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.

Primary Angle-Closure Disease: Suspects to Glaucoma

Primary angle-closure disease runs from primary angle-closure suspect (PACS, narrow angle only) through primary angle closure (PAC: synechiae or raised IOP) to primary angle-closure glaucoma (PACG) [S1] [S5]. Most suspects identified by screening do not progress, so prophylactic iridotomy has a modest benefit [S1] [S10], whereas for established PAC and PACG early lens extraction controls pressure better than iridotomy [S3] [S6].

Key points - Over an average 6.2 years, 14.2% of suspects progressed, mostly to PAC; acute angle closure (0.5%) and PACG (0.9%) were rare [S10]. - Laser peripheral iridotomy (LPI) reduces progression to PAC in suspects (HR 0.53 at 6 years, 0.31 at 14 years in China; 0.55 at 5 years in Singapore) [S1] [S5] [S9], but widespread prophylactic LPI of community-screened suspects was not recommended by the Zhongshan trial authors [S1]. - In chronic PACG and PAC, clear lens extraction gave drop-free good IOP control far more often than LPI (66% vs 18% at 36 months) [S6], with moderate-certainty Cochrane evidence favouring lens extraction [S3]. - Adding goniosynechialysis, viscogonioplasty or trabeculectomy to phacoemulsification showed no added benefit in low-certainty evidence [S3]; laser iridoplasty for chronic angle closure is not supported [S2].

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

Red flags

• Raised IOP or peripheral anterior synechiae in a narrow-angle eye: this is PAC, not a suspect [S5] [S9].
• Persistent angle closure after LPI, seen in 33.1% of treated eyes at 5 years, especially with a thick iris and narrow angle [S12].
• Higher baseline IOP and older age predicted progression in suspects [S5] [S9].
• Optic disc or field damage with a closed angle (PACG): lens extraction reduced visual field progression compared with LPI [S3].

Recognise it: who is at risk

• Trial participants with PACS were mostly aged 50 to 70, female (74.7% to 83%) and Chinese [S1] [S5] [S7] [S10].
• In Africa, the pooled prevalence of PACG was 0.98%, against 5.07% for primary open-angle glaucoma [S11].
• Suspects in trials were defined by appositional angle closure on gonioscopy (for example 2 or more quadrants) [S5].

Confirm it

• Gonioscopy defines the stage; trial end points were synechiae, IOP above 21 or 24 mmHg, or acute angle closure [S5] [S9].
• Dilation of PACS eyes raised IOP by a mean of about 1.5 mmHg, and acute angle closure after dilation was very rare (1.04 per 1000 dilations in untreated eyes) [S4]. Routine LPI before dilation was not recommended [S4].
• Anterior segment OCT measures of a thick iris (IT750) in a narrow angle predicted persistent closure after LPI [S12].

Manage it: stage by stage

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Tier A (primary care / no specialist)

• Refer adults with suspected narrow angles, raised IOP or disc damage for gonioscopy.
• Dilation of narrow-angle suspects carries a very low acute closure risk in trial data [S4]; local protocols decide whether to dilate before an eye assessment.

Tier B (general eye clinic)

1. PACS (suspects). Prophylactic LPI reduced PAC (NNT 15 in pooled data, 22 in the Singapore trial) [S10] [S5]. A Cochrane review found little to no difference in IOP or visual acuity at 1 and 5 years, wider angles and fewer synechiae at 5 years, and no clear reduction in acute angle closure (low certainty) [S8]. In a population with low event rates, LPI for everyone screened was judged of limited benefit [S1]. Decide case by case, weighing IOP, age and access to follow-up [S5] [S9] [S10].
2. Safety of LPI. LPI did not cause clinically meaningful cataract progression over 72 months (21.2% vs 19.4%) [S7]. Minor adverse events such as pain, redness and discomfort were more common after iridotomy [S8].
3. After LPI. Re-examine the angle: about one third remain closed at 5 years [S12]. Angle widening occurs within 2 years and then stays stable [S12].

Tier C (specialist centre)

• PAC and PACG with clear lens. In EAGLE, 90% met a good-response criterion after clear lens extraction vs 67% after LPI at 36 months; non-Chinese ethnicity, higher baseline IOP and prior glaucoma drops predicted worse response [S6]. Cochrane found less visual field progression (OR 0.35) and fewer medications with phacoemulsification than LPI, with little difference in quality of life or acuity at 12 months [S3]. The decision should be shared with the patient [S3].
• PACG with visually significant cataract. Phacoemulsification alone; adding viscogonioplasty or goniosynechialysis gave no extra benefit, and adding trabeculectomy may cause more complications (low or very low certainty) [S3].
• Laser iridoplasty for chronic angle closure may be no more effective than comparators and is not supported by trials to date [S2].

Refer when

Pitfalls

• Assuming LPI ends the problem; one third stay closed [S12].
• Offering LPI to all screened suspects regardless of risk [S1] [S10].
• Using LPI rather than lens extraction as first treatment for PACG [S3] [S6].
• Adding iridoplasty or extra angle procedures without evidence [S2] [S3].

Evidence notes

• PACS trials were almost entirely in Chinese populations, and loss to follow-up at 14 years was large (390 and 388 eyes) [S9]. No PACS trial reported visual field progression [S8].
• The PACS meta-analysis notes the lack of demonstrated clinical efficacy of LPI and calls for balanced decisions [S10]; this conflicts in emphasis with the relative risk reductions in individual trials [S1] [S5].
• Cochrane could not pool lens extraction trials; conclusions are short to medium term [S3].
• Not covered by these sources: screening strategies, plateau iris, cost-effectiveness, LPI technique and settings, and timing of surgery.

Related articles

• Acute Primary Angle Closure
• Gonioscopy and anterior-segment imaging of the angle
• Primary Open-Angle Glaucoma: Diagnosis and Treatment Targets

References

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