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.

Trabeculectomy

Trabeculectomy lowers intraocular pressure (IOP) by creating a filtering bleb, and antimetabolites such as mitomycin C (MMC) and 5-fluorouracil (5-FU) reduce failure from scarring [S3] [S4]. In advanced glaucoma, primary MMC-augmented trabeculectomy gave lower IOP and less field loss than drops at 5 years [S12], and it remains a benchmark against which newer devices are compared [S10] [S11].

Key points - In the TAGS trial of advanced glaucoma, trabeculectomy gave mean IOP 12.07 vs 14.76 mmHg with medication at 5 years and less field loss, with similar safety [S12]. - MMC may give lower IOP than 5-FU at one year (mean difference -3.05 mmHg; low-quality evidence) [S4]; postoperative 5-FU injections reduced failure in high-risk eyes (NNT 4.1) [S3]. - Trabeculectomy with MMC achieved higher 2-year success than the PreserFlo MicroShunt (64.4% vs 50.6%) but more hypotony (51.1% vs 30.9%) [S11]. - Trabeculectomy with MMC and tube surgery gave similar IOP and failure at 5 years, with fewer medications after trabeculectomy [S8]. - Outcomes of trabeculectomy appear poorer in people of African Caribbean descent than in people of European descent [S9].

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

Red flags

• Hypotony: occurred in 51.1% of trabeculectomy eyes by 2 years in one RCT [S11] and was more frequent with MMC than with an Ologen implant [S6].
• Late bleb leak: there is no evidence comparing most treatments; conjunctival advancement outperformed amniotic membrane in the one trial [S2].
• Endophthalmitis, wound leak, shallow anterior chamber: reported as rare events in antimetabolite trials [S5].
• Encapsulated bleb with rising IOP: in one small trial needling was not better than medical treatment [S1].

Recognise it: who needs trabeculectomy

• Advanced open-angle glaucoma at presentation [S12].
• Eyes at high risk of failure gained clear benefit from antimetabolites [S3] [S4].
• In people of African Caribbean descent, consider that aqueous shunts did not show poorer outcomes than in people of European descent [S9].

Confirm it: assessing the result

• Trials defined success by IOP thresholds with or without medication at 1 to 5 years [S8] [S11].
• Typical mean IOP after trabeculectomy was 10.7 to 13.0 mmHg at 2 to 5 years in recent RCTs [S8] [S11] [S12].

Manage it

Before acting on this section, check the national and local guidelines, product information and regulatory approvals that apply where you practise. See the medical disclaimer.

Tier A (primary care / no specialist)

• Tier A does not perform or manage trabeculectomy. After surgery, a patient with pain, redness, discharge or reduced vision needs the eye unit the same day [G1].

Tier B (general eye clinic)

• Recognise early complications (hypotony, leak, shallow anterior chamber) and refer to the surgeon [S5] [S11].
• Keep medication burden in mind: after trabeculectomy mean medications fell from 2.9 to 0.4 at 2 years [S11].

Tier C (specialist centre)

1. Antimetabolite choice. MMC may be more effective than 5-FU, with less epitheliopathy and hyphaema, in 11 trials across the US, Europe, Asia and Africa [S4]. Regular-dose postoperative 5-FU reduced failure in high-risk (RR 0.44) and primary (RR 0.21) surgery; low-dose postoperative 5-FU did not [S3].
2. MMC concentration. Trabeculectomy with 0.2 mg/mL MMC had higher complete success than with 0.4 mg/mL (as reported in [S6]). Ologen gave slightly less IOP reduction than MMC up to 12 months, with less hypotony [S6].
3. Anti-VEGF instead of MMC is not supported: IOP was 1.86 mmHg higher with anti-VEGF, on low-quality evidence [S5].
4. Conjunctival flap. Fornix-based and limbal-based flaps gave similar IOP at 12 and 24 months (moderate certainty) and similar medication use (high certainty) [S7].
5. Device-modified trabeculectomy. Ex-PRESS may give slightly lower IOP at 1 year (low certainty); PreserFlo gave higher IOP than trabeculectomy but less hypotony or shallow chamber (RR 0.44) [S10].
6. Bleb problems. Needling an encapsulated bleb was not better than medical treatment in one small trial [S1]. Conjunctival advancement is the standard comparator for late leaks [S2].

Refer when

Pitfalls

• Replacing MMC with anti-VEGF agents without evidence [S5].
• Using low-dose postoperative 5-FU and expecting benefit [S3].
• Needling encapsulated blebs routinely [S1].
• Ignoring higher failure in African Caribbean patients when choosing the operation [S9].

Evidence notes

• Most antimetabolite trials were small and at unclear or high risk of bias; 83% of 5-FU trial participants were white [S3] [S4].
• The bleb complication reviews each rest on a single small trial [S1] [S2].
• Not covered by these sources: surgical technique details, MMC exposure time, postoperative steroid regimens, blebitis management and training of surgeons in low-resource settings.

Related articles

• Glaucoma Drainage Devices
• Minimally Invasive Glaucoma Surgery (MIGS)
• 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.