence notes

• Thin evidence. The search sheet for this topic held mostly narrative reviews; no randomised trial of IOP lowering in NTG was available, so the article is shorter and treatment statements rest largely on expert opinion [S3] [S5] [S7].
• The Cochrane review covered POAG, NTG and pseudoexfoliation glaucoma together, and 86% of its studies were at high risk of bias [S10].
• The nicotinamide trial was short, without washout between periods, and measured electrophysiology rather than progression [S9].
• Not covered by these sources: randomised evidence for IOP lowering in NTG, the role of neuroimaging, 24-hour blood pressure monitoring protocols, and NTG in African populations.

Related articles

• Primary Open-Angle Glaucoma: Diagnosis and Treatment Targets
• Optic disc assessment in glaucoma
• Visual field testing and interpretation

References

See the numbered source list below. Each marker [S#] links to its PubMed and DOI record.