What is glaucoma and why is it a key topic in this context?

Glaucoma is a condition marked by damage to the optic nerve, often linked to elevated intraocular pressure (IOP). Effective management of IOP is crucial to prevent or slow the progression of visual field defects. The article emphasizes this by examining approaches to treat encapsulated blebs, which directly impacts the ability to control IOP after a surgical intervention like trabeculectomy.

What is trabeculectomy, and why is it relevant?

Trabeculectomy is a surgical procedure considered a gold standard for treating glaucoma. It works by creating a pathway for fluid drainage, thereby reducing IOP. However, a common complication is bleb failure, which can lead to encapsulated blebs. These encapsulated blebs impede filtration, potentially nullifying the benefits of the surgery. This makes addressing encapsulated blebs a critical aspect of post-operative care and maintaining the long-term success of trabeculectomy.

What are encapsulated blebs, and how do they impact eye health?

Encapsulated blebs are cysts that form after glaucoma surgery, often due to scarring. They arise from the Tenon's capsule, a layer of tissue. These blebs can compromise the filtration of aqueous humor, leading to increased IOP. The article explores how to manage encapsulated blebs by either disrupting the fibrotic tissue with TNR or using topical hypotensive medications as part of Medical Treatment (MT). The formation of these blebs can occur anytime after the initial surgery.

What is transconjunctival needling revision (TNR) and what does it do?

Transconjunctival Needling Revision (TNR) is a minimally invasive technique used to address encapsulated blebs. It involves using a needle to disrupt the scar tissue and re-establish aqueous flow. The effectiveness of TNR can be enhanced with antifibrotic agents like 5-fluorouracil (5-FU). The study in the article evaluates the effectiveness of TNR with 5-FU compared to medical treatment, assessing its ability to control IOP. The article specifically describes a TNR protocol using a 27-gauge needle to disrupt scar tissue and injecting 5-FU.

Stylized human eye with a transparent bleb-like bubble, inside the bubble, miniature figures are either 'needling' the bubble or administering eye drops.

Encapsulated Blebs: Is Needling the Best Bet for Glaucoma Relief?

Q: What were the key findings about TNR with 5-FU compared to medical treatment?

The article highlights a study comparing TNR with 5-FU and Medical Treatment (MT) for managing encapsulated blebs. Medical treatment involves the use of topical hypotensive medications. The study indicates that while both TNR with 5-FU and MT can effectively manage the condition, TNR with 5-FU offers a significant advantage in achieving lower mean IOP at the 12-month follow-up. The inclusion of only encapsulated blebs enhanced the accuracy of the study, minimizing variability due to morphological differences, which suggests that TNR with adjunctive 5-FU, without further medical therapy, is highly effective in maintaining successful IOP control for at least 12 months.

Avery Sinclair in Health & Wellness December 2025 • 5 min read.

"A head-to-head study reveals how a minimally invasive revision technique stacks up against traditional medication for glaucoma-related bleb encapsulation."

Glaucoma, a condition characterized by progressive visual field defects, demands effective management of intraocular pressure (IOP). While medication often serves as the first line of defense, surgical intervention becomes necessary when medical treatments fall short. Trabeculectomy, a surgical procedure, remains a gold standard among specialists. However, its long-term success hinges on meticulous post-operative care, particularly in addressing early signs of bleb failure.

Bleb failure, often resulting from scarring under or over the scleral flap, can lead to encapsulated blebs—Tenon's capsule cysts—that compromise filtration. These encapsulated blebs can occur anytime after the initial surgery. Transconjunctival needling revision (TNR) emerges as a minimally invasive technique to restore filtration by disrupting fibrotic tissue. The effectiveness of TNR can be enhanced with antifibrotic agents like 5-fluorouracil (5-FU) or mitomycin C (MMC).

In light of these challenges, researchers have explored medical treatment (MT) with topical hypotensive medications as an alternative for managing encapsulated blebs. Studies evaluating various success rates have considered factors such as target pressure, bleb morphology, the timing of the needling procedure, the number of procedures performed, and the use of antifibrotic agents. This article delves into a prospective study comparing early TNR with 5-FU to MT in eyes with encapsulated blebs, providing valuable insights for ophthalmologists and patients alike.

Needling vs. Medication: Which Approach Wins for Encapsulated Blebs?

Stylized human eye with a transparent bleb-like bubble, inside the bubble, miniature figures are either 'needling' the bubble or administering eye drops.

A study published in Clinics (2013) explored and compared the short-term efficacy of early TNR with 5-FU to medical treatment in eyes with encapsulated blebs and uncontrolled IOP after trabeculectomy. The prospective, randomized interventional study included 40 eyes of 39 patients with encapsulated blebs developed within five months or less after primary trabeculectomy with MMC and IOP ≥ 20 mmHg. Participants were treated at the Hospital das Clínicas of the University of São Paulo, Brazil.

The participants were randomized into two groups: one receiving TNR with 5-FU and the other receiving MT. TNR procedures were performed by a single surgeon (RS), with a maximum of two TNRs allowed per patient. The study strictly adhered to ethical guidelines, obtaining approval from the Ethics Committee of the Hospital das Clínicas of the University of São Paulo and securing written informed consent from all participants. Throughout the study, topical anesthesia and antibiotics were administered to ensure patient comfort and prevent infection.

TNR with 5-FU Protocol: A 27-gauge needle was used to enter the subconjunctival space, disrupt scar tissue, and reestablish aqueous flow. Following this, 5 mg of 5-FU was injected subconjunctivally.
Post-Operative Care: Patients received topical antibiotics and steroids, with steroid tapering guided by clinical response.
Medical Treatment (MT) Protocol: Topical hypotensive treatment was initiated, beginning with a nonspecific beta-blocker and/or prostaglandin, followed by carbonic anhydrase inhibitors and/or selective alpha agonists as needed.
Exclusion Criteria: Patients requiring further surgical procedures were excluded to maintain the integrity of the comparison.

Data collection involved measuring intraocular pressure (IOP) at various intervals—immediately after the procedure, one day after, and at one, three, six, and twelve months post-procedure. Statistical analyses were performed using Student’s t-test and Mann-Whitney U tests to compare variables between the two groups, with significance set at p < 0.05. The study aimed to provide a rigorous, data-driven comparison of TNR with 5-FU versus medical treatment for encapsulated blebs.

The Verdict: TNR with 5-FU Offers Promising IOP Control

The study's findings suggest that while both TNR with 5-FU and MT can effectively manage encapsulated blebs, TNR offers a significant advantage in achieving lower mean IOP at the 12-month follow-up. The inclusion of only encapsulated blebs enhanced the accuracy of the study, minimizing variability due to morphological differences. This suggests that TNR with adjunctive 5-FU, without further medical therapy, is highly effective in maintaining successful IOP control for at least 12 months.