Korean J Ophthalmol.  2019 Jun;33(3):214-221. 10.3341/kjo.2018.0110.

Encapsulated Bleb Excision with Collagen Matrix Implantation Following Failed Ahmed Glaucoma Valve Implantation

• Lee SE
• Kim KN
• Kim WJ
• Lee SB
• Kim CS

• KMID: 2448860
• DOI: http://doi.org/10.3341/kjo.2018.0110

Abstract

PURPOSE
To investigate the clinical features and surgical outcomes of encapsulated bleb excision with collagen matrix implantation performed in patients with failed Ahmed glaucoma valve (AGV) implantation.
METHODS
Eighteen eyes of 18 patients underwent encapsulated bleb excision and collagen matrix implantation. Patients were divided into two groups by reference to intraocular pressure (IOP) after preoperative ocular massage: group 1, patients who exhibited substantial IOP reductions; and group 2, patients who did not show substantial changes in IOP. Needling was conducted in group 2. The clinical features of the two groups were compared, including IOP changes after ocular massage and needling, AGV status, and surgical outcomes 6 months after surgery.
RESULTS
The mean preoperative IOP among the 18 patients was 30.6 ± 5.7 mmHg. After ocular massage, the IOPs decreased by 22 and 26 mmHg in the two patients in group 1 and the 16 patients in group 2 showed a mean IOP reduction of 1.6 ± 2.2 mmHg (p = 0.013). IOPs decreased after needling in group 2 (range, 6 to 30 mmHg; p < 0.001). Fibrovascular tissue ingrowth into the AGV was observed in the two patients in group 1 and the same ingrowth was observed in 10 of the 16 patients in group 2. Six months after surgery the mean IOP among the 18 patients decreased significantly (19.1 ± 3.2 mmHg, p < 0.001). There was no significant difference in the mean postoperative IOP at 6 months between group 1 (14.0 ± 2.8 mmHg) and group 2 (19.8 ± 2.6 mmHg, p = 0.052).
CONCLUSIONS
Encapsulated bleb excision with collagen matrix implantation resulted in a significant IOP-lowering effect 6 months after surgery. Fibrovascular ingrowth into the AGV was common but did not seem to be a major cause of AGV implantation failure.

Keyword

Bleb excision; Collagen matrix; Encapsulated bleb; Glaucoma; Intraocular pressure

MeSH Terms

Blister*
Collagen*
Glaucoma*
Humans
Intraocular Pressure
Massage
Collagen

Figure

• 

  Fig. 1 Encapsulated bleb excision with collagen matrix implantation. (A) Conjunctival incision 10 mm from the corneal limbus. (B) Encapsulated bleb incision. (C) The encapsulated bleb was carefully dissected. (D) Fibrovascular ingrowth into the Ahmed glaucoma valve chamber was checked. (E) The stalk of the fibrovascular tissue connecting encapsulated bleb was identified. (F) The fibrovascular tissue was removed, taking care not to cut the stalk. (G) Ologen was inserted between the Ahmed glaucoma valve and the conjunctiva. (H) Margins of both Ologen and the bleb excision were well approximated and a few anchoring sutures were performed. (I) Continuous conjunctival suture. (J) The anterior chamber was kept deep at the end of the surgery.

• 

  Fig. 2 Microscopic findings of the Ahmed glaucoma valve. (A) Thick fibrovascular ingrowth observed in ocular massage responders. (B) A relatively thin fibrovascular ingrowth observed in ocular massage non-responders. (C) No fibrovascular ingrowth was observed in ocular massage non-responders.

• 

  Fig. 3 The postoperative mean intraocular pressure (IOP) of patients. The postoperative time points were 2 weeks, 1 month, 2 months, 4 months, and 6 months. Although the IOP was lower in the ocular massage responders than in the ocular massage non-responders at all of the postoperative time points, the p-value of the difference was significant only at postoperative 2 months (*Mann-Whitney U-test, p = 0.026). The IOPs at all of the postoperative time points were significantly lower than preoperative IOPs in all patients (18 patients) and in ocular massage non-responders (16 patients; all, p ≤ 0.001).

• 

  Fig. 4 The numbers of mean intraocular pressure (IOP)-lowering medications of patients. The postoperative time points were at 2 weeks, 1 month, 2 months, 4 months, and 6 months. Although the number of IOP-lowering medications used by ocular massage responders was less than that used by ocular massage non-responders at all postoperative time points, there was no significant difference between the two groups at any postoperative time point (Mann-Whitney U-test; all, p > 0.05). The numbers of IOP-lowering medications used postoperatively were significantly lower than preoperatively at all postoperative time points in all patients (18 patients; all, p ≤ 0.011) and in ocular massage non-responders (16 patients; all, p ≤ 0.031).

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