Ologen Collagen Implant

Key Points of This Disease

Ologen is a porous biodegradable collagen implant composed of type I atelocollagen and glycosaminoglycans. It is used as an alternative to antimetabolites (mitomycin C) to suppress subconjunctival scarring after glaucoma filtration surgery. In trabeculectomy, it shows equivalent intraocular pressure-lowering success rates to mitomycin C over 2 years of follow-up. Advantages reported include fewer serious adverse events and simpler postoperative management.

1. What is Ologen?

Ologen is a porcine-derived biodegradable implant composed of freeze-dried, cross-linked type I atelocollagen (over 90%) and glycosaminoglycans (less than 10%). It is used to suppress postoperative subconjunctival fibrosis in glaucoma filtration surgery.

Trabeculectomy is the gold standard for filtration surgery, but postoperative scarring is the main cause of bleb failure. Antimetabolites (5-FU, MMC) suppress scarring but carry risks of late wound leakage, hypotony, blebitis, avascular blebs, and endophthalmitis. Ologen was developed as a safer alternative to these antimetabolites.

Q Is Ologen used as a replacement for antimetabolites?

A

It can be used as a replacement. Ologen shows equivalent intraocular pressure-lowering effect to mitomycin C in trabeculectomy. It is particularly useful in patients for whom mitomycin C is unsuitable (e.g., pregnant women, patients who developed blebitis after mitomycin C use in the contralateral eye).

2. Mechanism of Action and Structure

Mechanism of Fibrosis Suppression

The porous scaffold structure of Ologen provides an irregular growth space for fibroblasts, preventing the formation of dense connective tissue. It also acts as a reservoir, mechanically separating the scleral flap and conjunctival surface to limit adhesion.

Biodegradation

It degrades within about 5 months, leaving loose connective tissue.

3. Indications and Contraindications

Indications

• Adjunct to trabeculectomy
• Bleb revision
• Primary Xen gel stent implantation and Xen revision
• Adjunct to Ahmed glaucoma valve (AGV)
• Patients at high risk of postoperative scarring, such as those with prior conjunctival surgery, thick Tenon’s capsule, previous failed filtration surgery, uveitis, or neovascular glaucoma

Contraindications

No absolute contraindications have been reported. Caution is required in patients with hypersensitivity to porcine-derived collagen.

4. Surgical Technique

Ologen can be used with either a limbal-based or fornix-based approach. It is added before closing the conjunctival flap. No pre-shaping or fixation is required.

• Place it over the edges of the scleral flap
• Aqueous humor is absorbed by the implant, causing it to swell
• The tension of the conjunctival suture shapes the implant into its optimal form
• Both the swollen Ologen and the conjunctival suture control aqueous outflow and limit hypotony

Impact on laser suture lysis

Since Ologen is positioned above the posterior edge of the scleral flap, the scleral suture site is often hidden, which may interfere with future laser suture lysis (LSL). The use of adjustable sutures may be considered as an alternative.

5. Clinical Outcomes

Comparison in Trabeculectomy

Mitomycin C vs Ologen: At 2-year follow-up, Ologen showed similar intraocular pressure (IOP) lowering success rates as mitomycin C. In a study of 58 cases by Perez et al., no major adverse events occurred over 36 months. Posterior diffusion of the filtering bleb was observed in 88%. Laser suture lysis was not required, simplifying postoperative management.

Ex-PRESS vs Ologen: In an RCT of 33 cases by Bhatkoti et al., the postoperative IOP success rate (≤21 mmHg) was 85% in both groups. Visual recovery was faster with Ex-PRESS.

Combination with Other Procedures

Xen Gel Stent + Ologen: The Ologen combination group had a slightly greater IOP reduction (24.5% vs 19.7%) and a lower complication rate compared to the non-combination group.

Viscocanalostomy + Ologen: In a study by Gad et al., the 2-year success rate was 80% in the Ologen group versus 59% in the non-combination group, a significant difference.

AGV + Ologen (Adults): In a 1-year follow-up RCT by Sastre-Ibáñez et al., there was no significant difference between the two groups, and the usefulness of Ologen in AGV was not demonstrated.

AGV + Ologen (Pediatric): In a study by Jacobson et al., the success rate improved dramatically from 31% with AGV alone to 100% with Ologen combination. Shortening of the hypertensive phase and reduction of postoperative eye drop burden were also observed.

Q Which patients are particularly suitable for Ologen?

A

It is particularly suitable for patients in whom mitomycin C is not appropriate (e.g., pregnant women, history of bleb complications from MMC), and those at high risk of postoperative scarring (e.g., history of conjunctival surgery, uveitis, neovascular glaucoma). In pediatric AGV surgery, Ologen combination has been reported to significantly improve success rates.

8. References

1. He M, Wang W, Zhang X, Huang W. Ologen implant versus mitomycin C for trabeculectomy: a systematic review and meta-analysis. PLoS One. 2014;9(1):e85782. PMID: 24465704. DOI: 10.1371/journal.pone.0085782

2. Cillino S, Di Pace F, Cillino G, Casuccio A. Biodegradable collagen matrix implant vs mitomycin-C as an adjuvant in trabeculectomy: a 24-month, randomized clinical trial. Eye (Lond). 2011;25(12):1598-1606. PMID: 21921953. DOI: 10.1038/eye.2011.219

3. Cillino S, Casuccio A, Di Pace F, Cagini C, Ferraro LL, Cillino G. Biodegradable collagen matrix implant versus mitomycin-C in trabeculectomy: five-year follow-up. BMC Ophthalmol. 2016;16:24. PMID: 26946419. DOI: 10.1186/s12886-016-0198-0

4. Rosentreter A, Schild AM, Jordan JF, Krieglstein GK, Dietlein TS. A prospective randomised trial of trabeculectomy using mitomycin C vs an ologen implant in open angle glaucoma. Eye (Lond). 2010;24(9):1449-1457. PMID: 20733558. DOI: 10.1038/eye.2010.106

5. Yuan F, Li L, Chen X, Yan X, Wang L. Biodegradable 3D-porous collagen matrix (Ologen) compared with mitomycin C for treatment of primary open-angle glaucoma: results at 5 years. J Ophthalmol. 2015;2015:637537. PMID: 26078875. DOI: 10.1155/2015/637537